WO2022028487A1

WO2022028487A1 - Control and protection system for distributed series compensator

Info

Publication number: WO2022028487A1
Application number: PCT/CN2021/110604
Authority: WO
Inventors: 潘磊; 董云龙; 卢宇; 林艺哲; 常昊添; 张宝顺; 黄如海
Original assignee: 南京南瑞继保电气有限公司; 南京南瑞继保工程技术有限公司
Priority date: 2020-08-06
Filing date: 2021-08-04
Publication date: 2022-02-10
Also published as: BR112022025269A2; CN111934323B; DE112021002393T5; CN111934323A

Abstract

Provided is a control and protection system for a distributed series compensator. The control and protection system comprises a remote scheduling control layer, an in-station centralized control and protection layer and an in-situ module control layer, which are hierarchically arranged and hierarchically perform controlling, wherein the in-situ module control layer comprises module control and protection layers and module valve base control layers. The remote scheduling control layer obtains a power instruction according to a real-time operation state of an alternating-current power grid; the in-station centralized control and protection layer receives the power instruction and converts same into a voltage instruction for each in-situ series compensation module; each module control and protection layer receives the voltage instruction, and outputs an in-situ series compensation module output voltage instruction; and each module valve base control layer converts the in-situ module output voltage instruction into a turn-on/off command for a power electronic device within the in-situ module control layer.

Description

Control and Protection System of Distributed Series Compensator

Related applications

This application claims the priority of the Chinese patent application with the application number 202010782064.7 and the application title "Control and Protection System for Distributed Series Compensator", which was filed with the China Patent Office on August 6, 2020, the entire contents of which are incorporated herein by reference Applying.

technical field

The present application relates to the field of flexible power transmission in power systems, and in particular, to a control and protection system for distributed series compensators.

Background technique

With the interconnection of large power systems and the use of various new equipment, the scale and complexity of power systems have also increased while making power generation and transmission more economical and efficient. In addition, a large number of distributed generation systems are connected to the grid, which reverses the traditional fixed power flow from the transmission grid to the distribution grid. The ever-increasing user load requires power flow control to enhance the existing power delivery capacity. The complex power exchange between the booming smart grid and electricity market also requires frequent power flow optimization control.

Distributed series compensator, each small-capacity compensator can be made lightweight and directly distributed on the power line to realize the power flow control function and effect similar to the static synchronous series compensator, thus providing more flexibility for smart grid. , More advanced control methods, effectively improve the power supply capacity and safety and stability of the power system. The distributed series compensator has the characteristics of small size and light weight. A large number of distributed sub-units ensure the redundancy of the equipment, thereby improving the reliability of the device. At the same time, the Distributed Power Flow Controller (DPFC) devices can be dispersedly deployed on transmission lines or substations, occupying a small area.

At present, there are two demonstration projects of distributed series compensator (distributed static synchronous series compensator) projects in the world. The control and protection systems of the two projects are relatively simple, and both use the module local control mode. The control mode of this mode is inflexible, and the performance of power flow regulation is poor. Some universities and research institutes in China have carried out a variety of research projects on distributed series compensators (distributed series reactors, distributed static synchronous series compensators, distributed power flow controllers, etc.) , simulation modeling and control strategy, and there is no report on the structure and functional configuration of the control and protection system of the distributed power flow controller.

The patent "A Control Method of Distributed Series-Coupled Power Flow Controller" proposes a control method of a distributed series-coupled power flow controller, including three-layer control strategies, namely, the transient blocking strategy and the remote power flow total control strategy. and trend control strategies. The highest priority control strategy "transient blocking strategy" and the lowest control strategy "power flow automatic control strategy" are implemented by local modules. The second priority control strategy "remote power flow master control strategy" is implemented by the remote dispatch master console. This method classifies the control strategy of the distributed power flow controller according to the priority of the control or action of the actual control protection, but it is not hierarchical, so when there are many control strategies, there are many levels, which is not conducive to understanding and application.

