A static synchronous compensator control system for damping subsynchronous oscillations

Abstract

The utility model relates to power system and power electronics technical field, especially a kind of static synchronous compensator control system of inhibiting subsynchronous oscillation, including torsional vibration damping controller, the input of torsional vibration damping controller is electrically connected with generator shafting speed sensor;Static synchronous compensator controller, voltage outer ring reference voltage input terminal and reactive current reference current input terminal are equipped on the circuit board of static synchronous compensator controller;Converter;It is connected in generator stator side;Wherein, the output of torsional vibration damping controller is connected to the soldering pad node of voltage outer ring reference voltage input terminal;Or connected to the soldering pad node of reactive current reference current input terminal;The utility model is accurate by injecting subsynchronous damping control signal into voltage outer ring reference terminal or reactive current reference terminal, solves the key problem that bus voltage fluctuation 10% caused by damping signal straight-through current inner ring in stator side SSR inhibition.

Description

Technical Field

[0001] This utility model relates to the fields of power systems and power electronics, and in particular to a static synchronous compensator control system for suppressing subsynchronous oscillations. Background Technology

[0002] In power systems, large generator sets encounter subsynchronous resonance (SSR) problems when transmitting electricity through series-compensated transmission lines. The SSR phenomenon mainly manifests in three forms: induction generator effect (IGE), torsional vibration (TI), and transient torque amplification (TA). These oscillations can easily cause abnormal motor vibration or lead to permanent damage to the generator shaft, posing a threat to the safety of the power system.

[0003] In existing technologies, SSR suppression techniques are mainly divided into two categories: rotor-side solutions (SEDC) and stator-side solutions (see reference). Figure 3 The rotor-side scheme achieves the purpose of injecting damping torque through the rotor side by superimposing a subsynchronous voltage at the output of the excitation regulator (AVR+PSS). Although this type of scheme, represented by the PCS-987D device, can suppress SSR, it has some inherent defects, including the limitation of dynamic performance due to reliance on the response speed of the excitation winding, the need for shutdown to connect the rotor circuit during the retrofit process, the high engineering implementation cost, and it is only applicable to traditional synchronous units and is not compatible with new energy power plants.

[0004] The stator-side solution uses a Static Synchronous Compensator (STATCOM) to inject subsynchronous current into the generator stator. Compared to the rotor-side solution, the stator-side solution has a faster response speed and is easier to retrofit (parallel connection on the stator side). However, in practical applications, this solution reveals a serious flaw: when the torsional vibration damping signal (such as the PCS-987D output) is directly superimposed on the d-axis of the STATCOM current inner loop, it causes a severe fluctuation of approximately 10% in the DC bus voltage. This situation conflicts with the core requirement of the STATCOM to stabilize the DC bus voltage, not only reducing the oscillation suppression accuracy but also potentially triggering the converter overvoltage protection, and even causing a cascading system failure. Utility Model Content

[0005] In this section, as well as in the specification summary and utility names of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, specification summary, and utility names, and such simplifications or omissions shall not be used to limit the scope of this utility.

[0006] To address the shortcomings of existing technologies, one objective of this invention is to provide a static synchronous compensator control system for suppressing subsynchronous oscillations.

[0007] To achieve the above objectives, this utility model adopts the following technical solution: a static synchronous compensator control system for suppressing subsynchronous oscillations, including a torsional vibration damping controller, wherein the input terminal of the torsional vibration damping controller is electrically connected to a generator shaft speed sensor.

[0008] A static synchronizing compensator controller, wherein the circuit board of the static synchronizing compensator controller is provided with: a voltage outer loop reference voltage input terminal and a reactive current reference current input terminal disposed on the circuit board; and

[0009] A converter is connected to the stator side of the generator; the output of the static synchronous compensator controller is connected to the converter through a drive circuit, and is used to inject compensation current to suppress subsynchronous oscillations into the stator side of the generator.

[0010] The output terminal of the torsional vibration damping controller is connected to the pad node of the voltage outer loop reference voltage input terminal; or to the pad node of the reactive current reference current input terminal.

[0011] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, the static synchronous compensator controller further includes a switching switch disposed on its circuit board, the common terminal of which is connected to the output terminal of the torsional vibration damping controller, and the two outputs are respectively connected to the voltage outer loop reference voltage input terminal and the reactive current reference current input terminal.

[0012] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, wherein: the reference voltage input terminal of the outer voltage loop is connected to the in-phase input terminal of the outer voltage loop PI controller, and a signal superposition resistor is connected in series in the connection line between the in-phase input terminal and the output terminal of the torsional vibration damping controller.

