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EP-4742488-A1 - OPTICAL STORAGE POWER CONTROL METHOD AND SYSTEM

EP4742488A1EP 4742488 A1EP4742488 A1EP 4742488A1EP-4742488-A1

Abstract

The present disclosure relates to a power control method and system for a photovoltaic (PV) energy storage system, which acquire relevant electrical parameters, such as an output voltage and an output current, of a fuel generator, calculate a current real-time electricity transmission power or real-time operating frequency of the fuel generator based on the acquired relevant electrical parameters, and determine, based on a current power flow direction, whether the fuel generator is in a power output state or a power input state, thereby determining whether the fuel generator is in an abnormal state. When it is detected that the fuel generator experiences or is about to experience reverse flow, an inverter is controlled to reduce an absolute output of its output power, thereby increasing an absolute output of an output power of the fuel generator and avoiding the reverse flow. When it is detected that power overload occurs in the fuel generator, the inverter is controlled to increase the absolute output of its output power, thereby reducing the absolute output of the output power of the fuel generator and avoiding the overload of the fuel generator. Therefore, the fuel generator can be protected, and it is ensured that a load can operate stably, thereby extending a service life for both the fuel generator and the load.

Inventors

  • Qin, Yijin
  • ZHANG, ZHEN
  • ZHOU, TAO

Assignees

  • Shanghai Sigeyuan Intelligent Technology Co., Ltd

Dates

Publication Date
20260513
Application Date
20230808

Claims (20)

