Method and system for improving transient performance of an ac excitation phase modifier

Abstract

The application discloses an alternating-current excitation phase modifier transient performance improving method and system, wherein the method is applied to a rotor side converter in an alternating-current excitation phase modifier excitation system, and the method comprises the following steps: constructing a double closed-loop control model of a power outer ring and a current inner ring according to a mathematical model of the alternating-current excitation phase modifier excitation system; based on the double closed-loop control model, respectively outputting reference values of d-axis rotor current and q-axis rotor current according to reference values of active power and reactive power by using PI controllers on the d-axis and the q-axis of the power outer ring, and respectively outputting d-axis rotor voltage and q-axis rotor voltage according to the reference values of the d-axis rotor current and the q-axis rotor current by using linear active disturbance rejection controllers on the d-axis and the q-axis of the current inner ring; and generating pulse width modulation waves according to the d-axis rotor voltage and the q-axis rotor voltage and outputting the pulse width modulation waves to the alternating-current excitation phase modifier. Through the application, the rapid stability and control precision of current control of the alternating-current excitation phase modifier in a large-scale new energy station under power grid voltage failure are effectively improved.

Description

Technical Field

[0001] The present application belongs to the field of new energy power generation technology, and more specifically, relates to a method and system for improving the transient performance of an AC excitation phase regulator. Background Art

[0002] With the large-scale integration of high-proportion renewable energy, problems such as low grid inertia and weak support have become increasingly prominent. Phase condensers (SCs) have attracted widespread attention for their ability to improve the frequency and voltage of renewable energy. While traditional synchronous SCs can effectively regulate reactive power to maintain grid voltage levels, their response to sudden changes in voltage or frequency is limited by the long time constant of the excitation winding, resulting in limited effectiveness in providing dynamic reactive support and enhancing system inertia.

[0003] Unlike traditional synchronous condensers, AC-excited condensers are motors capable of operating in a controlled asynchronous state. Using appropriate excitation control strategies, they precisely regulate motor speed, active power, and reactive power. AC-excited condensers offer exceptional stability and high speed adaptability, dynamically synchronizing the stator and rotor magnetic fields while decoupling grid frequency from motor speed. This allows the motor to maintain stable operation even in the face of frequency or speed fluctuations, significantly improving grid safety and reliability.

[0004] In the actual application of phase regulators, as the power of the converter increases in large-scale new energy stations, the switching losses continue to increase, and the switching frequency of the converter also needs to be reduced accordingly, which leads to poor control performance of the motor. At the same time, the stator of the AC-excited motor is extremely sensitive to grid voltage disturbances. When a serious grid fault occurs, the electromotive force (EMF) on the rotor side usually far exceeds the DC bus voltage, which may cause rotor-side converter overcurrent and DC bus overvoltage. Current control is the key to the vector control system. Enhancing the control performance of the current loop of the AC-excited phase regulator is crucial to ensure stable operation of the system at low switching frequencies. Therefore, how to improve the rapid stability of current control of the AC-excited phase regulator in new energy stations under grid voltage faults has become an important issue that needs to be solved in the field of new energy power generation technology. Summary of the Invention

[0005] In response to the defects of the existing technology, the purpose of this application is to provide a method and system for improving the transient performance of AC excitation phase regulators, aiming to solve the problem of how to improve the rapid stability of current control of AC excitation phase regulators in new energy stations under grid voltage faults.

[0006] To achieve the above objectives, in a first aspect, the present application provides a method for improving transient performance of an AC excitation phase shifter, the method being applied to a rotor-side converter in an excitation system of an AC excitation phase shifter, the method comprising:

[0007] Based on the mathematical model of the AC excitation phase shifter excitation system, a dual closed-loop control model consisting of an outer power loop and an inner current loop is constructed.

[0008] Based on the dual closed-loop control model, PI controllers are used on the d and q axes of the power outer loop to output reference values ​​of the d and q axis rotor currents according to reference values ​​of active power and reactive power, and linear active disturbance rejection controllers are used on the d and q axes of the current inner loop to output d and q axis rotor voltages according to the reference values ​​of the d and q axis rotor currents.

[0009] A pulse width modulation wave is generated according to the d-axis and q-axis rotor voltages and output to the AC excitation phase shifter.

[0010] In an optional example, outputting the d-axis rotor voltage according to the reference value of the d-axis rotor current using a linear active disturbance rejection controller specifically includes:

[0011] The linear extended state observer in the linear active disturbance rejection controller is used to track and observe the d-axis rotor current and the corresponding total system disturbance to obtain the observed values ​​of the d-axis rotor current and the total system disturbance.

[0012] Utilizing the linear error state feedback control law and disturbance compensation link in the linear active disturbance rejection controller, error feedback and disturbance compensation are performed on the total system disturbance according to the observed values ​​of the d-axis rotor current and the total system disturbance, as well as the reference value of the d-axis rotor current, to obtain the d-axis rotor voltage.

[0013] In an optional example, a linear extended state observer and a linear error state feedback control law are designed based on the following steps:

[0014] According to the mathematical model of the AC excitation phase shifter excitation system, the d-axis rotor current i is determined. rd and d-axis rotor voltage u rd The relationship between them is used to extract the first-order differential equation of the d-axis rotor current; the d- and q-axis coupling terms are regarded as the total disturbance of the system, and the first-order differential equation of the d-axis rotor current is converted into the mathematical model of the linear active disturbance rejection controller:

[0015]

[0016] Where b0 = 1 / σL r ; f is the total disturbance of the system;

[0017] According to the mathematical model of the linear active disturbance rejection controller, the equation for designing the linear extended state observer is:

[0018]

[0019] Where b0 is the estimated value of the controller gain; β1 and β2 are the observer gains, and the parameters of the observer gain are configured according to the bandwidth method: β1 = 2ω o , z1 is i rd The tracking signal of z2 is the tracking signal of f;

[0020] Then the equations for designing the linear error state feedback control law and disturbance compensation link are:

[0021]

[0022] Where, is the reference value of the d-axis rotor current, ω c is the controller bandwidth.

[0023] In an optional example, the method further includes:

[0024] The linear extended state observer equation is analyzed in the frequency domain to obtain the relationship between z1, z2 and the d-axis rotor current and d-axis rotor voltage respectively:

[0025]

[0026] Based on the linear error state feedback control law and the equations of the disturbance compensation link, as well as the relationship between z1 and z2 and the d-axis rotor current and d-axis rotor voltage respectively, the transfer function of the linear active disturbance rejection controller outputting the d-axis rotor voltage is generated:

[0027]

[0028] Where,

[0029] The induced electromotive force e caused by the grid voltage fault on the rotor side r , the voltage drop across the rotor impedance is expressed as:

[0030] u RL =u rd -e r

[0031] According to the AC excitation motor rotor transfer function G(s) under the current inner loop, the relationship between the voltage drop on the rotor impedance and the d-axis rotor current is determined as follows:

[0032] u RL G(s)=i rd

[0033]

[0034] wherein R r is the rotor resistance, σ is the leakage inductance coefficient of the motor, L r is the rotor leakage inductance, and s is the Laplace operator;

[0035] According to the relationship between the voltage drop on the rotor impedance and the d-axis rotor current and the transfer function of the linear active disturbance rejection controller output d-axis rotor voltage, a closed-loop transfer function of the d-axis rotor current with respect to the rotor current reference value and the induced electromotive force is extracted:

[0036]

[0037] Further, the induced electromotive force disturbance transfer function of the current inner loop d-axis under the linear active disturbance rejection control is:

[0038]

[0039] According to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and the phase-frequency characteristics under different controller bandwidths and observer bandwidths are compared to determine the final controller bandwidth and observer bandwidth.

[0040] In an optional example, according to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and the phase-frequency characteristics under different controller bandwidths and observer bandwidths are compared to determine the final controller bandwidth and observer bandwidth, specifically comprising:

[0041] According to the switching frequency range requirement of the rotor-side converter, the upper limit of the controller bandwidth is determined;

[0042] According to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and the phase-frequency characteristics of different controller bandwidths that do not exceed the upper limit are compared first to determine the final controller bandwidth, and then the amplitude-frequency characteristics and the phase-frequency characteristics under different observer bandwidths are compared on the basis of the controller bandwidth to determine the final observer bandwidth.

[0043] In a second aspect, the application provides an alternating current field modulation machine transient performance improvement system, which is applied to a rotor-side converter in an alternating current field modulation machine excitation system, and comprises:

[0044] A model construction module is configured to construct a double-closed-loop control model of a power outer loop and a current inner loop according to a mathematical model of the alternating current field modulation machine excitation system;

[0045] a model application module for outputting reference values ​​of d-axis and q-axis rotor currents using a PI controller based on reference values ​​of active power and reactive power on the d-axis and q-axis of the power outer loop, and outputting reference values ​​of d-axis and q-axis rotor currents using a linear active disturbance rejection controller based on reference values ​​of the d-axis and q-axis rotor currents on the d-axis and q-axis of the current inner loop, based on the dual closed-loop control model;

[0046] The waveform output module is used to generate a pulse width modulation wave according to the d-axis and q-axis rotor voltages and output it to the AC excitation phase shifter.

[0047] In an optional example, the model application module is specifically configured to obtain the d-axis rotor voltage in the following manner:

[0048] The linear extended state observer in the linear active disturbance rejection controller is used to track and observe the d-axis rotor current and the corresponding total system disturbance to obtain the observed values ​​of the d-axis rotor current and the total system disturbance.

[0049] Utilizing the linear error state feedback control law and disturbance compensation link in the linear active disturbance rejection controller, error feedback and disturbance compensation are performed on the total system disturbance according to the observed values ​​of the d-axis rotor current and the total system disturbance, as well as the reference value of the d-axis rotor current, to obtain the d-axis rotor voltage.

[0050] In a third aspect, the present application provides an electronic device comprising: at least one memory for storing programs; and at least one processor for executing the programs stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method described in the first aspect or any possible implementation of the first aspect.

[0051] In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method described in the first aspect or any possible implementation of the first aspect.

[0052] In a fifth aspect, the present application provides a computer program product, which, when executed on a processor, enables the processor to execute the method described in the first aspect or any possible implementation of the first aspect.

[0053] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0054] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0055] The present application provides a method and system for improving the transient performance of an AC excitation phase regulator. By constructing a dual closed-loop control model of a power outer loop and a current inner loop, linear anti-disturbance control is adopted on the d and q axes of the rotor side current inner loop respectively to obtain the d and q axis rotor voltages, and then a stable pulse width modulation wave is generated based on the d and q axis rotor voltages and output to the AC excitation phase regulator, thereby effectively improving the rapid stability and control accuracy of the current control of the AC excitation phase regulator in large-scale new energy stations under grid voltage faults, improving the system's resistance to internal and external interference, ensuring the stable operation of the system at low switching frequencies, and thereby improving the operational safety and reliability of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is one of the flow charts of the method for improving the transient performance of an AC excitation phase shifter provided in an embodiment of the present application;

[0057] Figure 2 This is the second flow chart of the method for improving the transient performance of the AC excitation phase shifter provided in the embodiment of the present application;

[0058] Figure 3 This is a frame design diagram of the rotor-side converter of the AC excitation phase shifter excitation system provided in an embodiment of the present application;

[0059] Figure 4 This is a diagram showing the internal structure of a linear active disturbance rejection controller provided in an embodiment of the present application;

[0060] Figure 5 This is a simplified block diagram of the LADRC current loop provided by an embodiment of the present application;

[0061] Figure 6 This is a Bode diagram comparison of the interference rejection of LADRC control and PI control provided in the embodiment of the present application;

[0062] Figure 7 This is a comparison diagram of rotor current and power simulation waveforms using PI and LADRC control when a grid voltage fault occurs, as provided in an embodiment of the present application;

[0063] Figure 8 This is a comparison diagram of simulated waveforms of rotor three-phase current controlled by PI and LADRC when a grid voltage fault occurs, as provided in an embodiment of the present application;

[0064] Figure 9 This is a comparison diagram of simulated waveforms of rotor three-phase voltage controlled by PI and LADRC when a grid voltage fault occurs, as provided in an embodiment of the present application;

[0065] Figure 10 This is an architecture diagram of a system for improving transient performance of an AC excitation phase shifter provided in an embodiment of the present application;

[0066] Figure 11It is a structural diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0068] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0069] Linear Active Disturbance Rejection Control (LADRC) is based on the core concept of the Linear Extended State Observer (LESO), and estimates and compensates for the total disturbance inside and outside the system in real time, including model uncertainty and external disturbances. This method dynamically estimates the system state and disturbance by observing the system input and output, and then effectively compensates for the disturbance in the design of the Linear State Error Feedback (LSEF) control law. The control law design of LADRC adopts a simplified linear feedback form, aiming to compensate for the disturbance through appropriate control input to ensure that the system output tracks the desired reference trajectory or maintains a stable state. It can significantly improve the system's resistance to internal and external disturbances and further optimize the handling of the uncertain parts of the model.

[0070] To this end, the present application provides a method for improving the transient performance of an AC excitation phase shifter, which is applied to the rotor-side converter in the excitation system of the AC excitation phase shifter. Figure 1 This is one of the flow charts of the method for improving the transient performance of an AC excitation phase shifter provided in the embodiment of the present application, such as Figure 1 As shown, the method includes the following steps:

[0071] Step S101, constructing a dual closed-loop control model of a power outer loop and a current inner loop according to a mathematical model of an AC excitation phase shifter excitation system;

[0072] Step S102: Based on the dual closed-loop control model, PI controllers are used on the d and q axes of the power outer loop to output reference values ​​of the d and q axis rotor currents according to reference values ​​of active power and reactive power, and linear active disturbance rejection controllers are used on the d and q axes of the current inner loop to output reference values ​​of the d and q axis rotor currents according to the reference values ​​of the d and q axis rotor voltages.

[0073] Step S103 : generating a pulse width modulation wave according to the d-axis and q-axis rotor voltages, and outputting the pulse width modulation wave to an AC excitation phase shifter.

[0074] Specifically, the excitation system of the AC excitation phase regulator can be composed of an AC power supply, a rotor converter and a phase regulator; the rotor-side converter includes a power outer loop and a current inner loop; the power outer loop includes PI controllers corresponding to the d and q axes, respectively, which are used to perform PI control according to the reference values ​​of active power and reactive power, respectively, to obtain the reference values ​​of the d and q axis rotor currents; the current inner loop includes linear active disturbance rejection controllers corresponding to the d and q axes, respectively, which are used to perform linear active disturbance rejection control according to the reference values ​​of the d and q axis rotor currents, respectively, to obtain the d and q axis rotor voltages.

[0075] It should be noted that linear active disturbance rejection control is a model-free control with strong practical application capabilities and good adaptability to the complex mathematical model of AC excitation phase-shifting machine under grid voltage faults. Compared with traditional PI control, linear active disturbance rejection control has a stronger suppression effect on the induced electromotive force disturbance on the rotor side, effectively improving the control accuracy of AC excitation phase-shifting machine under grid voltage faults.

[0076] The method provided in the embodiment of the present application constructs a dual closed-loop control model of a power outer loop and a current inner loop, adopts linear anti-disturbance control on the d and q axes of the rotor side current inner loop respectively, obtains the d and q axis rotor voltages, and then generates a stable pulse width modulation wave based on the d and q axis rotor voltages and outputs it to the AC excitation phase regulator, thereby effectively improving the rapid stability and control accuracy of the current control of the AC excitation phase regulator in large-scale new energy stations under grid voltage faults, improving the system's resistance to internal and external interference, ensuring the stable operation of the system at low switching frequency, and thereby improving the operational safety and reliability of the power grid.

[0077] Based on the above embodiment, the d-axis rotor voltage is output according to the reference value of the d-axis rotor current using a linear active disturbance rejection controller, which specifically includes:

[0078] The linear extended state observer in the linear active disturbance rejection controller is used to track and observe the d-axis rotor current and the corresponding total system disturbance to obtain the observed values ​​of the d-axis rotor current and the total system disturbance.

[0079] Utilizing the linear error state feedback control law and disturbance compensation link in the linear active disturbance rejection controller, error feedback and disturbance compensation are performed on the total system disturbance according to the observed values ​​of the d-axis rotor current and the total system disturbance, as well as the reference value of the d-axis rotor current, to obtain the d-axis rotor voltage.

[0080] Correspondingly, the q-axis rotor voltage can be obtained in a similar way.

[0081] Based on any of the above embodiments, the linear extended state observer and the linear error state feedback control law are designed based on the following steps:

[0082] According to the mathematical model of the AC excitation phase shifter excitation system, the d-axis rotor current i is determined. rd and d-axis rotor voltage u rd The relationship between them is used to extract the first-order differential equation of the d-axis rotor current; the d- and q-axis coupling terms are regarded as the total disturbance of the system, and the first-order differential equation of the d-axis rotor current is converted into the mathematical model of the linear active disturbance rejection controller:

[0083]

[0084] Where b0 = 1 / σL r ; f is the total disturbance of the system;

[0085] According to the mathematical model of the linear active disturbance rejection controller, the equation for designing the linear extended state observer is:

[0086]

[0087] Where b0 is the estimated value of the controller gain; β1 and β2 are the observer gains, and the parameters of the observer gain are configured according to the bandwidth method: β1 = 2ω o , z1 is i rd The tracking signal of z2 is the tracking signal of f;

[0088] Then the equations for designing the linear error state feedback control law and disturbance compensation link are:

[0089]

[0090] Where, is the reference value of the d-axis rotor current, ω c is the controller bandwidth.

[0091] Based on any of the above embodiments, the further comprising:

[0092] The linear extended state observer equation is analyzed in the frequency domain to obtain the relationship between z1, z2 and the d-axis rotor current and d-axis rotor voltage respectively:

[0093]

[0094] Based on the linear error state feedback control law and the equations of the disturbance compensation link, as well as the relationship between z1 and z2 and the d-axis rotor current and d-axis rotor voltage respectively, the transfer function of the linear active disturbance rejection controller outputting the d-axis rotor voltage is generated:

[0095]

[0096] Where,

[0097] The induced electromotive force e caused by the grid voltage fault on the rotor side r , the voltage drop across the rotor impedance is expressed as:

[0098] u RL =u rd -e r

[0099] According to the AC excitation motor rotor transfer function G(s) under the current inner loop, the relationship between the voltage drop on the rotor impedance and the d-axis rotor current is determined as follows:

[0100] u RL G(s)=i rd

[0101]

[0102] Where R r is the rotor resistance, σ is the leakage inductance coefficient of the motor, L r is the rotor leakage inductance, s is the Laplace operator;

[0103] Based on the relationship between the voltage drop on the rotor impedance and the d-axis rotor current, as well as the transfer function of the d-axis rotor voltage output by the linear active disturbance rejection controller, the closed-loop transfer function of the d-axis rotor current with respect to the rotor current reference value and the induced electromotive force is extracted:

[0104]

[0105] Then, the induced electromotive force disturbance transfer function of the d-axis of the inner current loop under linear active disturbance rejection control is extracted as follows:

[0106]

[0107] According to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and phase-frequency characteristics under different controller bandwidths and observer bandwidths are compared to determine the final controller bandwidth and observer bandwidth.

[0108] It can be understood that by mathematically analyzing the tracking and disturbance characteristics of a current-loop linear active disturbance rejection control system containing a controlled object under grid voltage fault conditions, we obtain the current-loop closed-loop transfer function for the rotor current with respect to the induced electromotive force disturbance term. The first term of this transfer function reflects the control system's tracking performance with respect to the rotor current reference value, while the second term reflects the effect of the EMF disturbance on the rotor current. This allows us to derive the EMF disturbance transfer function of the current inner-loop control system under LADRC control, i.e., the transfer function expression for the effect of the induced electromotive force disturbance on the rotor current. The current-loop active disturbance rejection control system is the current inner-loop active disturbance rejection control system using a linear active disturbance rejection controller. The controlled object is the rotor of an AC-excited motor.

[0109] Based on the transfer function expression and Bode plot of the induced electromotive force (EMF) disturbance affecting the rotor current, key factors influencing disturbance rejection control are identified, and the parameter settings for the reconstructed current loop active disturbance rejection control (ADRC) are optimized. These parameters specifically refer to the controller bandwidth and observer bandwidth. The controller bandwidth is the bandwidth of the linear ADRC controller, and the observer bandwidth is the bandwidth of the linear extended state observer (LESO). The Bode plot allows analysis of the amplitude-frequency and phase-frequency characteristics at different bandwidths. If the amplitude-frequency and phase-frequency characteristics at multiple bandwidths are similar, the minimum bandwidth can be used as the final bandwidth.

[0110] Correspondingly, the controller bandwidth and observer bandwidth corresponding to the q-axis can be obtained in a similar manner, which will not be described in detail in the embodiments of the present application.

[0111] It should be noted that, within the low bandwidth constraints of high-power converters, a Bode plot is derived from the closed-loop transfer function of the rotor current with respect to the induced electromotive force disturbance. This Bode plot allows for the rapid determination of the ideal setting range or value for the observer and controller bandwidths of the active disturbance rejection controller. This improves the control performance of the linear active disturbance rejection controller for AC field condensers during grid voltage faults, enabling rapid and precise current control. Furthermore, this method simplifies the parameter tuning process of traditional linear active disturbance rejection controllers, enabling the rapid determination of the ideal controller parameter range.

[0112] Based on any of the above embodiments, according to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and phase-frequency characteristics under different controller bandwidths and observer bandwidths are compared to determine the final controller bandwidth and observer bandwidth, specifically including:

[0113] Determine the upper limit of the controller bandwidth based on the switching frequency range requirements of the rotor-side converter;

[0114] According to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and phase-frequency characteristics of different controller bandwidths that do not exceed the upper limit are first compared to determine the final controller bandwidth. Then, based on the controller bandwidth, the amplitude-frequency characteristics and phase-frequency characteristics under different observer bandwidths are compared to determine the final observer bandwidth.

[0115] For example, if the switching frequency range of the converter is required to be 1000Hz-2000Hz, 200Hz can be determined as the upper limit of the current loop controller bandwidth. Determining the ideal controller bandwidth within this upper limit can ensure control performance at low switching frequencies.

[0116] Based on any of the above embodiments, the present application proposes a method for improving the transient performance of an AC excitation phase regulator, the purpose of which is to improve the rapid stability of current control of the AC excitation phase regulator in a new energy station under a grid voltage fault. Figure 2 This is the second flow chart of the method for improving the transient performance of the AC excitation phase shifter provided in the embodiment of the present application, such as Figure 2 As shown, it is described in detail below:

[0117] In this embodiment of the present application, a simulation experiment is conducted using a 15MW AC-excited condenser as an example. The rotor current loop of the AC-excited condenser adopts a linear active disturbance rejection control strategy. The main parameters of the excitation system and controller of the AC-excited condenser are shown in Table 1.

[0118] Table 1 Main parameters of AC excitation phase shifter excitation system and controller

[0119] parameter symbol Numerical parameter symbol Numerical Rated power <![CDATA[P N ]]> 15MW Stator leakage inductance <![CDATA[L s ]]> 0.17lpu Rated grid line voltage <![CDATA[U g ]]> 690V Rotor resistance <![CDATA[R r ]]> 0.005pu Rated grid frequency f g ]]> 50Hz Rotor leakage inductance <![CDATA[L r ]]> 0.156pu DC bus voltage <![CDATA[U dc ]]> 1200V Mutual Induction <![CDATA[L m ]]> 2.902pu DC capacitors C 10mF Controller bandwidth <![CDATA[ω c ]]> 100 stator resistance <![CDATA[R s ]]> 0.007pu Observer bandwidth <![CDATA[ω0]]> 300

[0120] S1. Establish a mathematical model of the excitation system of the AC excitation phase shifter;

[0121] In specific implementation, the AC excitation phase condenser excitation system proposed in this application is composed of an AC power supply, a rotor-side converter, and a phase condenser. The converter adopts a power outer loop and a current inner loop control, such as Figure 3 The frame design diagram of the rotor-side converter of the AC excitation phase condenser excitation system provided by the embodiment of the present application is shown. The voltage and current relationship of the AC excitation phase condenser excitation system is:

[0122]

[0123] Where u rd and u rq are the d-axis and g-axis components of the rotor three-phase voltage; R r is the rotor resistance; i rd and i rq are the d-axis and g-axis components of the rotor three-phase current; σ is the leakage inductance coefficient of the motor; L r and L s Divided into rotor and stator leakage inductance; ω r is the rotor angular frequency;

[0124] From formula (1), the first-order differential equations of the rotor currents of the AC excitation phase shifter d and q axes can be obtained as follows:

[0125]

[0126] S2. Build a linear active disturbance rejection controller consisting of a linear extended state observer and a linear error state feedback control law. Combined with the mathematical model of the AC excitation phase condenser excitation system, a current loop active disturbance rejection control system is constructed.

[0127] Furthermore, the current loop active disturbance rejection control system adopts a linear active disturbance rejection controller to perform active disturbance rejection control of the current inner loop.

[0128] Furthermore, the linear extended state observer estimates the state variables of the AC excitation phase shifter excitation system and the total disturbance inside and outside the system in real time, including model uncertainty and external disturbances; the internal and external disturbances of the system are obtained through the linear extended state observer, and the influence of the disturbance on the system is eliminated by using the disturbance compensation link.

[0129] Furthermore, the linear error state feedback control law realizes error feedback and effective compensation of the total disturbance of the AC excitation phase shifter excitation system according to the input and output obtained by the observation system;

[0130] The AC excitation phase condenser excitation system controls the rotor side current of the AC excitation phase condenser through a linear active disturbance rejection controller, and the current inner loop control loop predicts and controls the system state quantity and internal and external disturbances based on the rotor current of the AC excitation phase condenser excitation system and the differential signal of the rotor current.

[0131] In specific implementation, the internal structure diagram of the linear active disturbance rejection controller provided in the embodiment of the present application is as follows: Figure 4 As shown, it consists of a linear extended state observer and an error state feedback control law;

[0132] According to the excitation system model of the AC excitation phase shifter of S1, taking the d-axis rotor current as an example, LADRC control is adopted in the current inner loop. rd is the state variable, and the output of the controller is u rd , considering the d-axis and q-axis coupling terms as disturbances, equation (2) can be written as:

[0133]

[0134] Where b0 = 1 / σL r ; is the total disturbance of the system.

[0135] Write equation (3) in state space form:

[0136]

[0137] Where x1 = i rd, x2=f; control gain b0=1 / σL r .

[0138] According to the mathematical model of the linear active disturbance rejection controller in state space form, the linear extended state observer of the current loop linear active disturbance rejection controller is designed as follows:

[0139]

[0140] Where b0 is the estimated value of the controller gain; β1 and β2 are the observer gains; z1 is the value of i rd ’s tracking signal; z2 is the tracking signal of f.

[0141] The linear active disturbance rejection controller offsets the impact of disturbance on the system through the linear extended state observer feedback, so b0u rd =u0-f, where u0 is u rd Initial value. At the same time, according to the bandwidth method, the parameter configuration of the observer gain is β1=2ω o , ω o is the observer bandwidth.

[0142] After disturbance compensation, the current loop can be equivalent to an integral link, and the linear error state feedback control law and disturbance compensation link are designed as follows:

[0143]

[0144] Where, ω c is the controller bandwidth.

[0145] In specific implementation, since the d-axis and q-axis rotor current equations are similar, the above design is also applicable to i rq .

[0146] S3. Based on the above-mentioned current loop active disturbance rejection control system, the electromagnetic transient process of the AC excitation phase shifter under grid voltage fault is introduced, and the rotor-side induced electromotive force disturbance is introduced to construct a transient excitation control model for the AC excitation phase shifter. The closed-loop transfer function of the current loop including the controlled object is derived from the transient model.

[0147] The rotor voltage can be decomposed into two parts, namely the voltage drop u on the rotor impedance RL The electromotive force e induced by the stator flux r In order to more clearly express the transient model of AC excitation phase shifter, equation (1) is reconstructed as:

[0148]

[0149] in, Represents the induced electromotive force, Lm is the mutual inductance between stator and rotor; s is the stator flux.

[0150] When a three-phase voltage fault occurs in the power grid, the induced electromotive force (EMF) will generate transient components, resulting in overvoltage and overcurrent. At this time, the EMF can be expressed as:

[0151]

[0152] Where ψ0 is the initial value of magnetic flux, τ s =L s / * s is the stator time constant, p is the grid voltage drop depth, s1 is the slip rate, and V0 is the initial value of the voltage at t=0.

[0153] Furthermore, according to equations (7) and (8), equation (2) can be reconstructed as:

[0154]

[0155] The induced electromotive force is introduced into the total disturbance as:

[0156]

[0157] Furthermore, the LADRC current loop closed-loop transfer function containing the controlled object is derived. The LESO tracks the total disturbance f through z2, which can be obtained analytically according to Equation (5):

[0158]

[0159] Combining equations (6) and (11), we can get the LADRC output u rd The transfer function is:

[0160]

[0161] Where,

[0162] The voltage drop on the rotor impedance is obtained from equation (7):

[0163] u RL =u rd -e r (13)

[0164] From equations (12) and (13) and the relationship between the voltage drop on the rotor impedance and the d-axis rotor current, we can get: Figure 5The simplified block diagram of the LADRC current loop provided by the embodiment of the present application is shown. The pulse width modulation wave is simplified without considering the adjustment. The current loop block diagram includes the simplified entire control link. The controlled object G(s) is specifically the rotor transfer function of the AC excitation phase-shifting motor. Figure 5 The closed-loop transfer function of the rotor current with respect to the current reference and the EMF disturbance can be extracted:

[0165]

[0166] Wherein, the first term reflects the tracking performance of the control system to the rotor current reference value, and the second term reflects the influence of EMF disturbance on the rotor current.

[0167] S4. Based on the above-mentioned current loop closed-loop transfer function containing the controlled object and its Bode diagram, provide key factors affecting anti-disturbance control and optimize the parameter settings of the current loop anti-disturbance control.

[0168] Furthermore, the closed-loop transfer function of the current loop containing the controlled object is mathematically analyzed for tracking and disturbance characteristics according to the current loop linear active disturbance rejection control system under grid voltage fault to obtain a closed-loop transfer function of the rotor current about the rotor current reference value and the induced electromotive force disturbance term.

[0169] Furthermore, the key factors affecting anti-disturbance control are provided as follows: under the low bandwidth limitation of the high-power converter, the Bode diagram of the induced electromotive force disturbance term to the rotor current is obtained through the current loop closed-loop transfer function, and the key factors affecting anti-disturbance control, namely the observer bandwidth and the controller bandwidth, are analyzed and proposed.

[0170] Furthermore, the parameters of the optimized current loop active disturbance rejection control are set to quickly determine the ideal setting range of the observer bandwidth and controller bandwidth of the active disturbance rejection controller through the Bode diagram, thereby improving the control performance of the linear active disturbance rejection controller of the AC excitation phase regulator during the grid voltage fault process and realizing fast and accurate current control.

[0171] Under traditional PI control, the EMF disturbance transfer function of the current inner loop control system is:

[0172]

[0173] Where,

[0174] According to formula (14), under LADRC control, the EMF disturbance transfer function of the current inner loop control system is:

[0175]

[0176] According to formula (15), (16), the amplitude-frequency and phase-frequency characteristics of the induced electromotive force to the rotor current under PI control and LADRC control are obtained, as shown in the following table. Figure 6 As shown in the Bode diagram of LADRC control and PI control anti-interference provided by the embodiment of the application, no matter the amplitude-frequency characteristic or the phase-frequency characteristic, the LADRC control is better than the PI control. Figure 6 The lower the response degree of the induced electromotive force disturbance is, the smaller the phase lag degree of the system is, and the stronger the anti-grid voltage capability of the control method is.

[0177] The parameter optimization first combines the requirement of low switching frequency (1000 Hz-2000 Hz) of the converter in the megawatt wind power system, and takes 200 Hz as the upper limit of the current loop controller bandwidth. Then, the Bode diagrams under different controller bandwidths and observer bandwidths are obtained, as shown in (a) and (b) in the following table. Figure 6 It is found that the change of the observer bandwidth has a greater influence on the anti-interference performance of the linear active disturbance rejection controller, and is a key factor affecting the anti-interference control performance.

[0178] Further, the bandwidth range is continuously reduced within the parameters of ideal control effect, and the initial observer bandwidth parameter range is obtained through iteration. The initial observer bandwidth parameter range is shown in the gray shadow part in the following table. Figure 6 In this area, the anti-interference performance of the LADRC control is stronger than that of the PI control, and the greater the bandwidth is, the stronger the anti-interference performance is. However, too large observer bandwidth will cause oscillation of the system, so the minimum bandwidth under similar anti-interference performance is selected as the optimization direction. Finally, the optimized controller parameters are brought into the simulation model for verification, and the parameter setting process is simplified.

[0179] Comparative experiment

[0180] Specifically, three-phase short-circuit fault is applied to the grid voltage, so that the voltage drops to 70% of the normal voltage, and the fault duration is 1.5 s. The PI controller and the linear active disturbance rejection controller with the optimized parameters are simulated and compared, as shown in the following table. Figure 7 , 8 , 9.

[0181] Figure 7 The simulation waveform comparison chart of the rotor current and power under PI and LADRC control when the grid voltage fails is provided by the embodiment of the application, wherein (a) is the simulation waveform comparison chart of the d-axis and q-axis rotor current, and (b) is the simulation waveform comparison chart of the rotor active power and reactive power. It is found that under the LADRC control, the grid voltage disturbance of the rotor current, the rotor active power and the rotor reactive power is more strongly suppressed, and the LADRC controller has better transient control performance than the PI controller.

[0182] Figure 8 , 9The following are comparison diagrams of the rotor three-phase current simulation waveforms and the rotor three-phase voltage simulation waveforms using PI and LADRC control when the grid voltage fails, respectively, as provided in the embodiments of the present application. It is found that LADRC has significantly improved control effects on rotor current and voltage compared with PI control under grid voltage failure.

[0183] In summary, compared with the prior art, this application has the following advantages:

[0184] This application addresses the problem of difficulty in quickly and accurately controlling the current of AC excitation phase-shifting condensers in large-scale new energy stations. A method for improving the transient performance of AC excitation phase-shifting condensers is proposed. LADRC control is used in the rotor-side current inner loop. System disturbances are observed and compensated through an extended state observer, improving the problem that traditional PI controllers cannot adaptively adjust nonlinearity and are greatly affected by grid voltage. Compared to traditional PI control, LADRC is a model-free control with strong practical application capabilities and good adaptability to the complex mathematical models of AC excitation phase-shifting condensers under grid faults. The parameter optimization method effectively simplifies the parameter tuning process of traditional linear active disturbance rejection controllers and can quickly and accurately determine the ideal parameter range of linear active disturbance rejection controllers. Compared with PI control, the linear active disturbance rejection control has a stronger suppression effect on rotor-side induced electromotive force disturbances, effectively improving the rotor current control accuracy under grid voltage faults. This application provides technical support for the safe and stable operation of new energy stations, promotes the sustainable development of new energy, and produces good ecological benefits.

[0185] Based on any of the above embodiments, the present application provides a system for improving transient performance of an AC excitation phase shifter, which is applied to a rotor-side converter in an excitation system of an AC excitation phase shifter. Figure 10 This is an architecture diagram of the system for improving the transient performance of AC excitation phase shifter provided in the embodiment of the present application. Figure 10 As shown, the transient performance improvement system includes:

[0186] A model building module 1010 is used to build a dual closed-loop control model of a power outer loop and a current inner loop based on a mathematical model of an AC excitation phase shifter excitation system;

[0187] A model application module 1020 is configured to, based on the dual closed-loop control model, output reference values ​​of the d-axis and q-axis rotor currents using a PI controller on the d-axis and q-axis of the outer power loop according to reference values ​​of active power and reactive power, and output reference values ​​of the d-axis and q-axis rotor voltages using a linear active disturbance rejection controller on the d-axis and q-axis of the inner current loop according to the reference values ​​of the d-axis and q-axis rotor currents;

[0188] The waveform output module 1030 is used to generate a pulse width modulation wave according to the d-axis and q-axis rotor voltages, and output the pulse width modulation wave to the AC excitation phase shifter.

[0189] It is understandable that the detailed functional implementation of each of the above modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0190] Based on the method in the above embodiment, an embodiment of the present application provides an electronic device. Figure 11 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application, such as Figure 11 As shown, the electronic device may include: a processor 1110, a communication interface 1120, a memory 1130, and a communication bus 1140, wherein the processor 1110, the communication interface 1120, and the memory 1130 communicate with each other via the communication bus 1140. The processor 1110 may call the logic instructions in the memory 1130 to execute the method in the above embodiment.

[0191] In addition, the logic instructions in the above-mentioned memory 1130 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0192] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0193] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0194] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0195] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0196] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in or transmitted by a computer readable storage medium. The computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through a wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) manner. The computer readable storage medium can be any available medium accessible by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media sets. The available media can be a magnetic medium (such as a floppy disk, a hard disk, a magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)), etc.

[0197] It can be understood that various numerical numbers involved in the embodiments of the present application are only distinguished for convenience of description, and are not used to limit the scope of the embodiments of the present application.

[0198] