Control system and method of expansion type unified power flow controller based on single-core phase shifter

Abstract

The invention relates to the technical field of flexible power flow control, in particular to a control system and method of a capacity expansion type unified power flow controller based on a single-core phase shifter, and the control system comprises the single-core phase shifter, the unified power flow controller, a control unit and a series transformer. The single-core phase shifter is used for adjusting the voltage amplitude and phase of a line and comprises a primary side winding and a secondary side voltage regulating winding, and the output end of the secondary side voltage regulating winding is connected with a secondary side transformation winding of the series transformer; the unified power flow controller is used for generating compensation voltage and comprises an inverter bridge and a parallel compensation unit, the output end of the inverter bridge is connected with a secondary side transformation winding of the series transformer, and the parallel compensation unit provides reactive power compensation; the control unit generates control signals of the single-core phase shifter and the unified power flow controller according to the acquired power grid operation parameters; the series transformer is used for adjusting the line voltage by injecting the compensation voltage. According to the invention, the power transmission capability and stability of the power grid are effectively solved and improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible power flow control, and in particular to a control system and method of an expandable unified power flow controller based on a single-core phase shifter. Background Art

[0002] In the power system, with the continuous growth and complexity of electric energy demand, the requirements for the reliability, efficiency and flexibility of power transmission are becoming more and more stringent. As an important power equipment, the unified power flow controller phase shifter is widely used in controlling power flow, regulating voltage and improving system stability. Due to its excellent power flow control ability and voltage regulation function, it has become one of the core research directions in the field of flexible power flow control technology.

[0003] Although the power flow control capability and voltage regulation function of the unified power flow controller have broad application potential in theory, the existing unified power flow controller scheme still faces many problems in practical applications, such as high equipment investment and operation and maintenance costs, complex topology, and difficulty in implementing control strategies. These problems limit its promotion and application in large-scale power grids. In response to the above problems, some improvement schemes have been proposed in the prior art, such as reducing system complexity by simplifying the topology or optimizing the control strategy, but these improvements are still insufficient in terms of efficiency and economy. In contrast, the single-core phase shifter has become another important power control device due to its simple structure, low cost, high safety, and long operating life. Under the same capacity, the equipment cost of the single-core phase shifter can be reduced by about 5 times, the operating cost can be reduced by about 10 times, and the economy is significantly improved. However, the existing single-core phase shifter also has the disadvantages of low regulation accuracy and insufficient dynamic response capability in application, which makes it difficult to meet the high-precision requirements of modern power grids for power flow control and voltage regulation. Therefore, how to improve the regulation accuracy and operating performance of the system while reducing costs has become a key issue that needs to be solved at present.

[0004] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present disclosure, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0005] The present invention provides a control system and method of an expandable unified power flow controller based on a single-core phase shifter, which can effectively solve the problems in the background technology.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A control system of an expandable unified power flow controller based on a single-core phase shifter, comprising a single-core phase shifter, a unified power flow controller, a control unit and a series transformer, wherein the control system:

[0008] The single-core phase shifter is used to adjust the voltage amplitude and phase of the line and perform independent decoupling adjustment of phase shifting and voltage regulation. The single-core phase shifter includes a primary winding and a secondary voltage regulating winding. The output end of the secondary voltage regulating winding is connected to the secondary transformer winding of the series transformer.

[0009] The unified power flow controller is used to generate a compensation voltage, and the unified power flow controller includes an inverter bridge and a parallel compensation unit, the output end of the inverter bridge is connected to the secondary side transformer winding of the series transformer, and the parallel compensation unit provides reactive power compensation;

[0010] The control unit is used to generate control signals for the single-core phase shifter and the unified power flow controller according to the acquired power grid operation parameters;

[0011] The series transformer is used to adjust the line voltage by injecting the compensation voltage, the primary side of the series transformer is connected to the power grid, and the secondary side transformer winding is respectively connected to the output end of the secondary side voltage regulating winding and the inverter bridge through electromagnetic coupling;

[0012] The control system performs expansion adjustment on the amplitude and phase of the line voltage according to the control signal of the control unit through the independent decoupling control, the compensation voltage and the electromagnetic coupling.

[0013] Furthermore, the secondary voltage regulating winding of the single-core phase shifter is composed of two groups of basic windings, and the secondary voltage regulating winding is respectively connected to each phase of the three-phase core;

[0014] Each group of the basic windings is controlled by two thyristors to output, so as to adjust the voltage amplitude and phase of the line and realize the voltage dynamic response in the operation of the power grid;

[0015] The secondary side voltage regulating winding connected to each phase of the three-phase core works in coordination with the trigger signal generated by the control unit to adjust the output characteristics of the winding, thereby completing phase shifting and voltage regulation of the line voltage respectively;

[0016] The secondary side voltage regulating winding is connected to the series transformer and injects the line voltage through electromagnetic coupling.

[0017] Further, the inverter bridge of the unified power flow controller generates a controllable voltage through pulse width modulation, and the dynamic adjustment of the amplitude and phase of the controllable voltage determines the variation amplitude and phase characteristics of the compensation voltage;

[0018] The output end of the inverter bridge is connected to the series transformer through a filter, and the filter is used to weaken the interference of high-frequency harmonics generated when the pulse width modulation generates the controllable voltage;

[0019] The inverter bridge and the parallel compensation unit work together to adjust the reactive power injected into the power grid and adjust the output compensation voltage under load fluctuation conditions.

[0020] Furthermore, the control unit comprises:

[0021] The data acquisition module performs real-time operation monitoring on the power grid through sensors, collects voltage amplitude, phase, power factor, frequency and load changes, and generates the power grid operation parameters;

[0022] A control signal generating module, which generates the control signal according to the grid operation parameters, wherein the control signal includes a phase shift angle signal, a compensation voltage signal and a gear switching instruction;

[0023] A collaborative control module, coordinating the operation of the single-core phase shifter and the unified power flow controller based on feedback;

[0024] The control system acquires the grid operation parameters according to the control unit to perform voltage anomaly detection and adjust the output states of the single-core phase shifter and the unified power flow controller.

[0025] Further, coordinating the operation of the single-core phase shifter and the unified power flow controller based on feedback includes:

[0026] Local feedback regulation, adjusting the output of the secondary side voltage regulating winding and the compensation voltage by collecting the output parameters of the single-core phase shifter and the unified power flow controller;

[0027] Global feedback optimization: data aggregation and analysis of the operating status, generation and distribution of global optimization instructions;

[0028] Distributed and centralized collaborative control, based on the local feedback regulation, combines the global optimization instructions to adjust the power flow distribution and correct the consistency of the voltage amplitude and phase of the entire network.

[0029] Furthermore, the series transformer includes a multi-component tap winding, and the tap winding is controlled by an adjustable electromagnetic switch. By switching the adjustable electromagnetic switch, the magnetic coupling ratio is adjusted, the output voltage amplitude is changed, and different grid voltage levels and load requirements are adapted;

[0030] The series transformer adjusts the amplitude and phase of the grid voltage by adjusting the magnetic coupling gear with the secondary voltage regulating winding of each phase.

[0031] Furthermore, the control system adjusts the voltage amplitude and phase of the line through the output end of the secondary voltage regulating winding of the single-core phase shifter and the compensation voltage of the unified power flow controller;

[0032] At the same time, when the load changes, the voltage characteristics are adjusted in conjunction with the single-core phase shifter and the parallel compensation unit.

[0033] Further, the single-core phase shifter adjusts the output voltage amplitude and phase of the secondary-side voltage regulating winding according to the phase shift angle signal generated by the control unit;

[0034] The unified power flow controller uses the compensation voltage signal generated by the control unit to superimpose the compensation voltage with the output of the single-core phase shifter and transmit it to the power grid via the series transformer, thereby optimizing the line voltage amplitude and phase;

[0035] The series transformer receives the output voltage from the single-core phase shifter and the unified power flow controller, and generates a final compensation voltage through electromagnetic synthesis;

[0036] The control unit also includes a feedback control module, which calculates cooperative compensation by collecting output data of the single-core phase shifter and the unified power flow controller.

[0037] A control method of an expandable unified power flow controller based on a single-core phase shifter, the control method comprising:

[0038] The control unit monitors the grid operation status, collects voltage amplitude, phase, power factor, frequency and load changes, and generates grid operation parameters;

[0039] Calculating active power regulation and reactive power regulation according to the power grid operation parameters;

[0040] Generate a thyristor trigger signal according to the active power adjustment amount and the reactive power adjustment amount, adjust the amplitude and phase of the line voltage output by the secondary side voltage regulating winding of the single-core phase shifter, and perform preliminary adjustment on the line voltage;

[0041] The control unit sends a regulation signal to the inverter bridge of the unified power flow controller, and the inverter bridge generates a compensation voltage coordinated with the output of the single-core phase shifter and injects it into the series transformer;

[0042] The series transformer adjusts the gear according to the signal generated by the control unit, adapts to different voltage levels and load requirements of the power grid, and injects the regulated voltage into the receiving end line;

[0043] In case of line abnormality, the gear position of the series transformer is adjusted, and the single-core phase shifter and the unified power flow controller are linked to restore the voltage stability and power transmission capacity of the line.

[0044] Furthermore, the series transformer adjusting the gear position according to the signal generated by the control unit includes:

[0045] The control unit determines the line load demand according to the grid operation parameters and preliminarily sets the gear position of the series transformer;

[0046] The series transformer combines the output of the single-core phase shifter and the compensation voltage, compares them with the target voltage requirement of the power grid, and corrects the gear position;

[0047] The gear adjustment of the series transformer is performed by the control unit monitoring the deviation between the output voltage and the target voltage, and correcting and adjusting through feedback;

[0048] When a sudden change occurs in the power grid, the series transformer is linked with the single-core phase shifter and the unified power flow controller for adjustment according to the gear adjustment signal transmitted by the control unit.

[0049] The technical solution of the present invention can achieve the following technical effects:

[0050] The economy of single-core phase shifters can be used to expand the capacity of traditional unified power flow controllers, achieve precise and rapid power flow control that is not affected by external grid parameters, flexibly adjust the amplitude and phase of line voltage, and independently adjust the active and reactive power flows of the lines, effectively improving the power transmission capacity and stability of the grid and adapting to a variety of application scenarios.

