CN116799802A - STATCOM-based harmonic treatment method, system and equipment - Google Patents
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Abstract
The application relates to the technical field of power electronics and discloses a STATCOM-based harmonic treatment method, a STATCOM-based harmonic treatment system and STATCOM-based harmonic treatment equipment. The method comprises the steps of collecting voltage data of a two-stage transformer connected with a STATCOM in a target power grid; determining a STATCOM filtering target value of a target branch according to the voltage data; taking the STATCOM filtering target value as an active filtering control input quantity, and executing an active filtering function; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, so as to achieve the purpose of active filtering; the application can ensure that the STATCOM further has the function of harmonic wave treatment on the basis of the original dynamic reactive power supporting function, and fully plays the role of the STATCOM.
Description
Technical Field
The application relates to the technical field of power electronics, in particular to a STATCOM-based harmonic treatment method, system and equipment.
Background
With the development of the trend of power electronics of the power grid, a large number of power electronic devices are arranged in the power grid, and generated harmonic waves are injected into the power grid, so that the harmonic wave problem of the power grid is increased. The transmission of harmonics in a power system will affect the quality of the power supplied by the power system and in severe cases may cause damage to the user or the power grid equipment, so that it is often necessary to configure a filtering system when equipment generating larger harmonics is connected in the power grid.
The current filtering systems are mainly divided into two categories: one type is a passive filter system, namely, a fixed capacitor, an inductor and a resistor element are adopted, and impedance low points with fixed tuning frequency are formed through a certain series-parallel connection so as to achieve the filtering effect; one type is an active filter system, namely equipment adopting pure electric electrons, and harmonic waves are filtered through detecting the harmonic wave level of a power grid and generating opposite-phase harmonic waves through the electric electronic system.
The conventional STATCOM (static synchronous compensator) mainly comprises a connection transformer, a phase unit, a connection reactor and other auxiliary equipment (such as a grid-connected switch, control and monitoring equipment, a cooling system and the like). The current STATCO-based control system structure comprises an alternating voltage outer ring, a power outer ring, a submodule direct voltage outer ring, a current inner ring and dq axis transformation. The current inner loop d-axis current reference value is generated by a submodule direct-current voltage outer loop, the q-axis current reference value is generated by an alternating-current voltage outer loop or a reactive power outer loop, and the current inner loop consists of a PI controller, a decoupling control link and voltage feedforward. Based on the control system structure, the control mode of the STATCOM is divided into a steady-state constant reactive power control mode, a steady-state constant voltage control mode, a remote control mode, a transient state rapid reactive power compensation control mode and a debugging mode, wherein the steady-state constant reactive power control mode, the steady-state constant voltage control mode and the remote control mode are all control strategies in steady state. In a steady-state constant reactive power control mode or a steady-state constant voltage control mode, when a power grid fails and meets starting conditions, the STATCOM can enter a transient state rapid reactive power compensation control mode. It can be seen that the conventional STATCOM has only a dynamic reactive power regulation function and does not have a filtering function. As new power systems are built, a large number of STATCOMs will be added to the system. If the STATCOM can further have the function of harmonic treatment on the basis of the original dynamic reactive power support function, the function of the STATCOM can be fully exerted, and the harmonic filtering cost of a power grid is greatly reduced.
STATCOM is a multi-level chain structure that facilitates the series connection of modules while being able to effectively control the harmonic size. The basic structure of the active power filter is a traditional two-level inverter structure, and the multi-level chain structure and the two-level inverter are different in structure, but can realize similar control functions. Therefore, in theory, the STATCOM can also realize the function of active filtering.
Disclosure of Invention
The application provides a STATCOM-based harmonic governance method, a STATCOM-based harmonic governance system and STATCOM-based harmonic governance equipment, which solve the technical problem of how to realize a STATCOM harmonic governance function.
