ELECTRIC POWER CONTROL SYSTEM 5 TECHNICAL FIELD [0001] The present invention relates to an electric power control system. In particular, the present invention relates to an electric power control system which controls the balance between supply and demand of electric power in an electric power system. 10 BACKGROUND ART [0002] A popularly employed method for controlling an electric power system is centralized control of an electric power system (for example, see Patent Document 1). Centralized control of 15 an electric power system requires building of a mechanism for centralizing information and a large-scale control system for grasping and analyzing the whole system configuration condition and also optimizing the whole system. Such a system is easily applied in countries and regions where electric power supply infrastructure has developed to some extent, because the system can be built additionally. However, new building of the above system in regions including emerging 20 countries where electric power infrastructure has not developed requires a large investment in development of the infrastructure. [0003] 2 On the other hand, in terms of optimization of the whole system, there is a proposed approach of di^ributed control, which is less efficient but allows electric power control without a large investment by regulating voltages between neighboring power plants or comparatively near power plants (for example, see Patent Document 2). In control of an electric power system, 5 generally, matrix calculation is carried out on the basis of information of each generator, and a solution is found. In the case of concentrated control mentioned above, large-scale matrix calculation should be done because all the information is included. On the other hand, in the case of distributed control, sparse matrix calculation is done because control between neighboring or near power plants is executed, and therefore, the amount of calculation is considerably less. TO [0004] In recentyears, in consideration of the protection of global environment and energy security, natural energy such as solar light, biomass and wind power has been introduced worldwide. However, such natural energy has a problem with the stability of supply and, as such power sources become more popular in the future, it will become a critical issue how to keep the 15 stability of the whole electric power network. In other words, when it comes to electric power generation by natural energy, new entrants to electric power supply increase because the introduction cost is low though the power generation capacity of each generator is small, and moreover, it is worried about that enough reserves cannot be secured in a small-scale electric power system configured mostly by such generators. When electric power supply from a system 20 stops (blackout), a diesel generator may be used as a backup. However, in most cases, the diesel generator does not interconnect with the system, and mis is not an idea of efficiently using distributed energy resources at all times. 3 [0005] As an example of the configuration of distributed control, a configuration in which a plurality of distributed energy resources are installed is disclosed in Patent Document 3. In this example, because a system with high balancing capability is connected at all times^ the 5 respective distributed energy resources can stably operate. A power distribution configuration connected to an electric power system and including distributed energy resources is shown in Fig. 1. As shown in Fig. 1, a distribution substation 1 connects to an electric power system 5, a plurality of generators 2 and a plurality of loads 4, and electric power supplied from the electric power system 5 and the generators 2 is supplied to the loads 4 and consumed thereby. When the 10 balance between supply and demand of electric power is kept, the following equation 1 holds: [0006] [Equation 1] m n [0007] 15 where Gjnain denotes electric power supplied from the electric power system 5, G_i denotes electric power generated by an i generator 2, Lj denotes electric power consumed by a ja load 4, m denotes the number of the generators 2, and n denotes the number of the loads 4. [0008] Patent Document 1: Japanese Unexamined Patent Application Publication No. JP-A 20 2002-165367 Patent Document 2: Japanese Unexamined Patent Application Publication No. JP-A 4 2010-057311 Patent Document 3: Japanese Unexamined Patent Application Publication No. JP-A 2000-333373 [0009] 5 Emerging countries and developing countries often face a situation that they cannot be supplied with electric power from an electric power system and, in this case, it is difficult to make a plurality of distributed energy resources stably operate while keeping the balance between supply and demand. In other words, because G_main on the left side of the equation 1 instantaneously becomes zero, generators need to balance supply and demand again, but there is 10 a case where it is impossible to respond to sudden change or it is impossible to supply electric power consumed by all the load5~~in-the first place. Moreover, when electric power supply from the electric power system stops or in a case where an electric power network is isolated at all times as in a remote island, high capability of balancing by the system cannot be expected. [0010] 15 In general, regulation of the amount of electric power generated by a generator in a short time period (from few seconds to few minutes) is autonomously executed by the generator in governor-free operation (referred to as governor control hereinafter). However, because of the failure to follow load change, it takes long time to make generators stable because there are a plurality of generators, or an unallowable abnormality in frequency and voltage occurs. In some 20 cases, it escalates to a critical problem that a generator is disconnected, for example. In particular, when electric power supply from the electric power system stops, a great difference in supply and demand of electric power is instantaneously made, and it becomes a problem for control. 5 [0011] Further, in a case where real-time control is possible, a control device can send a command to each of the generators and forcibly control generated electric power in order to fill the difference between supply and demand of electric power, or can control the loads in order to 5 limit demand. However, there is a need to install a fast and reliable communication network and a number of sensors and controlled devices, and there is a problem that installation cost is high particularly in emerging countries and developing countries. Therefore, a mechanism and control to allow a delay and an error in communication and autonomously perform stable balancing of supply and demand. 