[0051] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 It is a schematic diagram of the structure of the expandable unified power flow controller based on the single-core phase shifter;

[0054] Figure 2The figure is a flow chart of a control method of an expandable unified power flow controller based on a single-core phase shifter. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0057] Embodiment 1;

[0058] The present application provides a control system of an expandable unified power flow controller based on a single-core phase shifter, including a single-core phase shifter, a unified power flow controller, a control unit and a series transformer, wherein the control system:

[0059] The single-core phase shifter is used to adjust the voltage amplitude and phase of the line and perform independent decoupling adjustment of phase shifting and voltage regulation. The single-core phase shifter includes a primary winding and a secondary voltage regulating winding. The output end of the secondary voltage regulating winding is connected to the secondary transformer winding of the series transformer.

[0060] The unified power flow controller is used to generate a compensation voltage. The unified power flow controller includes an inverter bridge and a parallel compensation unit. The output end of the inverter bridge is connected to the secondary side transformer winding of the series transformer. The parallel compensation unit provides reactive power compensation.

[0061] The control unit is used to generate control signals for the single-core phase shifter and the unified power flow controller according to the acquired power grid operation parameters;

[0062] The series transformer is used to adjust the line voltage by injecting a compensation voltage, the primary side of the series transformer is connected to the power grid, and the secondary side transformer winding is respectively connected to the output end of the secondary side voltage regulating winding and the inverter bridge through electromagnetic coupling;

[0063] The control system adjusts the amplitude and phase of the line voltage through independent decoupling control, compensation voltage and electromagnetic coupling according to the control signal of the control unit.

[0064] Specifically, if Figure 1As shown, the main structure of the expanded unified power flow controller is a single-core phase shifter and a unified power flow controller; the structure of each phase of the single-core phase shifter is the same, and the structure of each phase of the unified power flow controller is the same. The thyristor output ends of the two sets of voltage regulating windings of the single-core phase shifter are connected in series with the secondary side windings of the series transformer part of the unified power flow controller according to phase, forming the expanded unified power flow controller topology. The primary side of the single-core phase shifter is grounded respectively, and there are 6 voltage regulating windings a1 and a2 on the secondary side connected to the A-phase iron core, b1 and b2 are connected to the B-phase iron core, and c1 and c2 are connected to the C-phase iron core, among which b1 and c2 are connected in series with the A-phase secondary winding of the unified power flow controller, c1 and a2 are connected in series with the B-phase secondary winding of the unified power flow controller, and a1 and b2 are connected in series with the C-phase secondary winding of the unified power flow controller, and the two are connected in series in phase; an expandable unified power flow control system based on a single-core phase shifter adjusts the line voltage and provides reactive power compensation through the cooperation of a single-core phase shifter, a unified power flow controller, a control unit and a series transformer. In implementation, the primary winding of the single-core phase shifter is connected to the power grid to sense the operating voltage, and its secondary voltage regulating winding is connected to the secondary winding of the series transformer through the secondary winding of the series transformer. The regulated voltage is injected to achieve coarse adjustment of the amplitude and phase of the line voltage. The unified power flow controller includes an inverter bridge and a parallel compensation unit, wherein the inverter bridge is connected to the secondary winding of the series transformer to output a high-precision compensation voltage, and the parallel compensation unit provides reactive power support for the power grid. The control unit generates a control signal according to the set target operating value by collecting grid parameters (such as voltage, current, and power factor, etc.), adjusts the output voltage of the single-core phase shifter, and controls the inverter bridge to generate the required compensation voltage, thereby achieving comprehensive dynamic adjustment of the line voltage. The specific implementation steps include: real-time collection of grid parameters, control of the single-core phase shifter for coarse adjustment, fine adjustment of the inverter bridge, injection of voltage through the series transformer, forming the compensation voltage required by the power grid, and continuous dynamic adjustment to achieve closed-loop control.

[0065] Through the technical solution of the present invention, accurate and rapid control of the power flow that is not affected by external grid parameters can be achieved, the amplitude and phase of the line voltage can be flexibly adjusted, the active power flow and reactive power flow of the line can be independently adjusted, the power transmission capacity and stability of the power grid can be effectively improved, and it can adapt to various application scenarios.

[0066] Further, the secondary voltage regulating winding of the single-core phase shifter is composed of two sets of basic windings, and the secondary voltage regulating winding is connected to each phase of the three-phase core respectively;

[0067] Each set of basic windings is controlled by two thyristors to adjust the voltage amplitude and phase of the line and realize the dynamic voltage response during grid operation;

[0068] The secondary voltage regulating windings connected to each phase in the three-phase core work together through the trigger signal generated by the control unit to adjust the output characteristics of the windings and complete the phase shift and voltage regulation of the line voltage respectively;

[0069] The secondary side voltage regulating winding is connected to the series transformer and the line voltage is injected through electromagnetic coupling.

