CN108695892A - A kind of distribution network voltage control method adjusted based on photovoltaic DC-to-AC converter - Google Patents

Abstract

To be simple and effective realize the voltage control to photovoltaic plant access point, the invention discloses a kind of distribution network voltage control methods adjusted based on photovoltaic DC-to-AC converter, it includes the following steps:When node voltage is out-of-limit and inverter power factor angle also be not up to capacity limit angle, into the reactive-load compensation stage of contravarianter voltage control strategy;In the case where node voltage is out-of-limit, the maximum power adjusting stage of inverter is then entered when inverter reaches maximum power but is also not up to maximum power factor angle;In the case where node voltage is out-of-limit, if inverter has reached the maximum power-factor angle, the power reduction stage of inverter is entered in the state that inverter is maintained at maximum power factor angle.The present invention obtains feeder load level and distribution situation without communicating, and can make full use of inverter capacity and carry out quick voltage adjustment, has good control effect and economy.

Description

A distribution network voltage control method based on photovoltaic inverter regulation

technical field

The invention relates to the technical field of voltage control for grid-connected photovoltaic power plants, in particular to a distribution network voltage control method based on photovoltaic inverter regulation.

Background technique

The access of photovoltaic power plants has a great impact on the operation of the distribution network, especially the impact on the voltage rise of the distribution network cannot be ignored, especially when the penetration rate of photovoltaic power plants is high, the voltage at the access point is prone to be too high, As a result, the voltage at this point exceeds the limit. At present, the allowable deviation of the three-phase power supply voltage of 10kV and below is ±7% of the rated voltage. Due to the decisiveness of the external environment on the photovoltaic output and the changing characteristics of the load demand throughout the day, according to the direction and magnitude of the output power of the distribution line, the power distribution The node voltage of the grid may be too high or too low, and the quality of the power supply voltage has a great impact on the performance of electrical equipment in the distribution network. Therefore, it is particularly important to control the voltage at the access point of the photovoltaic power station. Simple, fast and effective The voltage control measures are of great significance to the stable operation of photovoltaic power plants with high permeability.

Voltage control is an important daily task of the distribution network. At present, the control of the voltage at the access point of the photovoltaic power station in the literature is mostly realized through a parallel static var compensator (SVC), but the input SVC cannot be continuously adjusted and there are When the node voltage drops greatly, its reactive power output will drop and other disadvantages.

Therefore, it is necessary to provide a voltage control method for grid-connected photovoltaic power plants to overcome the above defects.

Contents of the invention

Aiming at the deficiencies of the existing technology, the present invention proposes a distribution network voltage control method based on photovoltaic inverter regulation, which can not only save equipment investment, but also make full use of the inverter to control the distribution network voltage. The capacity of the transformer can realize the rapid and continuous adjustment of the access point, which can better realize the voltage control of the access point of the photovoltaic power station.

The technical scheme that the present invention solves its technical problem to take is:

On the one hand, a distribution network voltage control method based on photovoltaic inverter regulation provided by an embodiment of the present invention includes the following steps:

When the node (photovoltaic power station access point) voltage exceeds the limit and the power factor angle of the inverter has not reached the capacity limit angle, enter the reactive power compensation stage of the inverter voltage control strategy;

When the node voltage exceeds the limit, when the inverter reaches the maximum power but has not yet reached the maximum power factor angle, it enters the maximum power adjustment stage of the inverter;

In the case that the node voltage exceeds the limit, if the inverter has reached the maximum power factor angle, enter the power reduction stage of the inverter when the inverter remains at the maximum power factor angle.

