A power quality conditioning method and power quality conditioner

Abstract

The application discloses a power quality regulation method and a power quality regulator, and relates to the technical field of circuit devices, and the method comprises the following steps: acquiring power quality monitoring data, decoupling the power quality monitoring data by using instantaneous reactive power, and acquiring abnormality identification data. The abnormality identification data is input into a transient recovery performance identification model to acquire a transient recovery performance index. If the transient recovery performance index is smaller than a preset transient recovery performance index, a compensation unit in a power quality regulation module is activated. The power quality regulation module feeds back recovery compensation according to the transient recovery performance index, outputs recovery compensation data, and the recovery compensation data is synchronous compensation data based on transient recovery. The series compensation unit and / or the parallel compensation unit are controlled according to the recovery compensation data to perform compensation regulation. The technical problems of insufficient line compensation capacity, frequent faults, high investment cost and low utilization rate of the power quality regulation method in the prior art are solved.

Description

Technical Field

[0001] This application relates to the technical field of circuit devices, specifically to a power quality regulation method and a power quality regulator. Background Technology

[0002] With the rapid development of the energy internet, the application of large-scale renewable energy and power electronic equipment in distribution networks is becoming increasingly widespread, especially in photovoltaic power generation systems, electric vehicle charging facilities, and DC distribution networks. The intermittent output of photovoltaics, the impulsive charging characteristics of electric vehicles, and the nonlinear characteristics of power electronic devices pose significant challenges to the power quality of distribution networks. Among these, significant voltage drops have the most pronounced impact on the load side, often leading to the shutdown or damage of critical equipment and causing significant economic losses. Currently, conventional parallel active power filters (APFs) can effectively filter current harmonics, but their compensation capabilities for voltage harmonics and deep voltage drops are insufficient. Simultaneously, the increase in nonlinear loads in distribution networks means that interharmonics introduced by power electronic devices can easily induce subsynchronous oscillations, disrupting the stability of motor load operation. Furthermore, short-circuit faults are frequent in distribution networks; if a separate short-circuit current limiter (FCL) is installed, the investment cost is high and the utilization rate is often low.

[0003] Therefore, existing power quality regulation methods suffer from technical problems such as insufficient line compensation capacity, frequent faults, high investment costs, and low utilization rates. Summary of the Invention

[0004] This application provides a power quality regulation method and a power quality regulator, solving the technical problems of insufficient line compensation capacity, frequent faults, high investment costs, and low utilization rates in existing power quality regulation methods. Through multiple feedback mechanisms including transient recovery performance indicators, coupling influence coefficients, and residual compensation data, it achieves coordinated and efficient compensation between series and parallel compensation units, significantly improving the speed and accuracy of power quality recovery in multi-disturbance scenarios.

[0005] This application provides a power quality regulation method, the method comprising: defining power quality monitoring items of a distribution network and acquiring power quality monitoring data, wherein the power quality monitoring items include voltage monitoring items and current monitoring items; decoupling the power quality monitoring data using instantaneous reactive power to acquire anomaly identification data; inputting the anomaly identification data into a transient recovery performance identification model, and acquiring a transient recovery performance index based on the transient recovery performance identification model; if the transient recovery performance index is less than a preset transient recovery performance index, activating a series compensation unit and / or a parallel compensation unit within a power quality regulation module based on the anomaly identification data; the power quality regulation module performing recovery compensation feedback based on the transient recovery performance index and outputting recovery compensation data, wherein the recovery compensation data is synchronous compensation data based on transient recovery; and controlling the series compensation unit and / or the parallel compensation unit to perform compensation regulation based on the recovery compensation data.

[0006] In the implementation, the series compensation unit and / or parallel compensation unit in the power quality adjustment module are activated according to the anomaly identification data. The method includes: analyzing the anomaly identification data; if it is a first type of anomaly, the series compensation unit is activated; if it is a second type of anomaly, the parallel compensation unit is activated. The first type of anomaly is voltage drop or flicker, and the second type of anomaly is harmonic current or reactive power fluctuation. If both the first type of anomaly and the second type of anomaly exist simultaneously, the series compensation unit and the parallel compensation unit are activated.

[0007] In the implementation method, the output of recovery compensation data further includes: if the series compensation unit is activated, the power quality regulation module performs series recovery compensation prediction based on the transient recovery performance index and outputs series-recovery compensation data; if the parallel compensation unit is activated, the power quality regulation module performs recovery compensation prediction based on the transient recovery performance index and outputs parallel-recovery compensation data; if both the series compensation unit and the parallel compensation unit are activated simultaneously, the power quality regulation module performs series-parallel recovery compensation prediction based on the transient recovery performance index and outputs both series-recovery compensation data and parallel-recovery compensation data.