[0013] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, wherein: the reactive current reference current input terminal is connected to the in-phase input terminal of the reactive current loop PI controller, and a signal isolation optocoupler is connected in parallel between the in-phase input terminal and the output terminal of the torsional vibration damping controller.

[0014] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, a signal transmission module is further provided between the torsional vibration damping controller and the static synchronous compensator controller, and the signal transmission module is a gigabit transceiver analog output module.

[0015] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, wherein: the digital input terminal of the signal transmission module is connected to the DA conversion interface of the torsional vibration damping controller, and the analog output terminal is connected to the AD sampling interface of the static synchronous compensator controller.

[0016] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, the torsional vibration damping controller is further provided with multiple parallel LC filters and operational amplifiers. The center frequencies of the multiple parallel LC filters and operational amplifiers correspond to an inherent torsional vibration frequency of the generator shaft system.

[0017] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, the inherent torsional vibration frequency is provided with at least three bandpass filters and bandstop filter groups connected in sequence, wherein the output terminals of the bandpass filters and bandstop filter groups are connected to the signal transmission module via a superposition module.

[0018] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, the static synchronous compensator controller is further provided with a Park inverse transformation module, which is used to convert the mode control signal into a three-phase compensation current reference value and drive the IGBT power unit through the PWM modulation module.

[0019] As a preferred embodiment of the static synchronous compensator control system for suppressing subsynchronous oscillations described in this utility model, the band-stop filter bank of the modal processing channel includes two parallel band-stop filters, and the center frequencies of the bandpass filters of each channel are set to 20Hz, 25Hz, and 30Hz, respectively.

[0020] This utility model, through the coordinated operation of the torsional vibration damping controller, the static synchronous compensator controller, and the signal path selection module, can accurately inject the subsynchronous damping control signal into the voltage outer loop reference terminal or the reactive current reference terminal. This solves the critical problem of 10% bus voltage fluctuation caused by the damping signal passing through the inner current loop in the stator-side SSR suppression, enabling the static synchronous compensator to achieve DC bus voltage stability (fluctuation <5%) while maintaining the subsynchronous oscillation suppression effect, thus facilitating the safe and stable operation of the power system. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the control system of the static synchronous compensator for suppressing subsynchronous oscillations in this practical application.

[0023] Figure 2This is a modular schematic diagram of the static synchronous compensator control system for suppressing subsynchronous oscillations in this practical application.

[0024] Figure 3 This is a schematic diagram of the modal processing channel in the static synchronous compensator control system for suppressing subsynchronous oscillations in this practical application.

[0025] Figure 4 This paper describes the structure and principle of a prior art subsynchronous damping controller.

[0026] In the diagram: 100, Torsional vibration damping controller; 101, Speed ​​sensor; 200, Static synchronous compensator controller; 201, Voltage outer loop reference voltage input terminal; 202, Reactive current reference current input terminal; 300, Converter; 103, Operational amplifier; 104, LC filter; 203, Switch; 204, Voltage outer loop PI controller; 205, Reactive current loop PI controller; 206, Signal transmission module; 207, Park inverse converter module; 208, PWM modulation module; 209, IGBT power unit; 210, Band-stop filter bank. Detailed Implementation

[0027] To make the objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of this utility model. However, this utility model may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this utility model. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0030] Reference Figure 1-3 This is one embodiment of the present invention. This embodiment provides a static synchronous compensator control system for suppressing subsynchronous oscillations, which can effectively suppress subsynchronous oscillations. It includes: a torsional vibration damping controller 100, the input terminal of which is electrically connected to the generator shaft speed sensor 101.

[0031] The static synchronizing compensator controller 200 has the following on its circuit board: voltage outer loop reference voltage input terminal 201 and reactive current reference current input terminal 202.

[0032] Converter 300; connected to the stator side of the generator;

[0033] The output of the torsional vibration damping controller 100 is connected to the pad node of the voltage outer loop reference voltage input terminal 201; or to the pad node of the reactive current reference current input terminal 202; the output of the static synchronous compensator controller 200 is connected to the converter 300 through the drive circuit, and is used to inject compensation current to suppress subsynchronous oscillations into the generator stator side.

[0034] Specifically, the torsional vibration damping controller 100 is designed to receive the speed signal (ω) from the generator shaft speed sensor 101, and the torsional vibration damping controller 100 contains a mode separation and phase compensation unit for extracting the subsynchronous frequency component from the speed signal and generating a subsynchronous damping control signal.