10 SUMMARY [0012] 4 An object of the present invention is to solve the abovementioned problem that it is impossible to secure sufficient reserve in a small-scale electric power system and it is difficult to 15 keep stability when a difference is instantaneously made between supply and demand of electric power. [0013] An electric power control system as an aspect of the present invention includes: an electric power supplying means for supplying electric power; 20 a load means for receiving supply of electric power and consuming the electric power; an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means; 6 a total supplied energy acquiring means for acquiring a total supplied energy, the total supplied energy being a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; a total consumed energy acquiring means for acquiring a total consumed energy, the 5 total consumed energy being a total of electric power consumed by the load means and electric power with which the energy storing means is charged; an energy storage controlling means for, when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric 10 power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means; and a supplied energy controlling means for executing control to change electric power 15 supplied by the electric power supplying means over a response time corresponding to a set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range. The time constant for energy storing means is set to be longer than the time constant for electric power supplying means. 20 [0014] Further, an electric power control device as another aspect of the present invention is an electric power control device connected to an electric power supplying means for supplying 7 electric power, a load means for receiving supply of electric power and consuming the electric power, and an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means. The electric power control device includes: 5 a total supplied energy acquiring means for acquiring a total supplied energy, the total supplied energy being a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; a total consumed -energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric 10 power with which the energy storing means is charged; and an energy storage controlling means for, when an- electric power supply and demand difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and 15 demand difference within the given range, and also controlling the energy storing means so as to decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means. In a case where the electric power supplying means includes a supplied energy controlling means, the time constant for energy storing means is set to be longer than a set time 20 constant for electric power supplying means, the supplied energy controlling means being for executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that 8 the electric power supply and demand difference is kept within the preset given range. [0015] Further, a program as another aspect of the present invention is a computer program including instructions for causing an electric power control device, which is connected to an 5 electric power supplying means for supplying electric power, a load means for receiving supply of electric power and consuming the electric power, and an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means, to realize: a total supplied energy acquiring means for acquiring a total supplied energy, the total 10 supplied energy being a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; a total consumed energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric power with which the energy storing means is charged; and 15 an energy storage controlling means for, when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to 20 decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means. In a case where the electric power supplying means includes a supplied energy 9 controlling means, the time constant for energy storing means is set to be longer than a set time constant for electric power supplying means, the supplied energy controlling means being for executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that 5 the electric power supply and demand difference is kept within the preset given range. [0016] Further, an electric power control method as another aspect of the present invention is an electric power control method for controlling electric power of an electric power supplying means for supplying electric power, a load means for receiving supply of electric power and 10 consuming the electric power, and an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means. The electric power control method includes: acquiring a total supplied energy which is a total of electric power supplied by the 15 electric power supplying means and electric power discharged by the energy storing means, and a total consumed energy which is a total of electric power consumed by the load means and electric power with which the energy storing means is charged; when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the 20 energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to decrease the charge or discharge electric power 10 over a response time corresponding to a set time constant for energy storing means; and executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range. The time constant for energy storing means is set to be longer than a set time constant for electric power supplying means. [0017] With the configurations as described above, the present invention makes it possible to keep stability even when a large difference of supply and demand of electric power is instantaneously made in a small-scale electric power system. BRIEF DESCRIPTION OF DRAWINGS [0018] Fig. 1 is a block diagram showing an overall configuration of an electric power control system relating to the present invention; Fig. 2 is a block diagram showing an overall configuration of an electric power control system according to a first exemplary embodiment of the present invention; Fig. 3 is a block diagram showing a detailed configuration of the electric power control system disclosed in Fig. 2; Fig. 4 is a block diagram showing a configuration of a control device disclosed in Fig. 3; 11 Fig. 5 is a flowchart showing operation of the control device disclosed in Fig. 3; Figs. 6A to 6D are diagrams showing an appearance during operation of the electric power control system disclosed in Fig. 3; Figs. 7A to 7D are diagrams showing an appearance during operation of the electric 5 power control system disclosed in Fig. 3; Figs. 8A to 8C are diagrams showing an appearance during operation of the electric power control system relating to the present invention disclosed in Fig. 1; Fig. 9 is a block diagram showing a configuration of an electric power control system according to a second exemplary embodiment of the present invention; 10 Fig. 10 