CN110198033B

CN110198033B - Flexible direct current transmission end new energy isolated network reactive voltage control method and device

Info

Publication number: CN110198033B
Application number: CN201910327267.4A
Authority: CN
Inventors: 吴林林; 徐曼; 刘辉; 张隽; 刘海涛; 刘莹; 邓晓洋
Original assignee: State Grid Corp of China SGCC; North China Electric Power Research Institute Co Ltd; State Grid Jibei Electric Power Co Ltd; Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
Current assignee: State Grid Corp of China SGCC; North China Electric Power Research Institute Co Ltd; State Grid Jibei Electric Power Co Ltd; Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
Priority date: 2019-04-23
Filing date: 2019-04-23
Publication date: 2021-06-29
Anticipated expiration: 2039-04-23
Also published as: CN110198033A

Abstract

The application provides a flexible direct current sending end new energy isolated network reactive voltage control method and device, and the method comprises the following steps: in the current control period, collecting system voltage and power data of a flexible direct current transmitting end isolated network system, wherein the isolated network system comprises a new energy station accessed into a flexible direct current power grid, a collecting system and a transmitting end converter station of the flexible direct current power grid; acquiring a voltage control target value of the next control period of the isolated network system according to system voltage data and a preset multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to active loss of the isolated network system and reactive power margin of a transmitting-end converter station; and performing reactive voltage control on the isolated network system in the next control period based on the voltage control target value in the next control period. The method and the device can effectively improve the safety and the economical efficiency of the isolated network system formed by the new energy cluster and the flexible direct current power grid sending end converter station, and the control process is reliable, stable and efficient.

Description

Flexible direct current transmission end new energy isolated network reactive voltage control method and device

Technical Field

The application relates to the technical field of electric power, in particular to a flexible direct current sending end new energy isolated network reactive voltage control method and device.

Background

After ten years of development, with the continuous increase of practical engineering application and the accumulation of operation experience, the flexible direct-current power transmission technology has proved to have feasibility and superiority in technology and engineering respectively. Compared with the traditional direct-current power transmission, the method has great technical advantages particularly in the aspects of renewable energy grid connection, distributed power generation grid connection, island grid connection, urban power supply and distribution and the like. The comprehensive advantages of the method are more obvious in the aspects of renewable energy power generation grid connection, island power supply and the like. The flexible direct-current transmission technology is applied to the new energy cluster grid connection, and the problem of voltage fluctuation caused by the fluctuation of the output power of the new energy cluster can be solved. Therefore, controlling the isolated grid formed by the new energy cluster accessing the flexible dc power grid and the transmitting end converter station of the flexible dc power grid is also an important issue in current power grid research.

In the prior art, reactive/voltage centralized optimization control systems are already put into operation in part of regions, the systems take the economic operation of the whole system as an optimization target, but the economic efficiency of the system is considered, the safety of the system is not paid enough attention, and the potential safety hazard of the system is caused. That is to say, the existing method for controlling reactive voltage of an isolated network formed by a new energy cluster connected to a flexible direct-current power grid and a transmitting end converter station of the flexible direct-current power grid has the problem that the safety and the economical efficiency of the isolated network system cannot be ensured at the same time.

Therefore, how to design a reactive voltage control method for isolated power grid, which can simultaneously guarantee the safety and the economy of the isolated power grid system, is a technical problem to be solved urgently.

Disclosure of Invention

Aiming at the problems in the prior art, the application provides a flexible direct current delivery end new energy isolated network reactive voltage control method and device, which can effectively improve the safety and economy of an isolated network system formed by an energy cluster and a delivery end converter station of a flexible direct current power grid, and the control process is reliable, stable and efficient.

In order to solve the technical problem, the application provides the following technical scheme:

in a first aspect, the application provides a flexible direct current sending end new energy isolated network reactive voltage control method, including:

in the current control period, collecting system voltage and power data of a flexible direct current transmitting end isolated network system, wherein the flexible direct current transmitting end isolated network system comprises a new energy station accessed into a flexible direct current power grid, a collecting system and a transmitting end converter station of the flexible direct current power grid;

acquiring a voltage control target value of the next control period of the flexible direct current sending end isolated network system according to the system voltage and power data at the end of the last control period and a preset multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to the active loss of the flexible direct current sending end isolated network system and the reactive power margin of the sending end converter station;

and performing reactive voltage control of the next control period on the flexible direct current transmission end isolated network system based on the voltage control target value of the next control period.

Further, still include:

and in each control period, acquiring system voltage and power data of the flexible direct current transmitting end isolated network system, acquiring a voltage control target value of the flexible direct current transmitting end isolated network system in the next control period according to the system voltage and power data and a preset multi-target reactive power optimization model, and performing reactive voltage control on the flexible direct current transmitting end isolated network system based on the voltage control target value of the next control period.

Further, the flexible direct current sending end isolated network system comprises: the system comprises an alternating current bus of the sending end converter station, a plurality of new energy stations forming a new energy cluster, and an alternating current collecting system for connecting the new energy stations into the sending end converter station;

correspondingly, the system voltage data includes:

the voltage and power data of the grid-connected point of each new energy station, the voltage data of each collecting station, the active power and reactive power data of the sending end converter station, and the alternating current bus voltage data of the sending end converter station.

Further, the obtaining of the voltage control target value of the next control period of the flexible direct current transmission end isolated grid system according to the system voltage and power data at the end of the last control period and the multi-target reactive power optimization model includes:

and inputting the system voltage and power data at the end of the last control period into an objective function of the multi-objective reactive power optimization model, and solving the multi-objective reactive power optimization model by applying a genetic algorithm according to the constraint conditions of the multi-objective reactive power optimization model to obtain a voltage control target value of the next control period of the flexible direct current sending end isolated network system.

Furthermore, reactive compensation devices are respectively arranged in the grid-connected points of the new energy stations and a collecting station for connecting the new energy stations to the sending end converter station, and the reactive compensation devices are dynamic reactive compensation devices with continuous adjustment capability;

correspondingly, in the process of solving the multi-target reactive power optimization model by applying a genetic algorithm, when an initial seed group is generated, coding solution is carried out in a mixed coding mode;

the reactive compensation capacity and the voltage reference value of the reactive compensation device are continuous variables, and real number coding is adopted;

and the transformer tap in the sending end converter station is a discrete variable and adopts integer coding.

Further, the performing reactive voltage control of the next control cycle on the flexible direct current transmission end isolated network system based on the voltage control target value of the next control cycle includes:

issuing the voltage control target value of each new energy station grid-connected point of the next control period to each corresponding new energy station, so that each new energy station adjusts the reactive power output of the corresponding reactive power compensation device according to the voltage control target value of each corresponding grid-connected point;

and sending the voltage control target value of the alternating current bus of the next control period to the sending end converter station, so that the sending end converter station adjusts the voltage set value of the alternating current bus in the next control period according to the voltage control target value of the alternating current bus.

Further, before the acquiring system voltage data of the flexible direct current transmitting end isolated network system, the method further comprises the following steps:

constructing a multi-target reactive power optimization model;

the multi-target reactive power optimization model comprises two objective functions, wherein one objective function is an active loss objective function of the flexible direct current transmitting end isolated network system, and the other objective function is a reactive power margin objective function of the transmitting end converter station.

Further, an active loss objective function of the flexible direct current transmitting end isolated network system is determined according to the number of nodes of the flexible direct current transmitting end isolated network system, the voltage of each node, the conductance, susceptance and phase angle difference among the nodes, and the loss of the transmitting end converter station;

and the nodes comprise the grid-connected points of all the new energy stations in the new energy cluster and the alternating current buses of the sending end converter stations.