The application provides a STATCOM-based harmonic treatment method, which is applied to a STATCOM, wherein the STATCOM is connected into a target power grid in a parallel mode, and the method comprises the following steps:
collecting voltage data of a two-stage transformer connected with a STATCOM in a target power grid;
determining a STATCOM filtering target value of a target branch according to the voltage data;
taking the STATCOM filtering target value as an active filtering control input quantity, and executing an active filtering function; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, and the purpose of active filtering is achieved.
According to one implementation manner of the first aspect of the present application, the voltage data includes a high-voltage side voltage and a low-voltage side voltage, and the determining a STATCOM filtering target value of a target branch according to the voltage data includes:
performing harmonic current transformation based on the high-side voltage and the low-side voltage:
in the formula Ix rms In is the current detection amplitude of the target branch circuit, U, for the current value obtained by harmonic current transformation 1 For high-side voltage, U 3 Is a low side voltage;
calculating a STATCOM filter target value of the target branch according to the following formula:
wherein Ix represents a STATCOM filtering target value, θ of the target branch 0 For the phase angle of In, xt is the total impedance of the two-stage transformer, X is the impedance of STATCOM, R is the transformer resistance, and ω is the angular velocity.
According to one implementation manner of the first aspect of the present application, the executing an active filtering function with the STATCOM filtering target value as an active filtering control input includes:
collecting three-phase voltage at a target port; the target port is a connection port of the STATCOM and a target power grid;
the three-phase voltage passes through a phase-locked loop to output corresponding three-phase angles;
transforming the STATCOM filtering target value from an abc static coordinate system to a dq rotating coordinate system based on the three-phase angle to obtain a d-axis current component and a q-axis current component of the STATCOM filtering target value under the dq rotating coordinate system;
acquiring direct current components of the d-axis current component and the q-axis current component;
determining a d-axis harmonic current reference value and a q-axis harmonic current reference value based on the received current command value;
subtracting the direct current component of the d-axis current component from the d-axis harmonic current reference value, and obtaining a d-axis n-time voltage reference value by a PI controller from the obtained difference value;
subtracting the direct current component of the q-axis current component from the q-axis harmonic current reference value, and passing the obtained difference through a PI controller to obtain a q-axis n-time voltage reference value;
transforming the d-axis n-time voltage reference value and the q-axis n-time voltage reference value from a dq rotating coordinate system to an abc static coordinate system to obtain corresponding three-phase voltage reference values;
superposing a target phase voltage reference value in the three-phase voltage reference values and a control command value output when the STATCOM executes fundamental wave control to obtain a total voltage reference value;
and modulating the trigger pulse based on the total voltage reference value.
According to one implementation manner of the first aspect of the present application, the control command value output when the STATCOM performs fundamental wave control is a voltage reference value of 50 Hz.
According to one implementation manner of the first aspect of the present application, the acquiring the d-axis current component and the direct-current component of the q-axis current component includes:
and inputting the d-axis current component and the q-axis current component into a low-pass filter for filtering to obtain direct current components of the d-axis current component and the q-axis current component.
According to one implementation manner of the first aspect of the present application, the transforming the d-axis n-time voltage reference value and the q-axis n-time voltage reference value from the dq rotating coordinate system to the abc stationary coordinate system includes:
calculating a corresponding delay compensation value by considering the delay of low-pass filtering of the low-pass filter and/or the delay of the boost variable impedance in the station on the harmonic signal;
and transforming the d-axis n times voltage reference value and the q-axis n times voltage reference value from the dq rotating coordinate system to the abc static coordinate system based on the delay compensation value.
According to one possible implementation of the first aspect of the present application, before performing the active filtering function, the method further comprises:
acquiring a current detection amplitude value of the target branch;
and when the current detection amplitude is larger than a preset current threshold value, starting the active filtering function.
The second aspect of the present application provides a harmonic governance system based on a STATCOM, applied to a STATCOM, the STATCOM being connected in parallel to a target power grid, the system comprising:
the acquisition module is used for acquiring voltage data of a two-stage transformer connected with the STATCOM in the target power grid;
the determining module is used for determining a STATCOM filtering target value of the target branch according to the voltage data;
the active filtering module is used for taking the STATCOM filtering target value as an active filtering control input quantity and executing an active filtering function; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, and the purpose of active filtering is achieved.