is a block diagram showing a configuration of an electric power control system according to a third exemplary embodiment of the present invention; Fig. 11 is a flowchart showing operation of a control device disclosed in Fig. 10; Fig. 12 is a flowchart showing operation of the control device disclosed in Fig. 10; and Figs. 13A to 13D are diagrams showing an appearance during operation of the electric 15 power control system disclosed in Fig. 10. EXEMPLARY EMBODIMENTS [0019] Tg) which is larger than the abovementioned value, for the 20 energy storage device 7 (step SI). Meanwhile, for the energy storage device 7, the value of the time constant (Tb) may be set in advance so as to satisfy Tb>Tg. [0038] 19 Subsequently, the control device 10 calculates a total supplied energy Ga and a total consumed energy La. As the total consumed energy La, the control device 10 calculates the total of energies consumed by all the loads 4 (step S2). As the total supplied energy Ga, the control device 10 calculates the total of energies supplied by all the generators 2 and the electric power 5 system 5 (step S3). [0039] At this moment, the energy storage device 7 has not been charged or discharged. Therefore, an energy resulting from charging or discharging the energy storage device 7 is not added to the total consumed energy La or the total supplied energy Ga. 10 [0040] The total consumed energy La and the total supplied energy Ga are calculated with Equation 2: [0041] [Equation 2] n EL / + m + LLr 1 + aiS i=l ~~ 15 [0042] where "Gjmain" denotes electric power supplied from the electric power system 5, "G__i" denotes the amount of energy generated by an 1th generator 2, "LJ" denotes electric power consumed by a j* load 4, "m" denotes the number of the generators 2, and "n" denotes the 20 number of the loads 4. Moreover, "a charge energy" and "a discharge energy" are the amounts of electric power of charge and discharge of the energy storage device 7, respectively. [0043] Subsequently, the control device 10 obtains the difference between the total supplied 5 energy Ga and the total consumed energy La calculated as described above (an electric power supply and demand difference), and determines whether the difference is beyond a given electric power variation allowance C set in advance (|Ga-La|C) (step S4: No), the control device 10 controls TO the energy storage device 7 to be charged or discharged. I [0044] i t> ■ Then, in a case where the total supplied energy Ga is larger than the total consumed energy La (Ga>La) (step S5: Yes), the control device 10 sets an initial charge energy of the ! energy storage device 7 to, for example, (Ga—La) (step S6), and starts charge of the energy i ' i. I 15 storage device 7 (step S7). Then, the control device 10 keeps the charge while decreasing the charge energy so that the charge energy changes from the initial charge energy to 0 over a response time corresponding to the time constant (Tb) set as described above. [0045] On the other hand, in a case where the total supplied energy Ga is smaller than the total | 20 consumed energy La (La>Ga) (step S5: No), the control device 10 sets an initial discharge I energy of the energy storage device 7 to, for example, (La-Ga) (step S8), and starts discharge of the energy storage device 7 (step S9). Then, the control device 10 keeps the discharge while 21 decreasing the discharge energy so that the discharge energy changes from the initial discharge energy to 0 over a response time corresponding to the time constant (Tb) set as described above. [0046] Now the appearance of the energies at the time of control of charge or discharge of the 5 energy storage device 7 as stated above will be described. Firstly, Figs. 6A to 6D show an example of a case where electric power is not or cannot be supplied from the electric power system 5. In Figs. 6 to 8 to be described below, the total of consumed energies of the loads 4 of a total consumed energy is expressed as a total load L, and the total of supplied energies of the generators 2 is expressed as a total generated energy G TO [0047]- When the total load L significantly decreases suddenly for any cause as shown in Fig. 6A, charge of the energy storage device 7 is started so as to fill the change. In other words, because there is a surplus of a generated energy that is a supplied energy due to decrease of the total load L, charge of the energy storage device 7 is performed so as to absorb the surplus of the 15 generated energy. At the time of charge, a charge energy is set so that an energy equivalent to the significant decrease of the total load L is an initial charge energy as shown in Fig. 6C, for example. Consequently, an electric power supply and demand difference remains 0 as shown in Fig. 6D. After that, the charge energy of the energy storage device 7 gradually decreases so as to change from the initial charge energy to 0 over the time constant Tb as shown in Fig. 6C. 20 [0048] Because the total consumed energy La in the distribution substation 1 at this moment includes the charge energy of the energy storage device 7, a decrease amount of the charge 22 energy of the energy storage device 7 becomes the electric power supply and demand difference. Thus, the generators 2 are controlled by governor control to decrease generated energies so as to fill the electric power supply and demand difference. Because the time constant (Tg) of the generators 2 is shorter than the time constant (Tb) of the energy storage device 7 corresponding 5 to the decreasing speed of the charge energy, the generators 2 operate so as to gradually decrease generated energies while following the gradually decreasing charge energy as shown in Fig. 6B. [0049] Now the appearance of change of the energies in an electric power control system which does not include a configuration controlling the energy storage device 7 unlike in this exemplary 10 embodiment is shown in Figs. 8A to 8D. In this example, with significant decrease of the total load L, the electric power supply and demand difference suddenly changes as shown in Fig. 8C, so that control of the amounts of power generated by the generators 2 cannot properly follow the electric power supply and demand difference and the balance of electric power cannot be stabilized. 