Further, an active loss objective function F of the flexible direct current transmitting end isolated network system₁Comprises the following steps:

in the formula I, N is the number of nodes of the isolated network system of the flexible direct current transmission end; u shape_iAnd U_jThe voltage amplitudes of nodes i and j, respectively; g_ij、B_ijAnd theta_ijRespectively the conductance, susceptance and phase angle difference between the nodes i and j; p_{dc_loss}Is the loss of the sending end converter station.

Further, the reactive power margin objective function of the sending-end converter station is determined according to the voltage of the grid-connected point of the new energy cluster and the output alternating voltage fundamental wave phasor of the sending-end converter station.

Further, a reactive power margin objective function F of the sending end converter station₂Comprises the following steps:

in formula two, Q_VSCThe reactive output of the flexible direct current convertor station under the current control mode is positive by inflow,

for the reactive upper limit of the flexible direct current converter station,Qthe lower reactive limit of the flexible direct current converter station is determined by a flexible direct current converter station PQ diagram.

Further, the multi-objective reactive power optimization model minF is as follows:

minF＝λ₁×F₁+λ₂×F₂formula three

In formula three, F₁The active loss objective function of the isolated network system of the flexible direct current transmission end is obtained; f₂Is a reactive power margin objective function, lambda, of said transmitting converter station₁And λ₂Respectively as active loss objective function F of the flexible direct current transmitting end isolated network system₁And a reactive power margin objective function F of the sending end converter station₂The weight coefficient of (c).

Further, the constraint conditions of the multi-target reactive power optimization model minF are as follows:

in formula four, P_GiAnd P_LiRespectively the active power and the active load sent by the node i; n is the number of nodes of the isolated network system of the flexible direct current transmission end; u shape_iAnd U_jThe voltage amplitudes of nodes i and j, respectively; g_ij、B_ijAnd theta_ijRespectively the conductance, susceptance and phase angle difference between the nodes i and j; p_{dc_loss}Is the loss of the sending end converter station; q_Gi、Q_CiAnd Q_LiRespectively the reactive power sent by the node i, the reactive power compensated by the reactive power compensation device and the reactive load; q_CimaxAnd Q_CiminRespectively compensating the upper limit and the lower limit of the reactive power for the node i reactive power compensation device; u shape_VmaxAnd U_VminRespectively, an upper limit and a lower limit of the voltage reference value; t is_tapRepresenting the gear of the converter transformer tap; u shape_imin、U_imaxRespectively representing the upper limit and the lower limit of the voltage of the node i; m represents the modulation ratio of the converter station; the node comprises a grid-connected point of each new energy station in the new energy cluster and a voltage reference point of the sending end converter station.

Further, an active loss objective function F of the flexible direct current transmitting end isolated network system₁And a reactive power margin objective function F of the sending end converter station₂Respectively corresponding weight coefficients lambda₁And λ₂And determining by adopting a sorting method.

In a second aspect, the application provides a flexible dc delivery end new forms of energy isolated network reactive voltage controlling means, includes:

the system comprises a data acquisition module, a data acquisition module and a data processing module, wherein the data acquisition module is used for acquiring system voltage and power data of a flexible direct current transmitting end isolated network system in a current control period, and the flexible direct current transmitting end isolated network system comprises a new energy station accessed into a flexible direct current power grid, a collecting system and a transmitting end converter station of the flexible direct current power grid;

the model solving module is used for acquiring a voltage control target value of the next control period of the flexible direct current sending end isolated network system according to the system voltage and power data at the end of the last control period and a preset multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to the active loss of the flexible direct current sending end isolated network system and the reactive power margin of the sending end converter station;

and the reactive voltage control module is used for controlling the reactive voltage of the next control period of the flexible direct current transmission end isolated network system based on the voltage control target value of the next control period.

Further, still include:

and the circulating control module is used for acquiring system voltage and power data of the flexible direct current transmitting end isolated network system in each control period, acquiring a voltage control target value of the flexible direct current transmitting end isolated network system in the next control period according to the system voltage and power data and a preset multi-target reactive power optimization model, and performing reactive voltage control on the flexible direct current transmitting end isolated network system based on the voltage control target value of the next control period.

correspondingly, the system voltage data includes:

Further, the model solution module includes:

and the genetic algorithm solving unit is used for inputting the system voltage and power data at the end of the last control period into an objective function of the multi-objective reactive power optimization model, solving the multi-objective reactive power optimization model according to the constraint conditions of the multi-objective reactive power optimization model and by applying a genetic algorithm, and obtaining the voltage control target value of the next control period of the flexible direct current transmitting end isolated network system.

Further, the reactive voltage control module comprises:

the new energy station control unit is used for issuing a voltage control target value of a grid-connected point of each new energy station in the next control period to each corresponding new energy station, so that each new energy station adjusts the reactive power output of the corresponding reactive power compensation device according to the voltage control target value of the grid-connected point corresponding to each new energy station;

and the sending end converter station control unit is used for sending the voltage control target value of the alternating current bus of the next control period to the sending end converter station, so that the sending end converter station adjusts the voltage set value of the alternating current bus in the next control period according to the voltage control target value of the alternating current bus.

Further, still include:

the model building module is used for building a multi-target reactive power optimization model;

minF＝λ₁×F₁+λ₂×F₂formula three

In formula three, F₁The active loss objective function of the isolated network system of the flexible direct current transmission end is obtained; f₂For reactive power of said transmitting end converter stationRate margin objective function, λ₁And λ₂Respectively as active loss objective function F of the flexible direct current transmitting end isolated network system₁And a reactive power margin objective function F of the sending end converter station₂The weight coefficient of (c).

In a third aspect, the present application provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the flexible dc transmitting end new energy isolated network reactive voltage control method when executing the program.

In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the flexible dc link new energy grid reactive voltage control method.

According to the technical scheme, the flexible direct current sending end new energy isolated network reactive voltage control method and device provided by the application comprise the following steps: in the current control period, collecting system voltage and power data of a flexible direct current transmitting end isolated network system, wherein the isolated network system comprises a new energy station accessed into a flexible direct current power grid, a collecting system and a transmitting end converter station of the flexible direct current power grid; acquiring a voltage control target value of the next control period of the isolated network system according to system voltage data and a preset multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to active loss of the isolated network system and reactive power margin of a transmitting-end converter station; based on the voltage control target value of the next control period, the reactive voltage control of the next control period is carried out on the isolated network system, from the two aspects of the economy of the whole isolated network system and the safety of the flexible direct current power grid converter station, the modulation ratio (MI, a concept in PWM) constraint range of the flexible direct current system converter station is considered, the voltage safety constraint of a new energy cluster central node is considered, the reactive voltage AVC master station optimization strategy is researched, the active loss of the system can be minimized, the reactive coordination capability of a new energy unit and reactive compensation equipment is fully utilized, the reactive power margin of a sending end converter station of the flexible direct current power grid is maximized, the new energy cluster central node voltage can be stabilized, namely, the safety and the economy of the isolated network system formed by the energy cluster and the sending end converter station of the flexible direct current power grid can be effectively improved, and the control process is reliable, Is stable and efficient.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic flow diagram of a flexible direct current transmission end new energy isolated grid reactive voltage control method according to the present application.

Fig. 2 is another schematic flow chart of the flexible direct current transmission end new energy isolated grid reactive voltage control method according to the present application.

Fig. 3 is a schematic structural diagram of the system of the present application.

Fig. 4 is a third flowchart schematic diagram of the flexible direct current transmission end new energy isolated grid reactive voltage control method according to the present application.

Fig. 5 is a schematic flow chart of an application example of the flexible direct current transmission end new energy isolated grid reactive voltage control method according to the present application.

Fig. 6 is a schematic diagram of the total active power output of the sink station a in a certain day in the application example of the present application.

Fig. 7 is a diagram illustrating the total active power of the sink station B on a certain day in the application example of the present application.

