Multi-feeder power quality flexible control system and quality control method

Abstract

The invention relates to the field of feeder quality control, in particular to a multi-feeder electric energy quality flexible control system and a multi-feeder electric energy quality flexible control method. The main feeder line section 1 is connected in series with the input side of the voltage transformation module 3 by accessing the isolation protection module 2; the low-voltage output side of the voltage transformation module 3 is connected in parallel with the alternating-current side of the current transformation module 4; the current transformation module 4 comprises a voltage regulation sub-module 41 and a power control sub-module 42 which are respectively used for providing a direct-current voltage reference and regulating an active power transmission quantity so as to realize the transfer of active power flow between the main feeder line sections 1. According to the invention, reactive power treatment, harmonic treatment and power flow treatment can be realized at the same time, an NPC three-level converter and common direct current bus architecture is adopted in hardware, and efficient parallel connection and energy interconnection of two sets of converters are realized. A multi-target collaborative algorithm is integrated, double-closed-loop decoupling control, neutral-point balance modulation and multi-mode seamless switching are realized under a dq coordinate system, and a flexible control system of master-slave control, optical fiber communication and modular power units is constructed.

Description

Technical Field

[0001] This invention relates to the field of feeder quality control, and in particular to a flexible power quality control system and method for multiple feeders. Background Technology

[0002] Current power quality management technologies have evolved into a coexistence of passive compensation and active control. Passive LC filters are still used in industrial applications due to their low cost, but they can only compensate for harmonics of fixed frequencies, are prone to system resonance, and cannot adapt to dynamic load changes. Static var compensators (SVCs) achieve a certain degree of dynamic reactive power regulation by controlling reactors with thyristors, but their response speed is slow and they are unable to cope with impulsive loads. Static var generators (SVGs) have a faster response, but they typically only have a single reactive power compensation function. Active power filters (APFs) can effectively suppress harmonics from the 2nd to the 50th orders, but they only address harmonic control and cannot simultaneously address reactive power and power flow regulation.

[0003] Current 10kV integrated governance devices have achieved multi-functional integration in some products, but overall there are still many prominent shortcomings. They are limited in function, have low integration and insufficient response speed and accuracy. They are limited to single feeder governance, lack flexible active / reactive power flow transfer mechanisms between feeders, and have difficulty solving the problems of uneven power distribution and fault isolation in multi-feeder networks. The equipment parameters are fixed, making it difficult to flexibly configure control targets and operating modes according to different application scenarios.

[0004] Therefore, there is a need for a flexible power quality control system and quality control method for multi-feeders that has strong cross-feeder collaborative governance capabilities, significantly improved response speed and compensation accuracy, strong scenario adaptability, convenient operation and maintenance, and solves the pain points of existing technologies such as single function, slow response and insufficient collaboration, to meet the needs of the current environment. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract and title of the invention. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0006] Given that the existing technologies mentioned above are limited in function, have low integration, and lack sufficient response speed and accuracy, are limited to single-feeder management, lack a flexible active / reactive power flow transfer mechanism between feeders, are difficult to solve the problems of uneven power distribution and fault isolation in multi-feeder networks, and have fixed equipment parameters, it is difficult to adapt to different application scenarios.

[0007] Therefore, the technical problem to be solved by this invention is to design a multi-feeder power quality flexible control system and quality control method with strong cross-feeder collaborative governance capability, significantly improved response speed and compensation accuracy, strong scenario adaptability, and convenient operation and maintenance, which solves the pain points of existing technologies such as single function, slow response and insufficient collaboration, and meets the needs of the current environment.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a multi-feeder power quality flexible control system, comprising, Main feeder segment, isolation protection module, transformer module and converter module; The main feeder section is connected in series with the input side of the transformer module by connecting to the isolation protection module; The low-voltage output side of the transformer module is connected in parallel to the AC side of the converter module; The converter module includes a voltage regulation submodule and a power control submodule, which respectively provide a DC voltage reference and regulate the active power transmission, enabling the transfer of active power flow between the main feeder segments.

[0009] As an improvement of the present invention, The converter module adopts an NPC three-level topology, which is composed of multiple power modules cascaded and connected in parallel; Each phase arm of the converter module is equipped with an IGBT power switch group. The IGBT power switch group of the upper arm is connected to the positive terminal of the DC bus, and the IGBT power switch group of the lower arm is connected to the negative terminal of the DC bus. The clamping diodes inside the converter module are connected in reverse to the neutral point N and the middle node O of the bridge arm, respectively. A voltage divider capacitor bank is electrically connected to the DC bus.

