Distributed power generation electric energy quality control method and device and new energy power generation system

Abstract

The invention relates to a distributed power generation electric energy quality control method and device and a new energy power generation system, and belongs to the technical field of electric energy control. When electric energy output to a power grid by an inverter connected with a distributed power generation unit (DG) does not meet the electric energy quality requirement but does not cause a fault, primary frequency modulation is performed on each DG by using classical droop control, and then secondary frequency modulation is performed; in the secondary frequency modulation, the distributed auxiliary control output is subtracted from the active frequency control output corresponding to each DG to obtain a frequency control variable corresponding to each DG, the active output reference value corresponding to each DG is obtained according to the frequency control variable to serve as the rated active power of each DG, and the frequency of the droop control output is adjusted, so that the frequency output by the DG is changed, and the electric energy quality is improved; the coordination control among the distributed power generation units is realized, and the problems in the prior art that the control system is collapsed due to the failure of the central controller, the pressure of the communication system is overlarge, and the coordination control among the distributed power generation units cannot be carried out due to no use of the central controller are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric energy control, and in particular relates to a distributed power generation power quality control method, device and a new energy power generation system. Background Art

[0002] The new power system is an important part of the new energy system. The future new power system will be infiltrated with a large number of new energy power generation represented by photovoltaic and wind power generation. Although new energy power generation has the advantages of being green and sustainable, it also has disadvantages such as instability, geographical restrictions, and high construction costs. The instability of resources such as wind and light has brought a series of problems to the power grid, such as difficulty in relay protection coordination and reduced power quality.

[0003] In order to solve the power quality problem of frequency fluctuation of renewable energy generation caused by uncertainty, randomness, volatility and load fluctuation of wind and light resources, some researchers have improved the power quality of renewable energy generation by adopting centralized control based on central controller. The coordinated control protection device installed at the point of common coupling (PCC) is used as the central controller, and the terminal installed at each distributed generation unit (DG) or load is used as the local controller. The central controller first receives and processes the information of the corresponding DG or load collected by each local controller, and then sends the processed information signal to each DG through the communication system to realize the control of DG; the local controller is responsible for collecting analog information and executing the command issued by the central controller. Although centralized control can improve the power quality problem, on the one hand, it is overly dependent on the central controller. If there is a problem with the central controller, the entire control system will crash; on the other hand, it is necessary to collect all DG information and send control instructions to each DG through the communication system, which will bring great pressure to the communication system and deteriorate the system control performance due to information transmission delay. In the prior art, another type of decentralized control does not have a central controller or a communication system, and only controls the DG locally through a local controller, but cannot achieve coordinated control between the DGs. Summary of the invention

[0004] The purpose of the present invention is to provide a distributed power generation power quality control method, device and new energy power generation system to solve the problems in the prior art such as central controller failure leading to control system crash, excessive pressure on the communication system and the inability to coordinate control between distributed power generation units due to the lack of a central controller.

[0005] In order to solve the above technical problems, the present invention provides a distributed generation power quality control method, the method comprising:

[0006] If the power output to the grid by the inverter connected to the distributed generation unit DG does not meet the power quality requirements but does not cause a fault, each DG is first subjected to primary frequency regulation using classic droop control, and then secondary frequency regulation;

[0007] The secondary frequency regulation is as follows: the output of the active frequency control corresponding to each DG is calculated minus the output of the distributed auxiliary control to obtain the frequency control variable corresponding to each DG, and the active output reference value corresponding to each DG is obtained according to the frequency control variable and used as the rated active power of each DG for improved droop control; the active frequency control is based on the deviation between the DG output active power and the rated active power, and the deviation between the DG output frequency and the rated frequency; the distributed auxiliary control is a multi-agent collaborative control with the ratio of the DG output active power to the available active capacity as the state variable of the agent and each adjacent DG adopts a finite-time consensus algorithm.

[0008] Furthermore, the calculation formula of distributed auxiliary control is as follows:

[0009]

[0010] In the formula, ψ i is the output of the distributed auxiliary control corresponding to the i-th distributed generation unit, b1 and b2 are control coefficients and b1>0, b2>0, n is the number of distributed generation units, a ij is the weight of the information transmitted from the jth distributed generation unit to the ith distributed generation unit, sign is the sign function, α is the control factor and 0<α<1, P i is the active power output of the i-th distributed generation unit, P j is the active power output of the jth distributed generation unit, P iky is the available active capacity of the ith distributed generation unit, P jky is the available active capacity of the jth distributed generation unit.

