WO2021088442A1

WO2021088442A1 - Method and system for coordinately controlling reactive voltage of wind farm

Info

Publication number: WO2021088442A1
Application number: PCT/CN2020/106750
Authority: WO
Inventors: 孙华东; 李文锋; 郭剑波; 许涛; 于钊; 陶向宇; 魏巍; 王官宏; 贾媛; 李莹; 张健
Original assignee: 中国电力科学研究院有限公司; 国家电网有限公司
Priority date: 2019-11-05
Filing date: 2020-08-04
Publication date: 2021-05-14
Also published as: CN110970906B; CN110970906A

Abstract

A method and system for coordinately controlling a reactive voltage of a wind farm. The method and system measure the voltage of a grid-connected point of a wind farm and that of a wind generator set in the wind farm, and compares the measured values with a preset first threshold interval of normal work. When a sudden increase/decrease occurs to the voltage transient of the grid-connected point of the wind farm during normal work, optimal voltage value adjustment is performed to coordinate reactive power distribution between an SVG and the wind generator set in the wind farm. When the voltage of the grid-connected point of the wind farm and a terminal voltage go beyond the first threshold interval, the SVG and the wind generator set in the wind farm enter an emergent closed-loop control mode, and separately perform reactive powder adjustment.

Description

Method and system for coordinated control of reactive voltage of wind farm

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 201911071218.5 on November 05, 2019, and the entire content of the application is incorporated into this application by reference.

Technical field

This application relates to the field of power control, for example, to a method and system for coordinated control of reactive voltage of a wind farm.

Background technique

As one of the most mature and promising renewable energy sources, photovoltaic power generation has maintained a strong momentum of development in recent years. In the near future, some local grid new energy sources may account for 80% or even higher. Energy grid-connected operation will become an important feature of the future power supply structure.

However, as the proportion of new energy in the power grid becomes higher and higher, the scope of the influence of new energy on the power grid has gradually expanded from some parts. The output of new energy units is obviously intermittent and fluctuating, which makes the large-scale integration of photovoltaic power generation put great pressure on the stable operation of local power grids, which leads to frequent occurrence of large-scale chain disconnection accidents.

When wind farms are connected to the grid, they rely on static var generators (SVG) to achieve the voltage support index of the grid connection point, and they have not fully utilized the reactive power regulation capabilities of the wind turbines in the farm. SVG consumes a large amount of factory electricity during work, which affects economy. In addition, in areas where a large number of new energy sources are connected to the grid, the simultaneous use of SVG actions at multiple grid points will also bring about the coordination and cooperation of dynamic voltage support. How to tap the reactive power regulation capabilities of new energy units and improve the reactive power and voltage coordinated control capabilities of new energy plants are key issues that need to be resolved urgently.

Summary of the invention

The present application provides a method for coordinated control of the reactive voltage of a wind farm to solve the problem that the wind farm does not fully tap its own reactive power regulation capability when the wind farm is connected to the power grid in the related art. The method includes:

_{Step 1. Measure the voltage U T at the} grid connection point of the wind farm, and measure the active power P output by the wind turbines in the farm, the reactive power Q output by the wind turbines in the farm and the terminal voltage U _{w of the} wind turbines in the farm;

Step 2. Determine the communication status between the wind farm station control system and the on-site wind turbines, and perform one of the following reactive power adjustments on the wind farm static var generator SVG and on-site wind turbines according to the communication status:

In the case of a communication failure between the wind farm station control system and the on-site wind turbines, the wind farm static reactive power generator SVG and the on-site wind turbines perform the first reactive power adjustment. The wind farm’s station control system and the on-site wind turbines perform the first reactive power adjustment. In the case of normal communication, when the voltage U _{T of the} grid connection point of the wind farm is within the preset first SVG voltage threshold interval, and the generator terminal voltage U _{w is} within the preset first generator terminal voltage threshold interval, the wind power The static reactive power generator SVG and the on-site wind turbines perform the second reactive power adjustment. When the wind farm station control system communicates with the on-site wind turbines normally, the voltage U _T at the grid connection point of the wind farm is not in advance. If the first SVG voltage threshold interval is set, and the terminal voltage U _{w is} not in the preset first terminal voltage threshold interval, the wind farm static var generator SVG and the on-site wind turbine perform the third reactive power adjustment ；

Step 3. When the wind farm static var generator SVG and the on-site wind turbines perform the third reactive power adjustment, respectively measure the wind farm SVG and all on-site wind turbines enter the voltage emergency control mode and perform power adjustment. wind farm and network voltage U _'T and the field of wind turbines terminal voltage U' _w, wind farm and network voltage U _'T in the case where the second SVG voltage threshold interval set in advance, and in the field of wind power unit terminal voltage U _'w in the case of the second terminal voltage, a threshold interval set in advance, processing returns to step 2 for the second reactive power control, and in the wind farm network voltage U' _T is not in the second set in advance SVG case where the threshold voltage range, or in the case of the second terminal voltage, a threshold voltage U section-side field of wind turbines' _w is not previously set, returns to the step 2 of the third reactive power regulation.

This application provides a system for coordinated control of the reactive voltage of a wind farm, and the system includes:

The data acquisition unit is set to measure the voltage U _{T at the} grid connection point of the wind farm, and measure the active power P output by the wind turbines in the farm, the reactive power Q output by the wind turbines in the farm and the terminal voltage U _{w of the} wind turbines in the farm;

The data communication unit is configured to perform data communication between the wind farm station control system and a plurality of inverters in the wind farm, and determine the communication status between the wind farm station control system and the wind turbines in the wind farm;

The first power adjustment unit is configured to perform the first reactive power adjustment on the wind farm static reactive power generator SVG and the on-site wind turbine in the case of a communication failure between the wind farm station control system and the on-site wind turbine;

The second power adjustment unit is set to: when the wind farm station control system communicates with the on-site wind turbines normally, the voltage U _T at the grid connection point of the wind farm is within the preset first SVG voltage threshold interval, and the machine terminal When the voltage U _{w is} in the preset first terminal voltage threshold interval, the second reactive power adjustment is performed on the wind farm static reactive power generator SVG and the on-site wind turbine;

The third power adjustment unit is set to, when the wind farm station control system communicates with the on-site wind turbines normally, the voltage U _T at the grid connection point of the wind farm is not in the preset first SVG voltage threshold interval, and the machine terminal In the case that the voltage U _{w is} not in the preset first terminal voltage threshold interval, the wind farm static reactive power generator SVG and the on-site wind turbine unit perform the third reactive power adjustment;

The coordinated control unit is set to measure the SVG through the data acquisition unit and enter the voltage emergency control mode of multiple in-station inverters through the data acquisition unit when the wind farm static var generator SVG and the inverter in the station perform the third reactive power adjustment wind farm after and power adjustment and network voltage U _'T and station inverter terminal voltage U' _w, wind farm and network voltage U 'in the second SVG voltage threshold range set in advance is _T next, the station and the terminal voltage of the inverter U _'w in the case of the second terminal voltage, a threshold interval set in advance, returned to the second power adjustment means, and in the wind farm network voltage U' _T is not set in advance SVG case where the second voltage threshold range, or in the case of stations within the inverter terminal voltage U _'w is not a preset terminal voltage of the second threshold interval, a third power adjustment unit continues to return a third reactive Power regulation.