  1. A power control method for a photovoltaic (PV) energy storage system, applicable to an operating condition in which a PV power generation system and a fuel generator jointly supply power to a load, wherein both an output phase line of an inverter of the PV power generation system and an output phase line of the fuel generator are connected to and supply power to an electrical load, the power control method comprising: S1, detecting an electricity transmission state of the fuel generator; S2, comparing detected electricity transmission state parameters with preconfigured thresholds, and determining an operating state of the fuel generator based on a comparison result; and S3, when determining that the fuel generator is in an abnormal operating state, adjusting an output power of the inverter and restoring the fuel generator to a normal operating state.
  2. The power control method for a PV energy storage system according to claim 1, wherein the preconfigured thresholds comprise a reverse flow threshold and an overload threshold, wherein the reverse flow threshold is configured to determine a reverse flow state of the fuel generator, and the overload threshold is configured to determine an overload state of the fuel generator.
  3. The power control method for a PV energy storage system according to claim 2, wherein the reverse flow threshold is a reverse-flow power threshold or a reverse-flow frequency threshold; and wherein in the step S2, a real-time electricity transmission power or a real-time operating frequency of the fuel generator is calculated based on the detected electricity transmission state parameters, or the real-time operating frequency is calculated based on a state signal fed back by the fuel generator, and wherein whether the fuel generator is in the reverse flow state is determined by comparing the real-time electricity transmission power with the reverse-flow power threshold, or by comparing the real-time operating frequency with the reverse-flow frequency threshold.
  4. The power control method for a PV energy storage system according to claim 3, wherein a power consumption symbol of the electrical load is defined as positive, output power symbols of the inverter and the fuel generator are defined as positive, and the reverse flow threshold is set as the reverse-flow power threshold, and wherein when the real-time electricity transmission power is less than the reverse-flow power threshold, it is determined that the fuel generator is in the reverse flow state, and the output power of the inverter is controlled and reduced.
  5. The power control method for a PV energy storage system according to claim 4, wherein the reverse-flow power threshold is 5% to 10% of an absolute value of a rated power of the fuel generator, and is a negative number.
  6. The power control method for a PV energy storage system according to claim 4, wherein in a process of controlling and reducing the output power of the inverter when the fuel generator is in the reverse flow state, a proportional-integral-derivative (PID) controller performs calculation based on a deviation between an allowable minimum operating power and the real-time electricity transmission power of the fuel generator to output an inverter power instruction, wherein a transfer function of the PID controller is as follows: H s = K p + K i 1 S + K d S wherein K p represents a proportional adjustment coefficient, K i represents an integral adjustment coefficient, K d represents a differential adjustment coefficient, and S represents a complex variable.
  7. The power control method for a PV energy storage system according to claim 3, wherein a power consumption symbol of the electrical load is defined as positive, output power symbols of the inverter and the fuel generator are defined as positive, and the reverse flow threshold is set as the reverse-flow frequency threshold, and wherein when the real-time operating frequency is greater than the reverse-flow frequency threshold, it is determined that the fuel generator is in the reverse flow state, and the output power of the inverter is controlled and increased.
  8. The power control method for a PV energy storage system according to claim 7, wherein the reverse-flow frequency threshold is 105% to 110% of a rated frequency of the fuel generator.
  9. The power control method for a PV energy storage system according to claim 7, wherein in a process of controlling and reducing the output power of the inverter when the fuel generator is in the reverse flow state, a PID controller performs calculation based on a deviation between an allowable maximum operating frequency and the real-time operating frequency of the fuel generator to output an inverter power instruction, wherein a transfer function of the PID controller is as follows: H s = K p + K i 1 S + K d S wherein K p represents a proportional adjustment coefficient, K i represents an integral adjustment coefficient, K d represents a differential adjustment coefficient, and S represents a complex variable.
  10. The power control method for a PV energy storage system according to any one of claims 3 to 9, wherein in the step S1, an electricity transmission voltage and an electricity transmission current of the fuel generator are detected in real time, and the real-time electricity transmission power or the real-time operating frequency is calculated based on the real-time electricity transmission voltage and electricity transmission current, or the real-time operating frequency is calculated based on the state signal fed back by the fuel generator.
  11. The power control method for a PV energy storage system according to claim 2, wherein the overload threshold is an overload power threshold or an overload frequency threshold, wherein in the step S2, a real-time electricity transmission power or a real-time operating frequency of the fuel generator is calculated based on the detected electricity transmission state parameters, or the real-time operating frequency is calculated based on a state signal fed back by the fuel generator, and wherein whether the fuel generator is in the overload state is determined by comparing the real-time electricity transmission power with the overload power threshold, or by comparing the real-time operating frequency with the overload frequency threshold.
  12. The power control method for a PV energy storage system according to claim 10, wherein a power consumption symbol of the electrical load is defined as positive, output power symbols of the inverter and the fuel generator are defined as positive, and the overload threshold is set as the overload power threshold, and wherein when the real-time electricity transmission power is greater than the overload power threshold, it is determined that the fuel generator is in the overload state, and the output power of the inverter is controlled and increased.
  13. The power control method for a PV energy storage system according to claim 12, wherein the overload power threshold is 105% to 110% of a rated power of the fuel generator, and is a positive number.
  14. The power control method for a PV energy storage system according to claim 12, wherein in a process of controlling and increasing the output power of the inverter when the fuel generator is in the overload state, a PID controller performs calculation based on a deviation between an allowable maximum operating power and the real-time electricity transmission power of the fuel generator to output an inverter power instruction, wherein a transfer function of the PID controller is as follows: H s = K p + K i 1 S + K d S wherein K p represents a proportional adjustment coefficient, K i represents an integral adjustment coefficient, K d represents a differential adjustment coefficient, and S represents a complex variable.
  15. The power control method for a PV energy storage system according to claim 11, wherein a power consumption symbol of the electrical load is defined as positive, output power symbols of the inverter and the fuel generator are defined as positive, and the overload threshold is set as the overload frequency threshold, and wherein when the real-time operating frequency is less than the overload frequency threshold, it is determined that the fuel generator is in the overload state, and the output power of the inverter is controlled and increased.
  16. The power control method for a PV energy storage system according to claim 15, wherein the overload frequency threshold is 90% to 95% of a rated frequency of the fuel generator.
  17. The power control method for a PV energy storage system according to claim 15, wherein in a process of controlling and increasing the output power of the inverter when the fuel generator is in the overload state, a PID controller performs calculation based on a deviation between an allowable minimum operating frequency and the real-time operating frequency of the fuel generator to output an inverter power instruction, wherein a transfer function of the PID controller is as follows: H s = K p + K i 1 S + K d S wherein K p represents a proportional adjustment coefficient, K i represents an integral adjustment coefficient, K d represents a differential adjustment coefficient, and S represents a complex variable.
  18. The power control method for a PV energy storage system according to any one of claims 11 to 17, wherein in the step S1, an electricity transmission voltage of the fuel generator is detected in real time, and the real-time operating frequency of the fuel generator is obtained through voltage phase-locking based on the real-time electricity transmission voltage, or the real-time operating frequency is calculated based on the state signal fed back by the fuel generator.
  19. The power control method for a PV energy storage system according to claim 1, wherein the fuel generator is a self-adaptive generator, and in the step S3, after the output power of the inverter is controlled and adjusted, the fuel generator adaptively adjusts an output power.
  20. The power control method for a PV energy storage system according to claim 1, wherein in the step S3, after the output power of the inverter is controlled and adjusted, an output power of the fuel generator is adjusted based on a total power of the electrical load and the output power of the inverter until the output power of the fuel generator is restored to an output power under the normal operating state.

