Power grid compensation device, transformer substation system and power grid compensation control method

Abstract

The invention relates to a power grid compensation device, a substation system and a power grid compensation control method. The power grid compensation device comprises a control unit, a twelve-switch power regulator, a first LC filter and a second LC filter, the control unit is connected with the control end of the twelve-switch power regulator; the first output end of the twelve-switch power regulator is connected with a target load through a first LC filter, and the second output end is connected with a target power supply through a second LC filter. The control unit performs pulse width modulation on the output of the first output end of the twelve-switch power regulator according to a first control strategy; and the control unit performs pulse width modulation on the output of the second output end of the twelve-switch power regulator according to a second control strategy. According to the invention, the voltage and current of the target power supply and the target load are respectively compensated and controlled through the two independent output units, so that the reliability of a power grid system is improved while the control logic is effectively simplified.

Description

Technical Field

[0001] The present application relates to the technical field of power grid compensation control, and in particular to a power grid compensation device, a substation system and a power grid compensation control method. Background Art

[0002] Most existing power conditioners adopt a back-to-back full-bridge converter structure, which requires a large number of semiconductor switches, usually 16, which makes the power conditioner costly and complex to control.

[0003] During the construction of a substation, the construction power supply is usually taken from the station transformer. Since most of the on-site construction tools use single-phase power, when the load is large, it is easy to cause the three-phase unbalanced load and excessive zero-sequence current of the station transformer. This situation may cause the switch to trip, or even trigger the zero-sequence protection of the station transformer, causing the 0.4kV busbar to lose pressure, posing a threat to the safe operation of the power station. Summary of the invention

[0004] Based on this, it is necessary to provide a power grid compensation device, a substation system and a power grid compensation control method that can reduce costs, simplify control logic, and effectively improve power grid reliability during substation construction to address the above technical problems.

[0005] In a first aspect, the present application provides a power grid compensation device, comprising: a control unit, a twelve-switch power regulator, a first LC filter and a second LC filter;

[0006] The control unit is connected to the control end of the twelve-switch power regulator;

[0007] The first output terminal of the twelve-switch power regulator is connected to a target load through the first LC filter;

[0008] The second output end of the twelve-switch power regulator is connected to the target power supply through the second LC filter;

[0009] The control unit performs pulse width modulation on the output of the first output terminal of the twelve-switch power regulator according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on one side of a target load;

[0010] The control unit performs pulse width modulation on the output of the second output terminal of the twelve-switch power regulator according to a second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on one side of a target power supply.

[0011] In one embodiment, the twelve-switch power regulator includes a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a sixth switch tube, a seventh switch tube, an eighth switch tube, a ninth switch tube, a tenth switch tube, an eleventh switch tube, a twelfth switch tube and a target capacitor;

[0012] Wherein, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube constitute a first three-phase four-wire output unit;

[0013] The fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube form a second three-phase four-wire output unit;

[0014] The first three-phase four-wire output unit is also connected to the second three-phase four-wire output unit via the target capacitor;

[0015] The three-phase output terminal and the zero-phase output terminal of the first three-phase four-wire output unit are connected to the target load;

[0016] The three-phase output terminal and the zero-phase output terminal of the second three-phase or four-phase output unit are connected to the target power supply.

[0017] In one embodiment, the control unit is connected to control electrodes of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube respectively;

[0018] The input electrodes of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all connected to one end of the target capacitor;

[0019] The output electrodes of the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube are all connected to the other end of the target capacitor;

[0020] The output electrode of the first switch tube is connected to the input electrode of the fifth switch, and the output electrode of the fifth switch tube is connected to the input electrode of the ninth switch tube; the output electrode of the second switch tube is connected to the input electrode of the sixth switch, and the output electrode of the fifth switch tube is connected to the input electrode of the tenth switch tube; the output electrode of the third switch tube is connected to the input electrode of the seventh switch, and the output electrode of the fifth switch tube is connected to the input electrode of the eleventh switch tube; the output electrode of the fourth switch tube is connected to the input electrode of the eighth switch tube, and the output electrode of the fifth switch tube is connected to the input electrode of the twelfth switch tube.

[0021] In one of the embodiments, the first LC filter includes a plurality of sets of resistors and capacitors connected in series;

[0022] The second LC filter includes a plurality of groups of resistors and capacitors connected in parallel.