[0010] As an improvement of the present invention, The gate of the IGBT power switch group is connected to the main control unit, which provides central signal regulation and has an internal PWM board to receive modulation signals. A group of voltage divider capacitors is connected in parallel to the DC side of the power module to provide signal filtering.

[0011] As an improvement of the present invention, The CPU inside the main control unit is connected to the PWM board, analog board, and digital board via an internal bus; The analog board acquires the output signal of the converter module and transmits it to the CPU through the AD conversion unit; The digital board processes the digital signals sent by the CPU and feeds them back into the protection system.

[0012] As an improvement of the present invention, The monitoring system connects to the CPU via an Ethernet interface and supports real-time curve display, while the display system connects to the monitoring system via a serial interface. The protection system collects feeder signal data through an analog board, performs fault determination, and generates protection signals that are input to the CPU. The protection system connects to the isolation protection module, triggering a mechanical isolation action.

[0013] A quality control method includes a multi-feeder power quality flexible control system, and, Real-time monitoring of load current and voltage signals, and separation of instantaneous active and reactive components through Park transformation; Based on the real-time status of the power grid, control modes are selected, including power factor control mode, harmonic compensation mode, and power flow transfer mode. In power factor control mode, the target power factor is set as the benchmark, the reactive current command is calculated, and the reactive power is dynamically compensated through the converter. In harmonic compensation mode, the dq components of the 2nd to 26th harmonics are separated to generate a reverse compensation current command to achieve cancellation; In the power transfer mode, a master-slave control strategy is adopted to achieve power transfer between feeders by sharing a DC bus.

[0014] As an improvement of the present invention, In the Park transform separation process The Park transform is based on the dq coordinate system and converts the three-phase signal into active components on the d-axis and reactive components on the q-axis for subsequent compensation command generation. Current transformers and voltage sensors are used to collect signals from the converter module. After preprocessing on the analog board, the signals are transmitted to the CPU for digital filtering and instantaneous reactive power calculation.

[0015] As an improvement of the present invention, In the power factor control mode process, Set a power factor threshold; when the actual power factor is lower than the threshold, enter the power factor control mode. The DC voltage deviation is converted into active current by a voltage outer loop PI controller, and the current inner loop performs PI regulation on the dq axis. By introducing cross-coupling terms to achieve decoupling, a three-phase modulation signal is ultimately generated to drive the converter module to adjust reactive power, thus avoiding load fluctuations that could cause the power factor to shift on the grid side.

[0016] As an improvement of the present invention, In the harmonic compensation mode process, Set a harmonic content threshold; when the actual harmonic content exceeds the threshold, enter harmonic compensation mode. The load current is analyzed in real time, and the final output is a current that is equal in magnitude and opposite in direction to the load harmonics, thereby achieving wideband harmonic suppression. By combining dq coordinate transformation, Fourier analysis is performed on the load current to extract harmonic components, so that the current flowing into the power grid is only the pure fundamental component.

[0017] As an improvement of the present invention, In the trend resale model process, Set a feeder power balance threshold. When the actual feeder power threshold is unbalanced, enter the power flow transfer mode. The voltage regulation submodule operates in constant DC voltage mode, maintaining a 750V reference. The power control submodule operates in constant active power mode, receiving active current commands to adjust the transmission amount and achieve feeder power balance.

[0018] The beneficial effects of this invention are as follows: a single device can simultaneously achieve reactive power, harmonic, and power flow management; the hardware adopts an NPC three-level converter + common DC bus architecture, realizing efficient parallel connection and energy interconnection of two converters; it integrates a multi-objective cooperative algorithm to achieve dual closed-loop decoupling control, midpoint balanced modulation, and seamless multi-mode switching in the dq coordinate system; it constructs a flexible control system of master-slave control + fiber optic communication + modular power units, successfully integrating three major functions: dynamic power factor compensation, precise suppression of wideband harmonics, and rapid power flow transfer between feeders. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a hardware architecture diagram of the multi-feeder power quality flexible control system in this invention.

[0020] Figure 2 This is a three-level topology diagram of the multi-feeder power quality flexible control system in this invention.