The patent "A Distributed Series Coupled Power Flow Controller Protection Device and Method" proposes a method of modifying the fault current protection setting to adapt to the fault protection requirements of power grid lines in different planning periods, and proposes the configuration of the protection device. The patent does not mention the layered structure and configuration of the control protection system.

The patent "A Distributed Power Flow Control System and Method" proposes a distributed power flow controller system, including a distributed power flow controller, a main controller and an energy management module. The distributed power flow controller mainly collects the running data of the line and transmits its own state information to the main controller, and executes the corresponding working mode according to the adjustment instructions sent by the main controller. The three parts of the control system are closely linked, and the distributed power flow controller cannot operate independently.

The paper "Research on the Strategy of Distributed Power Flow Controller Based on Centralized Control" proposes that the distributed power flow controller is implemented by means of distributed installation and master-slave control, and is composed of sub-control units and master controllers. The main controller is installed in the substation and controls all sub-units in a centralized manner. A wireless communication network is constructed between several sub-control units of the system and a main controller to exchange data. The paper proposes the main controller of DPFC to realize the system-level control strategy, and determines the running state and output capacity of the DPFC subunits on the line according to the system power flow regulation target and compensation mode set by the operator. The main control unit in the control and protection system proposed in this paper determines the running state and output capacity of each subunit. Since the line state is always changing, the control and protection system described in this paper needs to be iteratively put into sub-module units, resulting in a slow control response time.

SUMMARY OF THE INVENTION

Each exemplary embodiment of the present application provides a control and protection system for a distributed series compensator, which adopts a hierarchical arrangement and hierarchical control method, has a clear structure, can realize independent operation of distributed modules and centralized coordinated control and protection, and improves the overall The operating performance and reliability of the system are suitable for engineering applications.

According to an aspect of the present application, a control and protection system for a distributed series compensator is proposed. The distributed series compensator is composed of N local series compensation modules distributed in series on the line, or arranged in series in a substation in a centralized manner, where N is a natural number, and N is greater than 1; the control and protection system includes: a remote dispatching control layer, so The remote dispatching control layer adopts hierarchical arrangement and hierarchical control, and the remote dispatching control layer is configured to obtain the optimal adjustment of the power flow of the power grid by the distributed series compensator according to the real-time operating state of the AC power grid. The optimal line power command or the power control command curve is obtained according to the real-time operating state of the power grid and the load prediction result; the centralized control protection layer in the station, the centralized control protection layer in the station is configured to receive the first power command or obtain the second power command, Convert the first power command or the second power command into the first injection voltage command of each of the on-site series compensation modules, and coordinately control and centrally protect each of the on-site series compensation modules. the first power command is the optimal line power command, and the second power command is the power control command curve set or preset according to the real-time operating state of the power grid and a load prediction result; and On-site module control layer, the on-site module control layer includes: a module control protection layer, the module control protection layer includes a control protection unit, and the module control protection layer is configured to receive the information sent by the centralized control protection layer in the station. The first injection voltage command or the preset second injection voltage command is obtained, and the control and protection unit is configured to synthesize the first injection voltage command or the second injection voltage command to generate the in-situ series connection an output voltage command of a compensation module; and a module valve base control layer configured to convert the output voltage command of the in-place series compensation module into a voltage for use within the in-place series compensation module Turn-on or turn-off commands for power electronics.

In an embodiment, the centralized control and protection layer in the station includes: a coordinated control unit, a three-phase voltage unbalance control unit and a centralized protection unit of each of the on-site series compensation modules; wherein, each of the on-site series compensation modules The coordinated control unit is configured to realize the timing control of the input and withdrawal of each on-site series compensation module and the distribution of the first injection voltage command; the three-phase voltage unbalance control unit is configured as a three-phase balanced line voltage; and the centralized protection unit of each on-site series compensation module is configured to protect all the on-site series compensation modules when the AC system fails, and cooperate with the AC system protection.

In one embodiment, the coordinated control unit and the centralized protection unit are integrated into one device.

In one embodiment, the coordinated control unit, the three-phase voltage unbalance control unit and the centralized protection unit are integrated into one device.