[0023] In one of the embodiments, the control unit obtains a load current and a reference current;

[0024] Performing harmonic detection on the reference current to obtain an oscillating part of the load harmonic;

[0025] Perform proportional-integral control on the DC bus voltage to obtain harmonic compensation components;

[0026] Performing harmonic compensation on the oscillating part according to the harmonic compensation component;

[0027] Calculating a first error signal according to the compensated reference current and the load current;

[0028] Processing the first error signal according to a proportional resonant controller to obtain a first control action;

[0029] The first three-phase four-wire output unit is controlled to perform pulse width modulation according to the first control action.

[0030] In one of the embodiments, the control unit obtains a load voltage and a reference voltage;

[0031] After performing low-pass filtering on the reference voltage using a low-pass filter, a second error signal is calculated according to the reference voltage and the load voltage;

[0032] Processing the second error signal according to a proportional resonant controller to obtain a second control action;

[0033] The second three-phase four-wire output unit is controlled to perform pulse width modulation according to the second control action.

[0034] In a second aspect, the present application further provides a substation system, including the power grid compensation device, a target power source and a target load as described in the first aspect;

[0035] The first output end of the twelve-switch power regulator of the power grid compensation device is connected to the target load through a first LC filter;

[0036] The second output end of the twelve-switch power regulator of the power grid compensation device is connected to the target power supply through a second LC filter.

[0037] In a third aspect, the present application further provides a power grid compensation control method, which is applied to the substation system described in the second aspect, comprising:

[0038] Pulse width modulation is performed on the output of the first output terminal of the twelve-switch power regulator of the grid compensation device according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on one side of the target load;

[0039] The output of the second output terminal of the twelve-switch power regulator of the grid compensation device is pulse-width modulated according to a second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on one side of the target power supply.

[0040] In one embodiment, the pulse width modulation of the output of the first output terminal of the twelve switching power regulator of the power grid compensation device according to the first control strategy includes:

[0041] Get load current and reference current;

[0042] Performing harmonic detection on the reference current to obtain an oscillating part of the load harmonic;

[0043] Perform proportional-integral control on the DC bus voltage to obtain harmonic compensation components;

[0044] Performing harmonic compensation on the oscillating part according to the harmonic compensation component;

[0045] Calculating a first error signal according to the compensated reference current and the load current;

[0046] Processing the first error signal according to a proportional resonant controller to obtain a first control action;

[0047] According to the first control action, pulse width modulation is performed on the output of the first output terminal of the twelve switching power regulators of the power grid compensation device.

[0048] In one embodiment, the pulse width modulation of the output of the second output terminal of the twelve switching power regulator of the power grid compensation device according to the second control strategy includes:

[0049] Get the load voltage and reference voltage;

[0050] After performing low-pass filtering on the reference voltage using a low-pass filter, a second error signal is calculated according to the reference voltage and the load voltage;

[0051] Processing the second error signal according to a proportional resonant controller to obtain a second control action;

[0052] According to the second control action, pulse width modulation is performed on the output of the second output terminal of the twelve switching power regulator of the power grid compensation device.

[0053] In summary, the present application proposes a power grid compensation device, a substation system and a power grid compensation control method, including: a control unit, a twelve-switch power regulator, a first LC filter and a second LC filter; the control unit is connected to the control end of the twelve-switch power regulator; the first output end of the twelve-switch power regulator is connected to the target load through the first LC filter, and the second output end is connected to the target power supply through the second LC filter; the control unit performs pulse width modulation on the output of the first output end of the twelve-switch power regulator according to the first control strategy; the control unit performs pulse width modulation on the output of the second output end of the twelve-switch power regulator according to the second control strategy. The present application uses two independent output units to respectively perform compensation control on the voltage and current of the target power supply and the target load, which effectively simplifies the control logic and improves the reliability of the power grid system. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 A block diagram of a power grid compensation device in one embodiment;

[0055] Figure 2 is a circuit diagram of a twelve-switch power regulator in one embodiment;

[0056] Figure 3 A schematic diagram of an application circuit of a power grid compensation device in one embodiment;

[0057] Figure 4 is a schematic diagram of a first control strategy in one embodiment;

[0058] Figure 5 is a schematic diagram of a second control strategy in one embodiment;

[0059] Figure 6 A schematic diagram of a method flow of a power grid compensation control method in one embodiment;

[0060] Figure 7 A schematic flow chart of the steps of executing a first control strategy in a power grid compensation control method according to an embodiment;

[0061] Figure 8 The figure is a flowchart of the steps of executing the second control strategy in a power grid compensation control method in one embodiment.