According to one implementation manner of the second aspect of the present application, the voltage data includes a high-side voltage and a low-side voltage, and the determining module includes:
a harmonic current transformation unit for performing harmonic current transformation based on the high-voltage side voltage and the low-voltage side voltage:
in the formula Ix rms In is the current detection amplitude of the target branch circuit, U, for the current value obtained by harmonic current transformation 1 For high-side voltage, U 3 Is a low side voltage;
the calculating unit is used for calculating the STATCOM filtering target value of the target branch according to the following formula:
wherein Ix represents a STATCOM filtering target value, θ of the target branch 0 For the phase angle of In, xt is the total impedance of the two-stage transformer, X is the impedance of STATCOM, R is the transformer resistance, and ω is the angular velocity.
According to one manner of implementation of the second aspect of the present application, the active filtering module includes:
the acquisition unit is used for acquiring the three-phase voltage at the target port; the target port is a connection port of the STATCOM and a target power grid;
the phase-locked loop unit is used for outputting corresponding three-phase angles by passing the three-phase voltage through the phase-locked loop;
a first coordinate transformation unit, configured to perform transformation from an abc stationary coordinate system to a dq rotating coordinate system on the STATCOM filtering target value based on the three-phase angle, and obtain a d-axis current component and a q-axis current component of the STATCOM filtering target value under the dq rotating coordinate system;
an acquisition unit configured to acquire direct current components of the d-axis current component and the q-axis current component;
a determining unit for determining a d-axis harmonic current reference value and a q-axis harmonic current reference value based on the received current command value;
the first removing unit is used for subtracting the direct current component of the d-axis current component from the d-axis harmonic current reference value, and obtaining a d-axis n-time voltage reference value by a PI controller from the obtained difference value;
the second removing unit is used for subtracting the direct current component of the q-axis current component from the q-axis harmonic current reference value, and obtaining a q-axis n-time voltage reference value by a PI controller from the obtained difference value;
the second coordinate transformation unit is used for transforming the d-axis n-time voltage reference value and the q-axis n-time voltage reference value from the dq rotating coordinate system to the abc static coordinate system to obtain corresponding three-phase voltage reference values;
the superposition unit is used for superposing a target phase voltage reference value in the three-phase voltage reference values and a control command value output when the STATCOM executes fundamental wave control to obtain a total voltage reference value;
and the modulation unit is used for modulating the trigger pulse based on the total voltage reference value.
According to one implementation manner of the second aspect of the present application, the control command value output when the STATCOM performs the fundamental wave control is a voltage reference value of 50 Hz.
According to one possible manner of the second aspect of the present application, the obtaining unit is specifically configured to:
and inputting the d-axis current component and the q-axis current component into a low-pass filter for filtering to obtain direct current components of the d-axis current component and the q-axis current component.
According to one implementation manner of the second aspect of the present application, the second coordinate transformation unit is specifically configured to:
calculating a corresponding delay compensation value by considering the delay of low-pass filtering of the low-pass filter and/or the delay of the boost variable impedance in the station on the harmonic signal;
and transforming the d-axis n times voltage reference value and the q-axis n times voltage reference value from the dq rotating coordinate system to the abc static coordinate system based on the delay compensation value.
According to one manner in which the second aspect of the application can be implemented, before performing the active filtering function, the system further comprises:
the acquisition module is used for acquiring the current detection amplitude value of the target branch;
and the starting judgment module is used for starting the active filtering function when the current detection amplitude is larger than a preset current threshold value.
A third aspect of the present application provides a STATCOM-based harmonic remediation apparatus, comprising:
a memory for storing instructions; the instructions are used for realizing the STATCOM-based harmonic treatment method according to the mode which can be realized by any one of the above;
and the processor is used for executing the instructions in the memory.
