FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
SYSTEM AND METHOD FOR OPTIMIZING MINIGRID POWER
GENERATION AND MANAGEMENT
2. APPLICANT:
(a) NAME: AMPEREHOUR SOLAR TECHNOLOGY PRIVATE LIMITED
(b) NATIONALITY: An Indian Registered Company
(c) ADDRESS: # 403, Ekaika, Kharadi bypass road, Kharadi,
Pune -411014, Maharashtra, India.
3. PREAMBLE TO THE DESCRIPTION
COMPLETE: The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:
The present invention relates to Minigrid power systems and particularly relates to a system and method for optimizing Minigrid power generation and management.
BACKGROUND OF THE INVENTION:
The Minigrid or microgrid are the systems equipped with power generators, and possibly power storage systems interconnected to a distribution network that supplies electricity to a localized group of people. Their power delivery architecture can be of a single customer system or multicustomer system having connected to a centralized grid system, where the electricity is distributed over large distance from centralized power sources. Normally the Minigrid systems are designed for small scale power generation and to serve a limited number of customers through a distribution grid in isolation from a national electricity transmission network. Common challenges for the implementation of a Minigrid system are the lack of technology, poor maintenance and insufficient energy sources.
Drawbacks of prior art
Conventional Minigrids uses conventional inverter technology which uses separate Solar MPPT (Maximum power point tracking) and Bidirectional AC-DC (Alternate Current-Direct Current) inverters for generating power from solar photovoltaic (PV) system and storing power to lead acid batteries, they use AC inputs either to connect Grid or Diesel Generator set for back up sources. In many cases, these AC sources are converted to DC by rectifiers and connected in DCDB where battery and MPPT (Maximum power point transfer) outputs are connected. This makes the system too complex and inefficient due to multiple conversions. This also leads in reduction of battery life and reduction in usable energy from the battery. There are separate DCDB (Direct Current Distribution Board), Metering and AC connection panel either placed on walls of control room or in a panel, which houses standard equipments and connections. Most of the failures happens

only in the Inverters, MPPTs, DCDB, T&D (Transmission and Distribution) lines due to poor installation, different makes and numbers of equipment involved in the construction of Minigrid.
In conventional Minigrids inverters, MPPTs are monitored through dedicated device which is normally from same manufacturer and not have feature to add microgrid specific features like battery system and organization control, DG fuel savings , maximization of renewables , TOD control etc. Also there are no built in power management system (PMS) and no provisions available in the inverters to add sources like biogas, diesel generators, biomass, wind generators output at a time and their control based on Microgrid requirements.
Due to numbers of components combined through huge cabling and connections and terminations, there is huge possibility of faults and unavailability of system during operations. Further protections to each equipment is weak due to absence of protection devices at each stage. Normally protection is provided only to incoming and outgoing sources. Also there is transfer time of 8-10 milliseconds for transfer of power from one source to another in existing systems which is tripping sensitive loads like prepaid meters, base stations for Radio Frequency communications, household sensitive loads etc.
The conventional Minigrids normally suffers from issues like low voltage, low power factor of loads, breakdown of conductors, failure of household loads. It also increases their transmission and distribution losses to a great extent.
Conventional Minigrid equipments are rated for 45oC and hence difficult to operate them without having cooling system, which increase the aux consumption of the system and also failure rate of equipments/components. Also the conventional Minigrid inverters and Maximum Power Point Tracking (MPPT) are not battery agnostics and they are normally available for lead acid systems. There are no systems available which can integrate battery management system (BMS)