[0021] Figure 3 This is a block diagram of the constant DC voltage control of the voltage regulation submodule of the multi-feeder power quality flexible control system in this invention.

[0022] Figure 4 This is a block diagram of the constant power current control of the power control submodule in the current quality control method of the present invention.

[0023] Figure 5 This is a schematic diagram of the harmonic compensation control principle of the current quality control method in this invention.

[0024] Figure 6This is a framework connection diagram of the multi-feeder power quality flexible control system in this invention.

[0025] Figure 7 This is a block diagram of reactive current control in the current quality control method of the present invention.

[0026] Figure 8 This is a block diagram of the constant power factor control module in the current quality control method of the present invention.

[0027] Figure 9 This is a block diagram of the reactive current detection module in the current quality control method of the present invention. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Example 1 Reference Figures 1-2 This embodiment provides a flexible power quality control system for multiple feeders.

[0030] The multi-feeder power quality flexible control system includes a main feeder section 1, an isolation protection module 2, a transformer module 3, and a converter module 4. The system as a whole achieves power quality management for the multi-feeder 35kV distribution network through series and parallel connections between modules, with a focus on supporting active power flow transfer between feeders.

[0031] Main feeder section 1 consists of at least two 35kV feeder sections. Its core function is to connect various loads in the distribution network and serve as the main channel for system energy transmission. The principle of main feeder section 1 is based on the standard power grid feeder design. Each feeder section connects to the load end through parallel or segmented bus structures, such as sections I and II of the 35kV bus, supporting multi-source power supply and power distribution.

[0032] The main feeder section 1 serves to provide a grid-side access point and achieve series connection with the isolation protection module 2, ensuring that energy flows from the grid to the system. At the same time, it monitors the power imbalance between feeders. It is suitable for scenarios with a high proportion of renewable energy access in urban or industrial distribution networks, as well as substations with multiple feeders intertwined. When power flow imbalance or local overload occurs, the main feeder section 1 can transfer power by cooperating with other modules.

[0033] The isolation protection module 2 includes vacuum circuit breakers QF1 and QF2 and electric disconnect switches QS1-QS4. Its main function is to connect to the input side of the transformer module 3 through the main feeder section 1, and to provide electrical isolation and fault protection.

[0034] The principle of isolation protection module 2 is based on the working mechanism of high-voltage switchgear. Vacuum circuit breakers QF1 and QF2 can achieve rapid tripping by utilizing vacuum arc extinguishing, while electric disconnect switches QS1-QS4 can provide mechanical breaks to ensure the safety of maintenance procedures. In the event of a fault, isolation protection module 2 can automatically isolate the main feeder segment 1 to prevent the fault from spreading, and can also maintain circuit continuity during normal operation.

[0035] If a feeder is short-circuited, the isolation protection module 2 can disconnect the faulty section and work with the converter module 4 to transfer the current to another feeder.

[0036] Transformer module 3 consists of three-phase step-up transformers T1 and T2. Its core function is to transform the voltage, converting the 35kV high-voltage input to a 380V low-voltage output, which is then connected in parallel to the AC side of converter module 4. Based on electromagnetic induction, the transformer core and winding design of transformer module 3 supports efficient energy transmission, matching the capacity requirements of converter module 4. It also isolates the high-voltage grid from the low-voltage converter side, providing electrical insulation and impedance matching to ensure system compatibility.

[0037] When the access of new energy sources causes voltage fluctuations, transformer module 3 can stabilize the low-voltage side input to supply the converter module 4, and it is also easy to integrate with isolation protection module 2 in series to reduce system losses.

[0038] The converter module 4 includes a voltage regulation submodule 41 and a power control submodule 42. It can connect to the output of the transformer module 3 in parallel on the low-voltage side to achieve AC-DC-AC conversion and support active power flow transfer between feeders. The converter module 4 is based on the NPC three-level topology. Each phase bridge arm consists of four IGBTs and two clamping diodes, and the DC side is interconnected through a common bus.

[0039] The voltage regulation submodule 41 operates in constant DC voltage mode and can maintain a 750V reference through the PI controller to ensure the stability of energy exchange; the power control submodule 42 operates in constant active power mode, receives main control commands to adjust the active power transmission, and realizes the active power flow transfer between the main feeder segments 1 through the shared DC bus.

[0040] When a feeder is overloaded, the power control submodule 42 actively absorbs the excess power and transfers it to another feeder, which can optimize the active power distribution of the distribution network and improve the continuity of power supply.