Fig. 8 is a schematic diagram of the total active power output of the sink station C in an application example of the present application.

Fig. 9 is a schematic diagram of the total active power output of the direct-aggregate station in an application example of the present application.

Fig. 10 is a schematic diagram of voltage values before and after optimization in a certain day at the compiling station a in the application example of the present application.

Fig. 11 is a schematic diagram of voltage values before and after optimization in a certain day at the sink station B in the application example of the present application.

Fig. 12 is a schematic diagram of the voltage values before and after optimization in a certain day at the sink station C in the application example of the present application.

Fig. 13 is a schematic structural diagram of the flexible dc-link reactive voltage control apparatus according to the present application.

Fig. 14 is another schematic structural diagram of the flexible dc-link reactive voltage control device according to the present application.

Fig. 15 is a third structural schematic diagram of the flexible dc-link reactive voltage control device according to the present application.

Fig. 16 is a schematic structural diagram of an electronic device in an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In consideration of the problem that safety and economy of an isolated network system cannot be guaranteed simultaneously in a reactive voltage control method for the isolated network in the prior art, the application provides a flexible direct current transmission end new energy isolated network reactive voltage control method. In the current control period, collecting system voltage and power data of a flexible direct current transmitting end isolated network system, wherein the flexible direct current transmitting end isolated network system comprises a new energy station accessed into a flexible direct current power grid, a collecting system and a transmitting end converter station of the flexible direct current power grid; acquiring a voltage control target value of the next control period of the flexible direct current sending end isolated network system according to the system voltage and power data at the end of the last control period and a preset multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to the active loss of the flexible direct current sending end isolated network system and the reactive power margin of the sending end converter station; based on the voltage control target value of the next control period, carrying out reactive voltage control of the next control period on the flexible direct current sending end isolated network system, considering the modulation ratio (MI, a concept in PWM) constraint range of the flexible direct current system converter station and considering new energy cluster central node voltage safety constraint from the aspects of the economy of the whole isolated network system and the safety of the flexible direct current grid converter station, researching a reactive voltage AVC master station optimization strategy, minimizing the active loss of the system, fully utilizing the reactive coordination capability of a new energy unit and reactive compensation equipment, maximizing the reactive power margin of the sending end converter station of the flexible direct current grid, stabilizing the new energy cluster central node voltage, namely effectively improving the safety and the economy of the isolated network system formed by an energy cluster and the sending end converter station of the flexible direct current grid, and the control process is reliable, stable and efficient.

It can be understood that the automatic voltage control AVC means that under the normal operation condition, the reactive power/voltage condition of the power grid is monitored in real time, online optimization calculation is performed, and the reactive power supply and the transformer tap of each node of the power grid are controlled in a layered adjustment mode. The AVC master station performs real-time optimal closed-loop control on reactive compensation controllable equipment of each node accessed to the power grid with uniform voltage level, so that the optimized reactive power flow operation under the condition of full-network safe voltage constraint is met, and the voltage quality and the optimization target are best.

In order to effectively improve the safety and the economy of an isolated network system formed by a new energy cluster accessed to a flexible direct-current power grid and a delivery end converter station of the flexible direct-current power grid by taking the active loss of the isolated network system and the reactive power margin of the delivery end converter station as optimization targets, the application provides an embodiment of a flexible direct-current delivery end new energy isolated network reactive voltage control method, and referring to fig. 1, the flexible direct-current delivery end new energy isolated network reactive voltage control method specifically comprises the following contents:

step 100: in the current control period, system voltage and power data of a flexible direct current transmitting end isolated network system are collected, wherein the flexible direct current transmitting end isolated network system comprises a new energy station accessed into a flexible direct current power grid, a collecting system and a transmitting end converter station of the flexible direct current power grid.

It is understood that the control period is set according to the actual application, and may be set to several minutes, hours, days, weeks, months, years, etc.

Step 200: and acquiring a voltage control target value of the next control period of the flexible direct current sending end isolated network system according to the system voltage and power data at the end of the last control period and a preset multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to the active loss of the flexible direct current sending end isolated network system and the reactive power margin of the sending end converter station.

Step 300: and performing reactive voltage control of the next control period on the flexible direct current transmission end isolated network system based on the voltage control target value of the next control period.

As can be seen from the above description, in the flexible direct current delivery end new energy isolated grid reactive voltage control method provided by the present application, system voltage data of an isolated grid system is collected in a current control period, where the isolated grid system includes a new energy cluster accessing a flexible direct current power grid and a delivery end converter station of the flexible direct current power grid, and a voltage control target value of a next control period of the isolated grid system is obtained according to the system voltage data and a preset multi-target reactive power optimization model, where the multi-target reactive power optimization model is a comprehensive optimization target function of an active loss of the isolated grid system and a reactive power margin of the delivery end converter station, and based on the voltage control target value of the next control period, reactive voltage control of the next control period is performed on the isolated grid system, and from the aspects of economy of the whole isolated grid system and safety of the flexible direct current power grid converter station, considering the constraint range of the modulation ratio (MI, a concept in PWM) of the converter station of the flexible direct current system and considering the safety constraint of the central node voltage of the new energy cluster, researching the optimization strategy of the reactive voltage AVC main station, minimizing the active loss of the system, fully utilizing the reactive coordination capability of the new energy unit and the reactive compensation equipment, maximizing the reactive power margin of the sending end converter station of the flexible direct current power grid, and stabilizing the central node voltage of the new energy cluster, namely effectively improving the safety and the economy of an isolated network system formed by the new energy cluster accessed into the flexible direct current power grid and the sending end converter station of the flexible direct current power grid, and the control process is reliable, stable and efficient.

In order to further improve the safety and the economy of the isolated network system by improving the intelligent control degree of the whole isolated network system, in a specific embodiment, the flexible direct current delivery end new energy isolated network reactive voltage control method is a periodic control method, and the flexible direct current delivery end new energy isolated network reactive voltage control method specifically comprises the following contents:

in each control period, the steps from 100 to 300 are respectively executed to acquire system voltage and power data of the flexible direct current sending end isolated network system, obtain a voltage control target value of the flexible direct current sending end isolated network system in the next control period according to the system voltage and power data and a preset multi-target reactive power optimization model, and perform reactive voltage control on the flexible direct current sending end isolated network system based on the voltage control target value of the next control period.

Referring to fig. 2, the steps 100 to 300 are performed during the current control period, i.e., at time T. And then, when the time reaches the next control period, namely, the time T +1, the steps 100 to 300 are repeatedly executed.

In one example, referring to fig. 3, the flexible dc transmitting end lone network system includes: the system comprises an alternating current bus of the sending end converter station, a plurality of new energy stations forming a new energy cluster, and an alternating current collection system for connecting the new energy stations into the sending end converter station. In the present example, the new energy cluster is composed of three collection stations A, B and C and a direct collection station, and includes 11 wind power stations and 8 photovoltaic power stations, the three collection station buses are central nodes, and reactive power compensation devices are configured at each electric field grid connection point and the three collection stations. Each grid-connected point is also a common connection point, a V point is a voltage reference value point, and a delta point is an equal potential point of the upper bridge arm reactor and the lower bridge arm reactor.

Based on the above, the system voltage data at least includes the following items:

(1) voltage and power data of the grid-connected point of each new energy station;

(2) voltage data for each of the collection stations;

(3) active power and reactive power data of the sending end converter station;

(4) and alternating current bus voltage data of the sending end converter station.

In order to improve the solving accuracy of the multi-target reactive power optimization model and further improve the safety and economy of the isolated network system, in a specific embodiment, the step 200 in the flexible direct current transmission end new energy isolated network reactive voltage control method specifically includes the following contents:

It can be understood that each new energy station grid-connected point and a collecting station for connecting a plurality of new energy stations to a sending end converter station are respectively provided with a reactive power compensation device, and the reactive power compensation device is a dynamic reactive power compensation device with continuous adjustment capability; therefore, in the process of solving the multi-target reactive power optimization model by applying a genetic algorithm, when an initial seed group is generated, coding solution is carried out in a mixed coding mode.