systems of the battery for control and safety. Remote control facilities are not available in the conventional systems.
Accordingly, there exists need to provide a system for optimizing Minigrid power generation and management that can overcome the drawbacks in the prior art.
SUMMARY OF THE INVENTION:
The present invention system and method for optimizing Minigrid power
generation and management. The system comprises a plurality of power
generating sources, a storage unit, a transformer, an energy storage unit, a
plurality of protection circuits and a built in hybrid inverter unit with a power management system. The hybrid inverter unit comprises a priority circuit, a maximum power point tracking unit, an inverter circuit, a control unit and a human machine interface. The hybrid inverter unit is capable of feeding power into the grid and runs in parallel with a grid. The maximum power point tracking unit connects the renewable power sources to the inverter and the priority circuit connects all the renewable power sources to the inverter circuit. The inverter circuit interconnects all the power sources and energy storage unit to the load through the transformer. The transformer is capable of isolating the hybrid inverter unit from the load thereby protecting the electronic components during the erratic load conditions, line fault conditions and like. The control unit connected to all the individual units of the hybrid inverter unit is associated with a power management module. The control unit optimizes the power generation by setting priority to the plurality of power sources in accordance with stored data, monitoring the inverter circuit parameters, protection circuits and cooling fan status, and provides access to a remote user. The human interface is operably connected to the control unit and facilitating a user interaction with the hybrid inverter unit. Thus the hybrid inverter unit integrates the plurality of power sources and energy storage unit, sets priority of use to each power sources and supplies power to the load based on preset priority values, such that economical and renewable power source are used on priority and other sources being

consumed based on availability, cost and dynamic pricing conditions. Prioritizing of the plurality of power sources depends on the real time status of different sources, real time pricing and load requirements. There is a facility to provide inputs to priority circuits from remote based on Dynamic Algorithm working in the Internet Cloud.
Objects of the invention:
An object of the present invention is to integrate all the renewable and nonrenewable power sources for an optimized power generation and keep reliability in supplying to the loads.
Another object of the system is to provide priorities for operations of the energy sources at Minigrid environment that will optimize the cost of generation and increase the life of power sources.
Yet another object of the invention is to provide a robust, high quality inverter system for Minigrids systems.
Further object of the system is to reduce on-site work of Minigrid systems.
Another object of the invention is to avoid communication issues, compatibility and sizing issues at Minigrid sites due to numbers of equipment or components involved in the Minigrid system.
Yet another object of the invention is to provide forecasting of renewable energy generation through on board power management system and reduce cost of generation.
Further object of the invention is to reduce transmission and distribution losses of Minigrid power system.
Another object of the present invention is to provide a battery agnostic system.

Yet another object of the invention is to provide a simple and efficient method for optimizing Minigrid power generation and management.
BRIEF DESCRIPTION OF THE DRAWINGS:
The objects and advantages of the present invention will become evident when the disclosure is read in conjunction with the following figures, wherein
Figure 1 shows a functional block diagram of a system and method for optimizing Minigrid power generation and management in accordance with the present invention.
Figure 2a and 2b show a perspective view of the hybrid inverter unit accordance with the present invention.
Figure 3 shows a flow diagram showing the operation of the power management unit in accordance with the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS:
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The invention provides a system and method for optimizing Minigrid power generation and management. The system comprises a built in hybrid inverter unit integrating all the renewable and nonrenewable power sources and supply power to a grid. The system ensures an optimized power generation and provides reliability of the power supply to loads.
The present invention is illustrated with reference to the accompanying drawings, wherein numbers indicated in the bracket represent the components of the invention throughout the description and the table given below.
Table 1:

Component No: Component name:
100 System for optimizing Minigrid power generation and management
10 Power source
50 Hybrid inverter unit
11 Maximum power point tracking unit
12 Inverter circuit
13 Priority circuit
14 Control unit
15 Load
16 Bus bar unit
18 Transformer