[0041] In this scheme, the main feeder segment 1 can collect grid load signals and connect them in series with the transformer module 3 through the isolation protection module 2 to achieve high-voltage isolation and voltage transformation. The low-voltage output of the transformer module 3 is connected in parallel to the converter module 4. The voltage regulation submodule 41 of the converter module 4 can maintain the DC bus reference, and the power control submodule 42 adjusts the active power transfer according to the monitored feeder imbalance. In the event of a fault, the isolation protection module 2 responds quickly to ensure safety, and finally realizes power flow transfer and optimizes grid performance.

[0042] Example 2 Reference Figures 1-5 This embodiment is based on the previous embodiment, and differs from the previous embodiment in that... The converter module 4 adopts an NPC three-level topology, which is composed of multiple power modules 43 cascaded and connected in parallel. Its core function is to realize AC-DC-AC conversion and support three-level output. The voltage regulation submodule 41 and the power control submodule 42 are interconnected through the DC bus 432.

[0043] Converter module 4 is based on a neutral point clamping mechanism. Each phase arm of the three-level topology within converter module 4 is equipped with an IGBT power switch group 431. The IGBT power switch group 431 of the upper arm is connected to the positive terminal of the DC bus 432, and the IGBT power switch group 431 of the lower arm is connected to the negative terminal of the DC bus. Clamping diodes 433 are connected in reverse to the neutral point N and the middle node O of the bridge arm, respectively, ensuring a stable current path during zero-level output. A voltage divider capacitor group 4321 is electrically connected to the DC bus 432, which can equally divide the voltage into +Vdc / 2 and -Vdc / 2. This reduces the voltage stress on the switching devices to Vdc / 2, reduces harmonic content, and supports power transfer between feeders.

[0044] The main control unit 5 can provide central signal control and can be connected to the PWM board 51, analog board 53 and digital board 54 through the internal bus to realize signal acquisition, processing and modulation output.

[0045] The gate of the IGBT power switch group 431 is connected to the main control unit 5. The PWM board 51 receives the modulation signal and generates the VSVPWM waveform. The analog board 53 collects the output signal of the converter module 4 and transmits it to the CPU 52 through the AD conversion unit 55. The digital board 54 processes the digital signal sent by the CPU 52 and feeds it back to the protection system 6.

[0046] The voltage divider capacitor bank 4321 is connected in parallel to the DC side of the power module 43 to provide signal filtering. It can execute multi-objective cooperative algorithms, supporting dual closed-loop control and midpoint balancing in the dq coordinate system. When there are sudden load changes, the main control unit 5 can adjust the PWM signal to optimize the output, thereby improving control accuracy and system stability.

[0047] Monitoring system 7 can connect to CPU52 via an Ethernet interface, supporting real-time curve display, event query, and fault recording, and providing a human-machine interface. Display system 8 connects to monitoring system 7 via a serial interface to achieve data visualization. The combined function of the two systems is to monitor system status, display voltage and current parameters as curves, and query and record start and fault times.

[0048] The protection system 8 can acquire feeder signal data through the analog board 53, generate a protection signal after fault determination, input it to the CPU 52, and connect it to the isolation protection module 2 to trigger mechanical isolation action. The entire process is based on hierarchical protection logic, including DC overvoltage / undervoltage, overcurrent and overtemperature detection, and finally processed and fed back by the digital board 54. When an abnormality occurs, the protection system 8 can connect to the isolation protection module 2 to trigger tripping.

[0049] In the entire system, the NPC topology of the converter module 4 achieves three-level conversion through the IGBT power switch group 431 and clamping diode 433. Then, the DC bus 432 and the voltage divider capacitor group 4321 provide a stable reference. The main control unit 5 collects signals and processes them through the analog board 53 and the AD conversion unit 55. The CPU 52 generates a modulation signal to drive the IGBT. The monitoring system 7 displays data in real time, and the protection system 8 monitors abnormalities and triggers the isolation protection module to participate in the work, so that the whole process ensures safe and efficient power flow conversion and achieves power quality optimization.

[0050] Example 3 Reference Figures 1-9 This embodiment is based on the previous embodiment, and differs from the previous embodiment in that... The quality control method is based on a multi-feeder power quality flexible control system to achieve dynamic management of power quality in the distribution network.