The reactive compensation capacity and the voltage reference value of the reactive compensation device are continuous variables, and real number coding is adopted; and the transformer tap in the sending end converter station is a discrete variable and adopts integer coding.

It can be understood that the optimization model is solved by using a genetic algorithm, and the parameters of the genetic algorithm are set to be the population individual number of 100, the iteration times of 150, the binary digit number of the variable of 20 and the gully value of 0.9.

In order to improve the accuracy of controlling the reactive voltage of the flexible direct current sending end new energy isolated network, so as to further improve the safety and the economy of the isolated network system, in a specific embodiment, step 300 in the method for controlling the reactive voltage of the flexible direct current sending end new energy isolated network specifically includes the following steps:

step 301: and issuing the voltage control target value of each new energy station grid-connected point in the next control period to each corresponding new energy station, so that each new energy station adjusts the reactive power output of the corresponding reactive power compensation device according to the voltage control target value of each corresponding grid-connected point.

Step 302: and issuing the voltage control target value of the alternating-current bus in the next control period to the sending end converter station, so that the sending end converter station adjusts the voltage set value of the alternating-current bus in the next control period according to the voltage control target value of the alternating-current bus.

In order to ensure that the safety, the economy and the reliability of the isolated network system are improved, in a specific embodiment, referring to fig. 4, before step 100 in the flexible direct current delivery end new energy isolated network reactive voltage control method of the present application, the following contents are further specifically included:

step 000: and constructing a multi-target reactive power optimization model.

Based on the above content, the application process of the flexible direct current sending end new energy isolated network reactive voltage control method specifically includes the following contents:

(1) constructing a multi-target reactive power optimization model of the new energy cluster isolated network system through flexible direct current transmission;

(2) at the moment T, collecting the active/reactive power, the voltage, the collecting station voltage, the converter station active/reactive power and the converter station alternating current bus voltage of the grid-connected point of each new energy field station at the current moment, substituting the collected voltages into the constructed optimization model, and solving the optimization model by adopting a genetic algorithm to obtain the grid-connected point voltage control target value and the flexible direct current converter station alternating current bus voltage control target value of each new energy field station in the next period (at the moment T + 1);

(3) issuing the voltage control target value of the grid-connected point of each new energy field station in the next period to the isolated network substation of the new energy field station and the voltage control target value of the alternating current bus of the flexible direct current converter station to the AVC substation of the flexible direct current converter station;

(4) according to the issued control target value, the AVC substation of the new energy station adjusts the output of the reactive power compensation device of the station, and the AVC substation of the flexible direct current converter station adjusts the voltage set value of the alternating current bus of the flexible direct current converter station;

(5) and (4) collecting active/reactive power, voltage, collecting station voltage, converter station active/reactive power and converter station alternating current bus voltage of the grid-connected point of each new energy station at the moment of T +1, substituting the collected voltages into the constructed optimization model, and repeating the steps (2) to (4).

In a specific embodiment, the active loss objective function of the flexible direct current sending end isolated grid system is determined according to the number of nodes of the flexible direct current sending end isolated grid system, the voltage of each node, the conductance, susceptance and phase angle difference between each node, and the loss of the sending end converter station, wherein the nodes include a grid connection point of each new energy station in the new energy cluster and an alternating current bus of the sending end converter station.

Based on the active loss objective function F of the flexible direct current transmission end isolated network system₁Comprises the following steps:

in the formula I, N is the number of nodes of the isolated network system of the flexible direct current transmission end; u shape_iAnd U_jThe voltage amplitudes of nodes i and j, respectively; g_ij、B_ijAnd theta_ijRespectively the conductance, susceptance and phase angle difference between the nodes i and j; p_{dc_loss}The loss of the sending end converter station can be 1.5% of the rated capacity of the converter station.

In a specific embodiment, the reactive power margin objective function of the sending end converter station is determined according to the voltage of the grid-connected point of the new energy cluster and the output ac voltage fundamental phasor of the sending end converter station.

Based on the above, the reactive power margin target function F of the sending end converter station₂Comprises the following steps:

for the reactive upper limit of the flexible direct current converter station,Qfor the reactive lower limit, Q, of the flexible DC converter station_VSC、

AndQare determined by the flexible dc converter station PQ diagram.

Based on the second formula and the third formula, the multi-target reactive power optimization model minF is as follows:

minF＝λ₁×F₁+λ₂×F₂formula three

Wherein, the active loss objective function F of the isolated network system₁And a reactive power margin objective function F of the sending end converter station₂Respectively corresponding weight coefficients lambda₁And λ₂The method is determined by a sorting method and comprises the following steps:

(1) using the constraints and genetic algorithm of claim 2 to solve two single-target problems minF₁(x)、 minF₂(x) And is recorded as the optimal solution x¹、x²。

(2) Respectively calculate F₁ ¹＝F₁(x¹)、F₁ ²＝F₁(x²)、

(3) Calculating the deviation of the first and second targets

It is obvious that

And

are all greater than zero.

(4) Respectively calculating the mean difference

(5) Calculating a weight coefficient lambda₂＝m₁/(m₁+m₂)、λ₁＝m₂/(m₁+m₂) Satisfy lambda₁+λ₂＝1。

In addition, the constraint conditions of the multi-target reactive power optimization model minF are as follows:

in formula four, P_GiAnd P_LiRespectively the active power and the active load sent by the node i; n is the number of nodes of the isolated network system of the flexible direct current transmission end; u shape_iAnd U_jThe voltage amplitudes of nodes i and j, respectively; g_ij、B_ijAnd theta_ijRespectively the conductance, susceptance and phase angle difference between the nodes i and j; p_{dc_loss}Is the loss of the sending end converter station; q_Gi、Q_CiAnd Q_LiRespectively the reactive power sent by the node i, the reactive power compensated by the reactive power compensation device and the reactive load; q_CimaxAnd Q_CiminRespectively compensating the upper limit and the lower limit of the reactive power for the node i reactive power compensation device; u shape_VmaxAnd U_VminRespectively, an upper limit and a lower limit of the voltage reference value; t is_tapRepresenting the gear of the converter transformer tap; u shape_imin、U_imaxRespectively show the sectionsUpper and lower limits of the point i voltage; m represents the modulation ratio of the converter station; the node comprises a grid-connected point of each new energy station in the new energy cluster and a voltage reference point of the sending end converter station.

As can be seen from the above description, the method for controlling reactive voltage of the flexible direct current sending end new energy isolated network provided by the embodiment of the application can effectively improve the safety and economy of the isolated network system formed by the new energy cluster connected to the flexible direct current power grid and the sending end converter station of the flexible direct current power grid, and the control process is reliable, stable and efficient.

To further explain the scheme, the application example of the flexible direct current sending end new energy isolated network reactive voltage control method is also provided in the present application, and referring to fig. 5, the flexible direct current sending end new energy isolated network reactive voltage control method specifically includes the following contents:

(1) establishing a system mathematical model: and establishing a detailed mathematical model according to the new energy cluster scale and the control mode of the flexible direct current system sending end converter station.

It is to be understood that the mathematical model comprises a multi-objective reactive power optimization model. The input parameters comprise the active output of each new energy station of the new energy cluster and system network parameters. The output is the backbone node voltage amplitude.

(2) Reading data: and acquiring active output data at a certain moment by using the detection device. Namely, the active output of each station of the new energy cluster is read. The active output data refers to an active power value sent by the new energy station.

(3) Model optimization: and according to the established mathematical model, carrying out optimization solution on the model by using a genetic algorithm and a MATPOWER toolkit.