[0062] Summary of reference numerals:

[0063] Control unit-110; twelve-switch power regulator-120; first LC filter-130; second LC filter-140; target load-200; target power supply-300. DETAILED DESCRIPTION

[0064] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0065] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0066] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0067] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0068] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0069] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0070] In the related art, three-phase balanced compensation technology often relies on additional hardware devices, such as additional filters or compensators, which increase the size and cost of the power grid or distribution station system.

[0071] Most power conditioners adopt a back-to-back full-bridge converter structure, which requires more semiconductor switches, such as 16 semiconductor switches, which greatly increases the cost and complexity of the grid compensation device.

[0072] Power regulators in related technologies usually use complex control strategies, such as pulse width modulation (PWM) technology, which requires precise timing control and high computing power, which inevitably increases the reliance on high-performance processors. In addition, due to the large number of semiconductor switches, the number of fault points increases.

[0073] The power conditioner in the related technology has low compensation efficiency for the voltage and current of the power grid in specific application scenarios such as substation construction. During the construction of the substation, since most of the on-site construction tools use unidirectional power supply, when the load is large, it is easy to cause unbalanced load and excessive zero-sequence current on the three-phase occupied transformer. This situation may cause the switch to trip or even trigger the zero-sequence protection of the substation transformer, causing the busbar to lose pressure, which has a great impact on the safe operation of the power station. In addition, the operation of the transformer in an unbalanced state may cause problems such as equipment overheating, voltage instability, and reduced motor efficiency. The existing power supply box and distribution panel are only equipped with protection circuits for branch leakage and overcurrent. These measures cannot effectively protect the operation risks of the transformer under unbalanced conditions.

[0074] This embodiment provides a power grid compensation device for addressing the three-phase imbalance problem in the substation construction power consumption scenario. By compensating for the unbalanced current of the single-phase load, the three-phase balance of the maintenance power box is achieved, the neutral line current and system losses are reduced, and the switch over-tripping problem caused by unidirectional load overcurrent is avoided, so as to improve the power supply safety and reliability of the substation construction devices.

[0075] like Figure 1 As shown, a power grid compensation device is provided, including: a control unit 110, a twelve-switch power regulator 120, a first LC filter 130, and a second LC filter 140. The control unit 110 is connected to the control end of the twelve-switch power regulator 120. The first output end of the twelve-switch power regulator 120 is connected to the target load 200 through the first LC filter 130. The second output end of the twelve-switch power regulator 120 is connected to the target power supply 300 through the second LC filter 140.

[0076] In this embodiment, the twelve-switch power regulator 120 includes twelve semiconductor switches, which effectively reduces the number of semiconductor switches compared to the power regulator in the related art, and reduces the cost and control complexity of the grid compensation device. Figure 2 As shown, the twelve-switch power regulator 120 includes three parts, namely, an upper output unit (Top Unit), an intermediate switch (Intermediate Switches) and a lower output unit (Bottom Unit), wherein: The four semiconductor switches of the upper output unit are, from left to right, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube. The four semiconductor switches for mid-way switches are, from left to right, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube. These are four semiconductor switches of the lower output unit, which from left to right are the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube. , , , is the output of the top unit output, , , , is the output of the bottom unit.

[0077] In this embodiment, the input electrodes of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all connected to one end of the target capacitor. The output electrodes of the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube are all connected to the other end of the target capacitor. The output electrode of the first switch tube is connected to the input electrode of the fifth switch, and the output electrode of the fifth switch tube is connected to the input electrode of the ninth switch tube. The output electrode of the second switch tube is connected to the input electrode of the sixth switch, and the output electrode of the fifth switch tube is connected to the input electrode of the tenth switch tube. The output electrode of the third switch tube is connected to the input electrode of the seventh switch, and the output electrode of the fifth switch tube is connected to the input electrode of the eleventh switch tube. The output electrode of the fourth switch tube is connected to the input electrode of the eighth switch tube, and the output electrode of the fifth switch tube is connected to the input electrode of the twelfth switch tube.

[0078] It should be noted that the specific models and specifications of the switching tubes in the twelve power regulators can be adaptively configured according to the needs of the actual application scenarios. This embodiment does not specifically limit the type of switching tubes and can be adapted to any switching devices in the market that can realize the corresponding functions, such as semiconductor switches, switching circuits, switching elements, etc.

[0079] In actual application, Figure 2 and Figure 3 As shown, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube constitute a first three-phase four-wire output unit.

[0080] The fifth switching tube, the sixth switching tube, the seventh switching tube, the eighth switching tube, the ninth switching tube, the tenth switching tube, the eleventh switching tube and the twelfth switching tube form a second three-phase four-wire output unit.