[0070] As a preferred embodiment of the above, an expandable unified power flow controller based on a single-core phase shifter, whose secondary side voltage regulating winding is composed of two groups of basic windings, which are respectively connected to each phase of the three-phase core, and realize the phase shifting and voltage regulating functions of the line voltage through electromagnetic coupling. Each group of basic windings is controlled by two thyristors, and its output voltage amplitude and phase can be dynamically adjusted by adjusting the conduction angle of the thyristor. The single-core phase shifter includes phase A, phase B, and phase C, and the Y phase is any phase of the single-core phase shifter A, B, and C. The expression for adjusting the voltage amplitude and phase of each phase of the line under each gear of the phase shifting transformer is:

[0071]

[0072] Where U S It is the grid source voltage used by the expansion-type unified power flow controller to regulate the grid power flow. k1 and k2 are the voltages on the working gear phase voltage regulating windings of the two sets of voltage regulating windings of the single-core phase shifter respectively. e is a natural constant, π is the pi, and j is an imaginary unit. The control unit generates a trigger signal of the thyristor according to the real-time collected grid operation parameters (such as voltage, current, power factor, etc.), and adjusts the output characteristics of each phase winding respectively, so that the three-phase windings work together in the phase shifting and voltage regulation functions, and dynamically optimizes the line voltage characteristics. The secondary side voltage regulating winding injects the regulated voltage into the grid through the electromagnetic coupling of the series transformer to form a compensation voltage, thereby realizing the dynamic regulation of the line voltage. In the specific operation, the control unit first obtains the grid operation parameters. The line parameters are calculated, the target amplitude and phase adjustment value of the line voltage are calculated, and a trigger signal is generated to regulate the thyristor; the thyristor adjusts the conduction angle of the basic winding to change the output voltage characteristics; the voltage regulating winding injects the adjusted voltage through the series transformer to achieve line compensation and optimization. The three-phase winding is coordinated by the control unit to complete the phase shift and voltage regulation of the line voltage respectively on the basis of maintaining the three-phase balance. Through the cooperation of multiple groups of windings and thyristors, the voltage amplitude and phase can be efficiently adjusted to adapt to the real-time changes in the operation of the power grid. Through the compensation effect of the series transformer, high-precision dynamic voltage regulation is achieved, which improves the stability and operation efficiency of the power grid. It has good dynamic performance and adaptability, and meets the needs of modern power grids for line voltage control.

[0073] Furthermore, the inverter bridge of the unified power flow controller generates a controllable voltage through pulse width modulation, and the dynamic adjustment of the amplitude and phase of the controllable voltage determines the variation amplitude and phase characteristics of the compensation voltage;

[0074] The output end of the inverter bridge is connected to the series transformer through a filter, and the filter is used to weaken the interference of high-frequency harmonics generated when pulse width modulation generates a controllable voltage;

[0075] The inverter bridge and shunt compensation unit work together to regulate the reactive power injected into the grid and adjust the output compensation voltage under load fluctuation conditions.

[0076] As a preferred embodiment of the above, the inverter bridge of the unified power flow controller uses pulse width modulation (PWM) technology to generate a controllable compensation voltage, and the output end is connected to the series transformer through a filter. The filter is used to weaken high-frequency harmonics, ensure the quality of the compensation voltage, and avoid interference with the power grid. The unified power flow controller includes phase A, phase B, and phase C. The Z phase is any phase of the unified power flow controller A, B, and C. The expression for adjusting the voltage amplitude and phase of each phase of the line under each gear of the unified power flow controller is:

[0077]

[0078] in:

[0079]

[0080] A=X L2 X C1 +jR2 L2

[0081] B=R1R2+X L1 X C1 +j(R2X L1 -R1X C1 )

[0082] D=R1R2-X L1 X L2 +X L1 X C1 +X L2 X C1 +j(R1X L2 -R1X C1 +R2X L1 +R2X L2 )

[0083] Where U PWM is the midpoint voltage of the inverter bridge arm of the unified power flow controller, U L It is the voltage at the receiving end of the power grid used by the expansion type unified power flow controller to regulate the power grid power flow. L2 is the grid line reactance used by the expandable unified power flow controller to regulate the power flow, X C1 R2 and R3 are the reactance and equivalent resistance of the filter capacitor on the inverter side of the unified power flow controller, respectively.L1 and R1 are the reactance and equivalent resistance of the filter inductor on the inverter side of the unified power flow controller, respectively. During operation, the inverter bridge, under the coordination of the control unit, dynamically adjusts the compensation voltage amplitude and phase by adjusting the PWM signal in real time, thereby meeting the needs of the line power flow. In addition, the inverter bridge works together with the parallel compensation unit to adjust the reactive power injected into the grid. Under load fluctuation conditions, the inverter bridge quickly adjusts the compensation voltage to stabilize the line operation, while the parallel compensation unit provides dynamic reactive compensation support to maintain the system power factor and voltage stability. During the specific implementation process, the control unit collects the grid operation parameters in real time, calculates the target compensation voltage, and generates a PWM control signal; the inverter bridge adjusts the output voltage according to the control signal, and the filter smoothes it and injects it into the grid through the series transformer.

[0084] More specifically, the control unit comprises:

[0085] The data acquisition module uses sensors to monitor the power grid in real time, collect voltage amplitude, phase, power factor, frequency and load changes, and generate power grid operation parameters;

[0086] A control signal generation module generates a control signal according to the grid operation parameters, the control signal includes a phase shift angle signal, a compensation voltage signal and a gear switching instruction;

[0087] The collaborative control module coordinates the operation of the single-core phase shifter and the unified power flow controller based on feedback;

[0088] The control system obtains the grid operation parameters from the control unit to detect voltage anomalies and adjust the output states of the single-core phase shifter and the unified power flow controller.

