1. A method for operating an electrical power system, comprising; receiving, by a control system, one or more electrical parameters of a plurality of electrical equipment in the electrical power system from one or more servers associated with the electrical power system and one or more measurement devices provided in the electrical power system, wherein the one or more measurement devices measure the one or more electrical parameters in real-time; determining, by the control system, a plurality of values of maximum power using at least one of the one or more electrical parameters received from the one or more servers and the one or more measurement devices, wherein each of the plurality of values of the maximum power indicate maximum amount of power that the electrical power system can transfer to a plurality of loads connected to the electrical power system; determining, by the control system, an index using the one or more electrical parameters received from the one or more measurement devices; detecting, by the control system, a contingency in the electrical power system based on a comparison between the index and a range of the reference indices received from the one or more servers, wherein the range of reference indices is determined using the electrical parameters associated with the one or more servers; and estimating, by the control system, a voltage stability margin for the electrical power system using a value from the plurality of values of the maximum power based on the detection of the contingency, wherein the estimated voltage stability margin is used for operating the electrical power system.

2. The method as claimed in claim 1, wherein the one or more measurement devices comprises at least one of one or more analog devices and one or more digital devices.

3. The method as claimed in claim 1, wherein the contingency is detected if the index is outside the range of the reference indices.

4. The method as claimed in claim 1, wherein the one or more electrical parameters received from the one or more servers and the one or more measurement devices are received by the control system at different time period.

5. The method as claimed in claim 1, wherein the one or more electrical parameters comprises at least one of current, voltage, power and impedance.

6. A control system for estimating voltage stability of an electrical power system, comprising; a processor; and a memory, communicatively coupled to the processor, storing processor executable instructions, which on execution causes the processor to: receive one or more electrical parameters of a plurality of electrical equipment in the electrical power system from one or more servers associated with the electrical power system and one or more measurement devices provided in the electrical power system, wherein the one or more measurement devices measure the one or more electrical parameters in real-time; determine a plurality of values of maximum power using at least one of the one or more electrical parameters received from the one or more servers and the one or more measurement devices, wherein the one or more values of the maximum power indicate maximum amount of power that the electrical power system can transfer to a plurality of loads connected to the electrical power system; determine an index using the one or more electrical parameters received from the one or more measurement devices; detect a contingency in the electrical power system based on a comparison between the index and a range of reference indices received from the one or more servers, wherein the range of reference indices is determined using the electrical parameters associated with the one or more servers; and estimate a voltage stability margin for the electrical power system using a value from the plurality of values of the maximum power based on the detection of the contingency, wherein the estimated voltage stability margin is used for operating the electrical power system.

7. The control system as claimed in claim 6, wherein the one or more electrical parameters comprises at least one of current, voltage, power and impedance.

8. The control system as claimed in claim 6, wherein the processor is configured to receive the one or more electrical parameters from the one or more measurement devices comprises at least one of one or more analog devices and one or more digital devices.

9. The control system as claimed in claim 6, wherein the processor is configured to detect the contingency if the index is outside the range of the reference indices.

10. The control system as claimed in claim 6, wherein the processor receives the one or more electrical parameters from the one or more servers and the one or more measurement devices at different time period.

DESC:
TECHNICAL FIELD
The present disclosure relates in general to electrical power systems. More specifically, but not exclusively, the present disclosure relates to a system and method for real-time voltage stability margin computation.

BACKGROUND
In power systems voltage must be maintained within an acceptable range for optimal functioning of the power system. The ability of the power system to maintain acceptable voltages at all bus in the power system while satisfying the demand for power is known as voltage stability. Due to voltage instability the power system may undergo a voltage collapse if loads exceed the maximum permissible value.

Current drawn by a load increases as load impedance decreases. The power delivered to the load by a source (generators, batteries, etc) changes as the load impedance varies. As load impedance is decreased, the power delivered increases until a maximum is reached. If the impedance is reduced beyond this point, the power decreases. This is because the impact of the low impedance exceeds the impact of the increased current. The maximum power is delivered to the load when the source impedance and load impedance are complex conjugates of each other as specified in the Maximum Power Transfer Theorem.

