Novel topology of rotary power flow controller cascade static var compensator and control method

Abstract

The invention discloses a novel topology of a rotary power flow controller cascaded with a static var compensator and a control method, and belongs to the technical field of flexible interconnection configuration of a power distribution network, the novel topology comprises a rotary power flow controller RPFC and a static var compensator SVC, the RPFC is used as a flexible interconnection device and is integrally connected in series on a tie line, and the SVC is connected in parallel to a grid connection point of the RPFC; the RPFC is composed of two groups of rotating phase-shifting transformers RPST, and the two groups of RPST adopt a structure that rotors are connected in parallel and stators are connected in series; the SVC is formed by connecting a thyristor controlled reactor group TCR and three thyristor switched capacitor groups TSC in parallel; the TCR is formed by connecting a pair of antiparallel thyristors in series with a group of inductors, and the TSC is formed by connecting a pair of antiparallel thyristors in series with a group of capacitors. According to the invention, the reactive power compensation device-SVC is accessed to the flexible interconnection node to bear the effect of a reactive power supply so as to reduce the voltage deviation of the access point, the power flow regulation capability of the rotary power flow controller is fully released, and the regulation capability of the rotary power flow controller is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of flexible interconnection configuration technology for power distribution networks, and in particular to a novel topology and control method for a rotating power flow controller cascaded with a static var compensator. Background Technology

[0002] In the context of the "dual-carbon" goals and the construction of new power systems, the operational characteristics of distribution networks are becoming increasingly complex with the large-scale integration of new loads such as distributed photovoltaics, wind power, and charging piles. Currently, the radial distribution network operates with a single mode, limited regulation capacity, and insufficient control methods, leading to increasingly prominent problems such as weak absorption capacity, declining power quality, low equipment utilization, and insufficient disaster resilience under high-proportion renewable energy integration conditions. As a crucial hub connecting the large power grid and a vast number of users, the distribution system faces new challenges and development opportunities. Flexible interconnection technology, by achieving closed-loop connection and flexible control at key nodes in the distribution network, replaces the traditional AC interconnection method, transforming power flow from passively determined by line impedance and voltage difference to active and precise control. This is a key means to improve the flexibility and controllability of the distribution system.

[0003] Power electronic devices are a key means of achieving flexible interconnection. Flexible control equipment, using full-power conversion back-to-back interconnection and unified power flow controller interconnection, has gradually become the mainstream flexible interconnection method in current distribution networks due to its fast response and precise control characteristics. However, due to the susceptibility of power electronic devices to degradation during long-term operation, and the technical characteristics of using advanced power electronic devices and complex control systems, power electronic flexible interconnection devices generally suffer from low reliability, high cost, and weak shock resistance. Electromagnetic flexible interconnection devices, as a parallel regulation method, include Sen transformers, phase-shifting transformers, and Rotary Power Flow Controllers (RPFCs). They achieve voltage / power flow control of interconnected distribution networks through electromagnetic coupling principles, offering advantages such as simple structure, stable operation, and low cost. Among them, RPFCs, with their fast response speed, continuous control, and flexible regulation, have better application prospects in scenarios with frequent source-load disturbances in distribution networks. However, in distribution networks using RPFC for flexible interconnection, it can achieve flexible control of active and reactive power flow by adjusting the amplitude and phase of the series-injected voltage. However, when performing power flow regulation, especially when executing large-scale active power transfers, the series compensation effect of this device can cause significant fluctuations in the bus voltage at the connection point. This voltage issue, in turn, severely restricts the adjustment range of the rotating power flow controller itself, forcing the device to reserve a large reactive power margin to ensure voltage levels during operation. This prevents the full utilization of its inherent power flow regulation potential, resulting in a limited effective regulation range and failing to maximize the overall regulation capability and system operational flexibility. Summary of the Invention

[0004] The purpose of this invention is to provide a novel topology and control method for a rotating power flow controller cascaded with a static var compensator, aiming to solve the above-mentioned technical defects. By introducing an additional reactive power compensation device and a rotating power flow controller, voltage fluctuations caused by power flow regulation are dynamically compensated, thereby fully releasing the power flow regulation capability of the rotating power flow controller while ensuring the system voltage quality, and effectively improving its regulation capability.