[0089] As a preferred embodiment of the above, a control system of an expandable unified power flow controller based on a single-core phase shifter, wherein the control unit includes a data acquisition module, a control signal generation module and a collaborative control module, and a modular design is used to realize real-time monitoring, dynamic adjustment and power control of the power grid operation status. The data acquisition module uses sensors to monitor the voltage amplitude, phase, power factor, frequency and load changes of the power grid in real time, generates power grid operation parameters and transmits them to the control signal generation module. The control signal generation module generates a phase shift angle signal, a compensation voltage signal and a gear switching instruction based on the collected operation parameters using a built-in algorithm; the phase shift angle signal is used for phase adjustment of the single-core phase shifter, the compensation voltage signal acts on the inverter bridge of the unified power flow controller to generate the compensation voltage, and the gear switching instruction realizes the dynamic switching of the gear of the single-core phase shifter, thereby completing the regulation of the power grid power; in this process, the changes in active power and reactive power come from the fluctuations in the load demand of the power grid and the adjustment of the phase shift angle and the compensation voltage, and the output voltage phase difference is adjusted according to the output voltage phase difference. and voltage amplitude ratio Aratio The relationship between the active power P and the reactive power Q output by the expansion type unified power flow controller is:

[0090]

[0091] In the formula, sin is the cosine function; the collaborative control module coordinates the cooperation between the single-core phase shifter and the unified power flow controller in real time through the feedback mechanism. When the single-core phase shifter changes the phase shift angle, the active power transmission of the power grid is adjusted; when the unified power flow controller adjusts the compensation voltage, the power factor and stability of the power grid are optimized through dynamic compensation of reactive power. Especially in abnormal situations of voltage fluctuations or sudden load changes, the collaborative control module quickly adjusts the phase shift angle and compensation voltage according to the feedback information of the data acquisition module, dynamically adjusts the distribution of active power and reactive power, and quickly restores the operation status of the power grid.

[0092] Specifically, the operation coordination between the single-core phase shifter and the unified power flow controller based on feedback includes:

[0093] Local feedback regulation, by collecting the output parameters of the single-core phase shifter and the unified power flow controller, adjusts the secondary side voltage regulating winding output and compensation voltage;

[0094] Global feedback optimization: data aggregation and analysis of the operating status, generation and distribution of global optimization instructions;

[0095] Distributed and centralized collaborative control, based on local feedback regulation, combines global optimization instructions to adjust power flow distribution and correct the consistency of voltage amplitude and phase of the entire network.

[0096] As a preferred embodiment of the above, by combining local feedback regulation, global feedback optimization and distributed and centralized collaborative control, efficient collaboration between single-core phase shifters and unified power flow controllers and dynamic optimization and global adjustment of power grids are achieved. Local feedback regulation collects the output parameters of single-core phase shifters and unified power flow controllers in real time, including output voltage, phase shift angle, compensation voltage and reactive power of secondary voltage regulating windings, and dynamically adjusts the phase shift angle of single-core phase shifters and compensation voltage of unified power flow controllers according to the real-time collected data to ensure the balance and rapid response capability of local node power flow. At the same time, the adjustment of secondary windings and compensation voltage is combined to achieve real-time adjustment of power grid operation to meet the needs of rapidly changing loads. Global feedback optimization summarizes and analyzes the operation data of the entire network, adopts global optimization algorithms (such as power flow calculation, node voltage optimization algorithm, etc.), analyzes the voltage amplitude and phase distribution of the entire power grid, identifies the deviation of local nodes and the problem of power flow distribution of the entire network, and generates optimization instructions, which include target phase shift angle, target compensation voltage and power flow distribution adjustment strategy, and distributes them to each local control unit to guide the precise operation of single-core phase shifters and unified power flow controllers. The distributed and centralized coordinated control combines the advantages of local regulation and global optimization, which can not only achieve rapid response, but also ensure the comprehensive optimization of the whole network. The distributed control quickly responds to the collected grid parameters through the control unit of each local node, and adjusts the phase shift angle of the single-core phase shifter and the compensation voltage of the unified power flow controller in real time to ensure the stability of the voltage and power flow of the local node. The centralized control coordinates the local operating state according to the global optimization instruction, adjusts the operating parameters of each local node, corrects the consistency of the voltage amplitude and phase of the whole network, and optimizes the power flow distribution to solve the power transmission problem within the whole network. In actual operation, when the load fluctuation and voltage anomaly occur in the power grid, the local feedback regulation can quickly collect data and make real-time adjustments to maintain the voltage stability and power flow balance of the local node. At the same time, the global feedback optimization module is used to coordinate the operation state of the whole network, optimize the voltage distribution and power flow transmission, and ensure the efficiency and stability of the whole network operation. On the basis of ensuring local rapid response, the distributed and centralized coordinated control realizes the comprehensive optimization of the whole power grid through global instructions, which significantly improves the dynamic adjustment capability, operation efficiency and power grid stability of the system.