As a possible implementation of this embodiment, the process of entering the reactive power compensation stage of the inverter voltage control strategy includes the following steps:

When the voltage U _k of the access point of the photovoltaic power station exceeds the limit voltage U _k,lim and the power S of the inverter does not reach the maximum, it enters the reactive power compensation stage of the inverter;

In the reactive power compensation stage of the inverter, the reactive power Q _PV,b required to be emitted by the photovoltaic inverter is calculated by the following formula:

in, is the reactance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer;

By adjusting the power factor angle of the inverter, the reactive power of Q _PV,b is input, and the node voltage of the photovoltaic access point k is recorded as U _k,b at this time;

According to the node voltage U _k,b after reactive power compensation of the inverter, the reactive power Q _PV,b output by the inverter is corrected by the following formula:

Q _PV = Q _PV,b +ΔQ _PV,b

Among them, ΔQ _PV,b is the reactive power correction amount in the reactive power compensation stage of the inverter, and its calculation formula is as follows:

As a possible implementation of this embodiment, the process of entering the maximum power adjustment phase of the inverter includes the following steps:

When the power S of the inverter reaches its maximum capacity S _max but has not yet reached the maximum power factor angle θ _max , the voltage at the access point of the photovoltaic power station still exceeds the limit, record the voltage at the access point of the photovoltaic power station as U _k,l , and switch to Enter the maximum power adjustment stage of the inverter;

In the maximum power adjustment phase of the inverter, the active power P _PV,t required to be emitted by the photovoltaic inverter is calculated by the following formula:

in and Respectively, the resistance value and reactance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer;

Adjust the active power that the inverter puts into PP _{PV, t} , at this time, the node voltage of the photovoltaic access point k is recorded as U _k,t ;

According to the node voltage U _k,t after the maximum power adjustment stage of the inverter, the active power PP _PV,t output by the inverter is corrected by the following formula:

P _PV =P _PV,t +ΔP _PV,t

Among them, ΔP _PV,t is the active power correction amount in the inverter maximum power adjustment stage, and its calculation formula is as follows:

As a possible implementation of this embodiment, the process of entering the maximum power adjustment phase of the inverter includes the following steps:

When the inverter power factor angle θ reaches the maximum value θ _max , the voltage of the access point of the photovoltaic power station is still beyond the limit, record the voltage of the access point of the photovoltaic power station at this time as U _k,m , and transfer to the power reduction of the inverter stage;

In the power reduction stage of the inverter, the active power PP _PV,s required to be emitted by the photovoltaic inverter is calculated by the following formula:

in, and Respectively, the resistance value and reactance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer;

Adjust the active power PP _PV,s output by the inverter, and record the node voltage of the photovoltaic power plant access point k at this time as U _k,s ;

According to the node voltage U _k,s after the inverter power reduction stage, the active power PP _PV,s output by the inverter is corrected by the following formula:

P _PV =P _PV,s +ΔP _PV,s

Among them, ΔP _PV,s is the active power correction amount in the inverter maximum power adjustment stage, and its calculation formula is as follows:

In the second aspect, a distribution network voltage control method based on photovoltaic inverter regulation provided by an embodiment of the present invention further includes the following steps before entering the reactive power compensation stage of the inverter voltage control strategy:

Set the target voltage limit and inverter capacity of the access point of the photovoltaic power station, and monitor the power, power factor angle and node voltage of the inverter.

As a possible implementation of this embodiment, the process of monitoring the power, power factor angle and node voltage of the inverter includes the following steps:

Set the limit voltage U _k,lim of the photovoltaic power station node, the maximum power S _max and the maximum power factor angle θ _max of the photovoltaic inverter;

Real-time monitoring of the voltage U _k of the access point of the photovoltaic power station, the voltage U ₀ of the low-voltage bus of the main transformer, the power S of the inverter, and the angle θ of the power factor;

Calculate the resistance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer and reactance value

In the third aspect, a distribution network voltage control method based on photovoltaic inverter regulation provided by an embodiment of the present invention further includes the following steps after entering the maximum power adjustment stage of the inverter:

After implementing the inverter voltage adjustment strategy, continue to monitor the node voltage to form a closed-loop control.