(4) And (3) instruction decision: and after the model is optimized and solved, obtaining each central node value when the system objective function is optimal, and taking the voltage value as an execution instruction of the substation. The central node refers to buses of some main power plants or central substations capable of reflecting the voltage level of the system, refers to a class of nodes, and is not a node, and the central node in the patent is three collection station buses.

(5) Executing: and the substation executes according to the instruction issued by the AVC main station.

Specifically, the method comprises the following steps:

1. system mathematical model building

For analysis of multi-target reactive power optimization of a new energy cluster isolated network access flexible direct current power grid, when the new energy cluster is accessed to the flexible direct current power grid in an isolated network operation mode, a control mode of vf is adopted by the flexible direct current power grid sending end converter station, and the flexible direct current power grid sending end converter station provides a stable reference voltage value for the new energy cluster. Wherein vf refers to a control mode of a sending end converter station of the flexible direct current system when the flexible direct current power grid is connected with a passive system (a new energy cluster isolated grid system in the patent), and the control mode is constant alternating current voltage and constant alternating current frequency control.

2. Objective function

The application example of the method establishes the reactive voltage optimization multi-objective function from the viewpoints of system economy and safety of the flexible direct current power grid, and by taking the steady-state operation of the converter station and the voltage safety of the new energy station as constraints.

(1) System active network loss minimization

The active network loss of the isolated network system formed by the large-scale new energy cluster and the sending end converter station comprises the following steps: the active loss objective function adopted herein can be expressed as:

in the formula: f₁Expressed as system active network loss; n is the number of system nodes and comprises equivalent end nodes of the new energy field station, grid-connected nodes and a voltage reference point; u shape_iAnd U_jThe voltage amplitudes of the nodes i and j are respectively; g_ij、B_ij、θ_ijRespectively, conductance, susceptance and phase angle difference between the nodes i and j; p_{dc_loss}For sending end converter station loss, the converter station loss in the conventional direct current transmission system accounts for 0.5% -1% of rated power of the converter station. However, in operation of a flexible dc transmission system the voltage source converter valves are switched thousands of times within a cycle and soThe losses generated are relatively large and the losses of the whole converter station account for at least 1.5% of the rated capacity. The equivalent model only considers the reactive voltage optimization of the transmitting end converter station and the new energy cluster, so that the loss of the receiving end converter station and a direct current network line is not considered, wherein the equivalent end nodes of the new energy field station are three collecting station nodes.

(2) Maximum reactive power margin of sending end converter station

Setting the equivalent potential phasor of the equivalent system of the new energy cluster as

The fundamental phasor of the output voltage of the sending end converter station is

And is

Hysteresis

Is δ; and when the reactance between the converter station and the new energy cluster equivalent system is X, the active power and the reactive power input to the transmitting end converter station from the new energy cluster equivalent system are respectively as follows:

as can be seen from the above formula, the transmission of reactive power depends mainly on U_PCC-U_vcos δ. When U is turned_PCC-U_vcosδ>0, the new energy cluster equivalent system flows inductive reactive power into the sending end converter station; when U is turned_PCC-U_vcosδ<And when 0, the new energy cluster equivalent system flows capacitive reactive power into the sending end converter station. To ensure that the flexible direct current system sending end converter station has enough reactive support capability, namely, noAnd if the power margin is the maximum, the voltage difference between the common connection point and the voltage reference point is required to be the minimum, the reactive power flowing between the two points is the minimum, so that the reactive power margin of the sending end converter station is the maximum, and the common connection point is the point where the three collection stations are connected with the direct collection station. The objective function of the application example with the maximum reactive power margin can be expressed as:

3. constraint conditions

(1) Constraint of equality

The equality constraint, i.e. the power flow equation:

wherein, P_GiAnd P_LiRespectively, the active power and the active load, Q, sent by the node i_Gi、Q_CiAnd Q_LiRespectively the reactive power sent by the node i, the reactive power compensated by the reactive power compensation device and the reactive load; u shape_iAnd U_jThe voltage values of the node i and the node j are obtained;

G_ijis the node conductance between node i and node j, B_ijIs the node susceptance, θ, between node i and node j_ijIs the phase angle difference between node i and node j, and N is the total number of nodes.

(2) Constraint of inequality

A series of safety constraints in inequality constraint of reactive power optimization, including control variable constraint and state variable constraint, wherein each variable must be in a reasonable range in normal operation

Inequality constraints on the control variables:

wherein Q is_Cimax、Q_CiminAre respectively node i noneThe upper limit and the lower limit of the reactive power are compensated by the power compensation device; u shape_Vmax、U_VminRespectively, an upper limit and a lower limit of the voltage reference value; t is_tapIndicating the converter transformer tap gear.

Inequality constraints for state variables:

U_coremax、U_coreminrespectively representing the upper limit and the lower limit of the central bus voltage (namely the collection station A, the collection station B and the collection station C); m represents the converter station modulation ratio.

4. Solving of models

The data of the actual output of a new energy cluster in a certain area in one day, the installed capacity and the power factor of each power generation farm cluster are known.

Step 1: and calculating the total reactive power to be sent by the new energy clusters according to the total installed capacity of the new energy clusters in each collection station and an equal power factor distribution principle, and performing load flow calculation by using Matpower to obtain a better initial value of the voltage of the central node. The equal power factor distribution means that the power factor is the ratio of active power and apparent power, and reactive power is emitted according to the active power actually emitted by the station. The equal power factor means that the ratio of active power and apparent power emitted by each station is the same. The better initial value of the voltage of the central pivot node means that the waveform is relatively stable in the normal deviation range of the voltage. The voltage deviation range in engineering is as follows: 0.97p.u, -1.07 p.u. (per unit value).

Step 2: and importing the active output data at the moment T, establishing a region descriptor by utilizing a genetic algorithm, randomly acquiring an initial population, and controlling variables to be dynamic reactive power compensation, converter transformer ratio and voltage reference values of new energy cluster grid-connected points and collection points. And setting a penalty function, and normalizing the multi-objective function to obtain a single objective function and obtain an objective function value of the initial population. The active output data is an active power value sent by each new energy station; the penalty function is only related to the program, the multi-objective function refers to a plurality of single objective functions, and in the application example, two single objective functions are respectively F1 and F2. The objective function values are the results of each optimization, the values in the table in the case of the example analysis.

Step 3; and sequencing the objective function values according to the fitness, obtaining a new individual population through a selection operator, a crossover operator and a mutation operator, calculating the objective function values of the population, and transmitting the excellent characteristics of the individual population to the next generation by utilizing reinsertion so as to enter the next iteration. And obtaining a stable and optimal individual population after 100 iterations. Wherein the sorting standard is from large to small according to the fitness. The reinsertion is realized in the program, and the excellent genetic characteristics are that the objective function is optimal, and 100 times are values which can be set in the program.

Step 4: and performing reactive power optimization on the next time T (T + 1) according to the voltage of the central pivot node obtained by optimizing the time T, reestablishing a region description area, and randomly acquiring an initial population, wherein control variables are a normal offset range of the central pivot node, a converter transformer ratio and a voltage reference value. And calculating a sensitivity matrix, obtaining a reactive power regulation site sequence order influencing the size of the central pivot node according to the randomly obtained central pivot voltage offset, sequentially regulating, and calculating the power flow by applying a Mat power toolkit to obtain a target function value.

Step 5: and (4) obtaining the central node voltage and the objective function value after reactive power optimization at the moment T +1 by using a genetic algorithm.

Step 6: and repeating the optimization step at the moment T +1, and circulating to obtain the voltage curve of each central pivot node after the reactive power optimization of the new energy cluster.