Description

TECHNICAL FIELD The present disclosure relates to the technical field of photovoltaic (PV) control, and specifically, to a power control method and system for a PV energy storage system. BACKGROUND TECHNOLOGY A PV energy storage system is a PV power generation system that harnesses solar energy and includes electronic components made of special materials, such as solar panels composed of crystalline silicon panels and inverters. The PV energy storage system can be connected to a power grid or a fuel generator to achieve stable electricity transmission. When the PV energy storage system operates in an off-grid mode, the inverter in the PV energy storage system and the fuel generator can work simultaneously. For example, the fuel generator remains connected in the case of uninterrupted power supply for a load. When the inverter and the fuel generator work simultaneously, the fuel generator acts as a generator to output power externally, and ensures a stable frequency and amplitude of an output voltage. This not only ensures normal operation of the load, but also guarantees stable operation of a power generation device and extends a service life of the power generation device. In the PV energy storage system, when the inverter and the fuel generator work simultaneously, a change in a power demand of an external load results in a fluctuation in a required supply power. If no specific control is performed in this process, the fuel generator can enter an abnormal operating state such as reverse flow or overload. Reverse flow: In this state, power output of the fuel generator is reversed, meaning that an external power flows into the fuel generator. This is an abnormal operating condition and is generally not permitted. In the reverse flow state, there is a risk that an output power of the inverter flows back into the fuel generator. In this case, the fuel generator has transformed from the generator to an electric motor, and its rotational velocity can exceed a rated limit, thereby increasing the frequency of the output voltage of the fuel generator and further resulting in load damage and other problems. Overload: In this state, the output power of the fuel generator exceeds a capacity of the fuel generator. This is also an abnormal operating condition and is generally not allowed. In the overload state, there is a risk that the fuel generator is overloaded. In this case, the output power of the fuel generator exceeds the capacity of the fuel generator, and the rotational velocity of the fuel generator can drop, thereby decreasing the frequency of the output voltage of the fuel generator and further resulting in the load damage and other problems. Therefore, how to achieve power control for the PV energy storage system in combination with a specific operating condition to protect the fuel generator is a technical problem to be solved by the present disclosure. CONTENT OF THE INVENTION A primary objective of the present disclosure is to overcome at least one of the aforementioned drawbacks, and to provide a power control method and system for a PV energy storage system that can solve problems of reverse power flow and power overload of a fuel generator, ensure a stable supply voltage of a load, guarantee stable operation of the fuel generator, and extend a service life of a device. In order to achieve the above objective, the present disclosure adopts the following technical solutions: The present disclosure provides a power control method for a PV energy storage system, applicable to an operating condition in which a PV power generation system and a fuel generator jointly supply power to a load, where both an output phase line of an inverter of the PV power generation system and an output phase line of the fuel generator are connected to an electrical load to supply power to the electrical load, and including: S1, detecting an electricity transmission state of the fuel generator;S2, comparing detected electricity transmission state parameters with preconfigured thresholds, and determining an operating state of the fuel generator based on a comparison result; andS3, when determining that the fuel generator is in an abnormal operating state, adjusting an output power of the inverter and restoring the fuel generator to a normal operating state. In an implementation of the present disclosure, the preconfigured thresholds include a reverse flow threshold and an overload threshold, the reverse flow threshold is configured to determine a reverse flow state of the fuel generator, and the overload threshold is configured to determine an overload state of the fuel generator. In an implementation of the present disclosure, the reverse flow threshold is a reverse-flow power threshold or a reverse-flow frequency threshold; and in the step S2, a real-time electricity transmission power or a real-time operating frequency of the fuel generator is calculated based on the detected electricity transmission state parameters, or the