In one embodiment, the centralized control protection layer in the station includes a line overload control unit, and the line overload control unit is configured to be configured when the line current of the line to which the distributed series compensator is connected or the line current of the adjacent line exceeds a predetermined value. When the value is set, the first injection voltage command sent to the control layer of each local module is adjusted to control the line current within the set value.

In an embodiment, the centralized control and protection layer in the station is configured with two sets of centralized control and protection devices with the same function, and the two sets of centralized control and protection devices both include a main system and a backup system for realizing the two sets of devices. A coordination control unit for selecting functions, the host system is configured to preferentially execute instructions transmitted to the module control protection layer.

In an embodiment, the control protection unit of the module control protection layer includes: a DC voltage control unit, a line overload control unit, a voltage command limiting unit and an overcurrent protection unit; wherein the DC voltage control unit is configured as Stabilize the capacitor voltage of the on-site series compensation module; the line overload control unit is configured to control the current of the line connected to the distributed series compensator within a set value; and the overcurrent protection unit is used to avoid The on-site series compensating module is subjected to an overcurrent impact to protect the safety of the on-site series compensating module.

In one embodiment, the DC voltage control unit, the line overload control unit and the overcurrent protection sub-unit are integrated into one control board.

In one embodiment, the control and protection system is applied in a multi-circuit line.

In an embodiment, the intra-station centralized control protection layer further includes a multi-circuit line power coordination control unit, and the coordination control unit is configured to assign a multi-circuit line power command.

In one embodiment, all local series compensation modules in each circuit are configured with a set of centralized control equipment in the station, and the set of centralized control equipment in the station includes a coordination control unit and a centralized protection unit.

In one embodiment, the remote dispatching control layer communicates with the in-station centralized control protection layer through optical fiber or network cable; and the in-station centralized control and protection layer and the local module control and protection layer communicate through wireless or optical fiber.

After adopting the above scheme, the control and protection system of the distributed series compensator of the present application can realize the independent operation and centralized coordinated control and protection of the distributed modules, improve the operation performance and reliability of the overall system, and give better play to the distributed series compensator. The advantage of optimizing system flow. The control and protection system scheme of the above distributed series compensator adopts a layered arrangement, the system structure is clear and simple, the functions are comprehensive and cooperate with each other, and it is suitable for engineering applications.

It should be understood that the above generally described embodiments and the specific embodiments described in detail hereinafter are merely exemplary, and the present application is not limited thereto.

Description of drawings

FIG. 1 shows a structural diagram of a control and protection system of a distributed series compensator according to an embodiment of the present application.

FIG. 2 shows a structural diagram of a control and protection system of a distributed series compensator according to another embodiment of the present application.

FIG. 3 shows a structural diagram of a distributed series compensator system according to an embodiment of the present application.

FIG. 4 shows a structural diagram of a control and protection system of a distributed series compensator suitable for a double-circuit line application according to yet another embodiment of the present application.

detailed description

Example embodiments will now be described more fully with reference to the accompanying drawings. The above and other objects, features and advantages of the present application will become more apparent from the detailed description of example embodiments thereof with reference to the accompanying drawings. Example embodiments, however, can be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated descriptions will be omitted.

The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided in order to give a thorough understanding of the embodiments of the present disclosure. However, one skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or with other manners, components, materials, devices or operations, etc. In these instances, well-known structures, methods, devices, implementations, materials, or operations are not shown or described in detail.

The terms "first", "second" and the like in the description and claims of the present application and the above-mentioned drawings are used to distinguish different objects, not to describe a specific order, and not to be used for further limitation. Furthermore, the terms "including" and "having", and any derivatives thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes unlisted steps or units, or optionally also includes For other steps or units inherent to these processes, methods, products or devices.

In order to give full play to the characteristics of power flow optimization of the distributed series compensator, protect the safety of its equipment and power system, and promote the rapid development of the application of distributed power flow controllers, the inventor found that a better performance, clearer structure and more functions are needed. A comprehensive and more suitable distributed series compensator control and protection system for engineering applications.