[0008] In the implementation method, the transient recovery performance index is obtained according to the transient recovery performance identification model. The method includes: obtaining the initial response state of the distribution network; the transient recovery performance identification model performs transient response simulation on the anomaly identification data based on the initial response state, outputs transient response simulation data, and calculates the transient response simulation data to output the transient recovery performance index, wherein the expression for the transient response simulation includes:

[0009] ;

[0010] in, The response state of the distribution network at time t. This represents the system's natural response over time t when there is no external input. The impact of circuit parameters on changes in the response state of the distribution network. This represents the initial response state of the distribution network. This refers to the impact of external input signals on the response state of the distribution network. The input signal is the external disturbance caused by abnormal identification data. The integral effect of time t on the response state is the cumulative response of the system to the external input signal during the time interval from t=0 to t.

[0011] In the implementation, the power quality regulation module performs recovery compensation feedback based on the transient recovery performance index and outputs recovery compensation data. The method includes: recording the compensation response time of the series compensation unit and the parallel compensation unit; if the compensation response time is less than the preset compensation response time, and the series compensation unit or the parallel compensation unit is activated, recovery compensation feedback is performed using the series-recovery compensation parameter or the parallel-recovery compensation parameter as the response variable, and recovery compensation data is output, including series-recovery compensation data or parallel-recovery compensation data.

[0012] In the implementation, if the compensation response time is less than the preset compensation response time, and the series compensation unit and the parallel compensation unit are activated, the coupling influence coefficient of the series compensation unit and the parallel compensation unit is calculated; using the coupling influence coefficient as the influence variable, and the series-recovery compensation parameter and the parallel-recovery compensation parameter as the response variable, recovery compensation feedback is performed, and recovery compensation data, including series-recovery compensation data and parallel-recovery compensation data, is output.

[0013] In the implementation, if the compensation response duration is greater than or equal to the preset compensation response duration, and the series compensation unit or the parallel compensation unit is activated, the compensated data based on the transient recovery performance index under the preset compensation response duration is calculated; the remaining compensation data is determined based on the compensated data; the remaining compensation data is used as the response target, the transient recovery performance index is used as the input quantifier, and the series-recovery compensation parameter or the parallel-recovery compensation parameter is used as the response variable to perform recovery compensation feedback, and recovery compensation data, including series-recovery compensation data or parallel-recovery compensation data, is output.

[0014] In the implementation, if the compensation response duration is greater than or equal to the preset compensation response duration, and the series compensation unit and the parallel compensation unit are activated; the remaining compensation data is used as the response target, the transient recovery performance index is used as the input quantity, the coupling influence coefficient is used as the influence variable, and the series-recovery compensation parameters and the parallel-recovery compensation parameters are used as response variables to perform recovery compensation feedback, and the recovery compensation data is output, including the series-recovery compensation data and the parallel-recovery compensation data.

[0015] This application also provides a power quality regulator, which includes a series compensation regulation circuit and a parallel compensation regulation circuit, wherein the series compensation regulation circuit and the parallel compensation regulation circuit are connected in series and parallel with the power distribution network.

[0016] This application proposes a power quality regulation method and power quality regulator. The method involves defining power quality monitoring items for the distribution network to obtain power quality monitoring data, including voltage and current monitoring items. Instantaneous reactive power is used to decouple the power quality monitoring data to obtain anomaly identification data. This anomaly identification data is input into a transient recovery performance identification model to obtain a transient recovery performance index. If the transient recovery performance index is less than a preset transient recovery performance index, the series compensation unit and / or parallel compensation unit within the power quality regulation module are activated based on the anomaly identification data. The power quality regulation module performs recovery compensation feedback based on the transient recovery performance index and outputs recovery compensation data, which is synchronous compensation data based on transient recovery. The series compensation unit and / or parallel compensation unit are controlled to perform compensation regulation based on the recovery compensation data. This solves the technical problems of insufficient line compensation capacity, frequent faults, high investment costs, and low utilization rates in existing power quality regulation methods. By using multiple feedback mechanisms, including transient recovery performance indicators, coupling influence coefficients, and residual compensation data, the coordinated and efficient compensation of series and parallel compensation units is achieved, significantly improving the speed and accuracy of power quality recovery in the power grid under multiple disturbance scenarios. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments of this disclosure will be briefly described below. Flowcharts are used in this application to illustrate the operations performed by the system according to the embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, various steps can be processed in reverse order or simultaneously as needed. Furthermore, other operations can be added to these processes, or one or more steps can be removed from these processes.

[0018] Figure 1This is a schematic flowchart of a power quality regulation method provided in an embodiment of this application.

[0019] Figure 2 This is a schematic diagram of a series compensation regulation circuit in a power quality regulator provided in an embodiment of this application.

[0020] Figure 3 This is a schematic diagram of a parallel compensation regulation circuit in a power quality regulator provided in an embodiment of this application.

[0021] Figure 4 This is a schematic diagram of PI control of a series converter in a power quality regulation method provided in an embodiment of this application.