Modern power systems are made up of multiple sources and loads. These are interconnected by the transmission network made up of transmission lines, transformers and other power conditioning and flow control devices. These devices’ parameters determine how much power can be supplied to the loads. Transmission network operators need to know the voltage stability margin so that they can ensure that they can control the voltage throughout the system. The voltage stability margin is given by the difference between the current load being served and the maximum load that can be supplied considering the prevalent network topology.

Conventionally the voltage stability is computed using iterative algorithms which make use of network model to arrive at the maximum power that can be delivered to the load. The conventional systems evolved from the repeated power flow to the Continuation Power Flow (CPF). CPF works on the principle of prediction and correction steps. The main drawback of CPF is the prediction depends on various parameters of the network model. When a contingency occurs (line fault, transformer failure, etc), the model is not updated immediately and is updated after some time. Hence, the CPF cannot update the stability margin immediately resulting in incorrect margin estimates which may cause black-outs.

Few other conventional systems use Phasor Measurement Unit (PMU) for measuring current and voltages. The measurements are used to reduce the power system to an equivalent model. The equivalent model often does not consider non-linearities such as reactive power of source and compensating elements. Thus, using PMU is not accurate and thus voltage stability analysis is not accurate.

The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY
In an embodiment, the present disclosure relates to a method for operating an electrical power system. The method comprises receiving one or more electrical parameters of a plurality of electrical equipment in the electrical power system. The one or more electrical parameters of the plurality of electrical equipment may be received from at least one of one or more servers associated with the electrical power system and one or more measurement devices in the electrical power system. The method further comprises determining a plurality of values of maximum power using at least one of the one or more electrical parameters received from the one or more servers and the one or more measurement devices. Further, an index is determined using the one or more electrical parameters of the plurality of electrical equipment. Thereafter, any deviation in the maximum power due to a contingency are detected based on a comparison between the determined index and a range of reference indices. Lastly, voltage stability margin of the power system is updated using a value from the plurality of values of maximum power upon detecting the contingency.

In an embodiment, the present disclosure relates to a control system for operating an electrical power system. The control system comprises a processor and a memory communicatively connected to the processor. The processor is configured to receive one or more electrical parameters of a plurality of electrical equipment in the electrical power system. The one or more electrical parameters of the plurality of electrical equipment may be received from at least one of one or more servers associated with the electrical power system and one or more measurement devices in the electrical power system. The processor is further configured to determine a plurality of values of maximum power using at least one of the one or more electrical parameters received from the one or more servers and the one or more measurement devices. Further, the processor determines an index using the one or more electrical parameters of the plurality of electrical equipment. Thereafter, the processor detects a contingency based on a comparison between the determined index and a range of reference indices. Lastly, the processor estimates a voltage stability margin of the power system using a value from the plurality of values of maximum power upon detecting the contingency.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Figure 1 is a block diagram illustrating an exemplary electrical power system, in accordance with embodiments of the present disclosure;

Figure 2 is a flowchart illustrating calculation of voltage stability margin of an electrical power system, in accordance with embodiments of the present disclosure;

Figure 3A is a graph illustrating time variation in calculating maximum load in an electrical power system using conventional methods;

Figure 3B is a graph illustrating time variation in calculating maximum load in an electrical power system, in accordance with embodiments of the present disclosure; and

Figure 4 is a flow chart illustrating calculation of reference indices for each electrical equipment in an electrical power system, in accordance with embodiments of the present disclosure.

It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative systems embodying the principles of the present subject matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION
In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

The Figures and the following description relate to various embodiments by way of illustration only. It should be noted that from the following discussion, alternative embodiments of the structures and methods disclosed herein will be readily recognized as viable alternatives that may be employed without departing from the principles discussed herein. Reference will now be made in detail to several embodiments, examples of which are illustrated in the accompanying figures. It is noted that wherever practicable similar or like reference numbers may be used in the figures and may indicate similar or like functionality.

Embodiments of the present disclosure relate to operating an electrical power system by calculating voltage stability of the electrical power system in real-time. A control system provided in the electrical power system may utilize one or more Model Based methods (MOB) and one or more Measurements Based methods (MEB) for calculating voltage stability of the power system. The control system calculates a plurality of values of maximum power (Pmax) that can be delivered to loads connected to the power system using either individually or in combination with the Power (P) – Voltage (V) curve and the Reactive Power (Q) – Voltage (V) curve generated using the MOB methods. Also, the control system estimates a plurality of values of Pmax that can be delivered to the loads using the MEB methods.

In an embodiment, at least one value of Pmax calculated using the MOB methods and the MEB methods is considered as reference. In an exemplary embodiment, at least one value of Pmax calculated using the different MOB methods is considered as reference as the MOB method is generally more accurate compared to the MEB method if the model used is up-to-date.

In an exemplary embodiment, a first technique may be used to determine voltage stability margin of a power system using real-time values of electrical parameters and stored parameters of electrical parameters when a contingency occurs. In an alternate embodiment, a second technique may be used to determine voltage stability margin of the power system using stored values of electrical parameters only (MOB). In another alternate embodiment, a third technique may be sued to determine voltage stability margin of the power system using measured values of electrical parameters only (MEB). The first technique may comprise switching between MOB method and MEB method for calculating voltage stability margin. The second technique comprises switching between different MOB methods for calculating voltage stability margin. The third technique comprises switching between different MEB methods for calculating voltage stability margin.

In one implementation (first technique), a value of Pmax (Pmax0, Pmax1, Pmax2… PmaxN) corresponding to different time instances (T0, T1, T2…. TN) is considered as references at respective time instances. When a value of Pmax (Pmax_measT1) is calculated using the MEB at time instant T1, the corresponding Pmax (Pmax1) is considered as reference. In an alternate implementation, there may be a plurality of values of Pmax for a given time instant. The control system may choose one value of Pmax from the plurality of values of Pmax. In this embodiment, the methods of calculating the voltage stability margin switched from MOB methods to MEB methods during contingency and back to MOB method during normal operation.

In an alternate embodiment (second technique), different MOB methods are used to calculate value of Pmax. One such MOB method is used to calculate voltage stability margin during a contingency. In an embodiment, a plurality of values may be calculated for every time instant. In another embodiment, one time instant may be associated with one value of Pmax calculated from different MOB methods. As explained in the above paragraph, the reference may be chosen in two different ways, viz a reference value of Pmax for corresponding time instant, and a reference value of Pmax among a plurality of values of Pmax chosen arbitrarily. Thus, when a contingency occurs, one MOB method among plurality of MOB methods which give the correct value of Pmax is used and when the contingency is restored, the previous method may be used.

In yet another alternate embodiment (third technique), different MEB methods are used to calculate value of Pmax. One such MEB method is used to calculate voltage stability margin during a contingency. In an embodiment, a plurality of values may be calculated for every time instant. In another embodiment, one time instant may be associated with one value of Pmax calculated from different MEB methods. As explained in the above paragraph, the reference may be chosen in two different ways, viz a reference value of Pmax for corresponding time instant, and a reference value of Pmax among a plurality of values of Pmax chosen arbitrarily. Thus, when a contingency occurs, one MEB method among plurality of MEB methods which give the correct value of Pmax is used and when the contingency is restored, the previous method may be used.

Figure 1 shows a block diagram of a typical electrical power system in accordance with embodiments of the present disclosure. The electrical power system as shown in Figure 1 comprises a power generation substation (101), a transmission substation (102), transmission lines (103), transformer (104), load (105) and a server (106).

In an embodiment, the aspects disclosed in the present disclosure may relate only to one substation or a plurality of substations. Figure 1 is illustrated as an exemplary embodiment and does not limit the scope of the claimed aspects to the aspects disclosed in Figure 1. Further, the server (106) may reside in the power generation substation (101) or the subsequent substations (102) or can be remote to all the substations. In an embodiment, each substation comprises a plurality of electrical equipment. For example, the power generating substation (101) comprises boilers, turbines, generators, feed pump, etc. The transmission substations (102) comprises circuit breakers, relays, bus bars, etc. Transformer stations comprises current transformers, voltage transformers insulators, isolators, lightening arrestors, etc. All the electrical equipment is collectively referred as one or more electrical equipment in the present disclosure. Further, each electrical equipment is associated with one or more electrical parameters. For example, a transformer is associated with impedance and a transformation ratio, the load with real and reactive power, impedance, etc.