19 Human machine interface
20 Energy Storage unit
150 Method for optimizing Minigrid power generation and management by a system
Referring to Figures 1 to 3 a system (100) and method for optimizing Minigrid power generation and management (herein after referred to as “the system (100)” is shown in accordance with the present invention. The system (100) comprises a hybrid inverter unit (50), a plurality of power sources (10), an energy storage unit (20), a bus bar unit (16), a plurality of protection circuits and a transformer (18).
The plurality of power sources (10) includes renewable (10a) and nonrenewable sources (10b). In a preferred embodiment, the power sources include a solar power generator, diesel generator, biogas power generator, biomass power generator, wind energy, grid and like. The energy storage unit (20) includes a battery associated with a battery management circuit.
The hybrid inverter unit comprises a maximum power point tracking unit (11), an inverter circuit (12), a priority circuit (13), a control unit (14) and a human machine interface (19). The hybrid inverter unit (50) is capable of feeding power into a grid and runs in parallel with the grid.
The maximum power point tracking unit (MPPT) (11) connects the renewable power sources (10a) to the inverter circuit (12) by means of a protection circuit. In the embodiment, the protection circuit is a circuit breaker. Specifically, the MPPT (11) is unidirectional device which takes the power optimizes it and then feeds to the inverter circuit (12). The MPPT (11) helps to maximize power extraction under all the conditions.

The priority circuit (13) connects all the nonrenewable power sources (10b) to the inverter circuit (12) through a protection circuit. The priority circuit (13) comprises an ac input integration unit that receives energy from the power sources (10). This includes a plurality of circuit breakers, a plurality of current and voltage sensors, a plurality of relays, a plurality of automatic transfer switches and a control circuit to make integration and prioritization of the plurality of nonrenewable power sources (10b). The priority circuit (13) prioritizes the nonrenewable power sources (10b) including the storage unit (20), Grid other than solar power generator (10a) and wind power generator (10a). Thus, the system can work on one external source at a time or multiple sources feeding power to the load (15) and the energy storage unit (20).
The inverter circuit (12) includes bidirectional converters, AC to DC converters, Inverter board, solar charger board, battery charger board, control board assembled on a single printed circuit board with all protections. The inverter circuit (12) interconnects all the power sources (10) and energy storage unit (20) to the load (15) through the transformer (18).
The control unit (14) comprises a processing unit, a memory and plurality of interfacing modules. The control unit (14) is configured with a power management module and is connected to all the individual units of the hybrid inverter unit (50). The control unit (14) functions as a power management system and is a central controller that monitors the hybrid inverter unit parameters, meters, a plurality of sensor, cooling fans status, circuit breaker status, loads (15) and power source status (10). The plurality of sensors includes irradiation sensors, heat sensors, current and voltage sensors and like. The control unit (14) optimizes the power generation by setting a priority to the plurality of power sources (10) in accordance with stored data, monitoring the inverter circuit (12) parameters, protection circuits and cooling fan status. The control unit (14) also facilitates access of system to a remote user and also accepts command from remote to control.

The control unit is configured with a plurality of applications therein. In a specific embodiment, the applications include internal priority algorithm, TOD (Threshold Order-Dependent) algorithm, battery SOC (State-of-charge) algorithm, DG fuel reduction algorithm. Also the control unit (14) sets different modes of operation of hybrid inverter unit (50) like solar power generator (10a) first, energy storage unit (20) first, grid first, biogas generator (10b) second, diesel generator (10b) last, solar-biogas – energy storage unit (20), solar- wind- storage unit, biogas – battery, diesel generator– battery and so on. The control unit (14) also gives control of all the system (100) to a remote user.
In a preferred embodiment, a highest priority is given to charging of the storage unit (20) through a solar input. As the solar power input is based on the time of the day and the state of charge of the battery the second priority of the power source (10) is given to the biogas generator. A signal to check the availability of the biogas generator is performed. If the biogas is available, then the input is provided to the system and the energy storage unit (20) charging takes place. If the biogas is not available, then the controller unit (12) waits for a preset time period and a second signal is generated to start the diesel generator. Once the diesel generator (10b) is started, the controller unit (12) waits to read the voltage output from the diesel generator (10b). As the voltage is read on the input, the diesel generator (10b) output is proved to the energy storage unit (20) for charging.
The inverter circuit (12) includes bidirectional converters, AC to DC converters assembled on a single PCB board with all protections.
The human interface (HMI) (19) is operably connected to the control unit (14) and facilitating a user interaction with the hybrid inverter unit. The function of the HMI is to show the operational values and control the operation of the hybrid unit (50) for single interface. In a preferred embodiment, the HMI (19) comprises of a display and input keyboard that are positioned on the outdoor front panel of the product. The complete operational parameters of the system (100) are shown on