[0022] Figure 5 This is a schematic diagram of the feedback control of the series compensation part of a power quality regulation method provided in an embodiment of this application.

[0023] Figure 6 This is a schematic diagram of the feedback control of the parallel compensation part of a power quality regulation method provided in an embodiment of this application.

[0024] Figure 7 This is a schematic diagram of a parallel converter PI control method for power quality regulation provided in an embodiment of this application. Detailed Implementation

[0025] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application.

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description of this application will be provided in conjunction with the accompanying drawings. The described embodiments should not be considered as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] In the following description, references to "some embodiments" describe a subset of all possible embodiments. However, it is understood that "some embodiments" may be the same or different subsets of all possible embodiments and may be combined with each other without conflict. The terms "first" and "second" are used merely to distinguish similar objects and do not represent a specific ordering of objects. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or modules not explicitly listed or inherent to these processes, methods, products, or devices. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only.

[0028] This application provides a power quality regulation method and a power quality regulator, such as... Figure 1 As shown, the method includes:

[0029] Define power quality monitoring items for the distribution network and acquire power quality monitoring data, wherein the power quality monitoring items include voltage monitoring items and current monitoring items; decouple the power quality monitoring data using instantaneous reactive power to acquire anomaly identification data; input the anomaly identification data into the transient recovery performance identification model, and acquire transient recovery performance indicators based on the transient recovery performance identification model;

[0030] Power quality monitoring items for the distribution network are predefined, including voltage and current monitoring items. Voltage monitoring items include voltage amplitude, voltage frequency, voltage fluctuation, and voltage flicker. Current monitoring items include current amplitude, current harmonic components, and current imbalance. Subsequently, the power quality monitoring data is decoupled using instantaneous reactive power. This involves decomposing the acquired voltage and current signals to distinguish the power components caused by reactive power and harmonics. During decomposition, the system acquires three-phase voltage and current data, transforms the three-phase quantities to the αβ coordinate system, and then calculates active and reactive power using the instantaneous active and reactive power formulas in this coordinate system. After acquiring the active and reactive power, components of different frequencies or characteristics are analyzed. After decoupling, quantitative indicators reflecting multiple abnormal characteristics, such as voltage deviation, harmonic content, and simultaneous voltage and current anomalies, are obtained—i.e., anomaly identification data. Furthermore, the anomaly identification data is input into the transient recovery performance identification model. Based on the transient recovery performance identification model, transient recovery performance indicators are obtained. The transient recovery performance indicators are whether the power system has sufficient self-recovery capability when facing transient disturbances. If it is insufficient, power quality compensation measures need to be activated or strengthened to ensure that the system returns to normal working range as soon as possible and meets power quality requirements.

[0031] The method provided in this application embodiment further includes: obtaining the initial response state of the distribution network; the transient recovery performance identification model performs transient response simulation on the anomaly identification data based on the initial response state, outputs transient response simulation data, and calculates the transient response simulation data to output transient recovery performance indicators, wherein the expression for transient response simulation includes:

[0032] ;

[0033] in, The response state of the distribution network at time t. This represents the system's natural response over time t when there is no external input. The impact of circuit parameters on changes in the response state of the distribution network. This represents the initial response state of the distribution network. This refers to the impact of external input signals on the response state of the distribution network. The input signal is the external disturbance caused by abnormal identification data. Let r be the integral effect of time t on the response state, representing the cumulative response of the system to the external input signal during the time interval from t=0 to t, where r is the integral variable used to iterate through the time interval from 0 to t.

[0034] The initial response state of the distribution network is obtained. This initial response state refers to the steady-state or quasi-steady-state condition of the distribution network before the disturbance occurs, specifically the system state at t=0. The initial response state includes voltage amplitude, line current parameters, etc. Subsequently, the transient recovery performance identification model performs transient response simulation on the anomaly identification data based on the initial response state. This involves inputting the obtained initial response state parameters into a transient response simulation expression, obtaining the calculation result of the expression, and generating transient response simulation data. Based on the calculated transient response simulation data, a transient recovery performance index is output.

[0035] For an external disturbance input signal U, for example, if harmonic current or flicker is detected, the harmonic injection signal and flicker frequency can be incorporated into U at the corresponding time. The response state of the distribution network at each discrete moment is calculated iteratively using numerical simulation based on the above formula. During the calculation process, key quantities (bus voltage amplitude, harmonic current peak value, etc.) can be continuously monitored to obtain transient response simulation data. After obtaining the transient response simulation data, the trajectory of the system's state variables at different times is obtained, including the bus voltage change curve over time and the real-time values ​​of harmonic current or reactive power fluctuations. Based on the trajectory of the state variables, corresponding transient recovery performance indicators are obtained, such as the voltage recovery rate per unit time, the harmonic suppression effect, and the stability of reactive power fluctuations. The calculation of these transient recovery performance indicators is a prior art technique and will not be elaborated here.

[0036] If the transient recovery performance index is less than the preset transient recovery performance index, the series compensation unit and / or parallel compensation unit in the power quality adjustment module are activated according to the anomaly identification data; the power quality adjustment module performs recovery compensation feedback according to the transient recovery performance index and outputs recovery compensation data, which is synchronous compensation data based on transient recovery; the series compensation unit and / or the parallel compensation unit are controlled to perform compensation adjustment according to the recovery compensation data.

[0037] If the transient recovery performance index is less than the preset transient recovery performance index, it indicates that the system's recovery capability is poor and unable to combat abnormal interference. In this case, the series compensation unit and / or parallel compensation unit within the power quality regulation module are activated based on the anomaly identification data. The preset transient recovery performance index is a pre-set transient recovery performance requirement. When it is less than this preset index, it indicates that the system cannot combat abnormal interference and requires compensation through additional compensation units. Specific index requirements can be set according to actual needs. The power quality regulation module performs recovery compensation feedback based on the transient recovery performance index and outputs recovery compensation data, which is synchronous compensation data based on transient recovery. Finally, the series compensation unit and / or parallel compensation unit are controlled to perform compensation adjustment based on the recovery compensation data. This solves the technical problems of insufficient line compensation capability, frequent faults, high investment costs, and low utilization rate in existing power quality regulation methods. Through multiple feedback mechanisms including transient recovery performance index, coupling influence coefficient, and residual compensation data, coordinated and efficient compensation of series and parallel compensation units is achieved, significantly improving the speed and accuracy of power quality recovery in multi-disturbance scenarios.

[0038] The method provided in this application embodiment further includes: analyzing the anomaly identification data; activating the series compensation unit if it is a first type of anomaly, and activating the parallel compensation unit if it is a second type of anomaly, wherein the first type of anomaly is a voltage drop or flicker, and the second type of anomaly is a harmonic current or reactive power fluctuation; if both the first type of anomaly and the second type of anomaly exist simultaneously, activating the series compensation unit and the parallel compensation unit.

[0039] Activating the series compensation unit and / or parallel compensation unit within the power quality regulation module based on the anomaly identification data includes: analyzing the anomaly identification data to obtain existing anomaly indicators, such as voltage anomaly indicators (voltage drop depth, flicker, etc.) and current anomaly indicators (harmonic current, reactive power fluctuation, etc.). If the anomaly is of the first type (voltage anomaly), the series compensation unit is activated; if the anomaly is of the second type (current anomaly), the parallel compensation unit is activated. The first type of anomaly is voltage drop or flicker, and the second type of anomaly is harmonic current or reactive power fluctuation. If both types of anomalies exist simultaneously, both the series compensation unit and the parallel compensation unit are activated. The series compensation unit, designed based on a UPQC controller, can be considered a controlled voltage source, compensating the grid with a voltage equal to the difference between the load's rated voltage and the actual grid voltage. This compensates for voltage imbalances, harmonics, and fluctuations in the grid voltage, providing the load with an ideal three-phase voltage. The parallel compensation unit is designed based on the UPQC controller. The parallel part of the UPQC can be regarded as a controlled current source, compensating for load current imbalance, harmonics, and reactive power components, improving grid current quality, and ensuring a grid power factor of 1. Similar to series converters, parallel converters have strong coupling between the d and q axes in the dq coordinate system. When designing the controller, the mathematical model in the dq coordinate system is first transformed to the αβ coordinate system to achieve full decoupling, and then a current tracking controller is designed. The goal of the UPQC parallel part compensation is to ensure that the current waveform drawn from the grid by the load is an ideal sine wave, while maintaining a stable DC-side voltage. The goal of the UPQC control strategy is to achieve fast and accurate tracking of the output voltage and current of both converters to the command value. Therefore, the grid voltage and load current are first sampled, and the compensation voltage and compensation current commands are obtained through the UPQC detection algorithm. Then, the voltage and current tracking controllers implement closed-loop control. Finally, a switching pulse signal is generated through PWM modulation, amplified by the drive circuit, and used to control the converter to output the compensation voltage or current. It is important to note that the stability of the DC-side capacitor voltage of the UPQC is a crucial factor in ensuring its compensation effect, and maintaining the stability of the DC-side voltage is achieved by the parallel-side converter.

[0040] If the series compensation unit is activated, the power quality regulation module performs series recovery compensation prediction based on the transient recovery performance index and outputs series-recovery compensation data; if the parallel compensation unit is activated, the power quality regulation module performs recovery compensation prediction based on the transient recovery performance index and outputs parallel-recovery compensation data; if both the series compensation unit and the parallel compensation unit are activated simultaneously, the power quality regulation module performs series-parallel recovery compensation prediction based on the transient recovery performance index and outputs series-recovery compensation data and parallel-recovery compensation data, wherein the recovery compensation data is synchronous compensation data based on transient recovery.