[0081] The first three-phase four-wire output unit and the second three-phase four-wire output unit are connected to each other through a common intermediate switch part, namely, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube. The twelve-switch power regulator 120 also includes a target capacitor. The target capacitor can be a pulse capacitor or other capacitor that can store electrical energy. Figure 2 As shown, the target capacitance is , target capacitance Can be used to provide DC bus voltage for twelve-switch power converter The first three-phase four-wire output unit is also connected to the second three-phase four-wire output unit via a target capacitor.

[0082] like Figure 3 As shown, the three-phase output terminal and the zero-phase output terminal of the first three-phase four-wire output unit, namely , , and , connected to the target load 200 through the first LC filter 130. In actual application scenarios, the target load 200 may be a non-linear unbalanced and critical load.

[0083] The three-phase output terminal and the zero-phase output terminal of the second three-phase four-wire output unit, namely , , and , connected to the target power source 300 through the second LC filter 140. In an actual application scenario, the three-phase output terminal and the zero-phase output terminal of the second three-phase four-wire output unit are connected to a transformer connected between the target power source 300 and the target load 200 in the substation, so as to compensate for harmonics, voltage sags and surges in the grid voltage through the output of the second three-phase four-wire output unit.

[0084] In this embodiment, the first LC filter 130 includes multiple groups of resistors and capacitors connected in series. The second LC filter 140 includes multiple groups of resistors and capacitors connected in parallel. It should be noted that the actual connection positions of the first LC filter 130 and the second LC filter 140 can be configured according to the needs of the actual application scenario. For example, Figure 3 As shown, the first LC filter 130 includes an inductor connected in series. and capacitor , only one inductor is connected between the neutral line of the grid and the zero-phase output terminal of the first three-phase four-wire output unit The second LC filter 140 includes an inductor connected in parallel and capacitor The three-phase output terminal of the second three-phase four-wire output unit is connected in parallel with the inductor and capacitor One end of the secondary coil of the transformer in the three-phase power grid is connected. The other end of the secondary coil is connected to the zero-phase output end of the second three-phase four-wire output unit.

[0085] In this embodiment, the control electrodes of the switch tubes of the twelve switching power regulators 120 are all connected to the control unit 110. That is, the control unit 110 is respectively connected to the control electrodes of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube, and the twelfth switch tube.

[0086] The control unit 110 performs pulse width modulation on the output of the first output terminal of the twelve-switch power regulator 120 according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on one side of the target load 200 .

[0087] The control unit 110 performs pulse width modulation on the output of the second output terminal of the twelve-switch power regulator 120 according to a second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on one side of the target power supply 300 .

[0088] In this embodiment, the twelve-switch power regulator 120 is connected between the three-phase outgoing line of the maintenance power switch and the three-phase branch switch, and can dynamically monitor and respond to the imbalance of the load current. By adjusting its working mode, the regulator can effectively compensate for the unbalanced current and achieve the balance of the three-phase circuit.

[0089] The twelve-switch power regulator 120 can be functionally divided into two independent three-phase four-wire output units, one of which is connected in parallel with the target load 200 through a series LC filter and can be used to compensate for the current harmonics and imbalance of the target load 200. The other three-phase four-wire output unit is connected to the station transformer of the target power source 300 of the distribution network through a parallel LC filter to compensate for the harmonics, voltage sags and surges in the grid voltage.

[0090] In this embodiment, the control unit 110 may be one or more. By connecting the control electrodes of each semiconductor switch of the first three-phase four-wire output unit and the control electrodes of each semiconductor switch of the second three-phase four-wire output unit respectively with different control units 110, parallel compensation and series compensation can be realized according to different control strategies. The first control strategy may be a parallel compensation strategy. The second control strategy may be a series compensation strategy.

[0091] In summary, this embodiment provides a power grid compensation device, which implements a dual-unit control strategy through a twelve-switch power regulator 120, and the dual-unit control strategy significantly improves the stability of the power grid. Through real-time monitoring and dynamic adjustment, the power grid compensation device can quickly respond to voltage changes and current changes in the power grid, reducing the impact caused by load fluctuations or power grid disturbances. Especially in scenarios such as substation construction, the unbalanced current of a single-phase load can be effectively compensated, avoiding equipment overheating and switch tripping lights caused by three-phase imbalance, thereby ensuring the continuous and stable operation of the power grid.