[0097] Furthermore, the series transformer includes a multi-component tap winding, and the tap winding is controlled by an adjustable electromagnetic switch. By switching the adjustable electromagnetic switch, the magnetic coupling ratio is adjusted, the output voltage amplitude is changed, and different grid voltage levels and load requirements are adapted;

[0098] The series transformer adjusts the amplitude and phase of the grid voltage by adjusting the magnetic coupling position with the secondary voltage regulating winding of each phase.

[0099] As a preferred embodiment of the above, the series transformer realizes the function of adapting to different grid voltage levels and load requirements through the cooperation of multi-component joint windings and adjustable electromagnetic switches, and realizes precise control of voltage amplitude and phase through dynamic adjustment of magnetic coupling gears. The expandable three-phase unified power flow controller includes phase A, phase B, and phase C, and the X phase is any phase of the unified power flow controller A, B, and C. The expression for adjusting the voltage amplitude and phase of each phase of the line under each gear of the expandable unified power flow controller is:

[0100]

[0101] in:

[0102] λ = 1-β;

[0103] The secondary winding of the series transformer contains multiple groups of tap windings. Each group of windings is designed with multiple voltage gears, which can be switched by electromagnetic switches to dynamically adjust the output voltage amplitude to adapt to different grid operating environments. The control unit collects grid operating parameters (such as voltage amplitude, phase and load status) in real time, generates control signals according to the set operating goals, controls the electromagnetic switch to adjust the gear of the tap winding, thereby changing the output voltage amplitude and phase characteristics of the series transformer. The output voltage phase difference of the expansion type unified power flow controller and voltage amplitude ratio A ratio The relationship with the gear position satisfies:

[0104]

[0105] Wherein, arctan2 is the inverse tangent function, and cos is the cosine function; in addition, the tap winding further optimizes the phase and amplitude of the grid voltage by adjusting the magnetic coupling strength with the secondary voltage regulating winding, thereby realizing accurate control of the power flow. In order to achieve the output active power and reactive power of the expanded unified power flow controller, the gear setting should be:

[0106]

[0107] In the formula, when the phase shift angle When the voltage changes between –π and π, it can achieve full range control; it can quickly respond to load fluctuations under complex grid conditions, and ensure the stability and efficiency of grid operation by coordinating the output of single-core phase shifters and series transformers.

[0108] Further, the control system adjusts the voltage amplitude and phase of the line through the output of the secondary voltage regulating winding of the single-core phase shifter and the compensation voltage of the unified power flow controller;

[0109] At the same time, when the load changes, the voltage characteristics are adjusted through the linkage of the single-core phase shifter and the parallel compensation unit.

[0110] As a preferred embodiment of the above, the output end of the secondary voltage regulating winding of the single-core phase shifter and the compensation voltage of the unified power flow controller work together to achieve precise adjustment of the line voltage amplitude and phase; the single-core phase shifter mainly completes the coarse adjustment of the grid voltage by adjusting the output voltage amplitude and phase of the secondary voltage regulating winding; the unified power flow controller generates a high-precision compensation voltage through its inverter bridge and injects it into the grid to achieve fine adjustment and dynamic compensation of the voltage; when the load changes, the system optimizes the voltage characteristics to adapt to the load fluctuation through the linkage adjustment of the single-core phase shifter and the parallel compensation unit; specifically, the single-core phase shifter quickly adjusts the phase distribution of the line by changing the phase shift angle, and the parallel compensation unit maintains the stability of the voltage amplitude by providing reactive power compensation to prevent abnormal grid operation caused by load fluctuations; the control unit collects load and grid operation parameters in real time, generates linkage control signals according to dynamic changes, coordinates the output of the single-core phase shifter and the parallel compensation unit, ensures the adjustment accuracy of the voltage amplitude and phase, and improves the efficiency and stability of power flow control.

[0111] Further, the single-core phase shifter adjusts the output voltage amplitude and phase of the secondary-side voltage regulating winding according to the phase shift angle signal generated by the control unit;

[0112] The unified power flow controller uses the compensation voltage signal generated by the control unit to superimpose the compensation voltage with the output of the single-core phase shifter and transmit it to the power grid via the series transformer, thereby optimizing the line voltage amplitude and phase.

[0113] The series transformer receives the output voltage from the single-core phase shifter and the unified power flow controller, and generates the final compensation voltage through electromagnetic synthesis;

[0114] The control unit also includes a feedback control module, which calculates the cooperative compensation by collecting output data of the single-core phase shifter and the unified power flow controller.

[0115] As a preferred embodiment of the above-mentioned embodiment, the amplitude and phase of the line voltage are optimized through the coordinated work of the single-core phase shifter and the unified power flow controller and the real-time feedback control of the control unit; the single-core phase shifter dynamically adjusts the output voltage amplitude and phase of its secondary side voltage regulating winding according to the phase shift angle signal generated by the control unit to achieve preliminary regulation of the grid voltage; the unified power flow controller generates an accurate compensation voltage through the compensation voltage signal generated by the control unit, and after superimposing it with the output of the single-core phase shifter, transmits it to the grid through the series transformer to further optimize the line voltage characteristics; the series transformer receives the output voltage of the single-core phase shifter and the unified power flow controller, realizes voltage synthesis through electromagnetic coupling, and generates a final compensation voltage to act on the grid; the feedback control module in the control unit collects the output data of the single-core phase shifter and the unified power flow controller in real time, calculates the coordinated compensation scheme according to the operating status and target requirements of the grid, optimizes the output characteristics of the two, and achieves precise adjustment and matching of the amplitude and phase.