[0051] The quality control methods include real-time monitoring of load current and voltage signals, separating instantaneous active and reactive components through Park transformation; selecting control modes based on the real-time grid status, including power factor control mode, harmonic compensation mode, and power flow transfer mode; in power factor control mode, a target power factor is set as a benchmark, reactive current commands are calculated, and reactive power is dynamically compensated through converters; in harmonic compensation mode, the 2nd to 26th harmonic dq components are separated, and reverse compensation current commands are generated to achieve cancellation; in power flow transfer mode, a master-slave control strategy is adopted to achieve power transfer between feeders through a shared DC bus.

[0052] The entire approach can improve power grid stability by integrating the above-mentioned modes through multi-objective collaboration.

[0053] The function, principle, role, environment, application scenarios and beneficial effects of real-time monitoring of load current and voltage signals and separating instantaneous active and reactive components through Park transformation are explained. The function of this set of steps is to collect and decompose load signals to provide basic data for subsequent compensation.

[0054] The Park transformation, based on the dq coordinate system, converts the three-phase signals into active components on the d-axis and reactive components on the q-axis for subsequent compensation command generation. The signals from the converter module 4 are acquired using current transformers and voltage sensors, and after preprocessing by the analog board 53, they are transmitted to the CPU 52 for digital filtering and instantaneous reactive power calculation.

[0055] This process is designed to extract instantaneous power components in real time, enabling rapid response to load fluctuations.

[0056] When selecting the control mode based on the real-time status of the power grid, it is necessary to automatically or manually select the power factor control mode, harmonic compensation mode, and power flow transfer mode according to the monitoring data. Selecting the control mode can optimize resource allocation and avoid mode conflicts. In a multi-feeder network, the power factor mode is given priority when the power factor is low, and the harmonic mode is switched when the harmonics exceed the standard.

[0057] In the operation process of power factor control mode, a power factor threshold is set. When the actual power factor is lower than the power factor threshold, the power factor control mode is entered.

[0058] The DC voltage deviation is converted into active current by a voltage outer-loop PI controller, while the current inner loop performs PI regulation on the dq axis. A cross-coupling term is then introduced to achieve decoupling, ultimately generating a three-phase modulated signal to drive converter module 4 to adjust reactive power, preventing load fluctuations from causing power factor deviations on the grid side. The power factor control mode aims to stabilize grid reactive power, optimizing the power factor to 0.9-1.0. The entire operating environment is suitable for converter module 4 operation, reducing grid losses, meeting grid compliance requirements, and improving response capabilities through closed-loop regulation.

[0059] The harmonic compensation mode function is to separate and cancel harmonic components, thereby purifying the current.

[0060] First, a harmonic content threshold is set. When the actual harmonic content exceeds the threshold, the harmonic compensation mode is entered. The load current is analyzed in real time, and finally the current with the same magnitude and opposite direction as the load harmonic is output, so as to achieve wideband harmonic suppression. In the process, the dq coordinate transformation is combined to perform Fourier analysis on the load current to extract the harmonic components, so that the current flowing into the grid is only the pure fundamental component.

[0061] The harmonic compensation mode is designed to eliminate harmonics from the 2nd to the 26th order. It is suitable for areas with dense industrial loads. Once harmonic pollution is generated when the frequency converter is working, the harmonic compensation mode will reduce equipment aging and line losses by offsetting the harmonics.

[0062] The power transfer mode function uses a master-slave control strategy to achieve power transfer between feeders.

[0063] First, a feeder power balance threshold needs to be set. When the actual feeder power threshold is unbalanced, the power flow transfer mode will be entered. The voltage regulation submodule 41 operates in constant DC voltage mode to maintain a 750V reference. The power control submodule 42 operates in constant active power mode to receive active current commands to adjust the transmission amount, achieve feeder power balance, and optimize active power distribution.

[0064] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A flexible power quality control system for multi-feeders, characterized in that: include, Main feeder segment (1), isolation protection module (2), transformer module (3) and converter module (4); The main feeder segment (1) is connected in series with the input side of the transformer module (3) by connecting to the isolation protection module (2); The low-voltage output side of the transformer module (3) is connected in parallel to the AC side of the converter module (4); The converter module (4) includes a voltage regulation submodule (41) and a power control submodule (42), which respectively provide a DC voltage reference and regulate the active power transmission, so as to realize the transfer of active power flow between the main feeder segments (1).