the front display. The parameters include system voltage, system current, storage capacity, active load, energy storage unit charging / discharging status and like. Apart from displaying all the values on screen, the HMI is also used to control the operation of the hybrid unit (50) by setting modes of operations such as ECO mode, bypass mode, and maintenance mode can be initialized from the HMI. Specifically, display is a standard 7 inch HMI with touch screen capability.
The bus bar unit is inbuilt with the hybrid inverter unit. The bus bar unit is a critical part of the system where a plurality of power sources (10) is integrated together. The bus bar unit is capable of connecting all the renewable and nonrenewable sources (10a, 10b) to the MPPT and the priority circuit. The bus bar unit includes AC bus bar unit and DC bus bar unit. A DC bus bar unit connects the energy storage unit (20) to the inverter circuit (12) through protection circuit. The output from the inverter circuit (12) is connected to an AC Busbar unit and is separately connected to the transformer (18). The bus bar unit is designed in such a way that maximum clearance will be given and each power source (10) will be separated, monitored and controlled properly. This section avoids any ACDB (AC distribution box) requirement at the Minigrid site.
Thus the hybrid inverter unit (50) integrates the plurality of power sources (10) and energy storage unit (20) in a single module, sets priority of use to each power sources and supplies power to the load based on preset priority values of the power sources. This makes an economical and renewable power source can be used on priority and other sources being consumed based on availability, cost and dynamic pricing conditions.
The plurality of protection circuit is provided with electronic circuits comprising static relays and disconnecting relays that operate automatically. In an embodiment, the hybrid inverter unit is also provided with additional protection circuits that can be operated manually. The additional protection circuit provides an additional safety to the Minigrid environment by disconnecting the hybrid inverter unit (50) at the time of fault conditions. The hybrid inverter unit also

comprises a HVAC controller, a fire controller, a plurality of fans and an emergency stop button. The plurality of fans that operates only on a predefined settings to limit the auxiliary consumption of power. The emergency stop button is electrically connected to the all the circuit breakers of the protection unit to stop the operation of the system in case of emergency.
The transformer interconnects the hybrid inverter unit (50) and the load (15). The transformer (18) is capable of isolating the hybrid inverter unit (50) from the load (15). Hence protecting the electronic components of the hybrid inverter unit (50) during the erratic load conditions, line fault conditions and like. In the embodiment, the transformer is an isolation transformer that is capable of isolating the hybrid inverter unit (50) from any fault and load conditions. This avoids the issues existing at Minigrid sites and causes damages due to isolation issues. In the preferred embodiment, the transformer is a step up transformer. This increases the voltage by 5-15% so that transmission and distribution line length can be increased and reduce the losses.
Thus the system (100) integrates all the renewable and nonrenewable power sources (10) for optimized generation of power and distribution to the loads (15). The hybrid inverter unit (50) is capable of supplying power back to the grid or run in parallel with the grid. In a preferred embodiment, the system also comprises of an electric vehicle charging pod.
Specifically the hybrid inverter (50) functions in ECO and Bypass mode that would enhance the efficiency of the system (100). In this mode of operation AC power sources will directly supply power to the grid and the energy storage unit (20).
The hybrid inverter unit (50) is battery agnostic and is capable of connecting any battery chemistry selected from lead, lithium ion, Aqueous sodium, Vanadium redox, Zink air and like. In the preferred embodiment, the hybrid inverter (50) is compatible with a battery voltage ranges from 40 Vdc to 1500 Vdc.