[0116] Embodiment 2:

[0117] Based on the same inventive concept as the control system of the expandable unified power flow controller based on the single-core phase shifter in the aforementioned embodiment, the present invention further provides a control method of the expandable unified power flow controller based on the single-core phase shifter, the method comprising:

[0118] S10: Monitor the grid operation status through the control unit, collect voltage amplitude, phase, power factor, frequency and load change, and generate grid operation parameters;

[0119] S20: Calculating active power regulation amount and reactive power regulation amount according to power grid operation parameters;

[0120] S30: generating a thyristor trigger signal according to the active power adjustment amount and the reactive power adjustment amount, adjusting the amplitude and phase of the line voltage output by the secondary side voltage regulating winding of the single-core phase shifter, and performing preliminary adjustment on the line voltage;

[0121] S40: The control unit sends a regulation signal to the inverter bridge of the unified power flow controller, and the inverter bridge generates a compensation voltage coordinated with the output of the single-core phase shifter and injects it into the series transformer;

[0122] S50: The series transformer adjusts the gear position according to the signal generated by the control unit, adapts to different voltage levels and load requirements of the power grid, and injects the adjusted voltage into the receiving end line;

[0123] S60: In the event of line abnormality, adjust the gear position of the series transformer, and link the single-core phase shifter and unified power flow controller to restore the voltage stability and power transmission capacity of the line.

[0124] The above adjustment method in the present invention can effectively realize a control system of an expandable unified power flow controller based on a single-core phase shifter, and the technical effects that can be achieved are as described in the above embodiments, which will not be repeated here.

[0125] Specifically, the series transformer adjusts the gear position according to the signal generated by the control unit including:

[0126] The control unit determines the line load demand based on the grid operation parameters and makes a preliminary setting of the gear position of the series transformer;

[0127] The series transformer combines the output and compensation voltage of the single-core phase shifter, compares it with the target voltage requirement of the power grid, and corrects the gear position;

[0128] The gear adjustment of the series transformer is performed by the control unit monitoring the deviation between the output voltage and the target voltage, and making corrections through feedback;

[0129] When a sudden change occurs in the power grid, the series transformer links the single-core phase shifter and the unified power flow controller to make adjustments according to the gear adjustment signal transmitted by the control unit.

[0130] Similarly, the above-mentioned optimization schemes for the method can also respectively achieve the corresponding optimization effects of the method in Example 1, which will not be repeated here.

[0131] Although the present application has been described in conjunction with specific features and embodiments thereof, it is obvious that various modifications and combinations may be made thereto without departing from the spirit and scope of the present application. Accordingly, this specification and the accompanying drawings are merely exemplary illustrations of the present application as defined therein, and are deemed to have covered any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, a person skilled in the art may make various modifications and variations to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the present application and its equivalents, the present application is intended to include these modifications and variations.

Claims

1. A control system of an expandable unified power flow controller based on a single-core phase shifter, comprising a single-core phase shifter, a unified power flow controller, a control unit and a series transformer, characterized in that: The control system: The single-core phase shifter is used to adjust the voltage amplitude and phase of the line and perform independent decoupling adjustment of phase shifting and voltage regulation. The single-core phase shifter includes a primary winding and a secondary voltage regulating winding. The output end of the secondary voltage regulating winding is connected to the secondary transformer winding of the series transformer. The unified power flow controller is used to generate a compensation voltage, and the unified power flow controller includes an inverter bridge and a parallel compensation unit, the output end of the inverter bridge is connected to the secondary side transformer winding of the series transformer, and the parallel compensation unit provides reactive power compensation; The control unit is used to generate control signals for the single-core phase shifter and the unified power flow controller according to the acquired power grid operation parameters; The series transformer is used to adjust the line voltage by injecting the compensation voltage, the primary side of the series transformer is connected to the power grid, and the secondary side transformer winding is respectively connected to the output end of the secondary side voltage regulating winding and the inverter bridge through electromagnetic coupling; The control system performs expansion adjustment on the line voltage amplitude and phase according to the control signal of the control unit through the independent decoupling control, the compensation voltage and the electromagnetic coupling.

2. The control system of the expandable unified power flow controller based on the single-core phase shifter according to claim 1 is characterized in that: The secondary voltage regulating winding of the single-core phase shifter is composed of two sets of basic windings, and the secondary voltage regulating winding is respectively connected to each phase of the three-phase iron core; Each group of the basic windings is output through two thyristors to adjust the voltage amplitude and phase of the line and realize the dynamic voltage response during the operation of the power grid; The secondary side voltage regulating winding connected to each phase of the three-phase core works in coordination with the trigger signal generated by the control unit to adjust the output characteristics of the winding, thereby completing phase shifting and voltage regulation of the line voltage respectively; The secondary side voltage regulating winding is connected to the series transformer and injects the line voltage through electromagnetic coupling.