[0011] Furthermore, the calculation formula for active frequency control is as follows:

[0012]

[0013] In the formula, is the output of active frequency control corresponding to the i-th distributed generation unit, d is the proportional coefficient, f iDGsc is the output frequency of the ith distributed generation unit, f * is the rated frequency of the distributed generation unit, P iDGsc is the output active power of the i-th distributed generation unit, is the rated active power of the i-th distributed generation unit.

[0014] Furthermore, the calculation formula for obtaining the active output reference value of each distributed generation unit according to the frequency control variable is as follows:

[0015]

[0016] Where P ic is the active output reference value of the i-th distributed generation unit, n is the total number of distributed generation units, S i is the apparent power of the i-th distributed generation unit, Q i is the output reactive power of the i-th distributed generation unit, S n is the apparent power of the nth distributed generation unit, Q n is the output reactive power of the nth distributed generation unit, is the frequency control variable corresponding to the i-th distributed generation unit.

[0017] Furthermore, if the frequency output by the inverter to the low-voltage side of the transformer is greater than the upper limit of the power quality fluctuation frequency and less than the upper limit of the relay protection action frequency, or is less than the lower limit of the power quality fluctuation frequency and greater than the lower limit of the relay protection action frequency, then it is determined that the electric energy output to the power grid by the inverter connected to the distributed generation unit does not meet the power quality requirements but does not cause a fault, wherein the upper limit of the power quality fluctuation frequency is less than the upper limit of the relay protection action frequency, and the lower limit of the power quality fluctuation frequency is greater than the lower limit of the relay protection action frequency.

[0018] Furthermore, if the electric energy outputted to the power grid by the inverter connected to the distributed generation unit does not meet the power quality requirements and causes a fault, a relay protection action is performed.

[0019] Furthermore, if the frequency output by the inverter to the low-voltage side of the transformer is greater than the upper limit of the relay protection action frequency or less than the lower limit of the relay protection action frequency, it is determined that the electric energy output to the power grid by the inverter connected to the distributed power generation unit does not meet the power quality requirements, resulting in a fault, wherein the upper limit of the power quality fluctuation frequency is less than the upper limit of the relay protection action frequency, and the lower limit of the power quality fluctuation frequency is greater than the lower limit of the relay protection action frequency.

[0020] Furthermore, the classic droop control formula is as follows:

[0021] f iDGsc =f * -m i (P iDGsc -P i * )

[0022] In the formula, f iDGsc is the output frequency of the ith distributed generation unit, f * is the rated frequency of the distributed generation unit, mi is the active power droop coefficient of the i-th distributed generation unit, P iDGsc is the output active power of the i-th distributed generation unit, is the rated active power of the i-th distributed generation unit.

[0023] In order to solve the above technical problems, the present invention also provides a computer device, including a processor, which executes a computer program to implement the steps of the distributed generation power quality control method.

[0024] In order to solve the above technical problems, the present invention also provides a new energy power generation system, comprising at least two distributed power generation units, the distributed power generation units are used to connect to the power grid through corresponding inverters, adjacent distributed power generation units are communicated and connected, and the distributed power generation units are used to perform power quality control using a distributed power generation power quality control method.

[0025] The beneficial effects of the above technical solution are as follows: the present invention is an improved invention creation. When the inverter connected to the distributed generation unit DG outputs power to the grid that does not meet the power quality requirements but does not cause a fault, the present invention first uses the classic droop control to perform primary frequency modulation on each DG, and then performs secondary frequency modulation; since the droop control is a differential control, the distribution of the active power output by each DG during frequency modulation is not completely accurate, resulting in a deviation in the grid frequency, and therefore the output of the active frequency control corresponding to each DG is calculated by secondary frequency modulation minus the output of the distributed auxiliary control to obtain the frequency control variable corresponding to each DG, and the active output reference value corresponding to each DG is obtained according to the frequency control variable and used as the rated active power of each DG, and the frequency of the droop control output is adjusted, thereby changing the frequency of the DG output, so as to achieve the effect of reducing the deviation between the actual frequency of the grid and the rated frequency, thereby improving the power quality, realizing coordinated control between distributed generation units, and solving the problems in the prior art of the central controller failure leading to the collapse of the control system, the excessive pressure on the communication system, and the inability to coordinate control between distributed generation units due to the lack of the central controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a method flow chart of an embodiment of a new energy power generation system of the present invention;