Description of the drawings

Fig. 1 is a flowchart of a method for coordinated control of reactive voltage of a wind farm according to an embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a system for coordinated control of reactive voltage of a wind farm according to an embodiment of the present invention.

Detailed ways

Exemplary implementations of embodiments of the present invention are described below with reference to the accompanying drawings. However, the embodiments of the present invention can be implemented in many different forms and are not limited to the embodiments described here. In the drawings, the same units/elements use the same reference numerals.

Fig. 1 is a flowchart of a method for coordinated control of reactive voltage of a wind farm according to an embodiment of the present invention. As shown in FIG. 1, the method 100 for coordinated control of the reactive voltage of a wind farm described in this embodiment starts from step 101.

In step 101, measure the voltage U _{T of the} grid connection point of the wind farm, and measure the active power P output by the wind turbines in the farm, the reactive power Q output by the wind turbines in the farm and the terminal voltage U _{w of the} wind turbines in the farm.

In step 102, determine the communication status between the wind farm station control system and the on-site wind turbines, and adjust the reactive power of the wind farm static reactive power generator SVG and on-site wind turbines according to the communication status. When a communication failure occurs between the station control system and the on-site wind turbines, the wind farm static reactive power generator SVG and the on-site wind turbines perform the first reactive power adjustment. When the wind farm’s station control system communicates with the on-site wind turbines normally, all _{When the voltage U T of the} grid connection point of the wind farm is in the preset first SVG voltage threshold interval, and the generator terminal voltage U _{w is} within the preset first generator voltage threshold interval, the wind farm static var generator SVG and the field The wind turbine unit performs the second reactive power adjustment. When the wind farm station control system communicates with the on-site wind turbine unit normally, the voltage U _{T of} the wind farm grid connection point is not in the preset first SVG voltage threshold interval, and the terminal voltage When U _{w is} not in the preset first terminal voltage threshold interval, the wind farm static reactive power generator SVG and the on-site wind turbine perform the third reactive power adjustment.

In step 103, when the wind farm static var generator SVG and the on-site wind turbines perform the third reactive power adjustment, the wind farm SVG and all on-site wind turbines are respectively measured after entering the voltage emergency control mode and performing power adjustment. 'terminal voltage _T and the field of wind turbines U' wind farms and network voltage U _w, when the wind farm and network voltage U _'T in the second SVG voltage threshold range set in advance, and the spot machine the WTG the terminal voltage U _'W at the second end voltage threshold range set in advance, processing returns to step 102 for the second reactive power control, and when the wind farm network voltage U' SVG second voltage threshold _T is not set in advance the terminal voltage U interval or the spot of the wind turbine 'is not _w-side second preset voltage threshold range, the process returns to step 102 for the third reactive power regulation.

The method and system for coordinated control of the reactive voltage of a wind farm provided by the technical solutions of the embodiments of the present invention measure the grid-connected point voltage of the wind farm and the voltage of the inverter in the wind farm, and compare the measured value with the preset first threshold for normal operation Comparing the intervals, when the grid connection point of the wind farm has a voltage transient swell or sag in the normal working interval, the optimal voltage value is adjusted to coordinate the reactive power distribution between the SVG and the on-site wind turbines. When the grid-connection point voltage and the terminal voltage of the wind farm exceed the first threshold interval, the SVG and the on-site wind turbine enter the emergency closed-loop control mode, and adjust the reactive power separately. The method and system for coordinated control of the reactive voltage of a wind farm improves the wind farm by coordinating the reactive power distribution between the SVG and the wind turbines in the wind farm when the voltage transient rises/sags occur at the grid connection point of the wind farm. The transient reactive power support capability of the wind farm when the voltage transient rises/sags at the grid connection point.

Optionally, when a communication failure occurs between the wind farm station control system and the on-site wind turbine, the wind farm static reactive power generator SVG and the on-site wind turbine perform the first reactive power adjustment means when the wind farm station control system When there is a communication failure with the on-site wind turbines, the wind farm static var generator SVG and on-site wind turbines enter the voltage closed-loop control mode. The wind farm SVG is adjusted _{according to the voltage U T of the wind farm grid connection point read by the wind farm station control system} The generated reactive power is adjusted by the wind turbines in the field according to the terminal voltage U _w.

Optionally, when the communication between the station control system of the wind farm and the on-site wind turbines is normal, the voltage U _{T of the} grid connection point of the wind farm is within the preset first SVG voltage threshold interval, and the terminal voltage U _{w is} within the preset first SVG voltage threshold interval. When the first terminal voltage threshold interval is set, the second reactive power adjustment performed by the wind farm static reactive power generator SVG and on-site wind turbines includes:

When the communication between the wind farm station control system and the on-site wind turbines is normal, the wind farm station control system is based on the voltage U _T of the grid connection point, the active power P, reactive power Q of the on-site wind turbines, and the terminal voltage U _w , Determine the optimal value of reactive power of the on-site wind turbines and the optimal value of reactive power of the wind farm SVG, and send the optimal value instructions to the wind farm SVG and on-site wind turbines;

_{When the voltage U T of the} grid connection point of the wind farm is within the preset first SVG voltage threshold interval, the wind farm SVG performs power adjustment according to the SVG reactive power optimal value sent by the wind farm station control system;

When the generator terminal voltage U _{w is} within the preset first generator terminal voltage threshold interval, the on-site wind turbine receives the optimal reactive power value sent by the wind farm station control system to perform power adjustment.