[0092] In one embodiment, if Figure 4 As shown, the first control strategy can be a parallel compensation control strategy. When the control unit 110 executes the first control strategy, the control unit 110 obtains the load current and the reference current; performs harmonic detection on the reference current to obtain the oscillation part of the load harmonic; performs proportional integral control on the DC bus voltage to obtain the harmonic compensation component; performs harmonic compensation on the oscillation part according to the harmonic compensation component; calculates the first error signal according to the compensated reference current and the load current; processes the first error signal according to the proportional resonant controller to obtain the first control action; and controls the first three-phase four-wire output unit to perform pulse width modulation according to the first control action.

[0093] In this embodiment, if Figure 4As shown, the first control strategy includes a DC bus voltage controller, a reference current generation module, a current controller, and a first three-phase four-wire output unit pulse width modulation module (Duty cycles for PWMTop unit). In actual application, the DC bus voltage controller is used to perform proportional integral control on the DC bus voltage to obtain a harmonic compensation component. The reference current generation module is used to perform harmonic detection on the reference current to obtain the oscillation part of the load harmonic, and perform harmonic compensation on the oscillation part according to the harmonic compensation component. The current controller is used to calculate a first error signal based on the compensated reference current and the load current; and process the first error signal according to the proportional resonant controller to obtain a first control action. The first three-phase four-wire output unit pulse width modulation module is used to control the first three-phase four-wire output unit to perform pulse width modulation according to the first control action. The execution circuit and execution program corresponding to the first control strategy are configured in the control unit 110.

[0094] In this embodiment, if Figure 3 and Figure 4 As shown, when the control unit 110 executes the first control strategy, it first obtains current from the load side. and , where the current include , , , , current include , , , , current is the current output by the twelve-switch power regulator 120, and the current is the current received by the target load 200. In a specific application scenario, The first three-phase four-wire output unit of the twelve-switching power regulator 120 The current output from the phase output terminal. The first three-phase four-wire output unit of the twelve-switching power regulator 120 The current output from the phase output terminal. The first three-phase four-wire output unit of the twelve-switching power regulator 120 The current output from the phase output terminal. It is the current outputted from the zero-phase output terminal of the first three-phase four-wire output unit of the twelve-switch power regulator 120 .

[0095] The target load is 200 terminals. The current received by the phase, The target load is 200 terminals. The current received by the phase, The target load is 200 terminals. The current received by the phase, is the current received by the zero phase of the target load 200.

[0096] When obtaining the reference current, the control unit 110 converts the current received by the target load 200 into The current output from the output end of the first three-phase four-wire output unit is used as a reference current. as the load current.

[0097] In this embodiment, after the reference current is obtained, the reference current in the three-phase stationary coordinate system (abc coordinate system) is converted into a d-axis component, a q-axis component and a 0-sequence component in the two-phase stationary coordinate system dq coordinate system.

[0098] For example, the reference current in the three-phase stationary coordinate system Transformed into dq coordinate system , and In a specific implementation, this embodiment uses a phase-locked loop (PLL) to obtain the angular position of the grid voltage vector , used for dq transformation. It should be noted that the specific transformation method of dq transformation can select a suitable transformation algorithm according to the needs of the actual application scenario, such as Clark transformation or Park transformation.

[0099] The control unit 110 uses a high-pass filter (HPF) to filter the d-axis and q-axis reference current components to obtain the oscillating part of the load harmonics and compensate for the oscillating part. The superscript ~ represents the harmonic component obtained after the high-pass filter processing. Specifically, the control unit 110 obtains the actual value of the DC bus voltage. and reference value , and the actual value of the DC bus voltage and reference value Proportional integral control (PI control) is performed to obtain harmonic compensation components. The first control strategy in this embodiment ensures that the power regulator can operate stably under various load conditions by controlling the DC bus voltage.

[0100] In this embodiment, after the harmonic compensation is completed, the d-axis component, q-axis component and 0-sequence component of the reference current obtained after the harmonic compensation are subjected to dq inverse transformation to obtain the compensated reference current . For load current Perform the corresponding coordinate system transformation to obtain the current . According to the reference current and current A first error signal is calculated and inputted into a proportional-resonant controller (PR Controllers). The first error signal is processed by the proportional-resonant controller to generate a first control action. The control unit 110 performs pulse width modulation (PWM) on the first three-phase four-wire output unit according to the first control action.