[0027] Figure 2 It is a structural schematic diagram of an embodiment of a new energy power generation system of the present invention. DETAILED DESCRIPTION

[0028] The present invention focuses on providing a distributed generation power quality control method, the method comprising:

[0029] If the power output to the grid by the inverter connected to the distributed generation unit DG does not meet the power quality requirements but does not cause a fault, each DG is first subjected to primary frequency regulation using classic droop control, and then secondary frequency regulation;

[0030] The secondary frequency regulation is as follows: the output of the active frequency control corresponding to each DG is calculated minus the output of the distributed auxiliary control to obtain the frequency control variable corresponding to each DG, and the active output reference value corresponding to each DG is obtained according to the frequency control variable and used as the rated active power of each DG for improved droop control; the active frequency control is based on the deviation between the DG output active power and the rated active power, and the deviation between the DG output frequency and the rated frequency; the distributed auxiliary control is a multi-agent collaborative control with the ratio of the DG output active power to the available active capacity as the state variable of the agent and each adjacent DG adopts a finite-time consensus algorithm.

[0031] In the present invention, when the inverter connected to the distributed generation unit DG outputs power to the grid that does not meet the power quality requirements but does not cause a fault, each DG is first subjected to primary frequency modulation using classic droop control, and then subjected to secondary frequency modulation; since droop control is a differential control, the distribution of the active power output by each DG is not completely accurate during frequency modulation, resulting in a deviation in the grid frequency, and therefore, the output of the active frequency control corresponding to each DG is calculated by secondary frequency modulation minus the output of the distributed auxiliary control to obtain the frequency control variable corresponding to each DG, and the active output reference value corresponding to each DG is obtained according to the frequency control variable and used as the rated active power of each DG, and the frequency of the droop control output is adjusted, thereby changing the frequency of the DG output, and achieving the effect of reducing the deviation between the actual frequency of the grid and the rated frequency, thereby improving the power quality, realizing coordinated control between distributed generation units, and solving the problems in the prior art of control system collapse caused by failure of the central controller, excessive pressure on the communication system, and inability to coordinate control between distributed generation units due to the lack of the central controller.

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0033] A new energy power generation system embodiment:

[0034] A new energy power generation system of the present embodiment includes N distributed power generation units. The distributed power generation units in the present embodiment are specifically photovoltaic power generation units. Each photovoltaic power generation unit is connected to the power grid through an inverter, a transformer and an AC busbar connected in sequence. It also includes a frequency sampling module, a tripping module and a control module. The frequency sampling module is used to collect the low-voltage side frequency of the transformer of the distributed power generation unit. The control module is connected to the frequency sampling module. The communication module is used to enable information exchange between adjacent distributed power generation units. The tripping module is arranged between the inverter and the transformer for performing relay protection actions. The control module includes a liquid crystal display and an operating keyboard. The control module is used to implement a distributed power generation power quality control method. The specific connection relationship is as follows: Figure 2 shown.

[0035] The distributed generation power quality control method specifically includes the following steps: Figure 1 As shown:

[0036] 1) First, install a device with measurement, protection, and power quality control functions at the box-type transformer adjacent to the DG inverter. After the device is powered on, collect the frequency value of the inverter output to the low-voltage side of the box-type transformer through the installed voltage and current transformers, and use the analog quantities such as the transformer low-voltage side frequency as the inverter output analog quantity.

[0037] 2) Determine whether the frequency output from the inverter to the low-voltage side of the box-type transformer exceeds the upper limit of power quality fluctuation or the lower limit of power quality fluctuation, where the upper and lower limits of power quality fluctuation can be customized.

[0038] 3) If the frequency output from the inverter to the low-voltage side of the box-type transformer exceeds the upper limit of the power quality fluctuation frequency or exceeds the lower limit of the power quality fluctuation, determine whether the frequency output from the inverter to the low-voltage side of the box-type transformer exceeds the upper limit of the relay protection action or exceeds the lower limit of the relay protection action, otherwise return to step 2); the upper and lower limits of the relay protection action can be customized.

[0039] 4) If the frequency output from the inverter to the low-voltage side of the box-type transformer does not exceed the upper limit of the relay protection action or the lower limit of the relay protection action, power quality control is performed; if the frequency output from the inverter to the low-voltage side of the box-type transformer exceeds the upper limit of the relay protection action or the lower limit of the relay protection action, the relay protection action is performed to trip the circuit breaker between the inverter and the low-voltage side of the transformer and cut off the fault.