The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a structural diagram of a control and protection system of a distributed series compensator according to an embodiment of the present application. FIG. 2 shows a structural diagram of a control and protection system of a distributed series compensator according to another embodiment of the present application. FIG. 3 shows a structural diagram of a distributed series compensator system according to an embodiment of the present application.

Referring to FIG. 1 and FIG. 3 , the basic structure and the control and protection system of the distributed series compensator according to an embodiment of the present application are respectively shown. The distributed series compensator is composed of N local series compensation modules 113 (Local Series Compensation Module) distributed in series on the line or centrally arranged in series in the substation, where N is a natural number, and N is greater than 1. Each in-situ series compensation module 113 includes a voltage source converter 301 and a bypass device 303 .

The control and protection system of the distributed series compensator according to this embodiment of the present application adopts a three-level arrangement and a four-level control and protection structure. The three-level arrangement layer includes a remote scheduling control layer 103, a centralized control and protection layer 105 in the station, and a local module control layer. The four control protection layers include the remote scheduling control layer 103, the centralized control protection layer 105 in the station, the module control protection layer 109 and the module valve base control layer 111, wherein the remote scheduling control layer 103 and the centralized control protection layer 105 in the station pass through the optical fiber Or network cables communicate with each other, and the centralized control protection layer 105 and the module control protection layer 109 in the station communicate with each other through wireless or optical fibers.

It can be understood that the three-level arrangement layer means that the three levels are placed in different places; the four-level control means that the control system is divided into four levels to realize. The third-level arrangement is hardware, and the fourth-level control refers to software, wherein the software of the module control protection layer 109 and the module valve base control layer 111 are both arranged in the local unit module. The remote dispatching control layer 103 is arranged in the remote power dispatching center, and the centralized control protection layer 105 in the station is arranged in the control and protection room of the distribution string series compensator.

According to some embodiments, the remote dispatch control layer 103 obtains the optimal line power command for the distributed series compensator to perform the optimal adjustment of the power flow of the power grid 101 according to the real-time operating status of the AC power grid 101 or according to the real-time operating status and load of the power grid 101 The prediction result (Result of Load Forecasting) obtains the power control command curve. The power command refers to the target value to which the active power of the line needs to be adjusted by the distributed power flow controller. The power control command curve refers to a curve formed by different line power commands (obtained according to the real-time operating state of the power grid 101 and the load prediction result) in different time periods. The centralized control and protection layer 105 in the station converts the power command into the first injection voltage command of each on-site series compensation module 113 , and coordinates control and centralized protection of each on-site series compensation module 113 . Coordinated control and centralized protection are mainly realized in the following ways: the coordinated control unit of each local series compensation module is configured to realize the timing control of the input and withdrawal of each local series compensation module and the distribution of the first injection voltage command; three-phase voltage The unbalanced control unit is configured to balance the three-phase voltage of the line; the centralized protection unit of each local series compensation module is configured to protect all local series compensation modules when the AC system fails, and cooperate with the AC system protection.

The line power command can be sent by the remote dispatch control layer 103 , or set or preset by the operator in the station according to the real-time operating state of the power grid 101 and the load prediction result. The module control protection layer 109 receives the first injection voltage command sent by the centralized control protection layer 105 in the station or presets the second injection voltage command. The first injection voltage command and the second injection voltage command are controlled by the protection unit of the module control protection layer 109 After synthesis, the output voltage command of the local module is generated. The module valve base control layer 111 converts the local module output voltage command into a turn-on or turn-off command of the power electronic devices in the local series compensation module 113 .

According to some embodiments, the centralized control protection layer 105 in the station includes, but is not limited to: a coordinated control unit of each on-site series compensation module 113 , a three-phase voltage unbalance control unit, and a centralized protection unit. Wherein, the coordination control unit of each local series compensation module 113 realizes the input and withdrawal of each local series compensation module 113 and the distribution of the injection voltage command. The three-phase voltage unbalance control unit realizes the balance of the three-phase voltage of the line. The centralized protection unit of each local series compensation module 113 realizes the protection of the local series compensation module when the AC system fails, and the coordination function with the protection of the AC system.

