A method, system, storage medium and computing device for improving reactive support capability

Abstract

The present invention discloses a method, system, storage medium and computing device for improving reactive power support capability. The present invention is directed to an IPFC converter for improving reactive power support capability. When a connected main control line fails, the present invention obtains active current and reactive current dynamic limit values ​​according to the measured active current and reactive current, and limits the active current and reactive current output by an outer loop control by the dynamic limit values, thereby improving the reactive output of the IPFC converter and releasing the reactive power support potential of the IPFC.

Description

Technical Field

[0001] The present invention relates to a method, system, storage medium and computing device for improving reactive power support capability, belonging to the technical field of flexible alternating current transmission. Background Art

[0002] The inter-line power flow controller (IPFC) is a new generation of flexible AC transmission devices with extremely powerful power flow control functions. It can accurately and flexibly control the power flow of multiple transmission lines in the same corridor, thereby balancing the power flow of each transmission channel and improving the transmission efficiency of scarce corridor resources. In addition, IPFC can also switch its own topology structure. After the controlled line fails, it can continue to control the system power flow using the converters on the remaining lines to avoid further deterioration of the situation after the failure, and has high reliability.

[0003] IPFC can control the active power flow of the system on the one hand, and provide reactive power support to the system on the other hand. However, since the main function of IPFC is to adjust the distribution of active power of the system, its reactive power support capacity is subject to certain limitations. Summary of the invention

[0004] The present invention provides a method, system, storage medium and computing device for improving reactive power support capability, which solves the problem of limited reactive power support capability of IPFC.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for improving reactive power support capability, comprising:

[0007] If it is a preset IPFC converter with enhanced reactive power support capability and the connected main control line fails, the measured active current and the measured reactive current are obtained;

[0008] Obtaining an active current amplitude limit value according to the measured active current and a preset first dynamic adjustment rule;

[0009] Obtaining a reactive current amplitude limit value according to the measured reactive current and a preset second dynamic adjustment rule;

[0010] According to the active current limit value and the reactive current limit value, the active current and reactive current output by its own outer loop control are limited.

[0011] The first dynamic adjustment rule is:

[0012]

[0013] Among them, i dlim is the active current limit value, i d is the measured reactive current, i qis the measured active current, i lim is the total limit value of active current and reactive current, i Dlim It is the preset minimum value of active current.

[0014] The second dynamic adjustment rule is:

[0015]

[0016] Among them, i qlim is the reactive current limit value, i d is the measured reactive current, i q is the measured active current, i lim It is the total limit value of active current and reactive current.

[0017] A system for improving reactive power support capability, comprising:

[0018] Measurement module: If it is a preset IPFC converter with enhanced reactive power support capability and the connected main control line fails, the measured active current and reactive current are obtained;

[0019] Active current limiting module: obtains the active current limiting value according to the measured active current and the preset first dynamic adjustment rule;

[0020] Reactive current limiting module: obtains reactive current limiting value according to the measured reactive current and the preset second dynamic adjustment rule;

[0021] Output limiting module: limits the active current and reactive current output by its own outer loop control according to the active current limiting value and reactive current limiting value.

[0022] The first dynamic adjustment rule is:

[0023]

[0024] Among them, i dlim is the active current limit value, i d is the measured reactive current, i q is the measured active current, i lim is the total limit value of active current and reactive current, i Dlim It is the preset minimum value of active current.

[0025] The second dynamic adjustment rule is:

[0026]

[0027] Among them, i qlim is the reactive current limit value, i d is the measured reactive current, i q is the measured active current, ilim It is the total limit value of active current and reactive current.

[0028] A computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, and when the instructions are executed by a computing device, the computing device executes a method for improving reactive support capability.

[0029] A computing device includes one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing a method for improving reactive support capability.

[0030] The beneficial effects achieved by the present invention are as follows: The present invention is directed to an IPFC converter for improving reactive power support capability. When a connected main control line fails, the present invention obtains dynamic limiting values ​​of active current and reactive current based on the measured active current and reactive current, and limits the active current and reactive current output by the outer loop control through the dynamic limiting values, thereby improving the reactive output of the IPFC converter and releasing the reactive power support potential of the IPFC. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of the method of the present invention;

[0032] Figure 2 This is the topology diagram of IPFC;

[0033] Figure 3 Output active current limiting logic diagram for outer loop control;

[0034] Figure 4 Output reactive current limiting logic diagram for outer loop control;

[0035] Figure 5 It is the dynamic limiting mechanism diagram;

[0036] Figure 6 The three converters emit reactive power diagrams when there is no dynamic limiting link;

[0037] Figure 7 When there is a dynamic limiting link, the three converters emit reactive power diagrams. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0039] like Figure 1 As shown, a method for improving reactive power support capability includes:

[0040] Step 1: If the inverter is a preset IPFC converter with enhanced reactive power support capability and the connected main control line fails, obtain the measured active current and the measured reactive current;

[0041] Step 2, obtaining an active current limit value according to the measured active current and a preset first dynamic adjustment rule;

[0042] Step 3, obtaining a reactive current amplitude limit value according to the measured reactive current and a preset second dynamic adjustment rule;

[0043] Step 4: according to the active current limit value and the reactive current limit value, the active current and the reactive current output by the outer loop control are limited.