15 [0050] On the contrary, the electric power control system in this exemplary embodiment can keep the balance between supply and demand without causing a problem such as abnormality in frequency or voltage associated with a transitional supply and demand gap or disconnection of the generators. That is to say, the energy storage device 7 determines a time to regulate the 20 amounts of power generated by the generators 2 while keeping the balance of supply and demand, and serves as the source of the balancing capability. [0051] 23 Further, Figs. 7A to 7D show the appearance of the energies in a case where electric power supply from the electric power system 5 suddenly stops during supply of electric power from the electric power system 5 in the electric power control system of this exemplary embodiment. In this example, the total supplied energy Ga is the sum of the supplied energy 5 G_main of the electric power system 5 and the total generated energy G which is the total of supplied energies of the generators 2. [0052] When electric power supply from the electric power system 5 suddenly stops as shown in Fig. 7A', discharge by the energy storage device 7 is started so as to fill the change. In other 10 words, because shortage of a supplied energy occurs due to decrease of the total supplied energy Ga, discharge by the energy storage device 7 is performed so as to compensate for the shortage of the energy. At the time of discharge, a discharge energy is set so that an energy equivalent to the decrease of the supplied energy G_main of the electric power system 5 is an initial discharge energy as shown in Fig. 7C, for example. Consequently, the electric power supply and demand 15 difference remains 0 as shown in Fig. 7D. After that, the discharge energy of the energy storage device 7 gradually decreases so as to change from the initial discharge energy to 0 over the time constant Tb as shown in Fig. 7C. [0053] Because the total supplied energy Ga in the distribution substation 1 at this moment 20 includes a discharge energy of the energy storage device 7, a decrease amount of the discharge energy of the energy storage device 7 becomes the electric power supply and demand difference. Then, the generators 2 are controlled by governor control to increase generated energies so as to 24 fill the electric power supply and demand difference. Because the time constant (Tg) of the generators 2 is shorter than the time constant (Tb) of the energy storage device 7 corresponding to the decreasing speed of the charge energy, the generators 2 operate so as to gradually increase generated energies while following the gradually decreasing charge energy as shown in Fig. 7B. 5 Such operation makes it possible to keep the balance of supply and demand stable as in the case of Fig. 6 described above. [0054] In Figs. 6 and 7, the time constant of the total generated energy G is expressed as Tb' because change of a generated energy follows change of a charge or discharge energy. To be 10 exact, TV> Tb is satisfied, and a supply and demand gap does not become zero. However, in the case of Tg«Tb, Tb' almost equals Tb, and a supply and demand gap can be almost zero. [0055] ' 4 Thus, in this exemplary embodiment of the present invention, the problem caused by transitional imbalance of supply and demand can be avoided with the energy storage device 7. 15 Moreover, setting the time constants enables the generators 2 to autonomously regulate generated energies without introducing a mechanism of real-time control executed from outside between the generators 2 and the energy storage device 7, and allows stable operation of the electric power system. In addition, in setting the time constant of the energy storage device 7, it may be changed depending on the capability of the energy storage device 7, the energy stored 20 therein, and so on. [0056] The abovementioned "electric power variation allowance C" is a parameter which is 25 determined on the basis of the loss of the electric power system 5 and the load variation capability of the generators 2. For example, in a case where high-loss distribution lines are included or many of the generators 2 of the distribution substation 1 need time to regulate power generation capacity, the electric power variation allowance C is set to a high value. On the other 5 hand, in a case where the electric power system 5 is configured by low-loss distribution lines and generators 2 which are easy to regulate output, it is possible to set the electric power variation allowance C to be a low value, and it is possible to increase the efficiency of electric power generation. In addition, it is also possible to set the electric power variation allowance C to different values between when the total load L is more than the total generated energy G and 10 when the total load L is less than the total generated energy G [0057] j 20 The whole or part of the exemplary embodiments disclosed above can be described as the following supplementary notes. Below, the overview of the configurations of an electric power control system, a program and an electric power control method according to the present 35 invention will be described. However, the present invention is not limited to the following configurations. [0082] (Supplementary Note 1) 5 An electric power control system comprising: an electric power supplying means for supplying electric power; a load means for receiving supply of electric power and consuming the electric power; an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means; Iff a total supplied energy acquiring means for acquiring a total supplied energy, the total supplied energy being atotal of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; a total consumed energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric 15 power with which the energy storing means is charged; an energy storage controlling means for, when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and 20 demand difference within the given range, and also controlling the energy storing means so as to decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means; and 36 a supplied energy controlling means for executing control to change electric power supplied by the electric power supplying means over a response time corresponding to a set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range, 5 wherein the time constant for energy storing means is set to be longer than the time constant for electric power supplying means. [0083] (Supplementary Note 2) The electric power control system according to Supplementary Note 1, wherein: 10 when the electric power supply and demand difference exceeds the preset given range, the energy storage controlling means sets an energy equivalent to the electric power supply and demand difference as an initial energy, and executes control to make the energy storing means charged with the initial energy of electric power or discharge the initial energy of electric power, and also controls the energy storing means so as to gradually decrease the charge or discharge 15 electric power over the response time corresponding to the time constant for energy storing means so that the electric power changes from the initial energy to a given value; and the supplied energy controlling means executes control changing electric power supplied by the electric power supplying means over the response time corresponding to the time constant for electric power supplying means so that the electric power supply and demand 20 difference is kept within the given range, the electric power supply and demand difference being made as a result that the energy storage controlling means gradually decreases a charge or discharge energy of the energy storing means. 