[0041] The method provided in this application embodiment further includes: recording the compensation response duration of the series compensation unit and the parallel compensation unit; if the compensation response duration is less than the preset compensation response duration, and the series compensation unit or the parallel compensation unit is activated, performing recovery compensation feedback with the series-recovery compensation parameter or the parallel-recovery compensation parameter as the response variable, and outputting recovery compensation data, including series-recovery compensation data or series-recovery compensation data.

[0042] The power quality regulation module performs recovery compensation feedback based on the transient recovery performance index and outputs recovery compensation data. The method includes: when the power quality regulation module detects an anomaly and activates the series / parallel compensation unit, it starts timing and records the compensation execution time in each control cycle, that is, the time from activating the compensation unit to starting to execute parameter compensation, to obtain the compensation response time.

[0043] Subsequently, it is determined whether the compensation response time is less than the preset compensation response time, and the series compensation unit or the parallel compensation unit is activated. When the compensation response time is less than the preset compensation response time, the corresponding compensation response speed is faster, and the response process has less impact on the overall compensation. The preset compensation response time is the time taken from activating the compensation unit to starting parameter compensation under normal conditions. When the above conditions are met, recovery compensation feedback is performed using the series-recovery compensation parameter or the parallel-recovery compensation parameter as the response variable, and recovery compensation data is output, including series-recovery compensation data or parallel-recovery compensation data. That is, each measured value is used as input, and the series-recovery compensation parameter or the parallel-recovery compensation parameter is regarded as output to obtain the output recovery compensation data.

[0044] The UPQC system topology mainly consists of a three-phase AC power grid, a series transformer, a series converter, a parallel converter, DC-side capacitors, and loads. The three-phase AC power grid has a rated line voltage of 380 V and a frequency of 50 Hz; the power supply can simulate grid voltage disturbances, three-phase voltage imbalance, and voltage distortion. The series transformer TS is a single-phase high-frequency transformer, and a high-frequency isolated DC-DC converter provides a DC voltage to the series converters; the combination of the two is equivalent to a power frequency isolation transformer. The series converter V... SC1 The converter is connected in series with transformer T. S An LC filter, consisting of filter inductor L1 and capacitor C1, is connected to the power grid. A parallel converter V... SC2， The converter is filtered by inductor L. 21 Capacitor C2 and filter inductor L 22 The LCL-type filter is connected in parallel to the power grid. The DC-side capacitor C... DC， Connected in V SC1 and VSC2 The common DC terminal can store a certain amount of energy, mainly serving to maintain the stability of the DC side voltage. Load types include linear / nonlinear, symmetrical / asymmetrical, purely resistive / inductive loads, etc. R S L S These represent the resistance and reactance of the power grid, respectively; V C i 22 These are the output voltage on the series side and the output current on the parallel side of the UPQC, respectively.

[0045] UPQC integrates the functions of parallel and series compensation devices, and its control objectives include two parts. First, when the load current is distorted, reactive, or unbalanced in three phases, the parallel side of UPQC functions as an APF (Active Power Factor) to ensure that the grid current is a three-phase balanced sinusoidal current in phase with the fundamental positive sequence voltage. Second, when the grid voltage is distorted, fluctuating, or unbalanced, the series side of UPQC functions as a DVR (Diverterless Voltage Regulator) to ensure that the load voltage is an ideal three-phase voltage.

[0046] When acquiring the series-recovery compensation parameters, a classic PI controller is used as the core unit of the UPQC control section. For example... Figure 5 The series compensation feedback control shown, v s This refers to the grid voltage; v L This is the three-phase load voltage; v L * For ideal load voltage; v c * This is the command value for series-side voltage compensation; v c This is the actual compensation value on the series side; v ce * To compensate for the difference between the commanded value and the actual compensation; G c1 (s) is the transfer function of the series-side controller; k PWM1 Here, L1 is the transfer function of the series-side converter (a typical converter can be represented by a gain k); L1 and C1 are the output filter elements; H1(s) is the transfer function of the feedback network for the series-side closed-loop control, typically set to 1. In the series-compensated feedback control diagram:

[0047] make ;

[0048] Then there is .

[0049] In the above formula, , , These represent the positive-sequence, negative-sequence, and zero-sequence voltages of the power grid fundamental wave; v sh This represents the sum of all grid harmonic voltages; ∆v sfThis represents the voltage amplitude disturbance in the power grid. To achieve good compensation results, appropriate control parameters need to be determined.