According to some embodiments, the aforementioned coordinated control unit, three-phase voltage unbalance control unit and centralized protection unit are integrated on one device.

According to other embodiments, the aforementioned coordinated control unit and centralized protection unit are integrated on one device.

According to some embodiments, the centralized control protection layer 105 in the station includes a line overload control unit. When the current of the line connected to the distributed series compensator or the adjacent line exceeds the set value, the line overload control unit adjusts each local series compensation module. The injection voltage command of 113, the control circuit current is within the set value.

According to some embodiments, the control protection units of the module control protection layer 109 include, but are not limited to, a DC voltage control unit, a line overload control unit, a voltage command limiting unit, and an overcurrent protection unit. Among them, the DC voltage control unit realizes the stability of the capacitor voltage of the on-site series compensation module, the line overload control unit can control the current of the line connected to the distributed series compensator within the set value, and the over-current protection unit avoids on-site series compensation. The module withstands the overcurrent impact, and protects the on-site series compensation module 113 safety.

According to some embodiments, the aforementioned DC voltage control subunit, line overload control unit, voltage command limiting unit and overcurrent protection subunit may be integrated into one control board.

According to some embodiments, referring to FIG. 2 , the in-station centralized control protection layers 105 and 107 are configured with two sets of centralized control and protection systems with the same functions, and the functions of the two systems are respectively integrated into two devices, as shown in the figure for the in-station centralized control and protection systems Layer 105 and centralized control protection layer 107 in the station. Both systems include a coordinated control unit for realizing the selection function of the primary system and the backup system of the two systems. Commands transmitted by the host system to the module control protection layer 109 are preferentially executed. Both devices communicate with the remote scheduling control layer 103 and the module control protection layer 109 .

According to some embodiments, as shown in FIG. 4 , for the scenario of multi-circuit line application, each local series compensation module 113 of each circuit line is configured with a set of centralized control devices in the station, including a coordinated control unit and a centralized protection unit. In addition, the centralized control protection layer 105 in the station also includes a coordination control unit for the power of the multi-circuit lines, which realizes the distribution of the power commands of the multi-circuit lines.

Those of ordinary skill in the art can understand that all or part of the modules or layers in the above embodiments can be implemented by instructing relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer readable In the storage medium, when the computer program is executed by the processor of the computer, the functions of the above-mentioned relevant modules or layers can be realized. Wherein, any reference to memory, storage, database or other medium used in the various embodiments provided in this application may include non-volatile and/or volatile memory. Nonvolatile memory may include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous chain Road (Synchlink), DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

The embodiments of the present application have been described and explained in detail above. It should be expressly understood that this application describes how to make and use specific examples and that this application is not limited to any details of these examples. Rather, these principles can be applied to many other embodiments based on the teachings of the present disclosure.

From the description of the exemplary embodiments, those skilled in the art can easily understand that the technical solutions according to the embodiments of the present application have at least one or more of the following advantages.

After the above scheme is adopted, the control and protection system of the distributed series compensator of the present application can realize the independent operation of the distributed modules and the centralized coordinated control and protection, improve the operation performance and reliability of the overall system, and better utilize the optimization of the distributed series compensator. The advantages of system flow. The control and protection system scheme of the above distributed series compensator adopts a layered arrangement, the system structure is clear and simple, the functions are comprehensive and cooperate with each other, and it is suitable for engineering applications.