5. Example simulation and analysis

(1) Referring to fig. 3, the output data for each day is first presented for three aggregation stations and for the direct aggregation station. See the total active power output of the collection station a for a day of fig. 6, the total active power output of the collection station B for a day of fig. 7, the total active power output of the collection station C for a day of fig. 8, and the total active power output of the direct collection station for a day of fig. 9.

(2) According to the optimization strategy of the patent, a comparison graph and data of the voltages of the central hub nodes before and after optimization are obtained, wherein a graph 10 shows the voltage values before and after optimization in a certain day of a gathering station A, a graph 11 shows the voltage values before and after optimization in a certain day of a gathering station B, and a graph 12 shows the voltage values before and after optimization in a certain day of a gathering station C.

See table 1 for comparison of data before and after optimization:

TABLE 1

According to data comparison before and after optimization, the optimization strategy can obviously reduce the system network loss and reduce the voltage difference between a public connection point (central node) and voltage reference voltage, so that the flow of reactive power is reduced.

According to the flexible direct current sending end new energy isolated network reactive voltage control method provided by the application example, on the basis of the existing AVC (automatic voltage control) main station optimization strategy, the flexible direct current power grid sending end converter station has sufficient reactive power supporting capacity and the voltage safety stability of a new energy cluster in an isolated network operation mode are considered, and the AVC main station optimization control strategy suitable for accessing the new energy cluster isolated network into the flexible direct current power grid is provided. By means of the optimization strategy, system network loss is reduced, the reactive power margin of the converter station is improved, and the voltage stability of the new energy cluster center node can be guaranteed.

In order to effectively improve the safety and the economy of an isolated network system formed by a new energy cluster accessed to a flexible direct-current power grid and a delivery end converter station of the flexible direct-current power grid by taking the active loss of the isolated network system and the reactive power margin of the delivery end converter station as optimization targets, the application provides an embodiment of a flexible direct-current delivery end new energy isolated network reactive voltage control device, and the flexible direct-current delivery end new energy isolated network reactive voltage control device specifically comprises the following contents:

the data acquisition module 10 is configured to acquire system voltage and power data of a flexible direct-current sending end isolated network system in a current control period, where the flexible direct-current sending end isolated network system includes a new energy station accessed to a flexible direct-current power grid, a collection system, and a sending end converter station of the flexible direct-current power grid.

And the model solving module 20 is configured to obtain a voltage control target value of a next control period of the flexible dc transmitting end isolated network system according to the system voltage and power data at the end of the previous control period and a preset multi-target reactive power optimization model, where the multi-target reactive power optimization model is determined according to the active loss of the flexible dc transmitting end isolated network system and the reactive power margin of the transmitting end converter station.

And the reactive voltage control module 30 is configured to perform reactive voltage control of the next control period on the flexible dc transmission end isolated network system based on the voltage control target value of the next control period.

As can be seen from the above description, in the flexible dc transmitting end new energy isolated network reactive voltage control method provided by the present application, the data acquisition module 10 acquires system voltage and power data of a flexible dc transmitting end isolated network system in a current control period, where the flexible dc transmitting end isolated network system includes a new energy field station accessing a flexible dc power grid, a collection system, and a transmitting end converter station of the flexible dc power grid, and the model solving module 20 obtains a voltage control target value of a next control period of the flexible dc transmitting end isolated network system according to the system voltage and power data at the end of a previous control period and a preset multi-target reactive optimization model, where the multi-target reactive optimization model is a comprehensive optimization target function of an active loss of the flexible dc transmitting end isolated network system and a reactive power margin of the transmitting end converter station, the reactive voltage control module 30 performs reactive voltage control of the next control period on the flexible direct current sending end isolated network system based on the voltage control target value of the next control period, considers the modulation ratio (MI, a concept in PWM) constraint range of the flexible direct current system converter station from two aspects of the economy of the whole isolated network system and the safety of the flexible direct current grid converter station, gives consideration to the new energy cluster central node voltage safety constraint, researches a reactive voltage AVC master station optimization strategy, can minimize the active loss of the system, fully utilizes the reactive coordination capability of the new energy unit and the reactive compensation equipment, maximizes the reactive power margin of the sending end converter station of the flexible direct current grid, and can stabilize the new energy cluster central node voltage, that is, can effectively improve the safety and economy of the isolated network system formed by the new energy cluster accessed to the flexible direct current grid and the sending end converter station of the flexible direct current grid, and the control process is reliable, stable and efficient.

In order to further improve the safety and the economy of the isolated network system by improving the intelligent control degree of the whole isolated network system, in a specific embodiment, referring to fig. 14, the isolated network reactive power flexible direct current sending end new energy isolated network reactive voltage control device of the application further includes the following contents:

and the circulation control module 40 is configured to, in each control period, execute the steps of acquiring system voltage and power data of the flexible direct current sending end isolated network system, obtaining a voltage control target value of a next control period of the flexible direct current sending end isolated network system according to the system voltage and power data and a preset multi-target reactive power optimization model, and performing reactive voltage control on the flexible direct current sending end isolated network system based on the voltage control target value of the next control period.

Wherein, flexible direct current send end lone network system includes: the system comprises an alternating current bus of the sending end converter station, a plurality of new energy stations forming a new energy cluster, and an alternating current collecting system for connecting the new energy stations into the sending end converter station;

correspondingly, the system voltage data includes:

In order to improve the solving accuracy of the multi-target reactive power optimization model and further improve the safety and the economy of the isolated network system, in a specific embodiment, the model solving module 20 in the flexible direct current transmission end new energy isolated network reactive voltage control device specifically includes the following contents:

and the genetic algorithm solving unit 21 is used for inputting the system voltage and power data at the end of the last control period into an objective function of the multi-objective reactive power optimization model, and solving the multi-objective reactive power optimization model by applying a genetic algorithm according to the constraint conditions of the multi-objective reactive power optimization model to obtain a voltage control target value of the next control period of the flexible direct current transmission end isolated network system.

It can be understood that each of the new energy station grid-connected points and the collecting station for connecting a plurality of new energy stations to the sending end converter station are respectively provided with a reactive power compensation device, and the reactive power compensation device is a dynamic reactive power compensation device with continuous adjustment capability.

Correspondingly, in the process of solving the multi-target reactive power optimization model by applying a genetic algorithm, when an initial seed group is generated, coding solution is carried out in a mixed coding mode; the reactive compensation capacity and the voltage reference value of the reactive compensation device are continuous variables, and real number coding is adopted; and the transformer tap in the sending end converter station is a discrete variable and adopts integer coding.

In order to improve the accuracy of the flexible dc-sending-end new energy isolated network reactive voltage control, so as to further improve the safety and the economy of the isolated network system, in a specific embodiment, the reactive voltage control module 30 in the flexible dc-sending-end isolated network reactive power flexible dc-sending-end new energy isolated network reactive voltage control device of the present application specifically includes the following contents:

and the new energy station control unit 31 is configured to issue the voltage control target value of the grid-connected point of each new energy station in the next control period to each corresponding new energy station, so that each new energy station adjusts the reactive power output of the corresponding reactive power compensation device according to the voltage control target value of the corresponding grid-connected point.

And a sending end converter station control unit 32, configured to issue the voltage control target value of the ac bus in the next control period to the sending end converter station, so that the sending end converter station adjusts the voltage set value of the ac bus in the next control period according to the voltage control target value of the ac bus.

In order to ensure that the safety, the economy and the reliability of the isolated network system are improved, in a specific embodiment, referring to fig. 15, the isolated network reactive voltage control method of the new energy at the flexible direct current transmission end further specifically includes the following contents:

the model building module 00 is used for building a multi-target reactive power optimization model;

The active loss objective function of the flexible direct current transmitting end isolated grid system is determined according to the number of nodes of the flexible direct current transmitting end isolated grid system, the voltage of each node, the conductance, the susceptance and the phase angle difference among the nodes and the loss of the transmitting end converter station;

The active loss objective function F of the isolated network system in the flexible direct current sending end new energy isolated network reactive voltage control device₁Comprises the following steps:

And a reactive power margin objective function of the sending end converter station in the flexible direct current sending end new energy isolated network reactive voltage control device is determined according to the voltage of the grid-connected point of the new energy cluster and the output alternating voltage fundamental wave phasor of the sending end converter station.