37 [0084] (Supplementary Note 3) The electric power control system according to Supplementary Note 1 or 2, wherein: the electric power supplying means includes at least one generator; and 5 the supplied energy controlling means executes control changing a supplied energy over the response time corresponding to the time constant for electric power supplying means set for the generator so that the electric power supply and demand difference is kept within the preset given range, the supplied energy being an amount of electric power generated by the generator. [0085] 10 (Supplementary Note 4) The electric power control system according to Supplementary Note 3, wherein: the electric power supplying means includes a plurality of generators, and time constants for electric power supplying means are set for the respective generators; and the time constant for energy storing means is set to be longer than the time constant for 15 electric power supplying means set for at least one of the generators. [0086] (Supplementary Note 5) The electric power control system according to Supplementary Note 4, wherein: the electric power supplying means includes N generators; and 20 the time constant for energy storing means is set to be longer than a (N— 1)* in increasing order of the time constants for electric power supplying means set for the generators. [0087] 38 (Supplementary Note 6) The electric power control system according to Supplementary Note 4 or 5, wherein the time constant for electric power supplying means set for the generator is set so as to be shorter as a change amount of an amount of electric power generated by the generator, the change amount 5 being a set characteristic, and the amount of electric power being controlled by the supplied energy controlling means is larger. [0088] (Supplementary Note 7) The electric power control system according to any of Supplementary Notes 4 to 6, 10 comprising an electric power supplying means time constant setting means for setting the time constant for electric power supplying means for each of the generators. [0089] 4- (Supplementary Note 8) The electric power control system according to any of Supplementary Notes 1 to 7, 15 comprising a plurality of load means, the electric power control system comprising a supply and demand condition controlling means for controlling to stop electric power supply to some load means among the load means when the electric power supply and demand difference exceeds the preset given range, wherein the energy storage controlling means and the supplied energy controlling means 20 operate on a basis of the electric power supply and demand difference after stoppage of electric power supply to the some load means by the supply and demand condition controlling means. [0090] 39 (Supplementary Note 9) The electric power control system according to Supplementary Note 8, wherein: the electric power supplying means includes an electric power system supplying a given energy of electric power and at least one generator; 5 the supply and demand condition controlling means stops electric power supply to the some load means other than one or more load means among the load means when the electric power supply and demand difference exceeds the preset given range due to stoppage of electric power supply from the electric power system, the one or more load means being capable of operating with a total of amounts of electric power which can be generated by all the generators; 10 and the energy storage controlling means executes control to make the energy storing means charged with or discharge an initial energy of electric power, the initial energy being an energy keeping the electric power supply and demand difference within the given range, and the electric power supply and demand difference being that after stoppage of electric power supply to the 15 some load means by the supply and demand condition controlling means. [0091] (Supplementary Note 10) The electric power control system according to Supplementary Note 9, wherein: the some load means to which the supply and demand condition controlling means stops 20 electric power supply are preset on a basis of a total of amounts of electric power which can be generated, the amounts being preset for the respective generators; and an initial energy is preset on a basis of a difference between a total of amounts of 40 electric power generated by the generators and a total of consumed energies of the load means to which the supply and demand condition controlling means does not stop electric power supply, the initial energy being an amount of electric power which the energy storing means is charged with or discharges under control of the energy storage controlling means. 5 [0092] (Supplementary Note 11) An electric power control device connected to an electric power supplying means for supplying electric power, a load means for receiving supply of electric power and consuming the electric power, and an energy storing means for being charged with electric power supplied by ID the electric power supplying means or discharging electric power to be supplied to the load means, the electric power control device comprising: a total supplied energy acquiring means for acquiring a total supplied energy, the total supplied energy being a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; 15 a total consumed energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric power with which the energy storing means is charged; and an energy storage controlling means for, when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed 20 energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to 41 decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means, wherein in a case where the electric power supplying means includes a supplied energy controlling means, the time constant for energy storing means is set to be longer than a set time 5 constant for electric power supplying means, the supplied energy controlling means being for executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range. [0093] 10 (Supplementary Note 12) The electric power control device according to Supplementary Note 11, wherein: when the electric power supply and demand difference exceeds the preset given range, the energy storage controlling means sets an energy equivalent to the electric power supply and demand difference as an initial energy, and executes control to make the energy storing means 15 charged with the initial energy of electric power or discharge the initial energy of electric