Systems and methods for converterless solar PV operation in hybrid renewable microgrids

Patent metadata

Field	Value
Publication number	US-12355257-B2
Application number	US-202418647798-A
Country	US
Kind code	B2
Filing date	Apr 26, 2024
Priority date	Oct 10, 2023
Publication date	Jul 8, 2025
Grant date	Jul 8, 2025

Abstract

A device and method for managing power transmission to a power grid from a Hybrid Grid Connected System (HGCS) is presented. The HGCS includes a plurality of energy resources, including of solar photovoltaic cells (PV), wind power generation, a battery energy storage system (BESS) and a fuel cell system paired with an electrolyzer. Energy sources are connected by a DC-link to a power electronic converter which supplies power to the power grid. A controller is configured to calculate the total power, maximize transmission of power to the power grid from the primary sources, supply the net power to the power grid from the fuel cell system and use the power generated by the PV system and the wind power system for charging the BESS and powering the electrolyzer system based on the relative state of charge of the BESS and the voltage of the DC-link.

First claim

The invention claimed is:

1. A hybrid grid connected system (HGCS) for managing power transmission to a power grid from a plurality of power generation sources comprising:
a plurality of electrical generation sources including a primary source comprising a solar photovoltaic cell (PV) system and a wind power generation system, a secondary source comprising a battery energy storage system (BESS) and a tertiary source comprising a fuel cell system operatively connected to an electrolyzer system;
a DC-link connected to a power electronic converter of the HGCS, wherein the power electronic converter is connected to the power grid, wherein each of the plurality of electrical generations sources is connected to the DC-link, wherein the power electronic converter is configured to transmit power generated from the plurality of electrical generation sources to the power grid, wherein the DC-link is located between a rotor side converter (RSC) and a grid side converter (GSC);
a voltmeter configured to measure the voltage between the positive rail and the negative rail of the DC-link;
a power meter connected to the DC-link, wherein the power meter is configured to measure a net power in the DC-link;
a controller connected to the power electronic converter, wherein the controller includes electrical circuitry, a memory storing program instructions and at least one processor configured to execute the program instructions to:
maximize transmission of power to the power grid from the primary sources relative to the secondary source and the tertiary source via the GSC; a
supply the net power to the power grid from the fuel cell system when the voltage of the BESS is less than a reference voltage of the DC-link; and
use the power generated by at least one of the PV system and the wind power generation system for powering one of the BESS and the electrolyzer system based on the voltage of the DC-link being greater the reference voltage of the DC-link.

2. The HGCS system of claim 1 , wherein the controller is configured to:
receive the power generated by the PV system at the DC-link;
receive the voltage of the DC-link;
receive the net power of the DC-link;
calculate a sum of the powers of the PV system, the BESS, the wind power generation system and the fuel cell system;
compare the voltage of the DC-link to the reference voltage of the DC-link;
when the voltage at the DC-link is greater than less than a reference voltage of the DC-link, transmit the power generated by the PV system to the power grid via the GSC.

3. The HGCS system of claim 1 , wherein the controller is further configured to:
use at least a portion of the net power to recharge the BESS based on a state of charge of the BESS being below a first threshold, and
transmit a remaining portion of the net power to power the electrolyzer system when the state of charge of the BESS is equal to or exceeds the first threshold.

4. The HGCS system of claim 1 , wherein the controller is further configured to:
supply the net power to the power grid from the BESS based on a state of charge of the BESS being within a specified range, and
supply the net power to the power grid from the fuel cell system based on the state of charge of the BESS being outside of the specified range.

5. The HGCS system of claim 4 , wherein the controller is further configured to:
supply the net power to the power grid from the BESS based on a state of charge of the BESS is in the specified range of greater than or equal to 20% and less than or equal to 80%, and
supply the net power to the power grid from the fuel cell system based on the state of charge of the BESS is less than 20%; and
supply the net power to the electrolyzer based on the state of charge of the BESS being greater than 80%.