[0040] The power quality control is to first use classical droop control to perform primary frequency regulation on each DG, and then perform secondary frequency regulation; the secondary frequency regulation is: calculate the output of the active frequency control corresponding to each DG minus the output of the distributed auxiliary control to obtain the frequency control variable corresponding to each DG, and obtain the active output reference value corresponding to each DG according to the frequency control variable and use it as the rated active power of each DG for improved droop control; the active frequency control is based on the deviation between the DG output active power and the rated active power, and the deviation between the DG output frequency and the rated frequency; the distributed auxiliary control is a multi-agent collaborative control with the ratio of the DG output active power to the available active capacity as the state variable of the intelligent agent and each adjacent DG adopts a finite-time consensus algorithm.

[0041] Droop control simulates the droop characteristics of synchronous generators in traditional power systems. First, the voltage and current output by the DG are measured, and the power calculation is performed to obtain the active power and reactive power output by the DG. Then, the active power, reactive power, rated active power, and rated reactive power are passed through the droop control link to obtain the DG output frequency and voltage amplitude, so that the DG outputs a stable voltage and frequency, thereby reasonably distributing the active power and reactive power output by each DG in the system. Since droop control is a differential control, the distribution of the active power output of each DG is not completely accurate during frequency modulation, resulting in deviations in the grid frequency. Therefore, the rated active power of the DG can be changed through secondary frequency modulation to adjust the frequency of the droop control output, thereby changing the frequency of the DG output, and achieving the effect of reducing the deviation between the actual frequency of the grid and the rated frequency.

[0042] The classic droop control formula is as follows:

[0043] f iDGsc =f * -m i (P iDGsc -P i * )

[0044] In the formula, f iDGsc is the output frequency of the ith distributed generation unit, f * is the rated frequency of the distributed generation unit, m i is the active power droop coefficient of the i-th distributed generation unit, P iDGsc is the output active power of the i-th distributed generation unit, is the rated active power of the i-th distributed generation unit.

[0045] Secondary frequency regulation consists of two parts: one is active frequency control, and the other is distributed auxiliary control. The overall principle is to use the distributed auxiliary controller with multi-agent consensus algorithm to output the frequency deviation correction, and then use the frequency deviation correction for active frequency control, output the active power output reference value of the distributed power generation unit, and finally use the reference value for droop control, perform frequency control, and correct the deviation between the inverter output frequency and the rated frequency.

[0046] The formula for secondary frequency modulation is as follows:

[0047]

[0048] In the formula, is the frequency control variable corresponding to the i-th distributed generation unit, d is the proportional coefficient, f iDGsc is the output frequency of the ith distributed generation unit, f * is the rated frequency of the distributed generation unit, P iDGsc is the output active power of the i-th distributed generation unit, P i * is the rated active power of the i-th distributed generation unit, ψ i is the output of the distributed auxiliary control corresponding to the i-th distributed generation unit, b1 and b2 are control coefficients and b1>0, b2>0, n is the number of distributed generation units, a ij is the weight of the information transmitted from the jth distributed generation unit to the ith distributed generation unit, sign is the sign function, α is the control factor and 0<α<1, P i is the active power output of the i-th distributed generation unit, P j is the active power output of the jth distributed generation unit, P iky is the available active capacity of the ith distributed generation unit, P jky is the available active capacity of the jth distributed generation unit.

[0049] If the jth distributed generation unit does not transmit information to the ith distributed generation unit, then a ij =0.

[0050]

[0051] The above formula is distributed auxiliary control. The principle of distributed auxiliary control is: take the ratio of the active output of each distributed generation unit to the available active capacity as the state variable of the intelligent agent, and realize distributed control through the control law of the finite time consensus algorithm according to the active power output of each distributed generation unit and the active power output of the adjacent distributed generation units, and obtain the frequency deviation correction value ψ of the i-th distributed generation unit i .

[0052]

[0053] In the formula, is the output of active frequency control corresponding to the i-th distributed generation unit.

[0054] The above formula is active frequency control, and ψ i Used for active frequency control to calculate the frequency control variable Frequency control variable H i Used to control the active power output of distributed generation according to frequency changes.

[0055] Get the frequency control variable After that, the active output reference value P of the distributed generation unit is further calculated. ic , P ic For droop control, the classic droop control Update to P ic , thus achieving frequency control.