Reactive power margin objective function F of sending end converter station in flexible direct current sending end new energy isolated grid reactive voltage control device₂Comprises the following steps:

AndQare determined by the flexible dc converter station PQ diagram. The multi-target reactive power optimization model minF in the flexible direct current sending end isolated network reactive power flexible direct current sending end new energy isolated network reactive power voltage control device is as follows:

minF＝λ₁×F₁+λ₂×F₂formula three

The constraint conditions of the multi-target reactive power optimization model minF in the flexible direct current sending end isolated network reactive power flexible direct current sending end new energy isolated network reactive power voltage control device are as follows:

Active loss objective function F of the isolated network system in the flexible direct current transmission end voltage control device₁And a reactive power margin objective function F of the sending end converter station₂Respectively corresponding weight coefficients lambda₁And λ₂And determining by adopting a sorting method.

As can be seen from the above description, the flexible dc transmitting end voltage control device provided in the embodiment of the present application can effectively improve the safety and economy of an isolated network system formed by a new energy cluster connected to a flexible dc power grid and a transmitting end converter station of the flexible dc power grid, and the control process is reliable, stable, and efficient.

An embodiment of the present application further provides a specific implementation manner of an electronic device, which is capable of implementing all steps in the flexible direct current sending end new energy isolated grid reactive voltage control method in the foregoing embodiment, and referring to fig. 16, the electronic device specifically includes the following contents:

a processor (processor)601, a memory (memory)602, a communication Interface (Communications Interface)603, and a bus 604;

the processor 601, the memory 602 and the communication interface 603 complete mutual communication through the bus 604; the communication interface 603 is used for realizing information transmission among a server, a client terminal, various control units (an AVC main station and a plurality of AVC substations), a sensor and the like;

the processor 601 is configured to call a computer program in the memory 602, and when the processor executes the computer program, the processor implements all the steps in the flexible direct current transmission end new energy isolated network reactive voltage control method in the above embodiments, for example, when the processor executes the computer program, the processor implements the following steps:

As can be seen from the above description, the electronic device provided in the embodiment of the present application can effectively improve the safety and the economy of the isolated network system formed by the new energy cluster connected to the flexible dc power grid and the transmitting-end converter station of the flexible dc power grid, and the control process is reliable, stable, and efficient.

An embodiment of the present application further provides a computer-readable storage medium capable of implementing all steps in the method for screening a reactive voltage control manner of a flexible direct current delivery end new energy isolated grid in the above embodiment, where the computer-readable storage medium stores a computer program, and the computer program, when executed by a processor, implements all steps of the method for controlling a reactive voltage of a flexible direct current delivery end new energy isolated grid in the above embodiment, for example, when the processor executes the computer program, the processor implements the following steps:

As can be seen from the above description, the computer-readable storage medium provided in the embodiment of the present application can effectively improve the safety and the economy of the isolated network system formed by the new energy cluster accessing the flexible dc power grid and the transmitting-end converter station of the flexible dc power grid, and the control process is reliable, stable, and efficient.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the hardware + program class embodiment, since it is substantially similar to the method embodiment, the description is simple, and the relevant points can be referred to the partial description of the method embodiment.

The foregoing description has been directed to specific embodiments of this disclosure. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.

Although the present application provides method steps as described in an embodiment or flowchart, additional or fewer steps may be included based on conventional or non-inventive efforts. The order of steps recited in the embodiments is merely one manner of performing the steps in a multitude of orders and does not represent the only order of execution. When an actual apparatus or client product executes, it may execute sequentially or in parallel (e.g., in the context of parallel processors or multi-threaded processing) according to the embodiments or methods shown in the figures.

The systems, devices, modules or units illustrated in the above embodiments may be implemented by a computer chip or an entity, or by a product with certain functions. One typical implementation device is a computer. In particular, the computer may be, for example, a personal computer, a laptop computer, a vehicle-mounted human-computer interaction device, a cellular telephone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

The memory may include forms of volatile memory in a computer readable medium, Random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of a computer-readable medium.

Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, a computer readable medium does not include a transitory computer readable medium such as a modulated data signal and a carrier wave.

As will be appreciated by one skilled in the art, embodiments of the present description may be provided as a method, system, or computer program product. Accordingly, embodiments of the present description may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment. In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of an embodiment of the specification. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

The above description is only an example of the present specification, and is not intended to limit the present specification. Various modifications and variations to the embodiments described herein will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the present specification should be included in the scope of the claims of the embodiments of the present specification.

Claims

1. A flexible direct current sending end new energy isolated network reactive voltage control method is characterized by comprising the following steps:

constructing a multi-target reactive power optimization model, wherein the multi-target reactive power optimization model comprises two objective functions, one objective function is an active loss objective function of a flexible direct current sending end isolated network system, and the other objective function is a reactive power margin objective function of a sending end converter station of a flexible direct current power grid in the flexible direct current sending end isolated network system;

the multi-target reactive power optimization model min F is as follows:

minF＝λ₁×F₁+λ₂×F₂formula three

In formula three, F₁The active loss objective function of the isolated network system of the flexible direct current transmission end is obtained; f₂Is a reactive power margin objective function, lambda, of said transmitting converter station₁And λ₂Respectively as active loss objective function F of the flexible direct current transmitting end isolated network system₁And a reactive power margin objective function F of the sending end converter station₂The weight coefficient of (a);

the constraint conditions of the multi-target reactive power optimization model min F are as follows:

in formula four, P_GiAnd P_LiRespectively the active power and the active load sent by the node i; n is the number of nodes of the isolated network system of the flexible direct current transmission end; u shape_iAnd U_jThe voltage amplitudes of nodes i and j, respectively; g_ij、B_ijAnd theta_ijRespectively the conductance, susceptance and phase angle difference between the nodes i and j; p_{dc_loss}Is the loss of the sending end converter station; q_Gi、Q_CiAnd Q_LiRespectively the reactive power sent by the node i, the reactive power compensated by the reactive power compensation device and the reactive load; q_CimaxAnd Q_CiminRespectively compensating the upper limit and the lower limit of the reactive power for the node i reactive power compensation device; u shape_VmaxAnd U_VminRespectively, an upper limit and a lower limit of the voltage reference value; t is_tapRepresenting the gear of the converter transformer tap; u shape_imin、U_imaxRespectively representing the upper limit and the lower limit of the voltage of the node i; m represents the modulation ratio of the converter station; the nodes comprise a grid-connected point of each new energy station in the new energy cluster and a voltage reference point of the sending end converter station;

the flexible direct-current delivery end isolated network system comprises a delivery end converter station of a flexible direct-current power grid, an alternating-current bus of the delivery end converter station, a plurality of new energy stations forming a new energy cluster and an alternating-current collecting system for connecting the new energy stations into the delivery end converter station;

collecting system voltage and power data of the flexible direct current transmitting end isolated network system in a current control period; wherein the system voltage data comprises: voltage and power data of grid-connected points of each new energy station, voltage data of each collecting station, active power and reactive power data of the sending-end converter station, and alternating-current bus voltage data of the sending-end converter station;

acquiring a voltage control target value of a next control period of the flexible direct current sending end isolated network system according to the system voltage and power data at the end of the last control period and the multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to the active loss of the flexible direct current sending end isolated network system and the reactive power margin of the sending end converter station;

2. The flexible direct current delivery end new energy isolated network reactive voltage control method according to claim 1, characterized by further comprising:

3. The method for controlling reactive voltage of the flexible direct current delivery end new energy isolated network according to claim 1, wherein the step of obtaining the voltage control target value of the next control period of the flexible direct current delivery end isolated network system according to the system voltage and power data at the end of the last control period and the multi-objective reactive power optimization model comprises the following steps:

4. The flexible direct current delivery end new energy isolated network reactive voltage control method according to claim 3, wherein each new energy station grid-connected point and a collecting station for connecting a plurality of new energy stations to a delivery end converter station are respectively provided with a reactive power compensation device, and the reactive power compensation device is a dynamic reactive power compensation device with continuous adjustment capability;

5. The method for controlling reactive voltage of the flexible direct current transmitting end new energy isolated network according to claim 1, wherein an active loss objective function of the flexible direct current transmitting end isolated network system is determined according to the number of nodes of the flexible direct current transmitting end isolated network system, the voltage of each node, the conductance, susceptance and phase angle difference among the nodes, and the loss of the transmitting end converter station;

the node comprises a grid-connected point of each new energy station in the new energy cluster and a voltage reference point of the sending end converter station.