Exemplary embodiments of the present application have been specifically shown and described above. It should be understood that the present application is not limited to the detailed structures, arrangements or implementation methods described herein. On the contrary, this application is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

A control and protection system of a distributed series compensator, wherein:

The distributed series compensator consists of N local series compensation modules distributed in series on the line, or is arranged in series in a substation in a centralized manner, N is a natural number, and N is greater than 1;

The control and protection system includes:

The remote dispatching control layer adopts hierarchical arrangement and hierarchical control, and the remote dispatching and control layer is configured to obtain the distributed series compensator according to the real-time operating state of the AC power grid to perform the described The optimal line power command of the power flow optimization adjustment of the power grid or the power control command curve obtained according to the real-time operation state of the power grid and the load prediction result;

In-station centralized control protection layer, the in-station centralized control protection layer is configured to receive a first power command or obtain a second power command, and convert the first power command or the second power command into each of the in-situ series The first injection voltage command of the compensation module, and coordinated control and centralized protection of each of the in-situ series compensation modules, wherein the first power command is the optimal line power command, and the second power command is based on the power control command curve set or preset by the real-time operating state of the power grid and the load prediction result; and

On-site module control layer, the on-site module control layer includes:

a module control protection layer, the module control protection layer includes a control protection unit, and the module control protection layer is configured to receive the first injection voltage command sent by the centralized control protection layer in the station or obtain a preset second injection voltage a voltage command, the control protection unit configured to synthesize the first injection voltage command or the second injection voltage command to generate an output voltage command for the in-place series compensation module; and

a modular valve base control layer configured to convert the output voltage command of the on-site series compensation module into a power electronic device for turning on or off within the on-site series compensating module Order.
The control protection system of claim 1, wherein,

The centralized control protection layer in the station includes: a coordinated control unit, a three-phase voltage unbalance control unit and a centralized protection unit of each of the on-site series compensation modules;

Wherein, the coordination control unit of each in-situ series compensation module is configured to realize the timing control of the activation and deactivation of each in-situ series compensation module and the distribution of the first injection voltage command;

The three-phase voltage unbalance control unit is configured to balance the three-phase voltage of the line; and

The centralized protection unit of each on-site series compensation module is configured to protect all the on-site series compensation modules when the AC system fails, and to cooperate with the AC system protection.
The control protection system of claim 2, wherein,

The coordinated control unit and the centralized protection unit are integrated into one device.
The control protection system of claim 2, wherein,

The coordinated control unit, the three-phase voltage unbalance control unit and the centralized protection unit are integrated into one device.
The control protection system of claim 1, wherein,

The centralized control protection layer in the station includes a line overload control unit, and the line overload control unit is configured to adjust the transmission when the line current of the line connected to the distributed series compensator or the line current of the adjacent line exceeds a preset value. The first injection voltage command is given to each local module control layer to control the line current within a set value.
The control protection system of claim 1, wherein,

The centralized control and protection layer in the station is configured with two sets of centralized control and protection equipment with the same function, and the two sets of centralized control and protection equipment both include a coordination control unit for realizing the selection function of the main system and the backup system of the two sets of equipment , the host system is configured to preferentially execute the instructions transmitted to the module control protection layer.
The control protection system of claim 1, wherein,

The control protection unit of the module control protection layer includes: a DC voltage control unit, a line overload control unit, a voltage command limiting unit and an overcurrent protection unit;

Wherein, the DC voltage control unit is configured to stabilize the capacitor voltage of the on-site series compensation module;

The line overload control unit is configured to control the current of the line to which the distributed series compensator is connected within a set value; and

The overcurrent protection unit is used to prevent the on-site series compensation module from being subjected to an overcurrent shock and protect the safety of the on-site series compensation module.
The control protection system of claim 7, wherein,

The DC voltage control unit, the line overload control unit and the overcurrent protection sub-unit are integrated into one control board.
The control protection system of claim 1, wherein,

The control and protection system is applied to multi-circuit lines.
The control protection system of claim 9, wherein,

The in-station centralized control protection layer further includes a multi-circuit line power coordination control unit, and the coordination control unit is configured to assign a multi-circuit line power command.
The control protection system of claim 9, wherein,

All local series compensation modules in each circuit are configured with a set of centralized control equipment in the station, and the set of centralized control equipment in the station includes a coordinated control unit and a centralized protection unit.
The control protection system according to claim 1, wherein,

The remote dispatch control layer communicates with the centralized control protection layer in the station through optical fiber or network cable; and

The centralized control protection layer in the station and the local module control protection layer communicate through wireless or optical fiber.