[0005] To achieve the above objectives, the present invention provides a novel topology of rotating power flow controller cascaded static var compensator, including rotating power flow controller RPFC and static var compensator SVC. The RPFC is connected in series on the tie line as a flexible interconnection device, and the SVC is connected in parallel to the grid connection point of the RPFC. The RPFC consists of two sets of rotating phase-shifting transformers (RPSTs), with the two sets of RPSTs using a structure of parallel rotors and series stators. The SVC consists of a thyristor-controlled reactor (TCR) and three thyristor-controlled capacitor banks (TSC) connected in parallel. The TCR consists of a pair of anti-parallel thyristors connected in series with an inductor, and the TSC consists of a pair of anti-parallel thyristors connected in series with a capacitor.

[0006] Preferably, the relationship between the RPFC series-connected line equivalent voltage, the grid connection point voltage vector, the relative angle between the stator and rotor, and the equipment impedance is expressed as follows: ; ; ; ; in, The equivalent voltage vector of the RPFC series-inserted line. For the grid connection point voltage vector, The turns ratio of the stator and rotor windings, For equipment impedance, The equivalent impedance of the RPST series stator winding is... The equivalent impedance of the parallel rotor windings of RPST is... and These are the relative angles between the stator and rotor of the two RPSTs; SVC reactive power output Q SVC With grid connection point voltage amplitude U 1 and SVC equivalent susceptance B SVC The relationship is: .

[0007] Preferably, the SVC corresponds to the grid connection point voltage vector. The regulatory effect is expressed as: ; in, The voltage amplitude at the grid connection point. This represents the voltage amplitude at the system's beginning. and These are the active power and reactive power of the transmission line, respectively. and These are the resistance and reactance of the transmission line, respectively. The current at the end of the closed loop is expressed as: ; in, The line current vector flowing through the RPFC. This is the voltage vector below the RPFC.

[0008] Preferably, the RPFC injects series voltage. Inside RPFC ωL >>Under the premise of R Z RPFC =j X RPFC closed-loop power P 3+j Q 3 satisfies the following relationship: ; in, P 3 and Q 3 represents the closed-loop active power and reactive power, respectively. U 2 represents the voltage amplitude below RPFC. U RPFC This represents the equivalent voltage amplitude of the RPFC series-inserted line. X RPFC For RPFC equivalent reactance, for and The phase angle difference.

[0009] Preferably, the system voltage, the relative angle between the RPFC stator and rotor, and the closed-loop power are... P 3+j Q The relational expression for 3 is: .

[0010] This invention also provides a control method for a novel topology of rotating power flow controller cascaded static var compensator (RPFC). Through the millisecond-level fast response of the SVC and the second-level precise adjustment of the RPFC, power flow and voltage control are achieved, specifically including two stages: SVC control phase: First, the voltage amplitude at the grid connection point is acquired. U 1. Compare it with the preset voltage reference value. U 1ref The voltage deviation signal is generated by comparison; the voltage deviation signal is then input into the fast control loop of the SVC, and the reactive power output of the SVC is dynamically adjusted after a millisecond-level response. RPFC control phase: Power at the closing point of the lower-level RPFC controller P 3. Q 3. Compared with the given closed-loop power reference value P 3ref , Q 3ref The comparison is performed, and the results are input into the slow power optimization stage, based on the impact of the first stage. U 1. Through second-level optimization calculations, the stator-rotor relative angle control command of the RPFC is generated to drive the power control of the RPFC.

[0011] Preferably, during the SVC control phase, the system dynamically decides the number of TSCs to be switched on and the firing angle of the TCR based on the voltage deviation signal: when the voltage is low, the TSC capacitor bank is switched on and the TCR reactance is reduced to increase capacitive reactive power output; when the voltage is high, the TSC capacitor bank is switched off and the TCR reactance is increased to absorb inductive reactive power.