The power is generated in the power generation substation (101). The power generation substation (101) can be a hydel power plant, a nuclear power plant, a thermal power plant, etc. The power generated in the power generation substation (101) is transmitted over transmission lines (103) to the transmission substations (102). The voltage and current are regulated in the transmission substation (102) and is further transmitted to the transformer (104) via the transmission lines (103). The transformers (104) step down/ step up the voltage and transmits the power to the load (105). Each substation may be operated and controlled by Distributed Controlled Systems (DCS). Each DCS can be monitored and operated by Supervisory Control and Data Acquisition (SCADA)/ Enterprise Management Server (EMS) system and systems alike provided in the power system. The system like SCADA is used to monitor and control the entire power system (power generation substation, transmission substation). Each substation is capable of delivering certain amount of power to the load (105)/ subsequent substation. Voltage stability of the power system is calculated to determine stability of the power system. A voltage stability margin of the power system is used to determine maximum power that can be delivered to the load.

A control system can be used to determine the voltage stability margin of the power system. In an embodiment, the control system can be a part of the SCADA/EMS system or can be a dedicated system configured in any substation or configured remotely which is communicatively coupled to the power system. In an embodiment, the control system may include one or more servers. The control system may also comprise one or more measurement devices like analog measurement devices or digital measurement units. The measurement units may include but are not limited to Remote Terminal Units (RTU), Phasor Measurement Units (PMU), relays, current sensors, voltage sensors, and any other measurement devices capable of measuring one or more parameters of the one or more electrical equipment.

In an embodiment, the one or more parameters are associated with each electrical equipment. for example, a transformer is associated with values of impedance. Likewise, the one or more parameters may include current, voltage and impedance.

The control system receives the one or more electrical parameters (current, voltage, power) from the SCADA system and systems alike provided in the power system. The SCADA system may have a database storing the one or more electrical parameters of the power system. The SCADA is updated with the plurality of parameters at predefined time intervals (e.g., every 30 seconds or every 1 minute). The one or more electrical parameters are used for predicting maximum load that can be fulfilled and performing corrective steps for calculating voltage stability of the power system. The control system also receives current and voltage measurements from Phasor Measurement Units (PMUs). The PMUs provide the current and voltage measurements in the power system continuously to the control system. In an embodiment, the technique of deriving the maximum load that can be fulfilled from the SCADA system is referred as Model Based method (MOB) and the technique of deriving the maximum load from the PMU measurements is referred as Measurement Based method (MEB).

During normal condition (when the power system does not have any contingencies), control system calculates variation of voltage at the load terminal with respect to power delivered to load (P-V curve)/ Q-V curve (where Q represents reactive power) using the MOB. The P-V/ Q-V curve is calculated to estimate a plurality of values of maximum amount of power (Pmax) that can be delivered to the load under different operating conditions. By observation, the plurality of values of Pmax calculated using the MOB is found to be accurate. A band of P-V/ Q-V curve corresponding to different contingencies are calculated using the MOB. Also, corresponding Pmax corresponding to different contingencies are calculated.

Figure 2 shows a flow chart illustrating a method for operating the power system, in accordance with some embodiments of the present disclosure.

As illustrated in Figure 2, the method 200 may comprise one or more steps to enable operation of the power system, in accordance with some embodiments of the present disclosure. The method 200 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, and functions, which perform particular functions or implement particular abstract data types.

The order in which the method 200 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the spirit and scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

At step 201, the control system receives the one or more electrical parameters of the one or more electrical equipment from the one or more servers (SCADA/EMS) and the one or more measurement devices (e.g., RTUs and PMUs). The control system may be communicatively coupled with the RTUs, PMUs, relays, etc provided in the power system. The one or more measurement devices may provide the measured parameters to the control system at regular time intervals. In an embodiment, the RTUs provide the measured parameters to the SCADA system. The control system receives the measured parameters from the SCADA system. In an embodiment, the PMUs provide the control system the measured parameters. In an exemplary embodiment, the control system receives the one or more electrical parameters from the PMUs at a faster rate than from SCADA.