6. The HGCS system of claim 4 , wherein the controller is configured to power the electrolyzer system by the remaining portion of the net power to generate hydrogen and store the hydrogen in a hydrogen tank.

7. The HGCS system of claim 6 , further comprising:
an anode of the fuel cell connected to receive oxygen from an air compressor;
a cathode of the fuel cell connected to receive hydrogen from the hydrogen tank;
wherein electricity generated by the fuel cell is supplied to the GSC and delivered to the power grid when the voltage of the DC-link is less than the reference voltage of the DC-link and the state of charge of the BESS is less than 20%.

8. The HGCS system of claim 7 , further comprising:
a positive output terminal of the BESS connected to a first inductor, wherein the first inductor is connected to a positive input terminal of a DC/DC buck boost converter;
a negative output terminal of the BESS connected to a negative input terminal of the DC/DC buck boost converter;
a positive output terminal of the DC/DC buck boost converter connected to the positive rail of the DC-link;
a negative output terminal of the DC/DC buck boost converter connected to the negative rail of the DC-link;
a positive input terminal of a DC-DC buck converter connected to the positive rail of the DC-link;
a negative input terminal of the DC-DC buck converter connected to the negative rail of the DC-link;
a positive output terminal of the DC-DC buck converter connected to a second inductor;
an anode of the electrolyzer connected to the second inductor;
a negative output terminal of the DC-DC buck converter connected to a cathode of the electrolyzer, wherein the electrolyzer is configured to generate hydrogen and oxygen gases when the state of charge of the BESS is greater than 80%; and
a hydrogen tank configured to store the hydrogen generated by the electrolyzer.

9. The HGCS system of claim 8 , further comprising:
at least one wind turbine of the wind power generation system connected to an input terminal of a doubly fed induction generator (DFIG);
a first output terminal of the DFIG connected directly to the power grid;
a second output terminal of the DFIG connected to the RSC, wherein the RSC is connected to the DC-link based on one of the SOC of the BESS being less than the first threshold and a set of reactive components at the DC-link being less than or greater than a reactive reference threshold.

10. The HGCS system of claim 9 , wherein:
the electrolyzer is selected from a group including a solid oxide electrolyzer, an alkaline electrolyzer, and a membrane electrolyzer; and
the fuel cell system includes a solid oxide fuel cell.

11. A method of managing power transmission to a power grid from a hybrid grid connected system (HGCS), the HGCS including
a plurality of electrical generation sources including a primary source comprising a solar photovoltaic cell (PV) system and a wind power generation system, a secondary source comprising a battery energy storage system (BESS) and a tertiary source comprising a fuel cell system operatively connected to an electrolyzer system, wherein each electrical generation source is connected to a DC-link of a power electronic converter connected to the power grid, wherein the power electronic converter is configured to transmit power generated by the plurality of electrical generation sources of the HGCS to the power grid, wherein the DC-link is connected between a rotor side converter (RSC) and a grid side converter (GSC), the method comprising:
receiving the power generated from the PV system at the DC-link and transmitting the power to the power grid via the GSC;
measuring, with a voltage meter, a voltage of the DC-link;
receiving, by the controller, the voltage of the DC-link;
measuring, with a power meter, a net power in the DC-link;
receiving, by the controller, the net power in the DC-link;
calculating, by the

Assignees

• Univ King Fahd Pet & Minerals
• Saudi Data And Artificial Intelligence Authority Sdaia
• Saudi Data and Artificial Intelligence Authority

Inventors

• Gulzar Muhammad Majid
• Khalid Muhammad

Classifications

• H02J2103/35

  Grid-level management of power transmission or distribution systems, e.g. load flow analysis or active network management · CPC title

• H02J2101/40

  Hybrid power plants, i.e. a plurality of different generation technologies being operated at one power plant · CPC title

• H02J2101/30

  Fuel cells · CPC title

• H02J2101/28

  Wind energy · CPC title

• H02J2101/24

  Photovoltaics · CPC title