[0012] Preferably, in the RPFC control stage, specifically: the RPFC adopts a dual closed-loop PI control strategy. First, the phase of the grid-connected point voltage is detected in real time through a phase-locked loop (PLL), and this is used as the synchronous reference for the dq rotating coordinate system; the measured three-phase voltage at the grid-connected point... u 1.abc , u 2.abc and current i 2.abc After the abc / dq transformation, the voltage components in the dq coordinate system are obtained. u 1d , u 1q and current components i2d , i 2q Then, the actual power of the closed loop circuit is calculated using the power calculation module. P 3. Q 3; Compare the actual power with the preset power reference value. P 3ref , Q 3ref Comparison was performed, taking into account the stable grid connection point voltage amplitude during the SVC control phase. U 1. After second-level optimization calculation, the stator-rotor relative angle control command of RPFC is generated, which drives the servo motor to adjust the rotor angle of the two sets of RPST, thereby synthesizing the required series voltage.

[0013] Therefore, the beneficial effects of the novel topology and control method of the rotating power flow controller cascaded static var compensator described above are as follows: (1) This invention achieves power flow regulation and voltage support through multi-timescale control of RPFC and SVC, enabling RPFC to perform power flow regulation over a wider range without endangering voltage safety, thereby significantly improving the effective regulation capability of the system.

[0014] (2) The present invention effectively suppresses voltage deviation caused by RPFC operation or load fluctuation through SVC fast and accurate voltage compensation, and enhances the voltage safety of RPFC-based flexible interconnection system under different operating conditions.

[0015] (3) The control method of the present invention enhances the ability of the flexible interconnected system based on RPFC to resist disturbances, can better cope with the fluctuation of new energy output and load changes, reduce system power oscillations, and improve the dynamic performance of the interconnected system.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is the equivalent circuit diagram of RPFC; Figure 2 This is a schematic diagram of a novel topology of a cascaded static var compensator for a rotating power flow controller according to the present invention; Figure 3 This is a simplified circuit diagram of RPFC and SVC; Figure 4 This is a schematic diagram of a control method for a novel topology of a rotating power flow controller cascaded with a static var compensator, according to the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] Example 1: like Figure 1 The diagram shows the single-phase equivalent circuit of an RPFC. The Rotary Phase Shifting Transformer (RPST) is the core component of the RPFC. The RPFC synthesizes a stator voltage phasor with constant amplitude and adjustable phase angle by rotating the rotor angles of two sets of RPSTs. The two sets of stator voltage phasors are superimposed to inject a series voltage with adjustable amplitude and phase angle into the circuit. and These are the voltage and current vectors before the RPFC is connected, respectively. Z rt The equivalent impedance of the parallel rotor windings of RPST is... Z RPST1 , Z RPST2 These are the equivalent impedances of the series stator windings of RPST1 and RPST2, respectively. For rotor-side current, k The turns ratio of the stator and rotor windings, and These are the relative angles between the stator and rotor of the two RPSTs. The equivalent voltage vector of the RPFC series-inserted line. This is the voltage vector below the RPFC access point.

[0021] The relationship between the RPFC series-connected line equivalent voltage, the grid connection point voltage vector, the relative angle between the stator and rotor, and the equipment impedance is expressed as follows: (1) (2) In the formula, , .

[0022] in, For equipment impedance, This is the equivalent impedance of the RPST series stator winding.

[0023] From equation (1), it can be concluded that the magnitude of the voltage vector of the RPFC inserted into the line is determined by... The phase angle of the RPFC series-inserted line voltage vector is determined by... Decision. Therefore, by changing , The size directly affects the voltage vector of the RPFC series-in line.

[0024] The basic function of a SVC (Sustainable Dynamic Valve) is to absorb or supply continuously adjustable reactive power to the power grid to maintain constant voltage and reactive power balance at the installation point. The reactive power output of the SVC... Q SVC With grid connection point voltage amplitude U 1 and equivalent susceptance B SVC The relationship is: (3) Through the dynamic reactive power support and rapid voltage amplitude adjustment capabilities of the SVC, the power and voltage regulation capabilities of the RPFC can be effectively improved.