Optionally, when the communication between the station control system of the wind farm and the on-site wind turbine is normal, the voltage U _{T of the} grid connection point of the wind farm is not in the preset first SVG voltage threshold interval, and the terminal voltage U _{w is} not in the preset first SVG voltage threshold interval. When the first terminal voltage threshold interval is set, the third reactive power adjustment performed by the wind farm static reactive power generator SVG and the on-site wind turbine includes:

When the wind farm station control system communicates with the on-site wind turbines normally, and the voltage U _{T at the} grid connection point of the wind farm is not within the preset first SVG voltage threshold range, the wind farm SVG enters the voltage emergency control mode to lock the wind farm station The optimal value adjustment command of the reactive power of the wind farm SVG sent by the control system, and the adjustment power Q _SVG of the wind farm SVG is calculated before the power adjustment;

When the station control system of the wind farm communicates with the on-site wind turbines normally, and the terminal voltage U _{w of the} on-site wind turbines is not within the preset first terminal voltage threshold interval, the on-site wind turbines enter the voltage emergency control mode, Block the reactive power optimal value command of the on-site wind turbines sent by the wind farm station control system, and calculate the adjusted power Q _{w of the} on-site wind turbines for power adjustment.

Optionally, when the communication between the wind farm station control system and the on-site wind turbines is normal, the wind farm station control system is based on the voltage U _T at the grid-connection point of the wind farm, the active power P of the on-site wind turbines, and the reactive power Q and the terminal voltage U _w to determine the optimal value of the reactive power of the wind turbines in the field and the optimal value of the reactive power of the wind farm SVG include:

Step 1. Establish the equational constraints of the AC line, the equational constraints of the active power and voltage of the wind farm grid-connected point, the upper and lower limit constraints of the voltage of multiple nodes in the wind farm, and the non-limiting conditions of multiple inverters in the wind farm. Constraints on the upper and lower limits of power;

Step 2. Based on the equational constraints of the AC line, the equational constraints of the active power and voltage of the wind farm grid connection point, the upper and lower limit constraints of the voltage of multiple nodes in the wind farm, and the non-relevance of multiple inverters in the wind farm. Constraint conditions for the upper and lower limits of power and construct the objective function of the optimal reactive output of multiple power sources in the wind farm;

Among them, α and β are weighting factors, and satisfy

α+β=1

P _loss.ij is the active loss between grid node i and grid node j, and the calculation formula is:

Where V _i and V _j represent the voltages of node i and node j, respectively, θ _ij represents the voltage phase angle difference between grid node i and grid node j, and g _ij represents the i-th grid node in the node admittance matrix and The conductance parameter of the line between the j-th grid node, Q _svg.m is the reactive power output of the m-th wind farm SVG, N and M are positive integers, i=1, 2,...N, j=1, 2, …N, m=1, 2, …M;

Step 3. Construct a Lagrangian function based on the objective function of the optimal reactive output of multiple power sources in the wind farm, and the calculation formula is:

Among them, λ ₁ , λ ₂ and λ ₃ are all Lagrangian multipliers, ΔP _i is the active power error of node i, P _ord and V _ord are the active power and voltage commands issued by the upper-level scheduling, respectively, P _s and V _s are the active power and voltage at the grid connection point of the wind farm;

Step 4. According to the Lagrangian extremum evaluation conditions, we can get:

Among them, Q _wk is the reactive power output of the wind turbine in the k-th yard;

Step 5. When the power collection line in the wind farm has a chain structure, the solution of the equation set constructed by the Lagrangian function is solved, and the solution of the agenda set is taken as the reactive power of all wind turbines in the field The optimal value and the optimal value of the reactive power of the wind farm SVG, where, when the solution of the node exceeds the upper and lower limit constraints of the multiple node voltages in the wind farm and the reactive power of the multiple inverters in the wind farm In the case of a lower limit constraint condition, the inequality constraint condition is transformed into an equality constraint, and the value of the inequality constraint condition takes the boundary value of the constraint condition (that is, the upper and lower limit constraint conditions of the multiple node voltages in the wind farm and the wind farm The boundary value of the upper and lower limit constraint conditions of the reactive power of multiple inverters). In one embodiment, in the chain structure of the collector line in the wind farm, there is at most one branch between every two nodes, and no loop is formed. Therefore, the total number of branches in the network is N-1, so The number of unknown variables in the Lagrangian function is M+2N. In the same way, the number of equations that can be obtained according to the Lagrangian extreme value is also M+2N, and the equation has a unique solution. The wind farm station control system calculates the reactive power adjustable capacity of the wind turbines in the farm and the transmission capacity of the line, and replaces the reactive power of the SVG in the wind farm with the reactive power of the wind turbines in the farm to reduce the wind farm. The active power loss of the internal reactive power compensation device improves the overall economic benefits of the wind farm.

In an embodiment, the inequality constraints refer to the upper and lower limit constraints of the multiple node voltages in the wind farm and the upper and lower reactive power constraints of the multiple inverters in the wind farm, namely:

V _{i.min ≤V} _i _{≤V i.max}

Q _{wk.min ≤Q} _wk _{≤Q wk.max}

Q _svg.min _≤Q _{svg.m ≤Q svg.max}

Optionally, the equation constraint conditions for establishing the AC line, the equation constraint conditions for the active power and voltage of the wind farm grid connection point, the upper and lower limit constraints for the voltage of multiple nodes in the wind farm, and the multiple inverters in the wind farm The upper and lower limits of reactive power of the inverter include:

According to the topological structure of the electrical lines in the wind farm, the types of nodes in the wind farm are divided into nodes that only contain wind turbines on the site, nodes that contain only wind farm SVG, and nodes that neither contain wind turbines nor wind farm SVG. Node, and construct an AC line equation constraint condition for each node, where the AC line equation constraint condition is to make the node's active power error ΔP _i and reactive power error ΔQ _i equal to 0;

For the active power and voltage commands issued by the upper-level dispatcher, construct the equation constraint conditions for the active power and voltage of the wind farm grid connection point;

P _s ＝P _ord

V _s ＝V _ord

Among them, P _ord and V _ord are the active power and voltage commands issued by the upper-level dispatcher, and P _s and V _s are the active power and voltage of the wind farm grid connection point, respectively.

According to the actual operating requirements of the wind turbines and wind farm SVG, the upper and lower limit constraints of the multiple node voltages in the wind farm and the upper and lower reactive power constraints of the multiple inverters in the wind farm are constructed respectively. The formula is:

V _{i.min ≤V} _i _{≤V i.max}

Q _{wk.min ≤Q} _wk _{≤Q wk.max}

Q _svg.min _≤Q _{svg.m ≤Q svg.max}

In the formula, V _i.min and V _i.max are the upper limit and lower limit of the voltage of the grid node i respectively, and Q _wk.min and Q wk.max are the reactive power output of the wind turbines in the k- _{th yard, respectively.} The upper limit and the lower limit, Q _svg.min and Q _svg.max are the upper limit and the lower limit of the reactive power output of the wind farm SVG, respectively.