A fourth aspect of the present application is a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements a STATCOM-based harmonic remediation method according to any one of the above modes.
From the above technical scheme, the application has the following advantages:
the method comprises the steps of collecting voltage data of a two-stage transformer connected with a STATCOM in a target power grid; determining a STATCOM filtering target value of a target branch according to the voltage data; taking the STATCOM filtering target value as an active filtering control input quantity, and executing an active filtering function; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, so as to achieve the purpose of active filtering; the application can ensure that the STATCOM further has the function of harmonic wave treatment on the basis of the original dynamic reactive power supporting function, and fully plays the role of the STATCOM.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a STATCOM-based harmonic remediation method according to an alternative embodiment of the present application;
fig. 2 is a schematic diagram of a STATCOM according to an alternative embodiment of the present application accessing a target power grid in parallel;
FIG. 3 is a block diagram of an active filter control of a STATCOM according to an alternative embodiment of the application;
fig. 4 is a block diagram of structural connection of a STATCOM-based harmonic remediation system according to an alternative embodiment of the present application.
Reference numerals:
1-an acquisition module; 2-a determination module; 3-active filtering module.
Detailed Description
The embodiment of the application provides a STATCOM-based harmonic governance method, a STATCOM-based harmonic governance system and STATCOM-based harmonic governance equipment, which are used for solving the technical problem of how to realize a STATCOM harmonic governance function.
In order to make the objects, features and advantages of the present application more comprehensible, the technical solutions in the embodiments of the present application are described in detail below with reference to the accompanying drawings, and it is apparent that the embodiments described below are only some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The application provides a STATCOM-based harmonic treatment method. The method is applied to STATCOM.
Referring to fig. 1, fig. 1 shows a flowchart of a STATCOM-based harmonic treatment method according to an embodiment of the present application.
The STATCOM-based harmonic treatment method provided by the embodiment of the application comprises the steps S1-S3.
And S1, collecting voltage data of a two-stage transformer connected with a STATCOM in a target power grid.
As shown in fig. 2, the STATCOM is connected to the target grid in parallel. The voltage data of the two-stage transformer connected with the STATCOM in the target power grid can comprise a high-side voltage U 1 Voltage U at medium voltage side 2 And a low-side voltage U 3 。
And S2, determining a STATCOM filtering target value of the target branch according to the voltage data.
The target branch can be selected from all branches of the power grid according to actual conditions. As an example, when the branches from the station a to the station B In fig. 2 are selected as the target branches, the corresponding current detection amplitude is in=i 1 The method comprises the steps of carrying out a first treatment on the surface of the When the branches from station B to station C In fig. 2 are selected as the target branches, the corresponding current detection amplitude is in=i 2 。
In one implementation, the voltage data includes a high-side voltage and a low-side voltage, and determining the STATCOM filtering target value of the target branch according to the voltage data includes:
performing harmonic current transformation based on the high-side voltage and the low-side voltage:
in the formula Ix rms In is the current detection amplitude of the target branch circuit, U, for the current value obtained by harmonic current transformation 1 For high-side voltage, U 3 Is a low side voltage;
calculating a STATCOM filter target value of the target branch according to the following formula:
wherein Ix represents a STATCOM filtering target value, θ of the target branch 0 For the phase angle of In, xt is the total impedance of the two-stage transformer, X is the impedance of STATCOM, R is the transformer resistance, and ω is the angular velocity.
In the embodiment of the application, the determination of the STATCOM filtering target value is realized, and the acquisition accuracy of the active filtering control input quantity can be improved.
Step S3, the STATCOM filtering target value is used as an active filtering control input quantity, and an active filtering function is executed; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, and the purpose of active filtering is achieved.