[0025] This invention provides a novel topology of a rotating power flow controller cascaded with a static var compensator (SVC), comprising a rotating power flow controller (RPFC) and a SVC. The RPFC, as a flexible interconnect device, is connected in series on a tie line to achieve precise regulation of cross-regional active power flow. The SVC is connected in parallel to the grid connection point (excitation side) of the RPFC to provide rapid reactive power compensation to reduce voltage fluctuations at the grid connection point, forming a topology such as... Figure 2 The novel combined topology of RPFC and SVC is shown.

[0026] The RPFC consists of two sets of rotating phase-shifting transformers (RPSTs). When stationary, it resembles a single transformer, with a certain turns ratio between its stator and rotor voltages. The phase difference is related to the angle between the stator and rotor. and Regarding multi-pole RPSTs, the voltage phasor in the series circuit can be changed by only a small mechanical angle movement of the rotor angle. Two sets of RPSTs adopt a structure of parallel rotors and series stators to synthesize stator voltage phasors with constant amplitude and 360° adjustable phase angle. After superposition, a series voltage with adjustable amplitude and phase angle is injected into the circuit.

[0027] The SVC consists of a thyristor-controlled reactor (TCR) and three thyristor-controlled capacitor banks (TSCs) connected in parallel. The TCR is a pair of anti-parallel thyristors connected in series with an inductor. By controlling the firing angle of the thyristors, the conduction time of the current in the inductor can be changed, thereby continuously adjusting the reactance and controlling reactive power. The TSC is a pair of anti-parallel thyristors connected in series with a capacitor. By controlling the conduction and cutoff of the thyristors, the capacitor bank can be connected to or disconnected from the power grid to achieve discrete reactive power compensation.

[0028] The simplified circuit diagram of the combination of RPFC and SVC is obtained from equations (1), (2) and (3) as follows. Figure 3 As shown.

[0029] In the diagram, the voltage at the beginning of the system is The transmission line impedance is Z l The power of the transmission line is P 1+j Q 1. The grid connection point voltage vectors of the closed-loop circuit RPFC and SVC are: RPFC is equivalent to a series voltage source and impedance. Z RPFC SVC is equivalent to parallel variable susceptance j B SVC Its output reactive power is Q SVC The current vector flowing through the closed loop of the RPFC is The closed-loop power is P 3+j Q 3. At this time, SVC corresponds to the grid connection point voltage vector. The regulatory effect is expressed as: (4) in, The voltage amplitude at the grid connection point. This represents the voltage amplitude at the system's beginning. and These are the active power and reactive power of the transmission line, respectively. and These are the resistance and reactance of the transmission line, respectively.

[0030] The current at the end of the closed loop is expressed as: (5) RPFC Injection Series Voltage Inside RPFC ωL >>Under the premise of R Z RPFC =j X RPFC closed-loop power P3+j Q 3 satisfies the following relationship: (6) in, P 3 and Q 3 represents the closed-loop active power and reactive power, respectively. U 2 represents the voltage amplitude below RPFC. U RPFC This represents the equivalent voltage amplitude of the RPFC series-inserted line. X RPFC For RPFC equivalent reactance, for and The phase angle difference.

[0031] Substituting equation (1) into equation (6), the system voltage, the relative angle between the stator and rotor of the RPFC, and the closed-loop power can be derived and calculated. P 3+j Q The relational expression for 3 is: (7) In summary, SVC injects reactive power into the line. Q SVC It can quickly stabilize the grid connection point voltage vector. It also provides reactive power support by controlling the relative angle between the stator and rotor. and ( and The RPFC and SVC work together to enable precise regulation of transmission power, allowing the system to flexibly and accurately allocate power while maintaining voltage safety, which is key to achieving flexible interconnection.

[0032] Based on the above-mentioned novel topology of a rotating power flow controller cascaded with a static var compensator, the control method is as follows: Figure 4 As shown, by combining the millisecond-level fast response of SVC with the second-level precise adjustment of RPFC, the functions of active power flow control and reactive voltage stability are decoupled, specifically including two stages: SVC control phase: First, the voltage amplitude at the grid connection point is acquired. U 1. Compare it with the preset voltage reference value. U 1ref A voltage deviation signal is generated through comparison. This signal is then input into the fast control loop of the SVC. Based on the voltage deviation signal, the system dynamically decides the number of TSCs to be switched on and the firing angle of the TCR: when the voltage is low, the TSC capacitor bank is switched on and the TCR reactance is reduced to increase capacitive reactive power output; when the voltage is high, the TSC capacitor bank is switched off and the TCR reactance is increased to absorb inductive reactive power. The reactive power output of the SVC is dynamically adjusted after a millisecond-level response.