Optionally, the SVG enters the voltage emergency control mode when the wind farm station control system communicates with the on-site wind turbines normally, and the voltage U _{T of} the wind farm grid connection point is not within the preset first SVG voltage threshold interval, SVG enters the voltage emergency control mode, Block the reactive power optimal value adjustment command of the wind farm SVG sent by the wind farm station control system, and calculate the adjusted power Q of the wind farm SVG. The _{power adjustment after the SVG} refers to the ratio _{based on the voltage U T} at the grid connection point of the wind farm Integral (Proportional Integral, PI) control, which adjusts reactive power according to the output value of the PI control;

When the station control system of the wind farm communicates with the on-site wind turbines normally, and the terminal voltage U _{w of the} on-site wind turbines is not in the preset first terminal voltage threshold interval, the on-site wind turbines enter the voltage emergency control Mode, block the reactive power optimal value command of the wind turbines on the site sent by the station control system of the wind farm, and calculate the adjusted power Q _w of the wind turbines on the site. The power adjustment is based on the terminal voltage U of all the wind turbines on the site. _w Perform PI control, and perform reactive power adjustment according to the output value of the PI control.

Optionally, the range of the first SVG voltage threshold interval is greater than the range of the second SVG voltage threshold interval, and the range of the first machine terminal voltage threshold interval is greater than the range of the second machine terminal voltage threshold interval. In an embodiment, when the first SVG voltage threshold interval is 0.93 pu to 1.07 pu, the second SVG voltage threshold interval may be 0.95 pu to 1.05 pu, so that the range of the first voltage interval is greater than the range of the second voltage interval, It is avoided that when the reactive voltage is distributed between the SVG and the on-site wind turbines, the voltage always oscillates at the boundary value of the first voltage threshold, and the efficiency of voltage distribution is improved.

Fig. 2 is a schematic structural diagram of a system for coordinated control of reactive voltage of a wind farm according to an embodiment of the present invention. As shown in FIG. 2, the system 200 for coordinated control of reactive voltage of a wind farm according to this embodiment includes:

The data acquisition unit 201 is configured to measure the voltage U _{T at the} grid-connection point of the wind farm, and measure the active power P output by the wind turbines in the farm, the reactive power Q output by the wind turbines in the farm and the terminal voltage U _{w of the wind turbines in the farm} ；

The data communication unit 202 is configured to perform data communication between the wind farm station control system and a plurality of inverters in the wind farm, and to determine the communication state between the wind farm station control system and the wind turbines in the wind farm;

The first power adjustment unit 203 is configured to perform the first reactive power adjustment on the wind farm static reactive power generator SVG and the on-site wind turbine when a communication failure occurs between the wind farm station control system and the on-site wind turbine;

The second power adjustment unit 204 is configured to: when the wind farm station control system communicates with the on-site wind turbines normally, the voltage U _{T of the} grid connection point of the wind farm is within the preset first SVG voltage threshold interval, and the terminal voltage U _w Perform the second reactive power adjustment on the wind farm static reactive power generator SVG and the on-site wind turbines in the preset first terminal voltage threshold interval;

The third power adjustment unit 205 is configured to: when the wind farm station control system communicates with the on-site wind turbines normally, the voltage U _{T of the} grid connection point of the wind farm is not in the preset first SVG voltage threshold interval, and the terminal voltage U _{When w is} not in the preset first terminal voltage threshold interval, the wind farm static reactive power generator SVG and the on-site wind turbine perform the third reactive power adjustment;

The coordination control unit 206 is set to perform the third reactive power adjustment of the wind farm static reactive power generator SVG and the station inverter through the data acquisition unit to measure the SVG and the multiple station inverters to enter the voltage emergency control mode and perform wind farm after a power conditioner and dots voltage U _'T and station inverter terminal voltage U' _w, when the wind farm and network voltage U _'T in the second SVG voltage threshold range set in advance, and when the station the terminal voltage of the inverter U _'W at the second terminal voltage, a preset threshold value interval, returns to the second power adjustment means, and when the wind farm network voltage U' SVG second voltage threshold is not a preset interval _T or when the second threshold value interval, the terminal voltage of the inverter station terminal voltage U _'w is not set in advance, the power adjusting unit continues to return the third third reactive power regulation.

Optionally, the first power adjustment unit 203 is configured to perform the first reactive power adjustment by the wind farm static reactive power generator SVG and the on-site wind turbine generator when a communication failure occurs between the wind farm station control system and the on-site wind turbine generator It means that when a communication failure occurs between the wind farm station control system and the on-site wind turbines, the wind farm static reactive power generator SVG and on-site wind turbines enter the voltage closed-loop control mode. The wind farm SVG reads the wind power according to the wind farm station control system. The voltage U _{T of the} grid connection point adjusts the reactive power, and the wind turbine in the field adjusts the reactive power according to the terminal voltage U _w .

Optionally, the second power adjustment unit 204 is configured to: when the wind farm station control system communicates with the on-site wind turbines normally, the voltage U _{T of} the wind farm grid connection point is within a preset first SVG voltage threshold interval, And when the generator terminal voltage U _{w is} within the preset first generator terminal voltage threshold interval, the second reactive power adjustment performed by the wind farm static reactive power generator SVG and the on-site wind turbine generator includes:

When the communication between the wind farm station control system and the on-site wind turbines is normal, the wind farm station control system is based on the voltage U _T at the grid connection point of the wind farm, the active power P, the reactive power Q of the on-site wind turbines, and the terminal voltage U _w . Determine the optimal value of reactive power of the wind turbines on the site and the optimal value of reactive power of the wind farm SVG, and send the optimal value instruction to the wind farm SVG and the on-site wind turbines;

_{When the voltage U T of the} grid connection point of the wind farm is within the preset first SVG voltage threshold interval, the wind farm SVG performs power adjustment according to the reactive power optimal value of the wind farm SVG sent by the wind farm station control system;

Optionally, the third power adjustment unit 205 is configured to: when the wind farm station control system communicates with the on-site wind turbines normally, the voltage U _{T of} the wind farm grid connection point is not within the preset first SVG voltage threshold interval, Or when the generator terminal voltage U _{w is} not in the preset first generator terminal voltage threshold interval, the third reactive power adjustment performed by the wind farm static reactive power generator SVG and the on-site wind turbine generator includes:

When the wind farm station control system communicates with the on-site wind turbines normally, and the voltage U _{T of the} grid connection point of the wind farm is not within the preset first SVG voltage threshold range, the wind farm SVG enters the voltage emergency control mode and the wind farm station is blocked The wind farm SVG reactive power optimal value adjustment command sent by the control system, and the SVG adjustment power Q _{SVG is} calculated and then the power adjustment is performed;

Optionally, the second power adjustment unit 204 is configured to, when the wind farm station control system communicates with the on-site wind turbines normally, the wind farm station control system is based on the voltage U _T at the grid connection point of the wind farm, and the on-site wind turbines The active power P, the reactive power Q and the terminal voltage U _{w are} determined to determine the optimal value of the reactive power of the wind turbines in the field and the optimal value of the reactive power of the wind farm SVG including:

Among them, α and β are weighting factors, and satisfy

α+β=1

In the formula, V _i and V _j represent the voltages of grid node i and grid node j, respectively, θ _ij represents the voltage phase angle difference between grid node i and grid node j, and g _ij represents the grid node i and the grid node in the node admittance matrix. The conductance parameter of the line between the grid nodes j, Q _svg.m is the reactive power output of the m-th wind farm SVG, N and M are positive integers, i=1, 2,...N, j=1, 2,...N , M=1, 2,...M;

Among them, λ ₁ , λ ₂ and λ ₃ are all Lagrangian multipliers, ΔP _i is the active power error of grid node i, P _ord and V _ord are the active power and voltage commands issued by the upper-level dispatcher, P _s And V _s are the active power and voltage at the grid connection point of the wind farm;

Step 4. According to the Lagrangian extremum evaluation conditions, we can get:

Step 5. When the collection line in the wind farm has a chain structure, the solution of the equation set constructed by the Lagrangian function is solved, and the solution of the equation set is taken as the reactive power of all wind turbines in the field The optimal value and the optimal value of the reactive power of the wind farm SVG, where, when the solution of the node exceeds the upper and lower limit constraints of the multiple node voltages in the wind farm and the reactive power of the multiple inverters in the wind farm In the case of the lower limit constraint condition, the inequality constraint condition is transformed into an equality constraint, and its value takes the boundary value of the constraint condition.

Optionally, the third power adjustment unit 205 is configured to establish equation constraints for the AC line, equation constraints for the active power and voltage of the wind farm grid connection point, and upper and lower limit constraints for the voltages of multiple nodes in the wind farm The upper and lower limits of reactive power of multiple inverters in the wind farm include:

P _s ＝P _ord

V _s ＝V _ord

Among them, P _ord and V _ord are the active power and voltage commands issued by the superior dispatcher, and P _s and V _s are the active power and voltage of the wind farm grid connection point respectively;

V _{i.min ≤V} _i _{≤V i.max}

Q _{wk.min ≤Q} _wk _{≤Q wk.max}

Q _svg.min _≤Q _{svg.m ≤Q svg.max}

Where V _i.min and V _i.max are the upper limit and lower limit of the voltage of the grid node i respectively, and Q _wk.min and Q wk.max are the upper limit of the reactive power output of the wind turbines in the k- _{th yard, respectively.} Limit and lower limit, Q _svg.min and Q _svg.max are the upper limit and lower limit of SVG reactive power output respectively.

Optionally, the third power adjustment unit 205 is configured to when the wind farm station control system communicates with the on-site wind turbines normally, and the voltage U _{T of} the wind farm grid connection point is not within the preset first SVG voltage threshold interval , The wind farm SVG enters the voltage emergency control mode, blocks the wind farm SVG's reactive power optimal value adjustment command sent by the wind farm station control system, and calculates the wind farm SVG's adjusted power Q. The _{power adjustment after the SVG} is based on the above _{The voltage U T} of the grid-connected point of the wind farm is controlled by PI, and the reactive power is adjusted according to the output value of the PI control;

The third power adjustment unit 205 is set to when the wind farm station control system communicates with the on-site wind turbines normally, and the on-site wind turbine terminal voltage U _{w is} not within the preset first terminal voltage threshold interval, The on-site wind turbines enter the voltage emergency control mode, block the reactive power optimal value command of the on-site wind turbines sent by the wind farm station control system, and calculate the adjusted power Q _{w of the} on-site wind turbines. The terminal voltage U _{w of the} internal wind turbine is controlled by PI, and the reactive power is adjusted according to the output value of the PI control.

Optionally, the range of the first SVG voltage threshold interval is greater than the range of the second SVG voltage threshold interval, and the range of the first machine terminal voltage threshold interval is greater than the range of the second machine terminal voltage threshold interval.

The steps of the system for coordinated control of the reactive voltage of the wind farm according to the embodiment of the present invention are the same as the method for coordinated control of the reactive voltage of the wind farm according to the embodiment of the present invention. The steps are the same, and the technical effects achieved are also the same, so I won’t repeat them here.

All terms used in the claims are interpreted according to their ordinary meanings in the technical field, unless explicitly defined otherwise therein. All references to "a/the/the [device, component, etc.]" are openly interpreted as at least one example of the device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein need not be run in the exact order disclosed, unless explicitly stated.

The embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, this application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this application may use one or more computer-usable storage media containing computer-usable program codes (including disk storage, portable compact disk read-only memory (Compact Disc Read Only Memory, CD-ROM), optical storage, etc.) In the form of a computer program product implemented on it.