power, and also controls the energy storing means so as to gradually decrease the charge or discharge electric power over the response time corresponding to the time constant for energy storing means so that the electric power changes from the initial energy to a given value. [0094] 20 (Supplementary Note 13) A computer program comprising instructions for causing an electric power control device, which is connected to an electric power supplying means for supplying electric power, a 42 load means for receiving supply of electric power and consuming the electric power, and an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means, to realize: a total supplied energy acquiring means for acquiring a total supplied energy, the total 5 supplied energy being a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; a total consumed energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric power with which the energy storing means is charged; and 10 an energy storage controlling means for, when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed" energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to 15 decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means, wherein in a case where the electric power supplying means includes a supplied energy controlling means, the time constant for energy storing means is set to be longer than a set time constant for electric power supplying means, the supplied energy controlling means being for 20 executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range. 43 [0095] (Supplementary Note 14) The computer program according to Supplementary Note 13, wherein: when the electric power supply and demand difference exceeds the preset given range, 5 the energy storage controlling means sets an energy equivalent to the electric power supply and demand difference as an initial energy, and executes control to make the energy storing means charged with the initial energy of electric power or discharge the initial energy of electric power, and also controls the energy storing means so as to gradually decrease the charge, or discharge electric power over the response time corresponding to the time constant for energy storing 10 means so that the electric power changes from the initial energy to a given value. [0096] (Supplementary Note 15) An electric power control method for controlling electric power of an electric power supplying means for supplying electric power, a load means for receiving supply of electric 15 power and consuming the electric power, and an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means, the electric power control method comprising: acquiring a total supplied energy which is a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means, and 20 a total consumed energy which is a total of electric power consumed by the load means and electric power with which the energy storing means is charged; when an electric power supply and demand difference representing a difference between 44 the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to decrease the charge or discharge electric power 5 over a response time corresponding to a set time constant for energy storing means; and executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range, 10 wherein the time constant for energy storing means is set to be longer than a set time constant for electric power supplying means. [0097] (Supplementary Note 16) The electric power control method according to Supplementary Note 15, comprising: 15 when the electric power supply and demand difference exceeds the preset given range, setting an energy equivalent to the electric power supply and demand difference as an initial energy, and executing control to make the energy storing means charged with the initial energy of electric power or discharge the initial energy of electric power, and also controlling the energy storing means so as to gradually decrease the charge or discharge electric power over the 20 response time corresponding to the time constant for energy storing means so that the electric power changes from the initial energy to a given value; and executing control changing electric power supplied by the electric power supplying 45 means over the response time corresponding to the time constant for electric power supplying means so that the electric power supply and demand difference is kept within the given range, the electric power supply and demand difference being made as a result that a charge or discharge energy of the energy storing means gradually decreases. 5 [0098] The abovementioned program is stored in a storage device or recorded on a computer-readable recording medium. For example, the recording medium is a portable medium such as a flexible disk, an optical disk, a magneto-optical disk and a semiconductor memory. [0099] 10 Although the present invention has been described above referring to the exemplary embodiments and so on, the present invention is not limited to the abovementioned exemplary embodiments. The configurations and details of the present invention may be changed and modified in various manners that can be understood by one skilled in the art within the scope of the present invention. 15 INDUSTRIAL APPLICABILITY [0100] Because the present invention allows configuration of an autonomous decentralized electric power supply system, introduction of a small-scale and unstable generator such as 20 renewable energy is facilitated. Moreover, for example, in developing countries where power supply capability is considerably lower than demand due to delay of building of electric power infrastructure, applying the technique of the present invention makes it possible to stabilize by 46 autonomous decentralized control of generators in a small-scale electric power system without using advanced, reliable and fast real-time communication or real-time control which is a cost factor, and makes it possible to increase return on investment of building of an electric power supply network. [0101] The present invention is based upon and claims the benefit of priority from Japanese patent application No. 2013-081353, filed on April 9, 2013, the disclosure of which is incorporated herein in its entirety by reference. DESCRIPTIONOFREFERENCE NUMERALS [0102] 1 distribution substation 2 generator 3 distribution line 4, 41-44 load 5 electric power system 6 electric power measuring instrument 10 control device 10A arithmetic part 10B storage part 11 supplied energy acquisition part 12 consumed energy acquisition part 47 13 energy storage device control part 14 electric power control part 20 governor control part CLAIMS 1. An electric power control system comprising: an electric power supplying means for supplying electric power; 5 a load means for receiving supply of electric power and consuming the electric power; an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means; a