In one implementation manner, the executing an active filtering function with the STATCOM filtering target value as an active filtering control input quantity includes:
collecting three-phase voltage at a target port; the target port is a connection port of the STATCOM and a target power grid;
the three-phase voltage passes through a phase-locked loop to output corresponding three-phase angles;
transforming the STATCOM filtering target value from an abc static coordinate system to a dq rotating coordinate system based on the three-phase angle to obtain a d-axis current component and a q-axis current component of the STATCOM filtering target value under the dq rotating coordinate system;
acquiring direct current components of the d-axis current component and the q-axis current component;
determining a d-axis harmonic current reference value and a q-axis harmonic current reference value based on the received current command value;
subtracting the direct current component of the d-axis current component from the d-axis harmonic current reference value, and obtaining a d-axis n-time voltage reference value by a PI controller from the obtained difference value;
subtracting the direct current component of the q-axis current component from the q-axis harmonic current reference value, and passing the obtained difference through a PI controller to obtain a q-axis n-time voltage reference value;
transforming the d-axis n-time voltage reference value and the q-axis n-time voltage reference value from a dq rotating coordinate system to an abc static coordinate system to obtain corresponding three-phase voltage reference values;
superposing a target phase voltage reference value in the three-phase voltage reference values and a control command value output when the STATCOM executes fundamental wave control to obtain a total voltage reference value;
and modulating the trigger pulse based on the total voltage reference value.
The fundamental wave is controlled to be a main function of the STATCOM, the harmonic control part is an active filtering function, and in the embodiment of the application, the command value of the active filtering function (namely the target phase voltage reference value) is obtained by processing the STATCOM filtering target value, the command value of the active filtering function is superimposed into the main control command value, and then the trigger pulse is modulated, so that the active filtering function is realized.
In one implementation, the acquiring the d-axis current component and the direct current component of the q-axis current component includes:
and inputting the d-axis current component and the q-axis current component into a low-pass filter for filtering to obtain direct current components of the d-axis current component and the q-axis current component.
In the embodiment of the application, the harmonic extraction problem is considered, and the fundamental component is eliminated by adopting a coordinate transformation method so as to separate the harmonic component.
The input signals are assumed to be as follows:
wherein n represents the harmonic order, X a 、X b 、X c Respectively represent the corresponding physical quantity of a, b and c phases in the input signal omega 0 Represents the initial angular velocity, θ n Three-phase angle with the harmonic frequency n is represented;
and performing dq conversion on the input signal, wherein the dq conversion formula is as follows:
wherein X is d Representing d-axis component obtained by dq-transforming the input signal, X q Representing q-axis components obtained by dq conversion of the input signal, wherein θ is a three-phase angle;
with the above variation, the following expression can be obtained:
therefore, the power frequency component is converted into a direct current component after dq conversion, and other harmonic components are respectively reduced to n-1 harmonic after dq conversion.
According to the method, according to the filtering target of the filtering instruction, if the m-order harmonic is filtered, the m-order harmonic is calculated and extracted by adopting the following formula:
wherein X is dm For d-axis component with harmonic order m, X qm Is the q-axis component with harmonic order m.
After the transformed signal passes through the low-frequency filter, each subharmonic component can be filtered, and the direct-current component is well reserved.
In one possible implementation, the control command value output when the STATCOM performs fundamental wave control is a 50Hz voltage reference value.
In one implementation, the transforming the d-axis n times voltage reference value and the q-axis n times voltage reference value from a dq rotating coordinate system to an abc stationary coordinate system includes:
calculating a corresponding delay compensation value by considering the delay of low-pass filtering of the low-pass filter and/or the delay of the boost variable impedance in the station on the harmonic signal;
and transforming the d-axis n times voltage reference value and the q-axis n times voltage reference value from the dq rotating coordinate system to the abc static coordinate system based on the delay compensation value.