As a possible implementation of this embodiment, the process of continuing to monitor the node voltage to form a closed-loop control includes the following steps:

After the voltage control strategy adjustment of the inverter of the photovoltaic power station, the voltage of the access point of the photovoltaic power station is stabilized at the limit voltage U _k,lim ;

Continue to monitor the voltage U _k of the access point of the photovoltaic power station, the voltage U ₀ of the low-voltage bus of the main transformer, the inverter power S and the power factor angle θ to form a closed-loop control.

The beneficial effects that the technical solutions of the embodiments of the present invention may have are as follows:

In order to easily and effectively realize the voltage control of the access point of the photovoltaic power station, the voltage control strategy proposed by the technical solution of the embodiment of the present invention is divided into three stages according to the different operating states of the inverter. The active/reactive power of the inverter is used to adjust the voltage; the active/reactive power calculation method adopted is only related to the voltage of the photovoltaic power plant access point, the line impedance value and the inverter power factor angle, and all of them are linear formulas. few.

The technical solution of the embodiment of the present invention first estimates and adjusts the active/reactive power of the inverter according to the over-limit voltage of the access point of the photovoltaic power station, and then corrects the active/reactive power of the inverter according to the adjusted voltage. This method is simple to calculate, does not involve complex mathematical calculations, does not need to obtain the load distribution of the distribution network system, and has high calculation accuracy. It can accurately control the voltage amplitude of the photovoltaic power station access point, and has strong engineering practical value.

The technical scheme of the embodiment of the present invention uses the photovoltaic inverter to control the voltage of the distribution network, which can not only save equipment investment, but also make full use of the inverter capacity to realize rapid and continuous adjustment of the access point, and can better realize the connection of photovoltaic power stations Point voltage control, without communication to obtain feeder load level and distribution, and can make full use of inverter capacity for fast voltage adjustment, with good control effect and economy.

Description of drawings

Fig. 1 is a flow chart of a distribution network voltage control method based on photovoltaic inverter regulation shown according to an exemplary embodiment;

Fig. 2 is a schematic diagram of feeder wiring with photovoltaic power station access shown according to an exemplary embodiment;

Fig. 3 is a comparison diagram of calculation results obtained by using a distribution network voltage control method based on photovoltaic inverter regulation proposed by the present invention.

Detailed ways

In order to clearly illustrate the technical features of this solution, the present invention will be described in detail below through specific implementation modes and in conjunction with the accompanying drawings. The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in different instances. This repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or arrangements discussed. It should be noted that components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and processes are omitted herein to avoid unnecessarily limiting the present invention.

Example 1

As shown in Figures 1 to 3, a distribution network voltage control method based on photovoltaic inverter regulation provided by an embodiment of the present invention may include the following steps:

When the node voltage exceeds the limit and the inverter power factor angle has not reached the capacity limit angle, enter the reactive power compensation stage of the inverter voltage control strategy;

When the node voltage exceeds the limit, when the inverter reaches the maximum power but has not yet reached the maximum power factor angle, it enters the maximum power adjustment stage of the inverter;

In the case that the node voltage exceeds the limit, if the inverter has reached the maximum power factor angle, enter the power reduction stage of the inverter when the inverter remains at the maximum power factor angle.

In a possible implementation manner, the process of entering the reactive power compensation phase of the inverter voltage control strategy includes the following steps:

When the voltage U _k of the access point of the photovoltaic power station exceeds the limit voltage U _k,lim and the power S of the inverter does not reach the maximum, it enters the reactive power compensation stage of the inverter;

In the reactive power compensation stage of the inverter, the reactive power Q _PV,b required to be emitted by the photovoltaic inverter is calculated by the following formula:

in, is the reactance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer;

By adjusting the power factor angle of the inverter, the reactive power of Q _PV,b is input, and the node voltage of the photovoltaic access point k is recorded as U _k,b at this time;

According to the node voltage U _k,b after reactive power compensation of the inverter, the reactive power Q _PV,b output by the inverter is corrected by the following formula:

Q _PV = Q _PV,b +ΔQ _PV,b

Among them, ΔQ _PV,b is the reactive power correction amount in the reactive power compensation stage of the inverter, and its calculation formula is as follows:

In a possible implementation manner, the process of entering the maximum power adjustment phase of the inverter includes the following steps:

When the power S of the inverter reaches its maximum capacity S _max but has not yet reached the maximum power factor angle θ _max , the voltage at the access point of the photovoltaic power station still exceeds the limit, record the voltage at the access point of the photovoltaic power station as U _k,l , and switch to Enter the maximum power adjustment stage of the inverter;

In the maximum power adjustment phase of the inverter, the active power P _PV,t required to be emitted by the photovoltaic inverter is calculated by the following formula:

in and Respectively, the resistance value and reactance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer;

Adjust the active power that the inverter puts into PP _{PV, t} , at this time, the node voltage of the photovoltaic access point k is recorded as U _k,t ;

According to the node voltage U _k,t after the maximum power adjustment stage of the inverter, the active power PP _PV,t output by the inverter is corrected by the following formula:

P _PV =P _PV,t +ΔP _PV,t

Among them, ΔP _PV,t is the active power correction amount in the inverter maximum power adjustment stage, and its calculation formula is as follows:

In a possible implementation manner, the process of entering the maximum power adjustment phase of the inverter includes the following steps:

When the inverter power factor angle θ reaches the maximum value θ _max , the voltage of the access point of the photovoltaic power station is still beyond the limit, record the voltage of the access point of the photovoltaic power station at this time as U _k,m , and transfer to the power reduction of the inverter stage;

In the power reduction stage of the inverter, the active power PP _PV,s required to be emitted by the photovoltaic inverter is calculated by the following formula:

in, and Respectively, the resistance value and reactance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer;

Adjust the active power PP _PV,s output by the inverter, and record the node voltage of the photovoltaic power plant access point k at this time as U _k,s ;

According to the node voltage U _k,s after the inverter power reduction stage, the active power PP _PV,s output by the inverter is corrected by the following formula:

P _PV =P _PV,s +ΔP _PV,s

Among them, ΔP _PV,s is the active power correction amount in the inverter maximum power adjustment stage, and its calculation formula is as follows:

In order to easily and effectively realize the voltage control of the access point of the photovoltaic power station, the voltage control strategy proposed in this embodiment is divided into three stages according to the different operating states of the inverter. In different operating stages, by adjusting the active power of the photovoltaic /Reactive power for voltage adjustment; the active/reactive power calculation method adopted is only related to the voltage of the photovoltaic power plant access point, the line impedance value and the inverter power factor angle, and they are all linear formulas with less calculation.

Example 2

As shown in Figures 1 to 3, a distribution network voltage control method based on photovoltaic inverter regulation provided by an embodiment of the present invention may include the following steps:

Set the target voltage limit and inverter capacity of the access point of the photovoltaic power station, and monitor the power, power factor angle and node voltage of the inverter;

When the node voltage exceeds the limit and the inverter power factor angle has not reached the capacity limit angle, enter the reactive power compensation stage of the inverter voltage control strategy;

When the node voltage exceeds the limit, when the inverter reaches the maximum power but has not yet reached the maximum power factor angle, it enters the maximum power adjustment stage of the inverter;

In the case that the node voltage exceeds the limit, if the inverter has reached the maximum power factor angle, enter the power reduction stage of the inverter when the inverter remains at the maximum power factor angle.

In a possible implementation manner, the process of monitoring the power of the inverter, the power factor angle and the node voltage includes the following steps:

Set the limit voltage U _k,lim of the photovoltaic power station node, the maximum power S _max and the maximum power factor angle θ _max of the photovoltaic inverter;

Real-time monitoring of the voltage U _k of the access point of the photovoltaic power station, the voltage U ₀ of the low-voltage bus of the main transformer, the power S of the inverter, and the angle θ of the power factor;

Calculate the resistance value of the path from the access point of the photovoltaic power station to the low-voltage busbar of the main transformer and reactance value

The processes of entering the reactive power compensation phase of the inverter voltage control strategy, entering the maximum power adjustment phase of the inverter, and entering the power reduction phase of the inverter are the same as those in Embodiment 1.

In this embodiment, first set the target voltage limit and inverter capacity of the access point of the photovoltaic power station, and monitor the power, power factor angle and node voltage of the inverter, and then estimate the over-limit voltage of the access point of the photovoltaic power station And adjust the active/reactive power of the inverter, and then correct the active/reactive power of the inverter according to the adjusted voltage. This method is simple to calculate, does not involve complex mathematical calculations, does not need to obtain the load distribution of the distribution network system, and has high calculation accuracy. It can accurately control the voltage amplitude of the photovoltaic power station access point, and has strong engineering practical value.

Example 3

As shown in Figures 1 to 3, a distribution network voltage control method based on photovoltaic inverter regulation provided by an embodiment of the present invention may include the following steps:

When the node voltage exceeds the limit and the inverter power factor angle has not reached the capacity limit angle, enter the reactive power compensation stage of the inverter voltage control strategy;

When the node voltage exceeds the limit, when the inverter reaches the maximum power but has not yet reached the maximum power factor angle, it enters the maximum power adjustment stage of the inverter;

In the case that the node voltage exceeds the limit, if the inverter has reached the maximum power factor angle, enter the power reduction stage of the inverter when the inverter remains at the maximum power factor angle;

After implementing the inverter voltage adjustment strategy, continue to monitor the node voltage to form a closed-loop control.

In a possible implementation manner, the process of continuing to monitor the node voltage to form a closed-loop control includes the following steps:

After the voltage control strategy adjustment of the inverter of the photovoltaic power station, the voltage of the access point of the photovoltaic power station is stabilized at the limit voltage U _k,lim ;

Continue to monitor the voltage U _k of the access point of the photovoltaic power station, the voltage U ₀ of the low-voltage bus of the main transformer, the inverter power S and the power factor angle θ to form a closed-loop control.

The processes of entering the reactive power compensation phase of the inverter voltage control strategy, entering the maximum power adjustment phase of the inverter, and entering the power reduction phase of the inverter are the same as those in Embodiment 1.

In this embodiment, firstly, the active/reactive power of the inverter is estimated and adjusted according to the over-limit voltage of the access point of the photovoltaic power station, and then the active/reactive power of the inverter is corrected according to the adjusted voltage, and then the monitoring of the photovoltaic The voltage U _k of the access point of the power station, the voltage U ₀ of the low-voltage bus of the main transformer, the power S of the inverter and the angle θ of the power factor form a closed-loop control. This method is simple to calculate, does not involve complex mathematical calculations, does not need to obtain the load distribution of the distribution network system, and has high calculation accuracy. It can accurately control the voltage amplitude of the photovoltaic power station access point, and has strong engineering practical value.

Example 4

As shown in Figures 1 to 3, a distribution network voltage control method based on photovoltaic inverter regulation provided by an embodiment of the present invention may include the following steps:

Set the target voltage limit and inverter capacity of the access point of the photovoltaic power station, and monitor the power, power factor angle and node voltage of the inverter;

When the node voltage exceeds the limit and the inverter power factor angle has not reached the capacity limit angle, enter the reactive power compensation stage of the inverter voltage control strategy;

When the node voltage exceeds the limit, when the inverter reaches the maximum power but has not yet reached the maximum power factor angle, it enters the maximum power adjustment stage of the inverter;

In the case that the node voltage exceeds the limit, if the inverter has reached the maximum power factor angle, enter the power reduction stage of the inverter when the inverter remains at the maximum power factor angle;

After implementing the inverter voltage adjustment strategy, continue to monitor the node voltage to form a closed-loop control.

In this embodiment, first set the target voltage limit and inverter capacity of the access point of the photovoltaic power station, and monitor the power, power factor angle and node voltage of the inverter, and then estimate the over-limit voltage of the access point of the photovoltaic power station And adjust the active/reactive power of the inverter, then correct the active/reactive power of the inverter according to the adjusted voltage, and finally continue to monitor the voltage Uk of the access point of the photovoltaic power station and the voltage _U0 of the low-voltage bus of the main transformer , inverter power S and power factor angle θ, forming a closed-loop control. This method is simple to calculate, does not involve complex mathematical calculations, does not need to obtain the load distribution of the distribution network system, and has high calculation accuracy. It can accurately control the voltage amplitude of the photovoltaic power station access point, and has strong engineering practical value.

In a possible implementation manner, the specific implementation process of the embodiment of the present invention includes the following steps:

Step 1, set the limit voltage U _k,lim of the access point of the photovoltaic power station, the maximum power S _max and the maximum power factor angle θ _max of the photovoltaic inverter.

Step 2, real-time monitoring of the voltage U _k of the access point of the photovoltaic power station, the voltage U ₀ of the low-voltage bus of the main transformer, the power S of the inverter, and the angle θ of the power factor.

Step 3, according to the access location of the photovoltaic power station and the specific parameters of the distribution line, determine the calculation path from the photovoltaic power station access point k to the main transformer low-voltage busbar, and calculate the resistance value of the path from the photovoltaic power station access point to the main transformer low-voltage busbar and reactance value

Step 4, when the voltage U _k at the access point of the photovoltaic power station exceeds the limit voltage U _k,lim and the power S of the inverter does not reach the maximum, enter the reactive power compensation stage of the inverter.

Step 5, in the reactive power compensation phase of the inverter, the reactive power Q _PV,b required to be emitted by the photovoltaic inverter is calculated using the following formula

in

Step 6: Input the reactive power of Q _PV,b by adjusting the power factor angle of the inverter. At this time, the node voltage of the photovoltaic access point k is denoted as U _k,b .

Step 7: Correct the reactive power Q _{PV, b} output by the inverter according to the node voltage U _k,b after reactive power compensation of the inverter:

Q _PV = Q _PV,b +ΔQ _PV,b

Among them, ΔQ _{PV, b} is the reactive power correction amount in the reactive power compensation stage of the inverter, and its calculation method is as follows:

Step 8: After the reactive power compensation phase of the inverter, when the inverter power S reaches its maximum capacity S _max but has not yet reached the maximum power factor angle θ _max , the voltage at the access point of the photovoltaic power station still exceeds the limit. The voltage of the access point of the power station is U _k,l , and it is transferred to the maximum power adjustment stage of the inverter.

Step 9, in the phase of maximum power adjustment of the inverter, the active power P _PV,t required to be emitted by the photovoltaic inverter is calculated by the following formula:

in

Step 10, adjust the active power of the inverter input PP _PV,t , at this time, the node voltage of the photovoltaic access point k is denoted as U _k,t .

Step 11, correct the active power P _PV,t output by the inverter according to the node voltage U _k,t after the maximum power adjustment stage of the inverter:

P _PV =P _PV,t +ΔP _PV,t

Among them, ΔP _{PV, t} is the active power correction amount in the inverter maximum power adjustment stage, and its calculation method is as follows:

Step 12, after the maximum power adjustment stage of the inverter, when the power factor angle of the inverter reaches the maximum value, the voltage of the access point of the photovoltaic power station still exceeds the limit, record the voltage of the access point of the photovoltaic power station at this time, and transfer to The power reduction phase of the inverter.

Step 13, in the power reduction phase of the inverter, the active power P _PV,s required to be emitted by the photovoltaic inverter is calculated by the following formula:

Step 14, adjust the active power P _PV,s output by the inverter, record the node voltage of the photovoltaic power plant access point k at this time as U _k,s .

Step 15, correct the active power P _PV,s output by the inverter according to the node voltage U _k,s after the inverter power reduction stage:

P _PV =P _PV,s +ΔP _PV,s

Among them, ΔP _PV,s is the active power correction amount in the inverter maximum power adjustment stage, and its calculation method is as follows:

Step 16, after adjusting the voltage control strategy of the inverter of the photovoltaic power station, the voltage of the access point of the photovoltaic power station is stabilized at the limit voltage U _k,lim .

Step 17, continue to monitor the voltage U _k of the access point of the photovoltaic power station, the voltage U ₀ of the low-voltage bus of the main transformer, the inverter power S and the power factor angle θ to form a closed-loop control. When the voltage exceeds the limit, continue to carry out voltage control through the inverter.

In order to easily and effectively realize the voltage control of the access point of the photovoltaic power station, the voltage control strategy proposed in this embodiment is mainly divided into three stages: reactive power compensation, maximum power adjustment and power reduction according to the different operating states of the inverter. Voltage regulation is performed by adjusting the active/reactive power of the photovoltaic inverter in different operating stages. In actual operation, it includes the following steps: set the target voltage limit and inverter capacity of the photovoltaic power station access point, and monitor the power, power factor angle and node voltage of the inverter; when the node voltage exceeds the limit and The inverter power factor angle has not yet reached the capacity limit angle, and enters the reactive power compensation stage of the inverter voltage control strategy; when the node voltage Uk _exceeds the limit, when the inverter reaches the maximum power but has not yet reached the maximum power If the inverter has reached the maximum power factor angle, it will enter the maximum power adjustment stage of the inverter. The power reduction stage of the inverter; after implementing the inverter voltage adjustment strategy, continue to monitor the node voltage to form a closed-loop control. The invention does not need to communicate to obtain the load level and distribution of the feeder, and can make full use of the capacity of the inverter to adjust the voltage quickly, and has good control effect and economy.

The above is only a preferred embodiment of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered as the present invention. protection scope of the invention.

Claims (8)

1. A power distribution network voltage control method based on photovoltaic inverter regulation is characterized by comprising the following steps:

when the node voltage is out of limit and the power factor angle of the inverter does not reach the capacity limit angle, entering a reactive compensation stage of an inverter voltage control strategy;

under the condition that the node voltage is out of limit, entering a maximum power regulation stage of the inverter when the inverter reaches the maximum power but does not reach a maximum power factor angle;

if the inverter has reached the maximum power factor angle in the case where the node voltage is out of limit, the power reduction stage of the inverter is entered in a state where the inverter is maintained at the maximum power factor angle.

2. The method for controlling the voltage of the power distribution network based on the photovoltaic inverter regulation, as claimed in claim 1, wherein the process of entering the reactive compensation phase of the inverter voltage control strategy comprises the following steps:

when the voltage U of the access point of the photovoltaic power station_kExceeding the limit voltage U_k,limIf the power S of the inverter does not reach the maximum, entering a reactive compensation stage of the inverter;

in the reactive compensation stage of the inverter, the reactive power Q required to be emitted by the photovoltaic inverter_PV,bCalculated using the formula:

wherein, the reactance value of the path from the photovoltaic power station access point to the main transformer low-voltage bus;

by adjusting the power factor angle of the inverter to put Q_PV,bThe node voltage of the photovoltaic access point k is recorded as U_k,b；

According to node voltage U after reactive power compensation of inverter_k,bFor the reactive power Q output by the inverter_PV，bThe following correction was used:

Q_PV＝Q_PV，b+ΔQ_PV，b

wherein, is Δ Q_PV，bThe calculation formula of the reactive power correction quantity of the reactive compensation stage of the inverter is as follows:

3. the method according to claim 1, wherein the step of entering the maximum power regulation phase of the inverter comprises the steps of:

reaches its maximum capacity S at inverter power S_maxBut has not yet reached the maximum power factor angle theta_maxIn time, the voltage of the photovoltaic power station access point still exceeds the limit, and the voltage of the photovoltaic power station access point is recorded as U_k,lAnd transferring to the maximum power adjustment stage of the inverter;

active power P required to be generated by the photovoltaic inverter in the maximum power regulation stage of the inverter_PV，tCalculated using the formula:

wherein Andrespectively obtaining a resistance value and a reactance value of a path from a photovoltaic power station access point to a main transformer low-voltage bus;

adjusting inverter input P_PV，tActive power of (b), the node voltage of the photovoltaic access point k is recorded as U_k,t；

According to the node voltage U after the maximum power adjustment stage of the inverter_k,tTo active power P output by the inverter_PV，tThe following correction was used:

P_PV＝P_PV，t+ΔP_PV，t

wherein, Δ P_PV，tFor maximum power regulation of invertersThe calculation formula of the active power correction quantity of the stage is as follows:

4. the method according to claim 1, wherein the step of entering the maximum power regulation phase of the inverter comprises the steps of:

reaches a maximum value theta at an inverter power factor angle theta_maxIn time, the voltage of the photovoltaic power station access point still exceeds the limit, and the voltage of the photovoltaic power station access point is recorded as U_k,mAnd entering a power reduction stage of the inverter;

in the power reduction stage of the inverter, the active power P required to be emitted by the photovoltaic inverter_PV，sCalculated using the formula:

wherein,andrespectively obtaining a resistance value and a reactance value of a path from a photovoltaic power station access point to a main transformer low-voltage bus;

adjusting active power P output by inverter_PV，sAnd recording the node voltage of the photovoltaic power station access point k as U_k,s；

According to the node voltage U after the power reduction stage of the inverter_k,sTo active power P output by the inverter_PV,sThe following correction was used:

P_PV＝P_PV，s+ΔP_PV，s

wherein, Δ P_PV，sFor active work in the maximum power regulation stage of an inverterThe rate correction amount is calculated by the following formula:

5. the method for controlling the voltage of the power distribution network based on the regulation of the photovoltaic inverter as claimed in any one of the claims 1 to 4, characterized by further comprising the following steps before entering the reactive compensation stage of the inverter voltage control strategy:

and setting a target voltage limit value and an inverter capacity of the photovoltaic power station access point, and monitoring the power, the power factor angle and the node voltage of the inverter.

6. The method of claim 5, wherein the monitoring of the inverter power, power factor angle and node voltage comprises the steps of:

limiting voltage U for setting photovoltaic power station node_k,limMaximum power S of photovoltaic inverter_maxAnd maximum power factor angle theta_max；

Real-time monitoring photovoltaic power station access point voltage U_kAnd the voltage U of the low-voltage bus of the main transformer₀Inverter power S and power factor angle θ;

calculating resistance value of path from photovoltaic power station access point to main transformer low-voltage busAnd reactance value

7. The method for controlling the voltage of the power distribution network based on the regulation of the photovoltaic inverter as claimed in any one of claims 1 to 6, characterized by further comprising the following steps after entering the maximum power regulation stage of the inverter:

and after the inverter voltage adjustment strategy is executed, the node voltage is continuously monitored to form closed-loop control.

8. The method according to claim 7, wherein the step of continuing to monitor the node voltage to form the closed-loop control comprises the steps of:

after the voltage control strategy of the photovoltaic power station inverter is adjusted, the voltage of the photovoltaic power station access point is stabilized at the limit voltage U_k,lim；

Continuing to monitor photovoltaic power station access point voltage U_kAnd the voltage U of the low-voltage bus of the main transformer₀Inverter power S and power factor angle theta, forming a closed loop control.