total supplied energy acquiring means for acquiring a total supplied energy, the total supplied energy being a total of electric power supplied by the electric power supplying means 10 and electric power discharged by the energy storing means; a total consumed energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric power with which the energy storing means is charged; an energy storage controlling means for, when an electric power supply and demand 15 difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to decrease the charge or discharge electric power over a response time corresponding to a set time 20 constant for energy storing means; and a supplied energy controlling means for executing control to change electric power supplied by the electric power supplying means over a response time corresponding to a set time 49 constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range, wherein the time constant for energy storing means is set to be longer than the time constant for electric power supplying means. 5 2. The electric power control system according to Claim 1, wherein: when the electric power supply and demand difference exceeds the preset given range, the-energy storage controlling means sets an energy equivalent to the electric power supply and demand difference as an initial energy, and executes control to make the energy storing means 10 charged with the initial energy of electric power or discharge the initial energy of electric power, and also controls the energy storing means so as to gradually decrease the charge or discharge electric power over the response time corresponding to the time constant for energy storing means so that the electric power changes from the initial energy to a given value; and the supplied energy controlling means executes control changing electric power 15 supplied by the electric power supplying means over the response time corresponding to the time constant for electric power supplying means so that the electric power supply and demand difference is kept within the given range, the electric power supply and demand difference being made as a result that the energy storage controlling means gradually decreases a charge or discharge energy of the energy storing means. 20 3. The electric power control system according to Claim 1 or 2, wherein: the electric power supplying means includes at least one generator; and 50 the supplied energy controlling means executes control changing a supplied energy over the response time corresponding to the time constant for electric power supplying means set for the generator so that the electric power supply and demand difference is kept within the preset given range, the supplied energy being an amount of electric power generated by the generator. 5 4. The electric power control system according to Claim 3, wherein: the electric power supplying means includes a plurality of generators, and time constants for electric power supplying means are set for the respective generators; and the time constant for energy storing means is set to be longer than the time constant for 10 electric power supplying means set for at least one of the generators. 5. The electric power control system according to Claim 4. wherein: the electric power supplying means includes N generators; and the time constant for energy storing means is set to be longer than a (N-l)* in 15 increasing order of the time constants for electric power supplying means set for the generators. 6. The electric power control system according to Claim 4 or 5, wherein the time constant for electric power supplying means set for the generator is set so as to be shorter as a change amount of an amount of electric power generated by the generator, the change amount being a set 20 characteristic, and the amount of electric power being controlled by the supplied energy controlling means is larger. 51 7. The electric power control system according to any of Claims 4 to 6, comprising an electric power supplying means time constant setting means for setting the time constant for electric power supplying means for each of the generators. 5 8. The electric power control system according to any of Claims 1 to 7, comprising a plurality of load means, the electric power control system comprising a supply and demand condition controlling means for controlling to stop electric power supply to some load means among the load means when the electric power supply and demand difference exceeds the preset given range, 10 wherein the energy storage controlling means and the supplied energy controlling means operate on a basis of the electric power supply and demand difference after stoppage of electric power supply to the some load means by the supply and demand condition controlling means. 9. The electric power control system according to Claim 8, wherein: 15 the electric power supplying means includes an electric power system supplying a given energy of electric power and at least one generator; the supply and demand condition controlling means stops electric power supply to the some load means other than one or more load means among the load means when the electric power supply and demand difference exceeds the preset given range due to stoppage of electric 20 power supply from the electric power system, the one or more load means being capable of operating with a total of amounts of electric power which can be generated by all the generators; and 52 the energy storage controlling means executes control to make the energy storing means charged with or discharge an initial energy of electric power, the initial energy being an energy keeping the electric power supply and demand difference within the given range, and the electric power supply and demand difference being that after stoppage of electric power supply to the some load means by the supply and demand condition controlling means. 10. The electric power control system according to Claim 9, wherein: the some load means to which the supply and demand condition controlling means stops electric power supply are preset on a basis of a total of amounts of electric power which can be generated, the amounts being preset for the respective generators; and an initial energy is preset on a basis of a difference between a total of amounts of electric power generated by the generators and a total of consumed energies of the load means to which the supply and demand condition controlling means does not stop electric power supply, the initial energy being an amount of electric power which the energy storing means is charged with or discharges under control of the energy storage controlling means. 