[0035] The static synchronous compensator controller 200 includes a voltage outer loop control module and a reactive current control module for processing the subsynchronous damping control signal from the torsional vibration damping controller 100.

[0036] The converter 300 is connected to the stator side of the generator and is used to convert the output signal of the static synchronous compensator controller 200 into a current suitable for the stator side of the generator.

[0037] The drive circuit connects the output of the static synchronous compensator controller 200 to the converter 300 and is used to inject compensation current to suppress subsynchronous oscillations into the generator stator side.

[0038] In summary, the static synchronizing compensator control system acquires speed signals through the generator shaft speed sensor 101. These signals are transmitted to the torsional vibration damping controller 100, where they undergo mode separation and phase compensation processing to generate a subsynchronous damping control signal. This signal can be directly superimposed on the reference voltage input terminal of the voltage outer loop control module or the reference current input terminal of the reactive current control module of the static synchronizing compensator controller 200. Subsequently, the control signal generated by the static synchronizing compensator controller 200 is transmitted to the converter 300 through the drive circuit. The converter 300 injects compensation current into the generator stator side according to the control signal to effectively suppress subsynchronous oscillations and ensure the stability and safety of the power system.

[0039] Furthermore, the circuit board of the static synchronous compensator controller 200 is also equipped with a switching switch 203, whose common terminal is connected to the output terminal of the torsional vibration damping controller 100, and the two outputs are respectively connected to the voltage outer loop reference voltage input terminal 201 and the reactive current reference current input terminal 202.

[0040] Specifically, switch 203 is used to select the injection path of the subsynchronous damping control signal. The common terminal of switch 203 is connected to the output terminal of torsional vibration damping controller 100, and its two output terminals are respectively connected to the voltage outer loop reference voltage input terminal 201 and the reactive current reference current input terminal 202. By switching switch 203, the subsynchronous damping control signal can be directly superimposed onto the voltage outer loop control module reference voltage input terminal or directly superimposed onto the reactive current control module reference current input terminal. By comparing the system performance when the subsynchronous damping control signal is connected to the voltage outer loop control module reference voltage input terminal and the reactive current control module reference current input terminal, the optimal configuration can be selected.

[0041] Furthermore, the outer voltage loop reference voltage input terminal 201 is connected to the non-inverting input terminal of the outer voltage loop PI controller 204, and a signal superposition resistor is connected in series in the connection line between the non-inverting input terminal and the output terminal of the torsional vibration damping controller 100.

[0042] The reactive current reference current input terminal 202 is connected to the non-inverting input terminal of the reactive current loop PI controller 205. A signal isolation optocoupler is connected in parallel between the non-inverting input terminal and the output terminal of the torsional vibration damping controller 100.

[0043] In order to achieve precise injection of the subsynchronous damping control signal, a signal superposition resistor is connected in series in the connection line between the in-phase input terminal and the output terminal of the torsional vibration damping controller 100 to adjust the signal amplitude and matching impedance. At the same time, the reactive current reference current input terminal 202 is connected to the in-phase input terminal of the reactive power loop PI controller 205. A signal isolation optocoupler is connected in parallel between the in-phase input terminal and the output terminal of the torsional vibration damping controller 100 to achieve electrical isolation of the signal and protect the control system from the influence of high voltage or current. This design allows the subsynchronous damping control signal to be safely and effectively injected into the corresponding control loop of the static synchronous compensator controller 200.

[0044] Furthermore, a signal transmission module 206 is provided between the torsional vibration damping controller 100 and the static synchronous compensator controller 200. The signal transmission module 206 is a gigabit transceiver analog output module.

[0045] Furthermore, the digital input terminal of the signal transmission module 206 is connected to the DA conversion interface of the torsional vibration damping controller 100, and the analog output terminal is connected to the AD sampling interface of the static synchronous compensator controller 200.

[0046] Specifically, the digital input terminal of the signal transmission module 206 is directly connected to the digital-to-analog (DA) conversion interface of the torsional vibration damping controller 100 to receive the digital signal processed by the torsional vibration damping controller 100; while its analog output terminal is connected to the analog-to-digital (AD) sampling interface of the static synchronous compensator controller 200 so as to accurately transmit the analog signal to the static synchronous compensator controller 200 for subsequent control processing, and the signal transmission module 206 is connected to the drive circuit and the converter 300.

[0047] Furthermore, the torsional vibration damping controller 100 is also equipped with multiple parallel LC filters 104 and operational amplifiers 103. The center frequencies of the multiple parallel LC filters 104 and operational amplifiers 103 correspond to an inherent torsional vibration frequency of the generator shaft system.