At step 202, the control system determines a plurality of values of Pmax using MOB and MEB methods. For example, the control system may calculate a plurality of values of Pmax using different MOB methods. Alternatively, the control system may calculate plurality of values of Pmax using different MEB methods. In an exemplary embodiment the control system may calculate the plurality of values of Pmax using the MOB and the MEB method. The maximum power is calculated by determining the current network topology, operating point and possible contingencies. Typically, a P-V curve is generated to determine the variation in power and voltage and the maximum power is determined from the P-V curve. Alternatively, a Q-V curve can be generated using reactive power. A person skilled in the art will appreciate that different ways can be employed to determine the voltage stability margin and this disclosure is not limited to exemplary techniques explained and shall be compatible with any such techniques used for determining the voltage stability margin.

At step 203, the control system determines an index using the one or more electrical parameters received from the one or more measurement devices. For example, the control system determines a ratio of partial derivative of voltage with respect to power (?V/?P). The index may be calculated using any of the electrical parameters and may not be restricted to the example provided. In an embodiment, the index may be calculated for each electrical equipment in the power system. In an embodiment, the index may not be limited only to (?V/?P). The index may also include (1 - ?V/?P) or any such operations that is used to compare two measurements derived from two models/ techniques. In another embodiment, different electrical parameters such as impedance, current etc may also be used in any combination to derive an index.

At step 204, the control system detects contingencies in the power system by comparing the determined index with a range of reference indices. In an embodiment, each electrical equipment is associated with a band/ range of reference indices (?V/?P). The control system compares the index determined for each equipment with corresponding band/ range of indices. For example, the index (?V/?P) calculated for the transmission line (103) is compared with the band of reference indices (?V/?P) determined for the transmission line (103). Likewise, the index (?V/?P) calculated for a transformer (104) is compared with the band of reference indices (?V/?P) determined for the transformer (104). If the index is outside the range of the indices, then the control system detects that there is a contingency (fault) in the power system. For example, considering a scenario where a fault occurs on the line (103) and the line must be isolated to address the fault. The control system receives real-time values from the one or more measurement devices and determines the index for the line (103). The index is compared with the band of reference indices and the control system detects that the determined index is outside the range of the reference indices. Thus, the control system detects that there is a significant deviation in the operating condition, prompting a change in the maximum power that can be delivered by the system. In an embodiment, the contingency may be a fault, or a condition where condition of the electrical equipment is deteriorating.

At step 205, the control system determines the voltage stability margin using at least one value of the Pmax. In an exemplary embodiment, the voltage stability margin is calculated using at least one value of Pmax calculated using the MEB when the fault/ contingency is detected, as the MEB provides the up-to-date values of Pmax. In an embodiment, when the SCADA is updated with the electrical parameters when the contingency occurs, the control system switches the calculation of the voltage stability margin using at least one value of Pmax calculated using the MOB. Typically, the MOB is considered to be more accurate than the MEB. However, to attend to the contingency, the MEB is considered until the SCADA is updated and the MOB calculates the values of Pmax using the updated values.

In an exemplary embodiment, during normal operation of the power system, the voltage stability margin is calculated using the Pmax values received from the SCADA/EMS server as it is observed to be more accurate. The values of Pmax are constantly updated using the MOB methods and MEB methods. For every time instant (T0, T1… TN) corresponding values of Pmax are calculated using the MOB and MEB methods. The values of Pmax calculated at every time instant is considered as reference for that time instant. In an embodiment, many values of Pmax can be calculated for one time instant. When a fault occurs in any of the electrical equipment in the power system (e.g., a line fault due to felling of a tree), the fault is identified and immediately the voltage stability margin calculation is performed using real-time electrical parameters. The MEB method utilizes the real-time measurement of the electrical parameters. As the SCADA server is observed to take some time) to identify the change, the real-time values are considered for calculating the voltage stability margin. In one implementation, the index (?V/?P) is calculated using the measurements received from the PMUs. In another implementation, the index can be (1 - ?V/?P) and the resultant can be compared with corresponding reference index calculated using measurements present in the SCADA/ EMS server. Accordingly, the value of Pmax is chosen and the voltage stability is determined. The switching from MOB to MEB to calculate the voltage stability margin during contingency provides insight to an operator in the power system to immediately take suitable actions.