[0101] In one embodiment, if Figure 5 As shown, the second control strategy can be a series compensation control strategy. When the control unit 110 executes the second control strategy, the control unit 110 obtains the load voltage and the reference voltage; after low-pass filtering the reference voltage using a low-pass filter, the second error signal is calculated according to the reference voltage and the load voltage; the second error signal is processed according to the proportional resonant controller to obtain a second control action; and the second three-phase four-wire output unit is controlled to perform pulse width modulation according to the second control action.

[0102] like Figure 5 As shown, the second control strategy includes a reference voltage generation module (Voltage reference generation), a voltage controller (Voltage controller) and a second three-phase four-wire output unit pulse width modulation module (Duty cycles for PWM Bottom unit). In actual application, the reference voltage generation module is used to perform low-pass filtering on the reference voltage using a low-pass filter. The voltage controller is used to calculate the second error signal according to the reference voltage and the load voltage; and to process the second error signal according to the proportional resonant controller to obtain the second control action. The second three-phase four-wire output unit pulse width modulation module is used to control the second three-phase four-wire output unit to perform pulse width modulation according to the second control action. The execution circuit and execution program corresponding to the second control strategy are configured in the control unit 110.

[0103] In this embodiment, if Figure 3 and Figure 5 As shown, when the control unit 110 executes the second control strategy, it obtains the reference voltage from the grid side (the target power supply 300 side). and load voltage , reference voltage The voltage output by the target power supply 300. Load voltage It is the voltage outputted by each phase output terminal of the second three-phase four-wire output unit of the twelve-switching power regulator 120 .

[0104] Similar to the first control strategy in the aforementioned embodiment, the control unit 110 converts the reference voltage and the load voltage into a d-axis component, a q-axis component and a zero-sequence component in a dq coordinate system when executing the second control strategy.

[0105] In this embodiment, the control unit 110 filters the reference voltage through a low pass filter (LPF) to maintain stability during voltage sags or surges. And the load voltage obtained after the corresponding coordinate system conversion The second error signal is calculated. The control unit 110 processes the second error signal with a proportional-resonant controller to generate a second control action, and the control unit 110 performs pulse width modulation (PWM) on the second three-phase four-wire output unit according to the second control action.

[0106] In actual application, the second three-phase four-wire output unit can work as a dynamic voltage restorer, responsible for compensating for harmonics, voltage sags or surges in the grid voltage, and ensuring that the load receives a sinusoidal voltage waveform.

[0107] Through the above control strategy, the twelve-switch power regulator 120 can effectively compensate for the voltage and current imbalance in the power grid, improve the power quality, and ensure the stable operation of the load. The implementation of this control method depends on accurate monitoring and fast response, as well as accurate control of the power regulator output.

[0108] In summary, the present embodiment provides a power grid compensation device, which adopts a proportional-resonant controller based on a stationary reference frame, and the controller can accurately control the output of a twelve-switch power regulator to compensate for voltage and current problems in the power grid. Through the first control strategy and the second control strategy in the aforementioned embodiment, the system can ensure that the load receives a stable and undistorted sinusoidal voltage waveform. Optimized power quality is crucial to ensuring the stable operation of electrical equipment and extending its service life. The embodiment of the present application reduces the additional heat loss and mechanical stress of electrical equipment caused by voltage distortion by reducing the harmonic content of voltage and current. In addition, the stable voltage supply also reduces the current shock during the startup and operation of electrical equipment, thereby improving the overall energy efficiency and reliability.

[0109] Secondly, the twelve-switch power regulator used in the power grid compensation device provided in this embodiment reduces the number of semiconductor switches, thereby simplifying the circuit topology. At the same time, the simplified control strategy reduces the need for complex calculations and precise timing control. The reduced number of semiconductor switches directly reduces material costs and manufacturing costs. The simplified circuit design and control strategy also reduce the maintenance difficulty and maintenance cost of the system. In addition, the simplified design also helps to improve the reliability of the system because fewer components mean fewer failure points. In terms of the control system, the simplified control strategy reduces the reliance on high-performance processors, further reduces costs, and improves the operability and maintainability of the system.

[0110] A substation system is also provided, comprising the power grid compensation device, the target power source and the target load in the aforementioned embodiment.

[0111] The first output end of the twelve-switch power regulator of the power grid compensation device is connected to the target load through the first LC filter.

[0112] The second output end of the twelve-switch power regulator of the grid compensation device is connected to the target power supply through a second LC filter.

[0113] In this embodiment, the specific implementation of the substation system can refer to the specific implementation of the power grid compensation device in the aforementioned device embodiment, which will not be described in detail here.