The hybrid inverter unit (50) system is susceptible to operate in an environment of 0 Degree Celsius to 50 Degree Celsius without tripping the system due to excessive heat. In the preferred embodiment, the system ratings range from few kW to Megawatts.
Again referring to the figures 1 to 3, a method for optimizing Minigrid power generation and management (150) by a system (100) (hereinafter referred to as “the method (150)” in accordance with the present invention is described. The method (150) is explained in conjunction with the system (100).
The hybrid inverter unit (50) controls the power sources (10) and sets priority of use. The energy storage unit (20) and loads (15) are given with a first priority from solar power generator (10a) and then priority is shifted to other nonrenewable sources (10b) or grid. When the renewable power sources (10a) are limited or lower, then the energy storage unit (20) will take up the loads (15). If the energy storage unit (20) is not sufficient, then diesel generator (10b) will be automatically switch ON and run with highest efficiency though the power management system of the control unit (14). Further the controller unit (12) determines the excess energy available to supply the grid and start charging the energy storage unit (20). The controller unit (12) optimizes the charging level and provide a continuous supply dynamically to the load (15) by optimizing the usage of the power sources (10) and the energy storage unit (20). Hence the hybrid inverter unit (50) takes control of energy storage unit (20) and power sources (10b) so that life of both equipments increases.
ADVANTAGES OF THE INVENTION:
1. The system (100) controls each power source (10) based on preset priority of use so that low cost or renewable power will be used as a first priority and then other sources should be used based on availability or forecast and price per kWh.

2. The system (100) is capable of supplying single phase or three phase power based on selection on HMI (Human Machine interface). The system (100) also can be used for unbalanced three phases.
3. The control unit (14) that act as a power management system facilitates optimum generation from solar/ wind / biogas power generator and hence battery life can be increased by avoiding its charging and discharging rate and cycles.
4. The system (100) provides zero transfer time when shifting from one energy source to other avoiding unexpected tripping of sensitive communication and meter loads in Minigrids.
5. The system (100) extends the battery life by monitoring the temperature and controlling the charging and the discharging rate of battery based on %SOC.
6. The system (100) is capable of taking optimized decisions based on systematic monitoring and controlling of Diesel generator operation time, loading, temperature conditions and like. Thereby reduces the fuel consumption and extends the life of diesel generator.
7. The transformer (18) protects the electronic components during the erratic load conditions, fault conditions etc. The transformer (18) step up a voltage for the Minigrid system that reduces the transmission and distribution losses of the system (100). This increases the distribution cable length, thereby reaching to many consumers.
8. The system (100) is capable of recording the data from hybrid inverter unit, sensors, and meters and can control the system as per the applications set in the control unit (14).
9. The method (150) is simple in operation and effectively controls the system (100) capable of recording the data from hybrid inverter unit, sensors, and

meters and can control the system as per the applications set in the control unit (14).
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.

We claim:
1. A system for optimizing Minigrid power generation and management
(100), the system (100) comprising:
a plurality of power sources (10) including renewable power sources (10a), and nonrenewable power sources (10b);
an energy storage unit (20);
a hybrid inverter unit (50) interconnecting the plurality of power sources (10) and energy storage unit (20) to a load (15);
a plurality of protection circuits operably connected to the hybrid inverter unit (50); and
a transformer (18) interconnecting the hybrid inverter unit (50) and the load (15), wherein the transformer (18) is capable of isolating the hybrid inverter unit (50) from the load (15) thereby protecting the electronic components during the erratic load conditions, line fault conditions and like; characterized in that, the hybrid inverter unit (50) having,
an inverter circuit (12) inter connecting the plurality of power sources (10) and energy storage unit (20) to the transformer (18),
a maximum power point tracking unit (11) operably connected to the renewable power sources (10a) and inverter unit (12),
a priority circuit (13) operably connected to the nonrenewable power sources (10b) and inverter unit (12), capable of receiving power from the plurality of nonrenewable power sources (10b) based on preset priority value,
a control unit (14) operably connected to the inverter circuit (12), the priority circuit (13) and the plurality of protection circuits, wherein the control unit (14) includes a power management