In an alternate embodiment, the voltage stability margin is calculated using a value of Pmax calculated using only MOB when the fault/ contingency is detected. One MOB method among a plurality of MOB methods may be more accurate. For example, when the fault occurs, the SCADA/ EMS may be updated with various sets of the electrical parameters. Each set can be used to determine a value of Pmax using different MOB methods. To attend to the fault immediately, a first value of Pmax calculated from method 1 may be considered and the voltage stability margin can be estimated. Subsequently, when a plurality of values of electrical parameters are received by the SCADA, a more accurate value of Pmax may be determined using method 2 and the control system may use the accurate value of Pmax calculated using the method 2 to calculate the voltage stability margin. Thus, the control system can switch between different MOB methods to determine the voltage stability margin. A person skilled in the art would acknowledge that the similar technique can be applied for calculating the voltage stability margin using the MEB method.

Figure 3A shows a graph illustrating time variation in calculating maximum load using conventional techniques. As shown, the line 301 indicates the time taken for calculating the load using real-time values (MEB) and the line 302 represents the time taken for calculating the load using MOB technique. The line 303 represents the power system load variation. As seen, the time taken for calculating load requirements using MOB is more. Although MOB is preferred over MEB, due to the time constraint, the MOB may not be suitable when a contingency occurs.

Figure 3B shows a graph illustrating time variation in calculating maximum load in an electrical power system. As shown in Figure 3, the dotted line 304 indicates the value of Pmax of the power system and the continuous line 305 indicates the value of Pmax calculated using the proposed method. The x-axis indicates the time variation. As seen, the value of Pmax of the power system reduces during a contingency. However, the Pmax calculated using the proposed method is reliable during contingencies and is much faster than the conventional techniques. In conventional techniques as shown in Figure 3A, the value of Pmax is calculated using only MOB method which delays the calculation in value of Pmax, thereby causing blackouts. In other conventional techniques, the value of Pmax is calculated using only MEB method which may not be very accurate and thus the power system may not be operated in the accurate operating point. The proposed method provides a solution for achieving the accuracy and attends the time constraints.

Figure 4 shoes a flow chart for determining the range of indices for each electrical equipment which may indicate that a significant deviation from the pre-calculated Pmax has not occurred.

At step 401, the control system performs contingency analysis for each electrical equipment using the electrical parameters associated with each electrical equipment. Outage of different equipment is simulated, and the electrical parameters are accordingly modified by the control system. Outage of all elements can be considered or a set of critical elements as the case may be.

At step 402, the control system identifies the critical elements, whose outage causes the voltage stability margin varies by a threshold value. For example, a fault in the transformer (104) may cause variation in the voltage stability margin by 6%. Here, a threshold may be predetermined as a maximum variation of 5% can be tolerated. Thus, this transformer is considered a critical element.

At step 403 and 404, the control system calculates index for each electrical equipment using the identified value of electrical parameters based on variation of the electrical parameters. For example, a P-V curve may be generated and an index (?P/ ?V) may be calculated for all the critical elements identified in 402.

At step 405, the control system determines a range/ band of index for which the voltage stability margin is within the predefined threshold value.

The present disclosure provides a method and a system for calculating voltage stability of the power system in real-time. The voltage stability of the power system is thus calculated immediately when a contingency occurs in the power system. Thus, an operator in the power system can take an action immediately and reduce power cut and blackout.

In an embodiment, the proposed method and system can be used where there is growing power generation deficit due to delayed commissioning or high load growth. The proposed method and system can also be used in transmission substations having lack of infrastructure and which has increasing penetration of renewables.