[0114] In summary, the present embodiment provides a substation system that uses a proportional-resonant controller based on a stationary reference frame, which can accurately control the output of a twelve-switch power regulator to compensate for voltage and current problems in the power grid. Through the first control strategy and the second control strategy in the aforementioned embodiment, the system can ensure that the load receives a stable and distortion-free sinusoidal voltage waveform. Optimized power quality is essential to ensure the stable operation of electrical equipment and extend its service life. The embodiment of the present application reduces the additional heat loss and mechanical stress of electrical equipment caused by voltage distortion by reducing the harmonic content of voltage and current. In addition, the stable voltage supply also reduces the current shock during the startup and operation of electrical equipment, thereby improving the overall energy efficiency and reliability.

[0115] like Figure 6 As shown, a power grid compensation control method is also provided, which is applied to the substation system in the above embodiment, and includes the following steps:

[0116] S601, pulse width modulating the output of the first output terminal of the twelve switching power regulator of the power grid compensation device according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on one side of a target load;

[0117] S602, pulse width modulating the output of the second output terminal of the twelve switching power regulator of the grid compensation device according to the second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on a side of the target power supply.

[0118] In one embodiment, if Figure 7 As shown, pulse width modulation is performed on the output of the first output terminal of the twelve switching power regulators of the power grid compensation device according to the first control strategy, including:

[0119] S701, obtaining load current and reference current;

[0120] S702, performing harmonic detection on the reference current to obtain the oscillation part of the load harmonic;

[0121] S703, performing proportional-integral control on the DC bus voltage to obtain a harmonic compensation component;

[0122] S704, performing harmonic compensation on the oscillating part according to the harmonic compensation component;

[0123] S705, calculating a first error signal according to the compensated reference current and the load current;

[0124] S706, processing the first error signal according to the proportional resonant controller to obtain a first control action;

[0125] S707, performing pulse width modulation on the output of the first output terminal of the twelve switching power regulators of the power grid compensation device according to the first control action.

[0126] In one embodiment, if Figure 8 As shown, pulse width modulation is performed on the second three-phase four-wire output unit of the power regulator according to the second control strategy, including:

[0127] According to the second control strategy, pulse width modulation is performed on the output of the second output terminal of the twelve-switch power regulator of the power grid compensation device, including:

[0128] S801, obtaining a load voltage and a reference voltage;

[0129] S802, after performing low-pass filtering on the reference voltage using a low-pass filter, a second error signal is calculated according to the reference voltage and the load voltage;

[0130] S803, processing the second error signal according to the proportional resonant controller to obtain a second control action;

[0131] S804, performing pulse width modulation on the output of the second output terminal of the twelve switching power regulators of the grid compensation device according to the second control action.

[0132] In summary, the present embodiment provides a grid compensation control method, which adopts a proportional-resonant controller based on a stationary reference frame, and the controller can accurately control the output of a twelve-switch power regulator to compensate for voltage and current problems in the grid. Through the first control strategy and the second control strategy in the aforementioned embodiment, the system can ensure that the load receives a stable and undistorted sinusoidal voltage waveform. Optimized power quality is essential to ensure the stable operation of electrical equipment and extend its service life. The embodiment of the present application reduces the additional heat loss and mechanical stress of electrical equipment caused by voltage distortion by reducing the harmonic content of voltage and current. In addition, the stable voltage supply also reduces the current shock during the startup and operation of electrical equipment, thereby improving the overall energy efficiency and reliability.

[0133] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0134] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0135] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A power grid compensation device, characterized in that: include: a control unit, a twelve-switch power regulator, a first LC filter, and a second LC filter; The control unit is connected to the control end of the twelve-switch power regulator; The first output terminal of the twelve-switch power regulator is connected to a target load through the first LC filter; The second output end of the twelve-switch power regulator is connected to the target power supply through the second LC filter; The control unit performs pulse width modulation on the output of the first output terminal of the twelve-switch power regulator according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on one side of a target load; The control unit performs pulse width modulation on the output of the second output terminal of the twelve-switch power regulator according to a second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on one side of a target power supply.

2. The power grid compensation device according to claim 1, characterized in that: The twelve-switch power regulator includes a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a sixth switch tube, a seventh switch tube, an eighth switch tube, a ninth switch tube, a tenth switch tube, an eleventh switch tube, a twelfth switch tube and a target capacitor; Wherein, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube constitute a first three-phase four-wire output unit; The fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube form a second three-phase four-wire output unit; The first three-phase four-wire output unit is also connected to the second three-phase four-wire output unit via the target capacitor; The three-phase output terminal and the zero-phase output terminal of the first three-phase four-wire output unit are connected to the target load; The three-phase output terminal and the zero-phase output terminal of the second three-phase or four-phase output unit are connected to the target power supply.