module that optimizes the power generation by setting priority to the plurality of power sources (10) in accordance with stored data, monitoring the inverter circuit (12) parameters, protection circuits and cooling fan status, and provide access to a remote user; and
a human machine interface (HMI) (19) operably connected
to the control unit facilitating a user interaction with the hybrid
inverter unit (50);
wherein the maximum power point tracking unit (11), inverter circuit (12), priority circuit (13), control unit (14) and the human machine interface (19) are integrated together and assembled as a single unit to form the hybrid inverter unit (50) capable of supplying power to a grid and runs in parallel thereto;
wherein the hybrid inverter unit (50) integrates the plurality of power sources (10) and energy storage unit (20), sets priority of use to each power sources (10) and supplies power to the load (15) based on preset priority values by keeping zero milliseconds switching time for the power sources, such that renewable power source are used on priority and other sources being consumed based on availability, cost and dynamic pricing conditions.
2. The system (100) as claimed in claim 1, wherein the renewable and/or non-renewable sources (10) include solar power generator (10a), diesel generator, biogas generator, biomass generator, wind and like.
3. The system (100) as claimed in claim 1, wherein the energy storage unit (20) include a battery management unit and a plurality of battery having a battery chemistry selected from lead, advanced lead, lithium ion, Aqueous sodium, Vanadium redox and Zink air.
4. The system (100) as claimed in claim 1, wherein the protection circuits are any one selected from manually operating and automated.

5. The system as claimed in claim 1, wherein the human interface (19) comprises a touch screen display capable of displaying the values of system performance and facilitating control operations.
6. The system as claimed in claim 1, wherein the plurality of protection circuits include static relays and disconnecting relays that operate automatically, an HVAC controller, fire controller, a plurality of circuit breakers and an emergency switch.
7. The system as claimed in claim 1, wherein the control unit (14) comprises a processing unit, a memory unit and a plurality of interfacing modules.
8. The system as claimed in claim 1, wherein the priority circuit (13) includes a plurality of circuit breakers, a plurality of current and voltage sensors, a plurality of relays, a plurality of automatic transfer switches and a control circuit to make integration and prioritization of the plurality of renewable and nonrenewable power sources (10).
9. A method (150) for optimizing Minigrid power generation and management (100) by a system (100) having a plurality of renewable and/or non-renewable power sources (10) for supplying electrical energy, a hybrid inverter unit (50) integrating and interconnecting the plurality of power sources to a load (15) having a maximum power point tracking unit (11) connecting the renewable power sources (10), a priority circuit (13) connecting the nonrenewable power sources (10b) to an inverter circuit (12), a control unit (14) associated with a power management module, a transformer (18) isolating the hybrid inverter unit (50) from the load (15) and a plurality of protection circuits, the method (150) comprising:
a. control unit (14) receiving data from the energy storage unit (20) and power sources (10) and determining the availability of the power sources (10);

b. setting priority value to the power sources (10) by the controller;
c. allocating available energy source (10) to the load (15) by the
priority circuit (11) based on the priority value set;
d. supplying energy to the load (15) through the transformer (18);
e. controller unit (14) determining the excess energy available to
supply the grid;
f. supplying the excess energy to charge the storage device (20) and
optimize the charging level; and
g. providing a continuous supply dynamically to the load (15) by
optimizing the usage of the power sources (10) and the storage unit
(20);
wherein, the a plurality of power sources (10) and storage unit are integrated in the hybrid inverter unit (50) and supply power to a grid.
10. The method (150) as claimed in claim 7, wherein the prioritization of the power sources (10) is based on time of day, cost, status, availability and total amount of available energy from the power sources (10) during a selected time of the day.
11. The method (150) as claimed in claim 7, wherein the prioritization of the power sources (10) having a highest priority allotted to charging of the storage unit (20) through solar power generator (10a) input based on the time of the day and the status of the storage unit (20).