11. An electric power control device connected to an electric power supplying means for supplying electric power, a load means for receiving supply of electric power and consuming the electric power, and an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to be supplied to the load means, the electric power control device comprising: a total supplied energy acquiring means for acquiring a total supplied energy, the total 53 supplied energy being a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; a total consumed energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric 5 power with which the energy storing means is charged; and an energy storage controlling means for, when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and TO demand difference within the given range, and also controlling the energy storing means so as to decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means, wherein in a case where the electric power supplying means includes a supplied energy controlling means, the time constant for energy storing means is set to be longer than a set time 15 constant for electric power supplying means, the supplied energy controlling means being for executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range. 20 12. The electric power control device according to Claim 11, wherein: when the electric power supply and demand difference exceeds the preset given range, the energy storage controlling means sets an energy equivalent to the electric power supply and 54 demand difference as an initial energy, and executes control to make the energy storing means charged with Hie initial energy of electric power or discharge the initial energy of electric power, and also controls the energy storing means so as to gradually decrease the charge or discharge electric power over the response time corresponding to the time constant for energy storing 5 means so that the electric power changes from the initial energy to a given value. 13. A computer program comprising instructions for causing an electric power control device, which is connected to an electric power supplying means for supplying electric power, a load means for receiving supply of electric power and consuming the electric power, and an 10 energy storing means for being charged with electric power supplied by "the electric power supplying means or discharging electric power to be supplied to the load means, to realize: a total supplied energy acquiring means for acquiring a total supplied energy, the total supplied energy being a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means; 15 a total consumed energy acquiring means for acquiring a total consumed energy, the total consumed energy being a total of electric power consumed by the load means and electric power with which the energy storing means is charged; and an energy storage controlling means for, when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed 20 energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also controlling the energy storing means so as to 55 decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means, wherein in a case where the electric power supplying means includes a supplied energy controlling means, the time constant for energy storing means is set to be longer than a set time 5 constant for electric power supplying means, the supplied energy controlling means being for executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given range. 10 14". The computer program according to Claim 13, wherein: when the electric power supply and demand difference exceeds the preset given range, the energy storage controlling means sets an energy equivalent to the electric power supply and demand difference as an initial energy, and executes control to make the energy storing means charged with the initial energy of electric power or discharge the initial energy of electric power, 15 and also controls the energy storing means so as to gradually decrease the charge or discharge . electric power over the response time corresponding to the time constant for energy storing means so that the electric power changes from the initial energy to a given value. 15. An electric power control method for controlling electric power of an electric power 20 supplying means for supplying electric power, a load means for receiving supply of electric power and consuming the electric power, and an energy storing means for being charged with electric power supplied by the electric power supplying means or discharging electric power to 56 be supplied to the load means, the electric power control method comprising: acquiring a total supplied energy which is a total of electric power supplied by the electric power supplying means and electric power discharged by the energy storing means, and a total consumed energy which is a total of electric power consumed by the load means and 5 electric power with which the energy storing means is charged; when an electric power supply and demand difference representing a difference between the total supplied energy and the total consumed energy exceeds a preset given range, making the energy storing means charged with electric power or discharge electric power, and executing control to keep the electric power supply and demand difference within the given range, and also 10 controlling the energy storing means so as to decrease the charge or discharge electric power over a response time corresponding to a set time constant for energy storing means; and executing control to change electric power supplied by the electric power supplying means over a response time corresponding to the set time constant for electric power supplying means so that the electric power supply and demand difference is kept within the preset given 15 range, wherein the time constant for energy storing means is set to be longer than a set time constant for electric power supplying means. 16. The electric power control method according to Claim 15, comprising: 20 when the electric power supply and demand difference exceeds the preset given range, setting an energy equivalent to the electric power supply and demand difference as an initial energy, and executing control to make the energy storing means charged with the initial energy 57 of electric power or discharge the initial energy of electric power, and also controlling the energy storing means so as to gradually decrease the charge or discharge electric power over the response time corresponding to the time constant for energy storing means so that the electric power changes from the initial energy to a given varoe; and 5 executing control changing electric power supplied by the electric power supplying means over the response time corresponding to the time constant for electric power supplying means so that the electric power supply and demand difference is kept within-the given-range, the electric power supply and demand difference being made as a result that a charge or discharge energy of the energy storing means gradually decreases. itr