The terms "an embodiment", "embodiment", "embodiments", "the embodiment", "the embodiments", "one or more embodiments", "some embodiments", and "one embodiment" mean "one or more (but not all) embodiments of the invention(s)" unless expressly specified otherwise.

The terms "including", "comprising", “having” and variations thereof mean "including but not limited to", unless expressly specified otherwise. The enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms "a", "an" and "the" mean "one or more", unless expressly specified otherwise.

A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention.

When a single device or article is described herein, it will be readily apparent that more than one device/article (whether or not they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether or not they cooperate), it will be readily apparent that a single device/article may be used in place of the more than one device or article or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the invention need not include the device itself.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this description.

Referral Numerals:
Generation substation (101)
Transmission substation (102)
Transmission lines (103)
Transformer (104)
Load (105)
Server (106)
,CLAIMS:We claim:

1. A method for operating an electrical power system, comprising;
receiving, by a control system, one or more electrical parameters of a plurality of electrical equipment in the electrical power system from one or more servers associated with the electrical power system and one or more measurement devices provided in the electrical power system, wherein the one or more measurement devices measure the one or more electrical parameters in real-time;
determining, by the control system, a plurality of values of maximum power using at least one of the one or more electrical parameters received from the one or more servers and the one or more measurement devices, wherein each of the plurality of values of the maximum power indicate maximum amount of power that the electrical power system can transfer to a plurality of loads connected to the electrical power system;
determining, by the control system, an index using the one or more electrical parameters received from the one or more measurement devices;
detecting, by the control system, a contingency in the electrical power system based on a comparison between the index and a range of the reference indices received from the one or more servers, wherein the range of reference indices is determined using the electrical parameters associated with the one or more servers; and
estimating, by the control system, a voltage stability margin for the electrical power system using a value from the plurality of values of the maximum power based on the detection of the contingency, wherein the estimated voltage stability margin is used for operating the electrical power system.

2. The method as claimed in claim 1, wherein the one or more measurement devices comprises at least one of one or more analog devices and one or more digital devices.

3. The method as claimed in claim 1, wherein the contingency is detected if the index is outside the range of the reference indices.

4. The method as claimed in claim 1, wherein the one or more electrical parameters received from the one or more servers and the one or more measurement devices are received by the control system at different time period.

5. The method as claimed in claim 1, wherein the one or more electrical parameters comprises at least one of current, voltage, power and impedance.

6. A control system for estimating voltage stability of an electrical power system, comprising;
a processor; and
a memory, communicatively coupled to the processor, storing processor executable instructions, which on execution causes the processor to:
receive one or more electrical parameters of a plurality of electrical equipment in the electrical power system from one or more servers associated with the electrical power system and one or more measurement devices provided in the electrical power system, wherein the one or more measurement devices measure the one or more electrical parameters in real-time;
determine a plurality of values of maximum power using at least one of the one or more electrical parameters received from the one or more servers and the one or more measurement devices, wherein the one or more values of the maximum power indicate maximum amount of power that the electrical power system can transfer to a plurality of loads connected to the electrical power system;
determine an index using the one or more electrical parameters received from the one or more measurement devices;
detect a contingency in the electrical power system based on a comparison between the index and a range of reference indices received from the one or more servers, wherein the range of reference indices is determined using the electrical parameters associated with the one or more servers; and
estimate a voltage stability margin for the electrical power system using a value from the plurality of values of the maximum power based on the detection of the contingency, wherein the estimated voltage stability margin is used for operating the electrical power system.

7. The control system as claimed in claim 6, wherein the one or more electrical parameters comprises at least one of current, voltage, power and impedance.

8. The control system as claimed in claim 6, wherein the processor is configured to receive the one or more electrical parameters from the one or more measurement devices comprises at least one of one or more analog devices and one or more digital devices.

9. The control system as claimed in claim 6, wherein the processor is configured to detect the contingency if the index is outside the range of the reference indices.

10. The control system as claimed in claim 6, wherein the processor receives the one or more electrical parameters from the one or more servers and the one or more measurement devices at different time period.