[0044] The above method is implemented in an IPFC converter for improving reactive power support capability. For the IPFC converter, when a connected main control line fails, the dynamic limiting values ​​of active current and reactive current are obtained based on the measured active current and reactive current, and the active current and reactive current output by the outer loop control are limited by the dynamic limiting values, thereby improving the reactive output of the IPFC converter and releasing the reactive power support potential of the IPFC. When the connected main control line is normal, the active power regulation capability of the IPFC is guaranteed during the normal operation of the system.

[0045] like Figure 2 As shown in the figure, IPFC is mainly used to dynamically adjust the active and reactive power transmitted by the AC transmission system line and flexibly control the power flow of the transmission line. Its main structure is composed of a plurality of back-to-back voltage source converters (VSCs) interconnected by DC capacitors. Each converter is connected to a line, where 1, 2, ..., n are numbers.

[0046] When IPFC is operating normally, a certain line is selected as its auxiliary control line, and the rest of the lines are the main control lines. The main control line converter controls the active and reactive power of the lines connected to it at the same time. Since the auxiliary control line converter needs to maintain the DC bus voltage stability, it only controls the active or reactive power of the lines connected to it. Through this control method, one or several heavy-loaded lines can be selected as the main control line. On the premise of ensuring that the power flow of the main control line does not exceed the limit, the overloaded power flow can be reasonably allocated to other secondary priority lines. In this way, the power flow of each transmission channel can be effectively balanced, avoiding the occurrence of power flow overload, and greatly improving the system's power transmission capacity.

[0047] The converter is pre-selected as a converter to enhance the reactive power support capability. When the connected main control line is normal, the active power regulation capability of the IPFC is guaranteed during the normal operation of the system. When the connected main control line fails, the measured active current and the measured reactive current (i.e., the actual active current and reactive current of the IPFC itself) are obtained.

[0048] According to the measured active current and the first dynamic adjustment rule, the active current limit value is obtained; wherein the first dynamic adjustment rule may be:

[0049]

[0050] Among them, i dlim is the active current limit value, i d is the measured reactive current, i q is the measured active current, i lim is the total limit value of active current and reactive current, i Dlim It is the preset minimum active current value, that is, the active current value of the minimum active power that needs to be guaranteed.

[0051] According to the measured reactive current and the preset second dynamic adjustment rule, the reactive current amplitude limit value is obtained; wherein the second dynamic adjustment rule may be:

[0052]

[0053] Among them, i qlim is the reactive current limit value, i lim It is the total amplitude limit of active current and reactive current, which is the square of reactive current amplitude + square of active current amplitude.

[0054] like Figure 3 As shown, P sref is the active power reference value of the outer loop control, P s is the measured value of the active power of the outer loop control, K p +K i / s is PI control, and the active current output by PI control is limited according to the active current limit value.

[0055] like Figure 4 As shown, Q sref is the reactive power reference value of the outer loop control, Q s For the reactive power measurement value of the outer loop control, the reactive current output by the PI control is limited according to the reactive current limit value.

[0056] Under normal circumstances, the square of the active limit value + the square of the reactive limit value = a fixed value. Generally, the active limit value is fixed (such as 1.1), and the reactive limit value is also a fixed value (such as 0.5). In the event of a fault, under the premise that the sum of the squares is fixed, the reactive limit is not set to a fault, that is, the reactive limit will increase, thereby increasing the reactive output.

[0057] by Figure 2 Taking the IPFC in the example as an example, the limit is designed in the outer loop control link of converters 1 and 2. The mechanism is as follows Figure 5As shown, when the system is in a normal and stable state, the converter operates at point I, and its coordinates are (i d0 ,i q0 ), when the voltage drop is not large, the reactive current increases, and the system reaches a new stable operating point M, but is still within the limit range. When the voltage drop is large, the reactive current will increase to the maximum value N, and finally reach a new steady-state operating point D, whose coordinates are (i Dlim , i′ qlim ).

[0058] Without configuring the limiting link, Figure 1 In the circuits connected to converters 1 and 2, single-phase grounding faults are set. The fault occurs at 2.5 seconds and lasts for 0.1 seconds. The reactive output of the three converters (converter 1, converter 2 and converter n, the circuit connected to converter n is the auxiliary control circuit, and the circuits connected to the other converters are the main control circuits) is as follows: Figure 6 shown.