As a specific embodiment, as shown in fig. 3, when an active filtering function is performed, three-phase voltage Uabc is subjected to PLL (phase locked loop), corresponding three-phase angle θ is output, three-phase angle θ and STATCOM filtering target value Iabc are input to an abc/dq converter, d-axis current component Id and q-axis current component Iq of the STATCOM filtering target value under a dq rotation coordinate system are obtained, the d-axis current component Id and q-axis current component Iq are input to LPF (low pass filter) for filtering, and direct current components Idn and Idq of the d-axis current component and q-axis current component are obtained; determining a d-axis harmonic current reference value Idnref and a q-axis harmonic current reference value Idqref based on the received current command values; subtracting the direct current component Idn of the d-axis current component from the d-axis harmonic current reference value Idnref, and obtaining a d-axis n-time voltage reference value Udnref by a PI controller from the obtained difference value; subtracting the direct current component Idq of the q-axis current component from the q-axis harmonic current reference value Idqref, and obtaining a q-axis n-time voltage reference value Udqref by a PI controller from the obtained difference; taking the harmonic filtering link and the delay of the boost variable impedance in the station on the harmonic signal into consideration, inputting LPF time compensation, boost variable impedance delay compensation, d-axis n-time voltage reference value Udnref and q-axis n-time voltage reference value Udqref into a dq/abc converter to obtain corresponding three-phase voltage reference value Uanref, ubnref, ucnref; and (3) superposing Uanref, ubnref and a target phase voltage reference value (Uanef in fig. 3) in Ucnref and a control command value Uaref_50 output when the STATCOM performs fundamental wave control (namely main control), so as to obtain a total voltage reference value Uaref. Wherein, the corresponding Uaref_50, ubref_50 and Ucref_50 of a, b and c are respectively the voltage reference values of 50 Hz.
In the embodiment of the application, the delay of the harmonic signal by the harmonic filtering link and the boost variable impedance in the station is fully considered, and the delay is compensated, so that the harmonic phase can be more accurately compensated by the STATCOM-based harmonic treatment system.
In one manner that can be implemented, before performing the active filtering function, the method further comprises:
acquiring a current detection amplitude value of the target branch;
and when the current detection amplitude is larger than a preset current threshold value, starting the active filtering function.
The preset current threshold value is selected according to the harmonic current limit value specified by the national standard.
The embodiment of the application can ensure that the STATCOM further has the function of harmonic wave treatment on the basis of the original dynamic reactive power support function, and fully plays the role of the STATCOM.
The application also provides a STATCOM-based harmonic governance system, which is applied to the STATCOM, and the STATCOM is connected into a target power grid in a parallel mode.
Referring to fig. 4, fig. 4 shows a structural connection block diagram of a STATCOM-based harmonic treatment system according to an embodiment of the present application.
The embodiment of the application provides a STATCOM-based harmonic governance system, which comprises:
the acquisition module 1 is used for acquiring voltage data of a two-stage transformer connected with the STATCOM in a target power grid;
the determining module 2 is used for determining a STATCOM filtering target value of the target branch according to the voltage data;
an active filtering module 3, configured to execute an active filtering function with the STATCOM filtering target value as an active filtering control input; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, and the purpose of active filtering is achieved.
In one possible implementation, the voltage data includes a high-side voltage and a low-side voltage, and the determining module 2 includes:
a harmonic current transformation unit for performing harmonic current transformation based on the high-voltage side voltage and the low-voltage side voltage:
in the formula Ix rms In is the current detection amplitude of the target branch circuit, U, for the current value obtained by harmonic current transformation 1 For high-side voltage, U 3 Is a low side voltage;
the calculating unit is used for calculating the STATCOM filtering target value of the target branch according to the following formula:
wherein Ix represents a STATCOM filtering target value, θ of the target branch 0 For the phase angle of In, xt is the total impedance of the two-stage transformer, X is the impedance of STATCOM, R is the transformer resistance, and ω is the angular velocity.