3. The control system of the expandable unified power flow controller based on the single-core phase shifter according to claim 1 is characterized in that: The inverter bridge of the unified power flow controller generates a controllable voltage through pulse width modulation, and the dynamic adjustment of the amplitude and phase of the controllable voltage determines the variation amplitude and phase characteristics of the compensation voltage; The output end of the inverter bridge is connected to the series transformer through a filter, and the filter is used to weaken the interference of high-frequency harmonics generated when the pulse width modulation generates the controllable voltage; The inverter bridge and the parallel compensation unit work together to adjust the reactive power injected into the power grid and adjust the output compensation voltage under load fluctuation conditions.

4. The control system of the expandable unified power flow controller based on the single-core phase shifter according to claim 1 is characterized in that The control unit comprises: The data acquisition module performs real-time operation monitoring on the power grid through sensors, collects voltage amplitude, phase, power factor, frequency and load changes, and generates the power grid operation parameters; A control signal generating module, which generates the control signal according to the grid operation parameters, wherein the control signal includes a phase shift angle signal, a compensation voltage signal and a gear switching instruction; A collaborative control module, coordinating the operation of the single-core phase shifter and the unified power flow controller based on feedback; The control system acquires the grid operation parameters according to the control unit to perform voltage anomaly detection and adjust the output states of the single-core phase shifter and the unified power flow controller.

5. The control system of the expandable unified power flow controller based on the single-core phase shifter according to claim 4 is characterized in that: Coordinating the operation of the single-core phase shifter and the unified power flow controller based on feedback includes: Local feedback regulation, adjusting the output of the secondary side voltage regulating winding and the compensation voltage by collecting the output parameters of the single-core phase shifter and the unified power flow controller; Global feedback optimization: data aggregation and analysis of the operating status, generation and distribution of global optimization instructions; Distributed and centralized collaborative control, based on the local feedback regulation, combines the global optimization instructions to adjust the power flow distribution and correct the consistency of the voltage amplitude and phase of the entire network.

6. The control system of the expandable unified power flow controller based on the single-core phase shifter according to claim 1 is characterized in that: The series transformer includes a multi-component tap winding, and the tap winding is controlled by an adjustable electromagnetic switch. By switching the adjustable electromagnetic switch, the magnetic coupling ratio is adjusted, the output voltage amplitude is changed, and different grid voltage levels and load requirements are adapted; The series transformer adjusts the amplitude and phase of the grid voltage by adjusting the magnetic coupling gear with the secondary voltage regulating winding of each phase.

7. The control system of the expandable unified power flow controller based on the single-core phase shifter according to claim 1 is characterized in that: The control system adjusts the voltage amplitude and phase of the line through the output end of the secondary side voltage regulating winding of the single-core phase shifter and the compensation voltage of the unified power flow controller; At the same time, when the load changes, the voltage characteristics are adjusted in conjunction with the single-core phase shifter and the parallel compensation unit.

8. The control system of the expandable unified power flow controller based on the single-core phase shifter according to claim 1 is characterized in that: The single-core phase shifter adjusts the output voltage amplitude and phase of the secondary-side voltage regulating winding according to the phase shift angle signal generated by the control unit; The unified power flow controller uses the compensation voltage signal generated by the control unit to superimpose the compensation voltage with the output of the single-core phase shifter and transmit it to the power grid via the series transformer, thereby optimizing the line voltage amplitude and phase; The series transformer receives the output voltage from the single-core phase shifter and the unified power flow controller, and generates a final compensation voltage through electromagnetic synthesis; The control unit also includes a feedback control module, which calculates cooperative compensation by collecting output data of the single-core phase shifter and the unified power flow controller.

9. A control method of an expandable unified power flow controller based on a single-core phase shifter, characterized in that: The control method comprises: The control unit monitors the grid operation status, collects voltage amplitude, phase, power factor, frequency and load changes, and generates grid operation parameters; Calculating active power regulation and reactive power regulation according to the power grid operation parameters; Generate a thyristor trigger signal according to the active power adjustment amount and the reactive power adjustment amount, adjust the amplitude and phase of the line voltage output by the secondary side voltage regulating winding of the single-core phase shifter, and perform preliminary adjustment on the line voltage; The control unit sends a regulation signal to the inverter bridge of the unified power flow controller, and the inverter bridge generates a compensation voltage coordinated with the output of the single-core phase shifter and injects it into the series transformer; The series transformer adjusts the gear according to the signal generated by the control unit, adapts to different voltage levels and load requirements of the power grid, and injects the regulated voltage into the receiving end line; In case of line abnormality, the gear position of the series transformer is adjusted, and the single-core phase shifter and the unified power flow controller are linked to restore the voltage stability and power transmission capacity of the line.

10. The control method of the expandable unified power flow controller based on the single-core phase shifter according to claim 9, characterized in that: The series transformer adjusting the gear position according to the signal generated by the control unit comprises: The control unit determines the line load demand according to the grid operation parameters and preliminarily sets the gear position of the series transformer; The series transformer combines the output of the single-core phase shifter and the compensation voltage, compares them with the target voltage requirement of the power grid, and corrects the gear position; The gear adjustment of the series transformer is performed by the control unit monitoring the deviation between the output voltage and the target voltage, and correcting and adjusting through feedback; When a sudden change occurs in the power grid, the series transformer is linked with the single-core phase shifter and the unified power flow controller for adjustment according to the gear adjustment signal transmitted by the control unit.

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