[0056] Active output reference value P of distributed generation unit ic The specific calculation formula is as follows:

[0057]

[0058] Where P ic is the reference value of the active power output of the i-th distributed generation unit, σ i is the control coefficient of the active power output of the i-th distributed generation unit.

[0059] The control coefficient σ of the output active power of the i-th distributed generation unit i It is calculated by the available active capacity of the i-th distributed generation unit. The specific calculation formula is as follows:

[0060]

[0061] Where P iky is the available active capacity of the ith distributed generation unit, P nky is the available active capacity of all distributed generation units in the system, n is the total number of distributed generation units, S i is the apparent power of the i-th distributed generation unit, Q i is the output reactive power of the i-th distributed generation unit, S n is the apparent power of the nth distributed generation unit, Q n is the output reactive power of the nth distributed generation unit.

[0062] Distributed active frequency controlψ i The ratio of each DG's active output to available active capacity is used as the state variable of the intelligent agent. According to the active power output of each DG and the active power output of the adjacent DG, distributed control is achieved through the control law of the finite time consensus algorithm. This method can adjust the frequency of the distributed generation DG output by controlling the active power of the distributed generation, so that the DG output frequency and the DG output active power flow maintain a proportional relationship. Thus, the active power reference value is output for classic droop control to reduce the deviation between the frequency and the rated value.

[0063] The present invention establishes communication connection between devices in a hand-in-hand manner. Adjacent distributed generation units share information such as active power, reactive power, voltage, and current, realizes coordinated control of distributed generation units, and first uses classic droop control to perform primary frequency modulation on each DG, and then performs secondary frequency modulation; since droop control is a differential control, the distribution of active power output by each DG during frequency modulation is not completely accurate, resulting in deviation of the grid frequency, so the output of active frequency control corresponding to each DG is calculated by secondary frequency modulation minus the output of distributed auxiliary control to obtain the frequency control variable corresponding to each DG, and the active output reference value corresponding to each DG is obtained according to the frequency control variable and used as the rated active power of each DG, and the frequency of the droop control output is adjusted, thereby changing the frequency of the DG output, achieving the effect of reducing the deviation between the actual frequency of the grid and the rated frequency, thereby improving the quality of power, realizing coordinated control between distributed generation units, and solving the problems in the prior art of control system collapse caused by failure of the central controller, excessive pressure on the communication system, and inability to coordinate control between distributed generation units due to the lack of the central controller.

[0064] Computer device embodiment:

[0065] The present invention also provides a computer device, including a processor, which executes a computer program to implement the steps of the distributed power generation power quality control method. The specific process, principle and effect have been described in detail in the embodiment of the new energy power generation system, and will not be repeated here.

[0066] Distributed generation power quality control method embodiment:

[0067] A distributed power generation power quality control method, the method comprising:

[0068] If the power output to the grid by the inverter connected to the distributed generation unit DG does not meet the power quality requirements but does not cause a fault, each DG is first subjected to primary frequency regulation using classic droop control, and then secondary frequency regulation;

[0069] Secondary frequency regulation is: calculate the output of active frequency control corresponding to each DG minus the output of distributed auxiliary control to obtain the frequency control variable corresponding to each DG, obtain the active output reference value corresponding to each DG according to the frequency control variable and use it as the rated active power of each DG for improved droop control; active frequency control is based on the deviation between the DG output active power and the rated active power, and the deviation between the DG output frequency and the rated frequency; distributed auxiliary control is a multi-agent collaborative control with the ratio of DG output active power to available active capacity as the state variable of the agent and each adjacent DG adopts a finite time consensus algorithm. The specific process, principle and effect have been described in detail in the embodiment of the new energy power generation system, and will not be repeated here.

[0070] Specific implementation methods are given above, but the present invention is not limited to the described implementation methods. The basic idea of ​​the present invention lies in the above basic scheme. For ordinary technicians in this field, it does not take creative work to design various deformed models, formulas, and parameters according to the teachings of the present invention. Changes, modifications, substitutions, and variations of the implementation methods without departing from the principles and spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. A distributed power generation power quality control method, characterized in that: The method includes: If the power output to the grid by the inverter connected to the distributed generation unit DG does not meet the power quality requirements but does not cause a fault, each DG is first subjected to primary frequency regulation using classic droop control, and then secondary frequency regulation; The secondary frequency regulation is as follows: the output of the active frequency control corresponding to each DG is calculated minus the output of the distributed auxiliary control to obtain the frequency control variable corresponding to each DG, and the active output reference value corresponding to each DG is obtained according to the frequency control variable and used as the rated active power of each DG for improved droop control; the active frequency control is based on the deviation between the DG output active power and the rated active power, and the deviation between the DG output frequency and the rated frequency; the distributed auxiliary control is a multi-agent collaborative control with the ratio of the DG output active power to the available active capacity as the state variable of the agent and each adjacent DG adopts a finite-time consensus algorithm.