In one possible implementation, the active filtering module 3 comprises:
the acquisition unit is used for acquiring the three-phase voltage at the target port; the target port is a connection port of the STATCOM and a target power grid;
the phase-locked loop unit is used for outputting corresponding three-phase angles by passing the three-phase voltage through the phase-locked loop;
a first coordinate transformation unit, configured to perform transformation from an abc stationary coordinate system to a dq rotating coordinate system on the STATCOM filtering target value based on the three-phase angle, and obtain a d-axis current component and a q-axis current component of the STATCOM filtering target value under the dq rotating coordinate system;
an acquisition unit configured to acquire direct current components of the d-axis current component and the q-axis current component;
a determining unit for determining a d-axis harmonic current reference value and a q-axis harmonic current reference value based on the received current command value;
the first removing unit is used for subtracting the direct current component of the d-axis current component from the d-axis harmonic current reference value, and obtaining a d-axis n-time voltage reference value by a PI controller from the obtained difference value;
the second removing unit is used for subtracting the direct current component of the q-axis current component from the q-axis harmonic current reference value, and obtaining a q-axis n-time voltage reference value by a PI controller from the obtained difference value;
the second coordinate transformation unit is used for transforming the d-axis n-time voltage reference value and the q-axis n-time voltage reference value from the dq rotating coordinate system to the abc static coordinate system to obtain corresponding three-phase voltage reference values;
the superposition unit is used for superposing a target phase voltage reference value in the three-phase voltage reference values and a control command value output when the STATCOM executes fundamental wave control to obtain a total voltage reference value;
and the modulation unit is used for modulating the trigger pulse based on the total voltage reference value.
In one possible implementation, the control command value output when the STATCOM performs fundamental wave control is a 50Hz voltage reference value.
In one implementation manner, the acquiring unit is specifically configured to:
and inputting the d-axis current component and the q-axis current component into a low-pass filter for filtering to obtain direct current components of the d-axis current component and the q-axis current component.
In one possible implementation, the second coordinate transformation unit is specifically configured to:
calculating a corresponding delay compensation value by considering the delay of low-pass filtering of the low-pass filter and/or the delay of the boost variable impedance in the station on the harmonic signal;
and transforming the d-axis n times voltage reference value and the q-axis n times voltage reference value from the dq rotating coordinate system to the abc static coordinate system based on the delay compensation value.
In one manner that can be implemented, before performing the active filtering function, the system further comprises:
the acquisition module is used for acquiring the current detection amplitude value of the target branch;
and the starting judgment module is used for starting the active filtering function when the current detection amplitude is larger than a preset current threshold value.
The application also provides STATCOM-based harmonic governance equipment, which comprises:
a memory for storing instructions; the instructions are used for implementing the STATCOM-based harmonic governance method according to any one of the embodiments;
and the processor is used for executing the instructions in the memory.
The application also provides a computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, and the computer program realizes the STATCOM-based harmonic treatment method according to any embodiment when being executed by a processor.
It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses, modules and units may refer to corresponding procedures in the foregoing method embodiments, and specific beneficial effects of the above-described systems, apparatuses, modules and units may refer to corresponding beneficial effects in the foregoing method embodiments, which are not described herein again.
In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the system embodiments described above are merely illustrative, e.g., the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple modules or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with respect to each other may be through some interface, indirect coupling or communication connection of systems or modules, electrical, mechanical, or other form.
The modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules, i.e., may be located in one place, or may be distributed over a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist alone physically, or two or more modules may be integrated into one module. The integrated modules may be implemented in hardware or in software functional modules.
The integrated modules, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in part or all of the technical solution or in part in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims (10)
1. A harmonic governance method based on a STATCOM, applied to the STATCOM, the STATCOM being connected in parallel to a target power grid, the method comprising:
collecting voltage data of a two-stage transformer connected with a STATCOM in a target power grid;
determining a STATCOM filtering target value of a target branch according to the voltage data;
taking the STATCOM filtering target value as an active filtering control input quantity, and executing an active filtering function; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, and the purpose of active filtering is achieved.
2. A STATCOM based harmonic remediation method according to claim 1 wherein the voltage data includes a high side voltage and a low side voltage, the determining a STATCOM filtered target value for a target leg from the voltage data comprising:
performing harmonic current transformation based on the high-side voltage and the low-side voltage:
in the formula Ix rms In is the current detection amplitude of the target branch circuit, U, for the current value obtained by harmonic current transformation 1 For high-side voltage, U 3 Is a low side voltage;
calculating a STATCOM filter target value of the target branch according to the following formula:
wherein Ix represents a STATCOM filtering target value, θ of the target branch 0 For the phase angle of In, xt is the total impedance of the two-stage transformer, X is the impedance of STATCOM, R is the transformer resistance, and ω is the angular velocity.