6. The method for controlling reactive voltage of the flexible direct current delivery end new energy isolated network system according to claim 5, wherein an active loss objective function F of the flexible direct current delivery end isolated network system₁Comprises the following steps:

7. The method for controlling the reactive voltage of the isolated network of the new energy source of the flexible direct current transmission end according to claim 1, wherein a reactive power margin objective function of the transmission end converter station is determined according to the voltage of a grid-connected point of the new energy cluster and an output alternating voltage fundamental wave phasor of the transmission end converter station.

8. The method for controlling reactive voltage of the flexible direct current delivery end new energy isolated network according to claim 7, wherein a reactive power margin objective function F of the delivery end converter station₂Comprises the following steps:

AndQare determined by the flexible dc converter station PQ diagram.

9. The method for controlling reactive voltage of the flexible direct current transmission end new energy isolated network according to claim 1, wherein an active loss objective function F of the flexible direct current transmission end isolated network system₁And a reactive power margin objective function F of the sending end converter station₂Respectively corresponding weight coefficients lambda₁And λ₂And determining by adopting a sorting method.

10. The utility model provides a flexible direct current send end new forms of energy isolated network reactive voltage control device which characterized in that includes:

the system comprises a model construction module and a control module, wherein the model construction module is used for constructing a multi-target reactive power optimization model, the multi-target reactive power optimization model comprises two objective functions, one objective function is an active loss objective function of a flexible direct current sending end isolated network system, and the other objective function is a reactive power margin objective function of a sending end converter station of a flexible direct current power grid in the flexible direct current sending end isolated network system;

the multi-target reactive power optimization model min F is as follows:

minF＝λ₁×F₁+λ₂×F₂formula three

In formula three, F₁The active loss objective function of the isolated network system of the flexible direct current transmission end is obtained; f₂Is a reactive power margin objective function, lambda, of said transmitting converter station₁And λ₂Respectively being the flexible DC transmitting terminalActive loss objective function F of isolated network system₁And a reactive power margin objective function F of the sending end converter station₂The weight coefficient of (a);

the constraint conditions of the multi-target reactive power optimization model minF are as follows:

in formula four, P_GiAnd P_LiRespectively the active power and the active load sent by the node i; n is the number of nodes of the isolated network system of the flexible direct current transmission end; u shape_iAnd U_jThe voltage amplitudes of nodes i and j, respectively; g_ij、B_ijAnd theta_ijRespectively the conductance, susceptance and phase angle difference between the nodes i and j; p_{dc_loss}Is the loss of the sending end converter station; q_Gi、Q_CiAnd Q_LiRespectively the reactive power sent by the node i, the reactive power compensated by the reactive power compensation device and the reactive load; q_CimaxAnd Q_CiminRespectively compensating the upper limit and the lower limit of the reactive power for the node i reactive power compensation device; u shape_VmaxAnd U_VminRespectively, an upper limit and a lower limit of the voltage reference value; t is_tapRepresenting the gear of the converter transformer tap; u shape_imin、U_imaxRespectively representing the upper limit and the lower limit of the voltage of the node i; m represents the modulation ratio of the converter station; the nodes comprise a grid-connected point of each new energy station in the new energy cluster and a voltage reference point of the sending end converter station; the flexible direct-current delivery end isolated network system comprises a delivery end converter station of a flexible direct-current power grid, an alternating-current bus of the delivery end converter station, a plurality of new energy stations forming a new energy cluster and an alternating-current collecting system for connecting the new energy stations into the delivery end converter station;

the data acquisition module is used for acquiring system voltage and power data of the flexible direct current transmitting end isolated network system in the current control period; wherein the system voltage data comprises: voltage and power data of a grid-connected point of each new energy station, voltage data of each collecting station, active power and reactive power data of the sending-end converter station, and alternating-current bus voltage data of the sending-end converter station;

the model solving module is used for acquiring a voltage control target value of the next control period of the flexible direct current sending end isolated network system according to the system voltage and power data at the end of the last control period and the multi-target reactive power optimization model, wherein the multi-target reactive power optimization model is determined according to the active loss of the flexible direct current sending end isolated network system and the reactive power margin of the sending end converter station;

the reactive voltage control module is used for issuing a voltage control target value of a grid-connected point of each new energy station in the next control period to each corresponding new energy station, so that each new energy station adjusts the reactive output of the corresponding reactive power compensation device according to the voltage control target value of the corresponding grid-connected point; and sending the voltage control target value of the alternating current bus of the next control period to the sending end converter station, so that the sending end converter station adjusts the voltage set value of the alternating current bus in the next control period according to the voltage control target value of the alternating current bus.

11. The flexible direct current delivery end new energy isolated network reactive voltage control device of claim 10, further comprising:

12. The flexible direct current delivery end new energy isolated network reactive voltage control device according to claim 10, wherein the model solving module comprises:

13. The flexible direct current delivery end new energy isolated network reactive voltage control device according to claim 12, wherein each new energy station grid-connected point and a collecting station for connecting a plurality of new energy stations to a delivery end converter station are respectively provided with a reactive power compensation device, and the reactive power compensation device is a dynamic reactive power compensation device with continuous adjustment capability;

14. The flexible direct current delivery end new energy isolated network reactive voltage control device according to claim 10, wherein an active loss objective function of the flexible direct current delivery end isolated network system is determined according to the number of nodes of the flexible direct current delivery end isolated network system, the voltage of each node, the conductance, susceptance and phase angle difference among each node, and the loss of the delivery end converter station;

15. The flexible direct current delivery side new energy isolated grid reactive voltage control of claim 14The device is characterized in that an active loss objective function F of the flexible direct current transmitting end isolated network system₁Comprises the following steps:

16. The flexible direct current delivery end new energy isolated network reactive voltage control device according to claim 10, wherein a reactive power margin objective function of the delivery end converter station is determined according to a voltage of a grid-connected point of the new energy cluster and an output alternating voltage fundamental phasor of the delivery end converter station.

17. The flexible direct current delivery end new energy isolated network reactive voltage control device of claim 16, wherein a reactive power margin objective function F of the delivery end converter station₂Comprises the following steps:

AndQare determined by the flexible dc converter station PQ diagram.

18. The flexible direct current delivery end new energy isolated network reactive voltage control device according to claim 10, wherein an active loss objective function F of the flexible direct current delivery end isolated network system₁And a reactive power margin objective function F of the sending end converter station₂Respectively corresponding weight coefficients lambda₁And λ₂And determining by adopting a sorting method.

19. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the flexible dc delivery side new energy grid reactive voltage control method of any one of claims 1 to 9 when executing the program.

20. A computer readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the flexible direct current delivery side new energy grid reactive voltage control method according to any one of claims 1 to 9.