[0059] When converters 1 and 2 are equipped with limiting links, Figure 1 A single-phase ground fault is set again in the line connected to converters 1 and 2. The fault occurs at 2.5 seconds and lasts for 0.1 seconds. The reactive output of the three converters is as follows: Figure 7 It can be seen that the dynamic limiting link can greatly improve the reactive power output of the converter, thereby releasing the reactive power support potential of IPFC.

[0060] Based on the same technical solution, the present invention also discloses a software system of the above method, namely a system for improving reactive power support capability, comprising:

[0061] Measurement module: If it is a preset IPFC converter with enhanced reactive power support capability and the connected main control line fails, the measured active current and the measured reactive current are obtained.

[0062] Active current limiting module: obtains the active current limiting value according to the measured active current and the preset first dynamic adjustment rule.

[0063] The first dynamic adjustment rule is:

[0064]

[0065] Among them, i dlim is the active current limit value, i d is the measured reactive current, i q is the measured active current, i lim is the total limit value of active current and reactive current, i Dlim It is the preset minimum value of active current.

[0066] Reactive current limiting module: obtains the reactive current limiting value according to the measured reactive current and the preset second dynamic adjustment rule.

[0067] The second dynamic adjustment rule is:

[0068]

[0069] Among them, i qlim is the reactive current limit value, i d is the measured reactive current, i q is the measured active current, i lim It is the total limit value of active current and reactive current.

[0070] Output limiting module: limits the active current and reactive current output by its own outer loop control according to the active current limiting value and reactive current limiting value.

[0071] Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, and when the instructions are executed by a computing device, the computing device executes a method for improving reactive support capacity.

[0072] Based on the same technical solution, the present invention also discloses a computing device, including one or more processors, one or more memories and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing a method for improving reactive support capacity.

[0073] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0074] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0075] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0076] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0077] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A method for improving reactive power support capability, characterized in that: include: If it is a preset IPFC converter for improving reactive power support capability and the connected main control line fails, the measured active current and the measured reactive current are obtained; wherein, the IPFC converter is connected in series with the AC system; when IPFC is operating normally, a certain line is selected as its auxiliary control line, and the other lines are the main control lines. The main control line IPFC converter controls the active and reactive power of the connected main control line at the same time, and the auxiliary control line IPFC converter only controls the active or reactive power of the connected auxiliary control line; Obtaining an active current limit value according to the measured active current and a preset first dynamic adjustment rule; The first dynamic adjustment rule is: Among them, i dlim is the active current limit value, i d is the measured reactive current, i q is the measured active current, i lim is the total limit value of active current and reactive current, i Dlim is the preset minimum value of active current; Obtaining a reactive current amplitude limit value according to the measured reactive current and a preset second dynamic adjustment rule; The second dynamic adjustment rule is: Among them, i qlim is the reactive current limit value; According to the active current limit value and the reactive current limit value, the active current and reactive current output by its own outer loop control are limited; Under normal circumstances, the square of the active current limit value + the square of the reactive current limit value = a fixed value. In the event of a fault, under the premise that the square sum is fixed, the reactive current limit value is not set to a fault, thereby increasing reactive output.

2. A system for improving reactive power support capability, characterized in that: include: Measurement module: If it is a preset IPFC converter for improving reactive power support capability and the connected main control line fails, the measured active current and reactive current are obtained; the IPFC converter is connected in series with the AC system; when IPFC is operating normally, a certain line is selected as its auxiliary control line, and the other lines are the main control lines. The main control line IPFC converter controls the active and reactive power of the connected main control line at the same time, and the auxiliary control line IPFC converter only controls the active or reactive power of the connected auxiliary control line; Active current limiting module: obtains the active current limiting value according to the measured active current and the preset first dynamic adjustment rule; The first dynamic adjustment rule is: Among them, i dlim is the active current limit value, i d is the measured reactive current, i q is the measured active current, i lim is the total limit value of active current and reactive current, i Dlim is the preset minimum value of active current; Reactive current limiting module: obtains reactive current limiting value according to the measured reactive current and the preset second dynamic adjustment rule; The second dynamic adjustment rule is: Among them, i qlim is the reactive current limit value; Output limiting module: limits the active current and reactive current output by its own outer loop control according to the active current limiting value and the reactive current limiting value; under normal circumstances, the square of the active current limiting value + the square of the reactive current limiting value = a fixed value. In the event of a fault, under the premise that the sum of the squares is fixed, the reactive current limiting value is not set to a fault, and the reactive output is increased.

3. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform the method of claim 1 .

4. A computing device, characterized in that include: One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for executing the method according to claim 1.

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