3. The power grid compensation device according to claim 2, characterized in that: The control unit is respectively connected to control electrodes of the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, the sixth switch tube, the seventh switch tube, the eighth switch tube, the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube; The input electrodes of the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all connected to one end of the target capacitor; The output electrodes of the ninth switch tube, the tenth switch tube, the eleventh switch tube and the twelfth switch tube are all connected to the other end of the target capacitor; The output electrode of the first switch tube is connected to the input electrode of the fifth switch, and the output electrode of the fifth switch tube is connected to the input electrode of the ninth switch tube; the output electrode of the second switch tube is connected to the input electrode of the sixth switch, and the output electrode of the fifth switch tube is connected to the input electrode of the tenth switch tube; the output electrode of the third switch tube is connected to the input electrode of the seventh switch, and the output electrode of the fifth switch tube is connected to the input electrode of the eleventh switch tube; the output electrode of the fourth switch tube is connected to the input electrode of the eighth switch tube, and the output electrode of the fifth switch tube is connected to the input electrode of the twelfth switch tube.

4. The power grid compensation device according to claim 1, characterized in that: The first LC filter includes a plurality of groups of resistors and capacitors connected in series; The second LC filter includes a plurality of groups of resistors and capacitors connected in parallel.

5. The power grid compensation device according to claim 2, characterized in that: The control unit obtains the load current and the reference current; Performing harmonic detection on the reference current to obtain an oscillating part of the load harmonic; Perform proportional-integral control on the DC bus voltage to obtain harmonic compensation components; Performing harmonic compensation on the oscillating part according to the harmonic compensation component; Calculating a first error signal according to the compensated reference current and the load current; Processing the first error signal according to a proportional resonant controller to obtain a first control action; The first three-phase four-wire output unit is controlled to perform pulse width modulation according to the first control action.

6. The power grid compensation device according to claim 2, characterized in that: The control unit obtains a load voltage and a reference voltage; After performing low-pass filtering on the reference voltage using a low-pass filter, a second error signal is calculated according to the reference voltage and the load voltage; Processing the second error signal according to a proportional resonant controller to obtain a second control action; The second three-phase four-wire output unit is controlled to perform pulse width modulation according to the second control action.

7. A substation system, characterized in that: Comprising the power grid compensation device, the target power source and the target load according to any one of claims 1 to 6; The first output end of the twelve-switch power regulator of the power grid compensation device is connected to the target load through a first LC filter; The second output end of the twelve-switch power regulator of the power grid compensation device is connected to the target power supply through a second LC filter.

8. A power grid compensation control method, characterized in that: The substation system according to claim 7 comprises: Pulse width modulation is performed on the output of the first output terminal of the twelve-switch power regulator of the grid compensation device according to a first control strategy, wherein the first control strategy is used to generate a control action according to a reference current and a load current on one side of the target load; The output of the second output terminal of the twelve-switch power regulator of the grid compensation device is pulse-width modulated according to a second control strategy, wherein the second control strategy is used to generate a control action according to a reference voltage and a load voltage on one side of the target power supply.

9. The power grid compensation control method according to claim 8, characterized in that: The method of pulse width modulating the output of the first output terminal of the twelve switching power regulator of the power grid compensation device according to the first control strategy includes: Get load current and reference current; Performing harmonic detection on the reference current to obtain an oscillating part of the load harmonic; Perform proportional-integral control on the DC bus voltage to obtain harmonic compensation components; Performing harmonic compensation on the oscillating part according to the harmonic compensation component; Calculating a first error signal according to the compensated reference current and the load current; Processing the first error signal according to a proportional resonant controller to obtain a first control action; According to the first control action, pulse width modulation is performed on the output of the first output terminal of the twelve switching power regulators of the power grid compensation device.

10. The power grid compensation control method according to claim 8, characterized in that: The pulse width modulation of the output of the second output terminal of the twelve-switch power regulator of the power grid compensation device according to the second control strategy includes: Get the load voltage and reference voltage; After performing low-pass filtering on the reference voltage using a low-pass filter, a second error signal is calculated according to the reference voltage and the load voltage; Processing the second error signal according to a proportional resonant controller to obtain a second control action; According to the second control action, pulse width modulation is performed on the output of the second output terminal of the twelve switching power regulator of the power grid compensation device.

Images