[0048] Furthermore, the inherent torsional frequency is provided with at least three bandpass filters and bandstop filter groups connected in sequence, wherein the output terminals of the bandpass filters and bandstop filter groups are connected to the signal transmission module 206 via a superposition module.

[0049] The torsional vibration damping controller 100 is designed with multiple parallel LC filters 104 and operational amplifiers 103. The center frequencies of these filters and operational amplifiers are matched to an inherent torsional vibration frequency of the generator shaft system to achieve precise control and damping of that frequency. Furthermore, to finely adjust and optimize the damping effect, the processing of the inherent torsional vibration frequency involves at least three sequentially connected bandpass and bandstop filter groups. This design allows the system to allow or block signals within a specific frequency range, thereby more effectively suppressing unwanted vibrations. The outputs of these bandpass and bandstop filter groups are connected to the signal transmission module 206 via a superposition module, ensuring that the processed signal is effectively transmitted to the static synchronous compensator controller 200 to generate appropriate control signals to suppress subsynchronous oscillations and ensure the stability and safety of the power system. Through this design, the torsional vibration damping controller 100 can respond more accurately to the dynamic changes of the generator shaft system, providing more effective vibration control.

[0050] Furthermore, the static synchronous compensator controller 200 is also equipped with a Park inverse transformation module 207, which is used to convert the mode control signal into a three-phase compensation current reference value, and drive the IGBT power unit 209 through the PWM modulation module 208.

[0051] The Park inverse transform module is typically implemented in the software or digital signal processor (DSP) of power electronics and motor control systems.

[0052] The Park inverse transformation module 207 is a mathematical tool used in the fields of power electronics and motor control. It belongs to the category of coordinate transformation and is mainly used to convert signals in the synchronous rotating coordinate system (dq coordinate system) back to the three-phase stationary coordinate system (abc coordinate system).

[0053] The PWM modulation module 208 is generated by the PWM controller. Pulse Width Modulation (PWM) is an electronic control technology widely used in power electronics and motor control. It controls the effective value of the voltage or current output by power electronic equipment by adjusting the switching time of electronic switching devices (such as transistors, MOSFETs, and IGBTs).

[0054] Specifically, the Static Synchronous Compensator (SSC) controller 200 further integrates a Park inverse transformation module 207. This module converts the modal control signal processed by the torsional vibration damping controller 100 and signal transmission module 206 into a reference value for the three-phase compensation current. This process is crucial for ensuring that the SSC controller 200 can accurately inject the required compensation current into the grid. The converted three-phase compensation current reference value is then fed into a PWM (Pulse Width Modulation) modulation module, which generates precise control signals to drive the IGBT (Insulated Gate Bipolar Transistor) power units connected in the SSC controller 200. This achieves precise current compensation on the generator stator side, effectively suppressing subsynchronous oscillations and improving power system stability and power quality. Through this integrated controller design, the entire SSC controller 200 system can respond more flexibly and efficiently to the dynamic demands of the grid, ensuring the stable operation of the power system.

[0055] Furthermore, the band-stop filter bank of the modal processing channel contains two parallel band-stop filters, and the center frequencies of the bandpass filters of each channel are set to 20Hz, 25Hz, and 30Hz, respectively.

[0056] The modal processing channel in the static synchronizing compensator (SRC) control system is designed with two parallel band-stop filters. This configuration enhances the system's anti-interference capability and stability. Each channel is equipped with a bandpass filter, whose center frequencies are precisely set to 20Hz, 25Hz, and 30Hz, respectively. This frequency setting is designed to optimize damping for the specific inherent torsional vibration frequencies of the generator shaft system. This design allows the system to effectively identify and process vibration signals at the corresponding frequencies, thereby achieving precise suppression of subsynchronous oscillations. The combined use of bandpass and band-stop filters ensures that only signals within a specific frequency range can pass through, while interference at other frequencies is effectively filtered out. This signal processing strategy contributes to improving the performance and reliability of the entire SRC control system.