This application is described with reference to flowcharts and/or block diagrams of methods, devices (systems), and computer program products according to embodiments of this application. Each process and/or block in the flowchart and/or block diagram, and the combination of processes and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing equipment to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing equipment are generated It is a device that realizes the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device. The device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so as to execute on the computer or other programmable equipment. The instructions provide steps for implementing the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

Claims

A method for coordinated control of the reactive voltage of a wind farm includes:

Step 1. Measure the voltage U T of the grid connection point of the wind farm, and measure the active power P output by the wind turbines in the farm, the reactive power Q output by the wind turbines in the farm and the terminal voltage U w of the wind turbines in the farm;

Step 2. Determine the communication status between the wind farm station control system and the on-site wind turbines, and perform one of the following reactive power on the wind farm static reactive power generator SVG and the on-site wind turbines according to the communication status adjust:

In the case of a communication failure between the wind farm station control system and the on-site wind turbine, the wind farm SVG and the on-site wind turbine perform the first reactive power adjustment,

In the case that the wind farm station control system communicates with the on-site wind turbines normally, the voltage U T at the grid connection point of the wind farm is within the preset first SVG voltage threshold interval, and the terminal voltage U w In the case of the preset first terminal voltage threshold interval, the wind farm SVG and the in-farm wind turbines perform the second reactive power adjustment,

When the wind farm station control system communicates with the on-site wind turbines normally, the voltage U T at the grid connection point of the wind farm is not in the preset first SVG voltage threshold interval, and the terminal voltage U T is not in the preset first SVG voltage threshold interval. If w is not in the preset first terminal voltage threshold interval, the wind farm SVG and the on-site wind turbines perform a third reactive power adjustment;

Step 3. When the wind farm SVG and the on-site wind turbines perform the third reactive power adjustment, measure the wind farm SVG and all on-site wind turbines to enter the voltage emergency control mode and perform power the wind farm network and the adjusted voltage U 'T field of wind turbines and the terminal voltage U' w, the electric field in the air outlets and the voltage U 'T in the case where the second voltage threshold SVG interval set in advance and the terminal voltage U of the field of wind turbines' w in the case of the second terminal voltage, a threshold interval set in advance, processing returns to step 2 for the second reactive power control in the wind park and a second case-side voltage threshold interval 'SVG case where the second voltage threshold value interval T is not set in advance or the terminal voltage U of the field of wind turbines' dots voltage U W is not set in advance, Return to step 2 to perform the third reactive power adjustment.
The method according to claim 1, wherein, in the case of a communication failure between the wind farm station control system and the on-site wind turbine, the wind farm SVG and the on-site wind turbine perform the first Reactive power regulation, including:

In the case of a communication failure between the wind farm station control system and the on-site wind turbines, the wind farm SVG and the on-site wind turbines enter the voltage closed-loop control mode, and the wind farm SVG is based on the wind farm The voltage U T of the grid connection point of the wind farm read by the station control system adjusts the generated reactive power, and the on-site wind turbine unit adjusts the generated reactive power according to the terminal voltage U w .
The method according to claim 1, wherein, when the communication between the station control system of the wind farm and the wind turbines in the farm is normal, the voltage U T at the grid connection point of the wind farm is at the preset first If an SVG voltage threshold interval, and the generator terminal voltage U w is within the preset first generator terminal voltage threshold interval, the wind farm SVG and the on-site wind turbines performing the second reactive power adjustment includes :

When the wind farm station control system communicates with the on-site wind turbines normally, the wind farm station control system is based on the voltage U T at the grid-connection point of the wind farm, and the active power P of the on-site wind turbines , The reactive power Q and the terminal voltage U w determine the optimal value of the reactive power of the in-farm wind turbine and the optimal value of the reactive power of the wind farm SVG, and send an optimal value instruction To the wind farm SVG and the on-site wind turbine;

In the case that the voltage U T of the grid connection point of the wind farm is within the preset first SVG voltage threshold interval, the wind farm SVG is based on the optimal reactive power value of the wind farm SVG sent by the wind farm station control system Perform power adjustment;

In the case that the generator terminal voltage U w is in the preset first generator terminal voltage threshold interval, the on-site wind turbine receives the highest reactive power of the on-site wind turbine from the wind farm station control system. The merit is adjusted for power.
The method according to claim 3, wherein the voltage U T at the grid connection point of the wind farm is not in the preset first when the communication between the station control system of the wind farm and the on-site wind turbine is normal. An SVG voltage threshold interval, and the generator terminal voltage U w is not within the preset first generator terminal voltage threshold interval, the wind farm SVG and the on-site wind turbines performing a third reactive power adjustment, including :

When the wind farm station control system communicates with the on-site wind turbines normally, and the voltage U T of the wind farm grid connection point is not in the preset first SVG voltage threshold interval, the wind farm SVG enters the voltage Emergency control mode, blocking the reactive power optimal value adjustment command of the wind farm SVG sent by the wind farm station control system, and calculating the adjusted power Q SVG of the wind farm SVG to perform power adjustment;

In the case that the station control system of the wind farm communicates with the on-site wind turbines normally, and the terminal voltage U w of the on-site wind turbines is not in the preset first terminal voltage threshold interval, the on-site wind turbine The wind turbine enters the voltage emergency control mode, blocks the reactive power optimal value command of the on-site wind turbines sent by the wind farm station control system, and calculates the adjusted power Q w of the on-site wind turbines for power adjustment.
The method according to claim 3, wherein the wind farm station control system is based on the voltage at the grid connection point of the wind farm when the wind farm station control system communicates with the on-site wind turbines normally. U T , the active power P of the on-site wind turbines, the reactive power Q and the terminal voltage U w , determine the optimal reactive power of the on-site wind turbines and the SVG of the wind farm The optimal value of reactive power includes:

Step 1. Establish the equation constraint conditions of the AC line, the equation constraint conditions of the active power of the wind farm grid connection point, the equation constraint conditions of the voltage, the upper and lower limit constraints of the multiple node voltages in the wind farm and the multiple constraints in the wind farm Reactive power upper and lower limit constraints of the inverter;

Step 2. Based on the equation constraint conditions of the AC line, the equation constraint conditions of the active power of the wind farm grid connection point, the equation constraint conditions of the voltage, the upper and lower limit constraints of the multiple node voltages in the wind farm and the constraints in the wind farm Reactive power upper and lower limit constraints of multiple inverters to construct the objective function of the optimal reactive power output of multiple power sources in the wind farm;

Among them, α and β are weighting factors, and satisfy

α+β=1

Q svg.m is the reactive power output of the m-th typhoon wind farm SVG;

P loss.ij is the active loss between grid node i and grid node j, and the calculation formula is:

In the formula, V i and V j represent the voltages of grid node i and grid node j, respectively, θ ij represents the voltage phase angle difference between grid node i and grid node j, and g ij represents the grid node i and the grid node in the node admittance matrix. The conductance parameters of the line between the grid nodes j, N and M are positive integers, i=1, 2,...N, j=1, 2,...N, m=1, 2,...M;

Step 3. Construct a Lagrangian function based on the objective function of the optimal reactive output of multiple power sources in the wind farm, and the calculation formula is:

Among them, λ 1 , λ 2 and λ 3 are all Lagrangian multipliers, ΔP i is the active power error of grid node i, P ord and V ord are the active power and voltage commands issued by the upper-level dispatcher, P s And V s are the active power and voltage of the grid connection point of the wind farm;

Step 4. According to the Lagrangian extremum evaluation conditions, we can get:

Among them, Q wk is the reactive power output of the wind turbine in the k-th yard;

Step 5. In the case that the collection line in the wind farm has a chain structure, the solution of the equation set constructed by the Lagrangian function is solved, and the solution of the equation set is taken as the non-existent value of all wind turbines in the field. The optimal value of the power and the optimal value of the reactive power of the wind farm SVG, wherein the solution of the nodes in the wind farm exceeds the upper and lower limit constraints of the voltages of the multiple nodes in the wind farm and the multiple inverses in the wind farm In the case of the upper and lower limit constraint conditions of the reactive power of the converter, the inequality constraint condition is transformed into an equality constraint, and the value of the inequality constraint condition takes the boundary value of the constraint condition.
The method according to claim 5, wherein the equation constraint condition for establishing the AC line, the equation constraint condition for the active power of the wind farm grid connection point, the equation constraint condition for the voltage, and the multiple node voltages in the wind farm The upper and lower limit constraints and the reactive power upper and lower limit constraints of multiple inverters in the wind farm include:

According to the topological structure of the electrical lines in the wind farm, the types of nodes in the wind farm are divided into nodes that only contain the wind turbines in the farm, nodes that contain only the wind farm SVG, and nodes that neither contain the wind turbines nor the wind turbines. The nodes of the wind farm SVG are not included, and the AC line equation constraint conditions for each node are constructed, and the AC line equation constraint conditions are to make the active power error ΔP i and the reactive power error ΔQ of the grid nodes in the wind farm i is equal to 0;

For the active power and voltage commands issued by the upper-level dispatcher, construct an equation constraint condition for the active power and an equation constraint condition for the voltage at the grid-connected point of the wind farm;

P s ＝P ord

V s ＝V ord

According to the actual operating requirements of the on-site wind turbines and the wind farm SVG, the upper and lower limit constraints of the multiple node voltages in the wind farm and the reactive power upper and lower limits of the multiple inverters in the wind farm are constructed respectively. The lower limit constraint, the formula is:

V i.min ≤V i ≤V i.max

Q wk.min ≤Q wk ≤Q wk.max

Q svg.min ≤Q svg.m ≤Q svg.max

In the formula, V i.min and V i.max are the upper limit and lower limit of the voltage of the grid node i respectively, and Q wk.min and Q wk.max are the reactive power output of the wind turbines in the k- th yard, respectively. The upper limit and the lower limit, Q svg.min and Q svg.max are the upper limit and the lower limit of the reactive power output of the wind farm SVG, respectively.
The method according to claim 4, wherein the communication between the station control system of the wind farm and the on-site wind turbine generator is normal, and the voltage U T of the grid connection point of the wind farm is not at the preset first SVG voltage In the case of the threshold interval, the wind farm SVG enters the voltage emergency control mode, blocks the wind farm SVG's reactive power optimal value adjustment command sent by the wind farm station control system, and calculates the wind farm SVG adjustment power Performing power adjustment after QSVG includes: performing proportional integral PI control based on the voltage U T of the grid-connected point of the wind farm, and performing reactive power adjustment based on the output value of the PI control;

In the case where the station control system of the wind farm communicates with the on-site wind turbines normally, and the terminal voltage U w of the on-site wind turbines is not in the preset first terminal voltage threshold interval, the The on-site wind turbines enter the voltage emergency control mode, block the reactive power optimal value command of the on-site wind turbines sent by the wind farm station control system, and calculate the adjusted power Q w of the on-site wind turbines for power adjustment, It includes: performing PI control based on the terminal voltage U w of all wind turbines in the field, and performing reactive power adjustment according to the output value of the PI control.
The method according to claim 1, wherein the range of the first SVG voltage threshold interval is greater than the range of the second SVG voltage threshold interval, and the range of the first terminal voltage threshold interval is greater than the range of the second machine terminal voltage threshold interval. The range of the terminal voltage threshold interval.
A system for coordinated control of reactive power and voltage of wind farms, including:

The data acquisition unit is set to measure the voltage U T at the grid connection point of the wind farm, and measure the active power P output by the wind turbines in the farm, the reactive power Q output by the wind turbines in the farm and the terminal voltage U w of the wind turbines in the farm;

A data communication unit, configured to perform data communication between the wind farm station control system and multiple inverters in the wind farm, and determine the communication status between the wind farm station control system and the wind turbines in the wind farm;

The first power adjustment unit is configured to perform the first non-removal of the wind farm static var generator SVG and the on-site wind turbine generator in the case of a communication failure between the wind farm station control system and the on-site wind turbine generator. Power adjustment;

The second power adjustment unit is configured to, when the wind farm station control system and the on-site wind turbines communicate normally, the voltage U T at the grid connection point of the wind farm is within a preset first SVG voltage threshold interval , And when the generator terminal voltage U w is within the preset first generator terminal voltage threshold interval, the second reactive power adjustment is performed on the wind farm SVG and the in-farm wind turbine;

The third power adjustment unit is configured to, when the wind farm station control system and the on-site wind turbines communicate normally, the voltage U T at the grid connection point of the wind farm is not in the preset first SVG voltage threshold interval , And the generator terminal voltage U w is not in the preset first generator terminal voltage threshold interval, the wind farm SVG and the in-farm wind turbines perform a third reactive power adjustment;

The coordination control unit is configured to measure the wind farm SVG and all the inverters in the station to enter the voltage emergency through the data acquisition unit when the wind farm SVG and the inverter in the station perform the third reactive power adjustment. control mode and the wind farm power regulation and network voltage U 'T station and the terminal voltage of the inverter U' w, the wind farm network and the voltage U 'T in the second preset voltage SVG threshold value range, and within the terminal voltage of the inverter station U 'w in the case of the second terminal voltage, a threshold value preset interval, returning the second power adjusting unit performs the second power adjustment in the wind farm and the network voltage U 'when the second SVG voltage threshold interval T is not set in advance, or in the station-side voltage of the inverter U' a second terminal voltage, a threshold interval w is not set in advance In this case, return to the third power adjustment unit to continue the third reactive power adjustment.
The system according to claim 9, wherein the first power adjustment unit is configured to: in the case of a communication failure between the wind farm station control system and the on-site wind turbine, the wind farm SVG and the wind turbine generator The wind turbines in the farm enter the voltage closed-loop control mode. The wind farm SVG adjusts the reactive power generated by the wind farm grid connection point voltage U T read by the wind farm station control system. The terminal voltage U w regulates the reactive power sent out.
The system according to claim 9, wherein the second power adjustment unit is configured to:

When the wind farm station control system communicates with the on-site wind turbines normally, the wind farm station control system is based on the voltage U T at the grid-connection point of the wind farm, and the on-site wind turbine active power P, The reactive power Q and the terminal voltage U w determine the optimal value of the reactive power of the wind turbine in the farm and the optimal value of the reactive power of the wind farm SVG, and send an instruction of the optimal value to The wind farm SVG and the on-site wind turbine;

In the case that the voltage U T of the grid connection point of the wind farm is within the preset first SVG voltage threshold interval, the wind farm SVG is based on the optimal reactive power value of the wind farm SVG sent by the wind farm station control system Perform power adjustment;

In the case that the generator terminal voltage U w is in the preset first generator terminal voltage threshold interval, the on-site wind turbine receives the highest reactive power of the on-site wind turbine from the wind farm station control system. The merit is adjusted for power.
The system according to claim 11, wherein the third power adjustment unit is configured to:

When the wind farm station control system communicates with the on-site wind turbines normally, and the voltage U T of the wind farm grid connection point is not in the preset first SVG voltage threshold interval, the wind farm SVG enters the voltage Emergency control mode, blocking the reactive power optimal value adjustment command of the wind farm SVG sent by the wind farm station control system, and calculating the adjusted power Q SVG of the wind farm SVG to perform power adjustment;

In the case that the station control system of the wind farm communicates with the on-site wind turbines normally, and the terminal voltage U w of the on-site wind turbines is not in the preset first terminal voltage threshold interval, the on-site wind turbine The wind turbine enters the voltage emergency control mode, blocks the reactive power optimal value command of the on-site wind turbines sent by the wind farm station control system, and calculates the adjusted power Q w of the on-site wind turbines for power adjustment.
The method according to claim 11, wherein the second power adjustment unit is configured to:

Step 1. Establish the equation constraint conditions of the AC line, the equation constraint conditions of the active power of the wind farm grid connection point, the equation constraint conditions of the voltage, the upper and lower limit constraints of the multiple node voltages in the wind farm and the multiple constraints in the wind farm Reactive power upper and lower limit constraints of the inverter;

Step 2. Based on the equation constraint conditions of the AC line, the equation constraint conditions of the active power of the wind farm grid connection point, the equation constraint conditions of the voltage, the upper and lower limit constraints of the multiple node voltages in the wind farm and the constraints in the wind farm Reactive power upper and lower limit constraints of multiple inverters to construct the objective function of the optimal reactive power output of multiple power sources in the wind farm;

Among them, α and β are weighting factors, and satisfy

α+β=1

P loss.ij is the active loss between grid node i and grid node j, and the calculation formula is:

In the formula, V i and V j represent the voltages of grid node i and grid node j, respectively, θ ij represents the voltage phase angle difference between grid node i and grid node j, and g ij represents the grid node i and the grid node in the node admittance matrix. The conductance parameter of the line between the grid nodes j, Q svg.m is the reactive power output of the m-th wind farm SVG, N and M are positive integers, i=1, 2,...N, j=1, 2,...N , M=1, 2,...M;

Step 3. Construct a Lagrangian function based on the objective function of the optimal reactive power output of the multiple power sources in the wind farm, and its calculation formula is:

Among them, λ 1 , λ 2 and λ 3 are all Lagrangian multipliers, ΔP i is the active power error of grid node i, P ord and V ord are the active power and voltage commands issued by the upper-level dispatcher, P s And V s are the active power and voltage at the grid connection point of the wind farm;

Step 4. According to the Lagrangian extremum, the conditions can be obtained

Among them, Q wk is the reactive power output of the wind turbine in the k-th yard;

Step 5. In the case that the collection line in the wind farm has a chain structure, the solution of the equation set constructed by the Lagrangian function is solved, and the solution of the equation set is taken as the non-existent value of all wind turbines in the field. The optimal value of the power and the optimal value of the reactive power of the wind farm SVG, wherein the solution of the node in the wind farm exceeds the upper and lower limit constraints of the multiple node voltages in the wind farm and the multiple inverters in the wind farm In the case of the upper and lower limit constraint conditions of reactive power, the inequality constraint condition is transformed into an equality constraint, and the value of the inequality constraint condition takes the boundary value of the constraint condition.
The system according to claim 13, wherein the third power adjustment unit is configured to:

According to the topological structure of the electrical lines in the wind farm, the types of nodes in the wind farm are divided into nodes that only contain the wind turbines in the farm, nodes that contain only the wind farm SVG, and nodes that neither contain the wind turbines nor the wind turbines. The nodes of the wind farm SVG are not included, and the AC line equation constraint conditions for each node are constructed, and the AC line equation constraint conditions are to make the active power error ΔP i and the reactive power error ΔQ of the grid nodes in the wind farm i is equal to 0;

For the active power and voltage commands issued by the upper-level dispatcher, construct an equation constraint condition for the active power and an equation constraint condition for the voltage at the grid-connected point of the wind farm;

P s ＝P ord

V s ＝V ord

According to the actual operating requirements of the on-site wind turbines and the wind farm SVG, the upper and lower limit constraints of the multiple node voltages in the wind farm and the reactive power upper and lower limits of the multiple inverters in the wind farm are constructed respectively. The lower limit constraint, the formula is:

V i.min ≤V i ≤V i.max

Q wk.min ≤Q wk ≤Q wk.max

Q svg.min ≤Q svg.m ≤Q svg.max

In the formula, V i.min and V i.max are the upper limit and lower limit of the voltage of the grid node i respectively, and Q wk.min and Q wk.max are the reactive power output of the wind turbines in the k- th yard, respectively. The upper limit and the lower limit, Q svg.min and Q svg.max are the upper limit and the lower limit of the reactive power output of the wind farm SVG, respectively.
The system according to claim 12, wherein the third power adjustment unit is configured to: perform proportional integral PI control based on the voltage U T of the grid connection point of the wind farm, and perform reactive power based on the output value of the PI control. Power regulation

The third power adjustment unit is configured to perform PI control based on the terminal voltage U w of all wind turbines in the farm, and perform reactive power adjustment based on the output value of the PI control.
The system according to claim 9, wherein the range of the first SVG voltage threshold interval is greater than the range of the second SVG voltage threshold interval, and the range of the first terminal voltage threshold interval is greater than the range of the second terminal voltage threshold interval. The range of the terminal voltage threshold interval.