2. The distributed generation power quality control method according to claim 1, characterized in that: The calculation formula of the distributed auxiliary control is as follows: In the formula, ψ i is the output of the distributed auxiliary control corresponding to the i-th distributed generation unit, b1 and b2 are control coefficients and b1>0, b2>0, n is the number of distributed generation units, a ij is the weight of the information transmitted from the jth distributed generation unit to the ith distributed generation unit, sign is the sign function, α is the control factor and 0<α<1, P i is the active power output of the i-th distributed generation unit, P j is the active power output of the jth distributed generation unit, P iky is the available active capacity of the ith distributed generation unit, P jky is the available active capacity of the jth distributed generation unit.

3. The distributed generation power quality control method according to claim 1, characterized in that: The calculation formula of the active frequency control is as follows: In the formula, is the output of active frequency control corresponding to the i-th distributed generation unit, d is the proportional coefficient, f iDGsc is the output frequency of the ith distributed generation unit, f * is the rated frequency of the distributed generation unit, P iDGsc is the output active power of the i-th distributed generation unit, is the rated active power of the i-th distributed generation unit.

4. The distributed generation power quality control method according to claim 1, characterized in that: The calculation formula for obtaining the active output reference value of each distributed generation unit according to the frequency control variable is as follows: Where P ic is the active output reference value of the i-th distributed generation unit, n is the total number of distributed generation units, S i is the apparent power of the i-th distributed generation unit, Q i is the output reactive power of the i-th distributed generation unit, S n is the apparent power of the nth distributed generation unit, Q n is the output reactive power of the nth distributed generation unit, is the frequency control variable corresponding to the i-th distributed generation unit.

5. The distributed generation power quality control method according to claim 1, characterized in that: If the frequency output from the inverter to the low-voltage side of the transformer is greater than the upper limit of the power quality fluctuation frequency and less than the upper limit of the relay protection action frequency, or is less than the lower limit of the power quality fluctuation frequency and greater than the lower limit of the relay protection action frequency, it is determined that the electric energy output to the grid by the inverter connected to the distributed generation unit does not meet the power quality requirements but does not cause a fault, wherein the upper limit of the power quality fluctuation frequency is less than the upper limit of the relay protection action frequency, and the lower limit of the power quality fluctuation frequency is greater than the lower limit of the relay protection action frequency.

6. The distributed generation power quality control method according to claim 1, characterized in that: If the power output to the grid by the inverter connected to the distributed generation unit does not meet the power quality requirements and causes a fault, the relay protection action is performed.

7. The distributed generation power quality control method according to claim 6, characterized in that: If the frequency output from the inverter to the low-voltage side of the transformer is greater than the upper limit of the relay protection action frequency or less than the lower limit of the relay protection action frequency, it is determined that the electric energy output from the inverter connected to the distributed generation unit to the grid does not meet the power quality requirements, resulting in a fault, wherein the upper limit of the power quality fluctuation frequency is less than the upper limit of the relay protection action frequency, and the lower limit of the power quality fluctuation frequency is greater than the lower limit of the relay protection action frequency.

8. The distributed generation power quality control method according to claim 1, characterized in that: The classic droop control formula is as follows: In the formula, f iDGsc is the output frequency of the ith distributed generation unit, f * is the rated frequency of the distributed generation unit, m i is the active power droop coefficient of the i-th distributed generation unit, P iDGsc is the output active power of the i-th distributed generation unit, is the rated active power of the i-th distributed generation unit.

9. A computer device comprising a processor, characterized in that: The processor executes a computer program to implement the steps of the distributed generation power quality control method according to any one of claims 1 to 8.

10. A new energy power generation system, comprising at least two distributed power generation units, wherein the distributed power generation units are connected to a power grid through corresponding inverters, characterized in that: Adjacent distributed power generation units are communicatively connected, and the distributed power generation units are used to perform power quality control using the distributed power generation power quality control method as described in any one of claims 1 to 8.

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