[0050] The corresponding current differential equation for the UPQC series converter is shown below, along with its αβ coordinate system state equation:

[0051] ;

[0052] The voltage differential equation corresponding to the UPQC series converter is given by the following αβ coordinate system state equation:

[0053] ;

[0054] Based on the current differential equation and voltage differential equation of the series converter, with v 1α v 1β As the control variable, a PI controller is used, v cα * v cβ * As the command value for voltage compensation, v can be obtained. 1α v 1β The governing equations are as follows:

[0055] ;

[0056] This results in PI control of the UPQC series converter, such as... Figure 4 As shown, G cα1 (s), G cβ1 (s) represent the transfer functions of the PI controllers for the α and β axes, respectively. The s-domain model of the UPQC series converter in the αβ coordinate system is completely decoupled. Furthermore, based on the UPQC single-phase equivalent circuit principle, the open-loop and closed-loop transfer functions of the system output compensation voltage to the voltage command signal are shown below (only the transfer function for the α axis is listed; the β axis is similar).

[0057] ;

[0058] ;

[0059] In the formula, It is the transfer function of the proportional-integral element on the α-axis, used to adjust the distance from the asymptote of the system transfer function to the imaginary axis in order to improve the stability margin of the system.

[0060] When acquiring the parallel-restoration compensation parameters, a classic PI controller is used as the core unit of the UPQC control section. The goal of the parallel compensation is to ensure that the current waveform drawn by the load from the grid is an ideal sine wave, while maintaining DC-side voltage stability. The feedback control of the parallel compensation section is as follows: Figure 6 As shown, is Indicates grid current; i 22 Indicates the compensation current output by the parallel-side converter; i L Indicates the three-phase load current; i 22 * (s) represents the parallel-side compensation command value; i 22 (s) represents the actual compensation value on the parallel side; i ce * (s) represents the difference between the compensation command signal and the actual compensation; d2(s) is the duty cycle of the PWM modulation signal; G d2 (s) is the transfer function of the parallel-side detection algorithm; G c2 (s) is the transfer function of the parallel-side controller, k PWM2 For the equivalent gain of the parallel-side converter, L 21 C2, L 22 For the parallel-side filter, H2(s) is the transfer function of the feedback network of the parallel-side closed-loop control, which is generally set to 1. Stable DC-side voltage is a prerequisite for UPQC operation. This paper uses a parallel-side converter of the UPQC to regulate the DC-side voltage. V DCref This is the reference value for the DC-side voltage of the UPQC, v DC G represents the actual value of the DC-side voltage of the UPQC. DC (s) is the transfer function of the DC-side voltage regulator.

[0061] ,make: ;

[0062] Then there is; .

[0063] In the formula: i Lf +， i Lf ¯ i Lf 0 For the fundamental positive-sequence, negative-sequence, and zero-sequence currents of the load; i q i is the load reactive current; Lh This represents the sum of all load harmonic currents.

[0064] The differential equations for the UPQC parallel converter are shown below, along with its αβ coordinate system state equations.

[0065] ;

[0066] With v 2α v 2β As the control variable, a PI controller is used, i 22α * i 22β *As the command value for current compensation, k PWM2 It is the equivalent gain of the parallel-side converter, from which v can be obtained. 2α v 2β The governing equations are as follows:

[0067] ;

[0068] The s-domain model of the UPQC parallel converter in the αβ coordinate system is also completely decoupled, allowing independent control of variables on either axis. Furthermore, as... Figure 7 The PI control diagram of the parallel converter shown can be used to derive the open-loop and closed-loop transfer functions of the system output compensation current to the command current signal, as follows (only the transfer function of the α axis is listed; the β axis is similar).

[0069] ;

[0070] .

[0071] If the compensation response time is less than the preset compensation response time, and the series compensation unit and the parallel compensation unit are activated, both the series compensation unit and the parallel compensation unit are triggered. Then, the coupling influence coefficient of the series compensation unit and the parallel compensation unit is calculated by fitting the coupling influence coefficient.

[0072] The fitting relationship of the coupling influence coefficient is obtained through experimental simulation. Specifically, this includes: building a simulation model of UPQC; in the simulation model, under typical operating conditions such as rated voltage and load power, allowing the system to operate to steady state, where the series and parallel compensation units are in basic operating mode but without significant dynamic adjustments; subsequently, small-step, ramp, or frequency-sweep excitations are applied to the "series control command" (such as voltage injection amplitude reference) and the "parallel control command" (such as reactive current or harmonic current reference); and the degree of coupling is evaluated by recording the output or state changes on the other side (parallel or series). During the simulation, the changes in the excitation input and the changes in the output on the other side are recorded, and the collected time-domain waveforms are preprocessed by denoising, filtering, or steady-state truncation. The cross-coupling ratio is obtained and calculated. Finally, an empirical function, namely the coupling influence coefficient, is fitted by multivariate regression or interpolation. This fitted relationship is used to reflect the voltage adjustment ratio coefficient or the current adjustment ratio coefficient under the premise that the current adjustment amount remains unchanged when performing voltage and current adjustment. This is used by the subsequent control strategy for scheduling during operation.