3. A STATCOM-based harmonic remediation method according to claim 1, wherein the performing an active filtering function with the STATCOM filtering target value as an active filtering control input includes:
collecting three-phase voltage at a target port; the target port is a connection port of the STATCOM and a target power grid;
the three-phase voltage passes through a phase-locked loop to output corresponding three-phase angles;
transforming the STATCOM filtering target value from an abc static coordinate system to a dq rotating coordinate system based on the three-phase angle to obtain a d-axis current component and a q-axis current component of the STATCOM filtering target value under the dq rotating coordinate system;
acquiring direct current components of the d-axis current component and the q-axis current component;
determining a d-axis harmonic current reference value and a q-axis harmonic current reference value based on the received current command value;
subtracting the direct current component of the d-axis current component from the d-axis harmonic current reference value, and obtaining a d-axis n-time voltage reference value by a PI controller from the obtained difference value;
subtracting the direct current component of the q-axis current component from the q-axis harmonic current reference value, and passing the obtained difference through a PI controller to obtain a q-axis n-time voltage reference value;
transforming the d-axis n-time voltage reference value and the q-axis n-time voltage reference value from a dq rotating coordinate system to an abc static coordinate system to obtain corresponding three-phase voltage reference values;
superposing a target phase voltage reference value in the three-phase voltage reference values and a control command value output when the STATCOM executes fundamental wave control to obtain a total voltage reference value;
and modulating the trigger pulse based on the total voltage reference value.
4. A STATCOM-based harmonic remediation method according to claim 3 wherein the control command value output when the STATCOM performs fundamental wave control is a 50Hz voltage reference value.
5. A STATCOM based harmonic remediation method according to claim 3 wherein the obtaining of the d-axis current component and the direct current component of the q-axis current component includes:
and inputting the d-axis current component and the q-axis current component into a low-pass filter for filtering to obtain direct current components of the d-axis current component and the q-axis current component.
6. A STATCOM based harmonic remediation method according to claim 5 wherein the transforming the d-axis n times voltage reference and the q-axis n times voltage reference from a dq rotating coordinate system to an abc stationary coordinate system includes:
calculating a corresponding delay compensation value by considering the delay of low-pass filtering of the low-pass filter and/or the delay of the boost variable impedance in the station on the harmonic signal;
and transforming the d-axis n times voltage reference value and the q-axis n times voltage reference value from the dq rotating coordinate system to the abc static coordinate system based on the delay compensation value.
7. A STATCOM based harmonic remediation method according to claim 1, wherein prior to performing the active filtering function, the method further comprises:
acquiring a current detection amplitude value of the target branch;
and when the current detection amplitude is larger than a preset current threshold value, starting the active filtering function.
8. A STATCOM-based harmonic remediation system for use with a STATCOM, the STATCOM being connected in parallel to a target power grid, the system comprising:
the acquisition module is used for acquiring voltage data of a two-stage transformer connected with the STATCOM in the target power grid;
the determining module is used for determining a STATCOM filtering target value of the target branch according to the voltage data;
the active filtering module is used for taking the STATCOM filtering target value as an active filtering control input quantity and executing an active filtering function; the active filtering function is used for generating modulation current with the same magnitude and opposite direction as the harmonic current of the target branch circuit, and the purpose of active filtering is achieved.
9. A STATCOM-based harmonic remediation apparatus comprising:
a memory for storing instructions; wherein the instructions are for implementing a STATCOM-based harmonic remediation method as claimed in any one of claims 1 to 5;
and the processor is used for executing the instructions in the memory.
10. A computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, which when executed by a processor implements a STATCOM based harmonic remediation method according to any one of claims 1 to 5.
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