[0033] U 1 represents the SVC grid connection point voltage. U 1ref This is the reference value for the grid connection point voltage. B ref This is the SVC equivalent susceptance reference value. B max and B min These are the maximum and minimum values ​​of the equivalent susceptance, respectively. B svc This is the equivalent susceptance of the SVC. The control objective of the SVC is to maintain the grid connection point voltage. U The amplitude of 1 is within the allowable deviation range. Based on the reactive power demand, the switching signal of the capacitor bank TSC and the firing angle signal of the TCR are generated to output reactive power to the line. Q svc .

[0034] RPFC control phase: Power at the closing point of the lower-level RPFC controller P 3. Q 3. Compared with the given closed-loop power reference value P 3ref , Q 3ref The comparison is performed, and the results are input into the slow power optimization stage, based on the impact of the first stage. U 1. Through second-level optimization calculations, the stator-rotor relative angle control command for the RPFC is generated to drive the power control of the RPFC, specifically: RPFC employs a dual closed-loop PI control strategy. u 1.abc , u 2.abc , i 2.abc The three-phase voltage and current at the grid connection point are measured below. The phase-locked loop (PLL) uses the real-time detection of the grid connection point voltage phase as a synchronous reference for the dq rotating coordinate system. The measured phasors are obtained through an abc / dq transformation. u 1d , u 1q , u 2d , u 2q , i 2d , i 2q The power of the RPFC series-in line is obtained through the power calculation module. P 3ref , Q3ref The active and reactive power control targets are respectively used as inputs to the outer power controller to obtain the voltage reference value. u RPFCd * , u RPFCq * The actual voltage component u 1d , u 1q , u 2d , u 2q and voltage reference value u RPFCd * , u RPFCq * The input voltage inner loop controller obtains the output voltage amplitude of the RPFC. With phase angle Finally, the phase-shifted electrical angle is obtained by inputting it into the RPST angle generator. , The RPFC rotor is driven by a servo motor, thereby achieving precise control of the power flow of the line.

[0035] Therefore, this invention adopts a novel topology and control method for a cascaded static var compensator (RPFC) using a rotating power flow controller (RPFC). This fully leverages the advantages of the electromagnetic RPFC's high reliability and economy, as well as the SVC's fast response capability. While improving system performance, it avoids the high cost and low reliability issues associated with using a fully power electronic solution. This approach has good economic and engineering application value, enhances the distribution network's ability to accommodate distributed energy sources and its proactive power flow control, and helps build a more flexible and robust smart distribution network, promoting energy transformation and low-carbon development.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. 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 still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A novel topology of a rotating power flow controller cascaded with a static var compensator, characterized in that: It includes a rotating power flow controller (RPFC) and a static var compensator (SVC). The RPFC, as a flexible interconnection device, is connected in series on the tie line, and the SVC is connected in parallel to the grid connection point of the RPFC. The RPFC consists of two sets of rotating phase-shifting transformers (RPSTs), with the two sets of RPSTs using a structure of parallel rotors and series stators. The SVC consists of a thyristor-controlled reactor (TCR) and three thyristor-controlled capacitor banks (TSC) connected in parallel. The TCR consists of a pair of anti-parallel thyristors connected in series with an inductor, and the TSC consists of a pair of anti-parallel thyristors connected in series with a capacitor.