[0073] Using the coupling influence coefficient as the influencing variable and the series-recovery compensation parameter and parallel-recovery compensation parameter as the response variables, recovery compensation feedback is performed, and recovery compensation data is output. When outputting the recovery compensation parameters, the series-recovery compensation parameter is used as the benchmark, i.e., the series-recovery compensation parameter remains unchanged. The parallel-recovery compensation parameter is multiplied by the coupling influence coefficient to obtain the final output series-recovery compensation data and parallel-recovery compensation data, including both series-recovery compensation data and parallel-recovery compensation data. The acquisition method of the series-recovery compensation parameter and parallel-recovery compensation parameter is consistent with the acquisition method described above.

[0074] Furthermore, if the compensation response duration is greater than or equal to the preset compensation response duration, and the series compensation unit or the parallel compensation unit is activated, the compensation response duration exceeds the expected response time, and the response duration is relatively long. Therefore, it is necessary to compensate for the parameters that the system self-recovers within the compensation response duration. The compensated data based on the transient recovery performance index under the preset compensation response duration is calculated, and the remaining compensation data is determined based on the compensated data. When obtaining the compensated data, historical power grid self-recovery data is collected to determine the unit time recovery amount corresponding to each transient recovery performance index, obtaining the unit recovery amount, i.e., the voltage or current recovery amount per unit time. The compensated data is obtained by multiplying the unit recovery amount by the compensation response duration. The remaining compensation data = target - compensated data. For example, the preset duration of the system setting is 100 ms, and 120 ms has been run, indicating that the expected time has been exceeded. If the target is to restore the voltage from 0.7 pu to 0.95 pu, and the voltage has been restored to 0.9 pu within 120 ms, the compensated data ≈ 0.2 pu voltage recovery. The remaining compensation data ≈ 0.05 pu takes the remaining compensation data as the response target, the transient recovery performance index as the input quantification, and the series-recovery compensation parameter or parallel-recovery compensation parameter as the response variable to perform recovery compensation feedback, and outputs recovery compensation data, including series-recovery compensation data or parallel-recovery compensation data.

[0075] If the compensation response duration is greater than or equal to the preset compensation response duration, and the series compensation unit and the parallel compensation unit are activated, then compensation is performed for dual anomalies. The compensated data for voltage and current at the compensation response duration are obtained, and the corresponding remaining compensation data is obtained. Using the remaining compensation data as the response target, the transient recovery performance index as the input quantifier, and the coupling influence coefficient as the influencing variable, the series-recovery compensation parameters and the parallel-recovery compensation parameters are used as response variables for recovery compensation feedback, outputting recovery compensation data. When outputting recovery compensation parameters, the series-recovery compensation parameters are used as a benchmark (i.e., the series-recovery compensation parameters remain unchanged), and the coupling influence coefficient is used to multiply the parallel-recovery compensation parameters to obtain the final output series-recovery compensation data and parallel-recovery compensation data. Alternatively, the parallel-recovery compensation parameters are used as a benchmark (i.e., the parallel-recovery compensation parameters remain unchanged), and the coupling influence coefficient is used to multiply the series-recovery compensation parameters to obtain the final output series-recovery compensation data and parallel-recovery compensation data.

[0076] In the above text, refer to Figure 1 A power quality conditioning method according to an embodiment of the present invention has been described in detail. Next, reference will be made to... Figure 2 , Figure 3 A power quality regulator according to an embodiment of the present invention is described.

[0077] According to an embodiment of the present invention, a power quality regulator solves the technical problems of insufficient line compensation capacity, frequent faults, high investment costs, and low utilization rate in existing power quality regulation methods. Through multiple feedback mechanisms including transient recovery performance indicators, coupling influence coefficients, and residual compensation data, it achieves coordinated and efficient compensation between series and parallel compensation units, significantly improving the speed and accuracy of power quality recovery in power grids under multiple disturbance scenarios. The power quality regulator includes a series compensation regulation circuit and a parallel compensation regulation circuit, which are connected in series and parallel with the distribution network.

[0078] The power quality regulator provided in this embodiment of the invention can execute a power quality regulation method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0079] Although this application makes various references to certain modules in the system according to the embodiments of this application, any number of different modules can be used and run on user terminals and / or servers. The various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional unit are only for easy distinction between each other and are not used to limit the scope of protection of this invention.

[0080] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A power quality regulation method, characterized in that, The method includes: Define power quality monitoring items for the distribution network and acquire power quality monitoring data, wherein the power quality monitoring items include voltage monitoring items and current monitoring items; The instantaneous reactive power theory is used to decouple the power quality monitoring data to obtain anomaly identification data; The anomaly identification data is input into the transient recovery performance identification model, and transient recovery performance indicators are obtained based on the transient recovery performance identification model. If the transient recovery performance index is less than the preset transient recovery performance index, the series compensation unit and / or parallel compensation unit in the power quality adjustment module are activated according to the anomaly identification data. The power quality regulation module performs recovery compensation feedback based on the transient recovery performance index and outputs recovery compensation data, which is synchronous compensation data based on transient recovery. The series compensation unit and / or the parallel compensation unit are controlled to perform compensation adjustment based on the recovery compensation data.

2. The method as described in claim 1, characterized in that, Activating the series compensation unit and / or parallel compensation unit within the power quality conditioning module based on the anomaly identification data, the method includes: The abnormal identification data is analyzed. If it is a first type of abnormality, the series compensation unit is activated. If it is a second type of abnormality, the parallel compensation unit is activated. The first type of abnormality is voltage drop or flicker, and the second type of abnormality is harmonic current or reactive power fluctuation. If both Type I and Type II anomalies exist simultaneously, the series compensation unit and the parallel compensation unit are activated.

3. The method as described in claim 2, characterized in that, The method for outputting recovery compensation data also includes: If the series compensation unit is activated, the power quality regulation module performs series recovery compensation prediction based on the transient recovery performance index and outputs series-recovery compensation data. If the parallel compensation unit is activated, the power quality regulation module performs recovery compensation prediction based on the transient recovery performance index and outputs parallel-recovery compensation data. If the series compensation unit and the parallel compensation unit are activated simultaneously, the power quality adjustment module performs series and parallel recovery compensation prediction based on the transient recovery performance index and outputs series-recovery compensation data and parallel-recovery compensation data.

4. The method as described in claim 1, characterized in that, The method for obtaining transient recovery performance indicators based on the transient recovery performance identification model includes: Obtain the initial response state of the distribution network, wherein the initial response state is the steady-state or quasi-steady-state operating condition of the distribution network before the disturbance occurs; The transient recovery performance identification model combines the initial response state and anomaly identification data, calculates transient response simulation data using a transient response simulation expression, and outputs transient response simulation data. Based on the transient response simulation data, a transient recovery performance index is calculated. The transient response simulation expression includes: ； in, The response state of the distribution network at time t. This represents the system's natural response over time t when there is no external input. The impact of circuit parameters on changes in the response state of the distribution network. This represents the initial response state of the distribution network. This refers to the impact of external input signals on the response state of the distribution network. The input signal is the external disturbance caused by abnormal identification data. Let r be the integral effect of time t on the response state, representing the cumulative response of the system to the external input signal during the time interval from t=0 to t, where r is the integral variable used to iterate through the time interval from 0 to t.

5. The method as described in claim 1, characterized in that, The power quality regulation module performs recovery compensation feedback based on the transient recovery performance index and outputs recovery compensation data, the method of which includes: Record the compensation response time of the series compensation unit and the parallel compensation unit; If the compensation response time is less than the preset compensation response time, and the series compensation unit or the parallel compensation unit is activated, the series-recovery compensation parameter or the parallel-recovery compensation parameter is used as the response variable to perform recovery compensation feedback, and recovery compensation data is output, including series-recovery compensation data or parallel-recovery compensation data.

6. The method as described in claim 5, characterized in that, If the compensation response time is less than the preset compensation response time, and the series compensation unit and the parallel compensation unit are activated, calculate the coupling influence coefficient of the series compensation unit and the parallel compensation unit; Using the coupling influence coefficient as the influencing variable and the series-recovery compensation parameter and the parallel-recovery compensation parameter as the response variables, recovery compensation feedback is performed, and recovery compensation data is output, including series-recovery compensation data and parallel-recovery compensation data.

7. The method as described in claim 5, characterized in that, If the compensation response duration is greater than or equal to the preset compensation response duration, and the series compensation unit or the parallel compensation unit is activated, calculate the compensated data based on the transient recovery performance index under the preset compensation response duration; Based on the already compensated data, determine the remaining compensation data to obtain; Using the remaining compensation data as the response target, the transient recovery performance index as the quantitative input, and the series-recovery compensation parameter or the parallel-recovery compensation parameter as the response variable, recovery compensation feedback is performed, and recovery compensation data, including series-recovery compensation data or parallel-recovery compensation data, is output.

8. The method as described in claim 7, characterized in that, If the compensation response duration is greater than or equal to the preset compensation response duration, the series compensation unit and the parallel compensation unit are activated; Using the remaining compensation data as the response target, the transient recovery performance index as the quantitative input, the coupling influence coefficient as the influencing variable, and the series-recovery compensation parameters and parallel-recovery compensation parameters as response variables, recovery compensation feedback is performed, and recovery compensation data, including series-recovery compensation data and parallel-recovery compensation data, is output.

9. A power quality regulator, characterized in that, The power quality regulator is used to perform a power quality regulation method as described in any one of 1 to 8. The power quality regulator includes a series compensation regulation circuit and a parallel compensation regulation circuit, and the series compensation regulation circuit and the parallel compensation regulation circuit are connected in series and parallel with the distribution network.

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