[0057] Working Principle: The generator shaft speed sensor 101 collects the speed signal, which is transmitted to the torsional vibration damping controller 100. Inside the controller, the signal is processed by a mode separation and phase compensation unit, and optimized by multiple parallel LC filters 104, operational amplifiers 103, and bandpass and bandstop filter banks to generate a sub-synchronous damping control signal. This signal is transmitted to the static synchronizing compensator controller 200 via the signal transmission module 206. This controller includes a switching switch 203 to select the signal injection path, injecting the sub-synchronous damping control signal into either the voltage outer loop reference voltage input terminal 201 or the reactive current reference current input terminal 202. The Udc_ref terminal is connected to the non-inverting input terminal of the voltage outer loop PI controller 204 and connected in series with a signal superposition resistor, while the Q_ref terminal is connected to the reactive current reference current input terminal. The non-inverting input of the loop PI controller 205 is connected in parallel with a signal isolation optocoupler. Subsequently, the control signal generated by the static synchronizing compensator controller 200 is transmitted to the converter 300 through the drive circuit. The converter 300 injects compensation current into the generator stator side according to the control signal to suppress subsynchronous oscillation. At the same time, the Park inverse transformation module 207 on the static synchronizing compensator controller 200 converts the modal control signal into a three-phase compensation current reference value, which is then driven by the PWM modulation module 208 to the IGBT power unit 209 to achieve precise current compensation. Finally, the band-stop filter bank of the modal processing channel contains two parallel band-stop filters. The center frequencies of the bandpass filters of each channel are set to 20Hz, 25Hz, and 30Hz, respectively, to optimize the damping effect, thereby improving the performance and reliability of the entire static synchronizing compensator control system.

[0058] It should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A static synchronous compensator control system for suppressing subsynchronous oscillations, characterized in that: include, Torsional vibration damping controller (100), the input terminal of which is electrically connected to generator shaft speed sensor (101); A static synchronizing compensator controller (200) includes a voltage outer loop reference voltage input terminal (201) and a reactive current reference current input terminal (202) disposed on a circuit board; and, A converter (300) is connected to the stator side of the generator. The output of the static synchronous compensator controller (200) is connected to the converter (300) through a drive circuit and is used to inject a compensation current to suppress subsynchronous oscillations into the stator side of the generator. The output terminal of the torsional vibration damping controller (100) is connected to the pad node of the voltage outer loop reference voltage input terminal (201); or the output terminal of the torsional vibration damping controller (100) is connected to the pad node of the reactive current reference current input terminal (202).

2. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 1, characterized in that: The static synchronous compensator controller (200) also includes a switching switch (203) on its circuit board, whose common terminal is connected to the output terminal of the torsional vibration damping controller (100), and the two outputs are respectively connected to the voltage outer loop reference voltage input terminal (201) and the reactive current reference current input terminal (202).

3. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 2, characterized in that: The outer voltage loop reference voltage input terminal (201) is connected to the non-inverting input terminal of the outer voltage loop PI controller (204), and a signal superposition resistor is connected in series in the connection line between the non-inverting input terminal and the output terminal of the torsional vibration damping controller (100).

4. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 2 or 3, characterized in that: The reactive current reference current input terminal (202) is connected to the non-inverting input terminal of the reactive current loop PI controller (205), and a signal isolation optocoupler is connected in parallel between the non-inverting input terminal and the output terminal of the torsional vibration damping controller (100).

5. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 4, characterized in that: A signal transmission module (206) is also provided between the torsional vibration damping controller (100) and the static synchronous compensator controller (200), and the signal transmission module (206) is a gigabit transceiver analog output module.

6. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 5, characterized in that: The digital input terminal of the signal transmission module (206) is connected to the DA conversion interface of the torsional vibration damping controller (100), and the analog output terminal is connected to the AD sampling interface of the static synchronous compensator controller (200).

7. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 5 or 6, characterized in that: The torsional vibration damping controller (100) is also provided with multiple parallel LC filters (104) and operational amplifiers (103); the center frequencies of the parallel LC filters (104) and operational amplifiers (103) correspond to an inherent torsional vibration frequency of the generator shaft system.

8. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 7, characterized in that: The inherent torsional vibration frequency is processed by at least three sequentially connected bandpass filters and bandstop filter groups (210), wherein the bandpass filters and bandstop filter groups (210) form a mode processing channel, and their output terminals are connected to the signal transmission module (206) via a superposition module.

9. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 8, characterized in that: The static synchronous compensator controller (200) is also equipped with a Park inverse transformation module (207) for converting the mode control signal into a three-phase compensation current reference value and driving the IGBT power unit (209) via the PWM modulation module (208).

10. The static synchronous compensator control system for suppressing subsynchronous oscillations as described in claim 9, characterized in that: The band-stop filter bank (210) of the modal processing channel includes two parallel band-stop filters, and the center frequencies of the bandpass filters of each channel are set to 20Hz, 25Hz, and 30Hz, respectively.

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