2. The novel topology of a rotating power flow controller cascaded with a static var compensator according to claim 1, characterized in that: The relationship between the RPFC series-connected line equivalent voltage, the grid connection point voltage vector, the relative angle between the stator and rotor, and the equipment impedance is expressed as follows: ； ； ； ； in, The equivalent voltage vector of the RPFC series-inserted line. For the grid connection point voltage vector, The turns ratio of the stator and rotor windings, For equipment impedance, The equivalent impedance of the RPST series stator winding is... The equivalent impedance of the parallel rotor windings of RPST is... and These are the relative angles between the stator and rotor of the two RPSTs; SVC reactive power output Q SVC With grid connection point voltage amplitude U 1 and SVC equivalent susceptance B SVC The relationship is: 。 3. A novel topology of a rotating power flow controller cascaded with a static var compensator according to claim 2, characterized in that: SVC on grid connection point voltage vector The regulatory effect is expressed as: ； in, The voltage amplitude at the grid connection point. This represents the voltage amplitude at the system's beginning. and These are the active power and reactive power of the transmission line, respectively. and These are the resistance and reactance of the transmission line, respectively. The current at the end of the closed loop is expressed as: ； in, The loop current vector flowing through the RPFC is the current vector of the closed loop. This is the voltage vector below RPFC.

4. A novel topology of a rotating power flow controller cascaded with a static var compensator according to claim 3, characterized in that: RPFC Injection Series Voltage Inside RPFC ωL >>Under the premise of R Z RPFC =j X RPFC closed-loop power P 3+j Q 3 satisfies the following relationship: ； in, P 3 and Q 3 represents the closed-loop active power and reactive power, respectively. U 2 represents the voltage amplitude below RPFC. U RPFC This represents the equivalent voltage amplitude of the RPFC series-inserted line. X RPFC For RPFC equivalent reactance, for and The phase angle difference.

5. A novel topology of a rotating power flow controller cascaded with a static var compensator according to claim 4, characterized in that: System voltage, RPFC stator-rotor relative angle and closed-loop power P 3+j Q The relational expression for 3 is: 。 6. A control method for a novel topology of a rotating power flow controller cascaded with a static var compensator, characterized in that: Power flow and voltage control are achieved through the millisecond-level fast response of SVC and the second-level precise adjustment of RPFC, specifically including two stages: SVC control phase: First, the voltage amplitude at the grid connection point is acquired. U 1. Compare it with the preset voltage reference value. U 1ref The voltage deviation signal is generated by comparison; the voltage deviation signal is then input into the fast control loop of the SVC, and the reactive power output of the SVC is dynamically adjusted after a millisecond-level response. RPFC control phase: The lower-level RPFC controller will control the loop-closed point power. P 3. Q 3. Compared with the given closed-loop power reference value P 3ref , Q 3ref The comparison is performed, and the results are input into the slow power optimization stage, based on the impact of the first stage. U 1. Through second-level optimization calculations, the stator-rotor relative angle control command of the RPFC is generated to drive the power control of the RPFC.

7. The control method for a novel topology of a rotating power flow controller cascaded with a static var compensator according to claim 6, characterized in that: During the SVC control phase, based on the voltage deviation signal, the system dynamically decides the number of TSCs to be switched on and the firing angle of the TCR: when the voltage is low, the TSC capacitor bank is switched on and the TCR reactance is reduced to increase capacitive reactive power output; when the voltage is high, the TSC capacitor bank is switched off and the TCR reactance is increased to output inductive reactive power.

8. The control method for a novel topology of a rotating power flow controller cascaded with a static var compensator according to claim 6, characterized in that: In the RPFC control phase, specifically: RPFC adopts a dual closed-loop PI control strategy. First, the phase of the grid-connected point voltage is detected in real time through a phase-locked loop (PLL), and this is used as the synchronous reference for the dq rotating coordinate system; the measured three-phase voltage at the grid-connected point... u 1.abc , u 2.abc and current i 2.abc After the abc / dq transformation, the voltage components in the dq coordinate system are obtained. u 1d , u 1q , u 2d , u 2q and current components i 2d , i 2q Then, the actual power of the closed loop circuit is calculated using the power calculation module. P 3. Q 3; Compare the actual power with the preset power reference value. P 3ref , Q 3ref Comparison was performed, taking into account the stable grid connection point voltage amplitude during the SVC control phase. U 1. After second-level optimization calculation, the stator-rotor relative angle control command of RPFC is generated, which drives the servo motor to adjust the rotor angle of the two sets of RPST, thereby synthesizing the required series voltage.

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