2. The multi-feeder power quality flexible control system according to claim 1, characterized in that: The converter module (4) adopts an NPC three-level topology and is composed of multiple power modules (43) cascaded and connected in parallel. Each phase arm of the converter module (4) is equipped with an IGBT power switch group (431). The IGBT power switch group (431) of the upper arm is connected to the positive terminal of the DC bus (432), and the IGBT power switch group (431) of the lower arm is connected to the negative terminal of the DC bus. The clamping diodes (433) inside the converter module (4) are connected in reverse to the neutral point N and the middle node O of the bridge arm, respectively; A voltage divider capacitor bank (4321) is electrically connected to the DC bus (432).

3. The multi-feeder power quality flexible control system according to claim 2, characterized in that: The gate of the IGBT power switch group (431) is connected to the main control unit (5). The main control unit (5) provides central signal regulation and has an internal PWM board (51) to receive modulation signals. The voltage divider capacitor bank (4321) is connected in parallel to the DC side of the power module (43) to provide signal filtering.

4. The multi-feeder power quality flexible control system according to claim 3, characterized in that: The CPU (52) inside the main control unit (5) is connected to the PWM board (51), analog board (53) and digital board (54) through the internal bus. The analog board (53) collects the output signal of the converter module (4) and transmits it to the CPU (52) through the AD conversion unit (55); The digital board (54) processes the digital signals transmitted by the CPU (52) and feeds them back into the protection system (6).

5. The multi-feeder power quality flexible control system according to claim 4, characterized in that: The monitoring system (7) is connected to the CPU (52) via an Ethernet interface and supports real-time curve display. The display system (8) is connected to the monitoring system (7) via a serial interface. The protection system (8) collects feeder signal data through the analog board (53), performs fault judgment, and generates a protection signal to input to the CPU (52). The protection system (8) connects to the isolation protection module (2) and triggers the mechanical isolation action.

6. A quality control method, characterized in that: Including the multi-feeder power quality flexible control system as described in claim 5, and, Real-time monitoring of load current and voltage signals, and separation of instantaneous active and reactive components through Park transformation; Based on the real-time status of the power grid, control modes are selected, including power factor control mode, harmonic compensation mode, and power flow transfer mode. In power factor control mode, the target power factor is set as the benchmark, the reactive current command is calculated, and the reactive power is dynamically compensated through the converter. In harmonic compensation mode, the dq components of the 2nd to 26th harmonics are separated to generate a reverse compensation current command to achieve cancellation; In the power transfer mode, a master-slave control strategy is adopted to achieve power transfer between feeders by sharing a DC bus.

7. The quality control method according to claim 6, characterized in that: In the Park transform separation process The Park transform is based on the dq coordinate system and converts the three-phase signal into active components on the d-axis and reactive components on the q-axis for subsequent compensation command generation. The current transformer and voltage sensor are used to collect the signal of the converter module (4). After preprocessing by the analog board (53), the signal is transmitted to the CPU (52) for digital filtering and instantaneous reactive power calculation.

8. The quality control method according to claim 7, characterized in that: In the power factor control mode process, Set a power factor threshold; when the actual power factor is lower than the threshold, enter the power factor control mode. The DC voltage deviation is converted into active current by a voltage outer loop PI controller, and the current inner loop performs PI regulation on the dq axis. Decoupling is achieved by introducing cross-coupling terms, and finally a three-phase modulation signal is generated to drive the converter module (4) to adjust the reactive power and avoid load fluctuations causing the power factor of the grid side to deviate.

9. The quality control method according to claim 8, characterized in that: In the harmonic compensation mode process, Set a harmonic content threshold; when the actual harmonic content exceeds the threshold, enter harmonic compensation mode. The load current is analyzed in real time, and the final output is a current that is equal in magnitude and opposite in direction to the load harmonics, thereby achieving wideband harmonic suppression. By combining dq coordinate transformation, Fourier analysis is performed on the load current to extract harmonic components, so that the current flowing into the power grid is only the pure fundamental component.

10. The quality control method according to claim 9, characterized in that: In the trend resale model process, Set a feeder power balance threshold. When the actual feeder power threshold is unbalanced, enter the power flow transfer mode. The voltage regulation submodule (41) operates in constant DC voltage mode, maintaining a 750V reference. The power control submodule (42) operates in constant active power mode, receives active current commands, adjusts the transmission amount, and achieves power balance of the feeder.

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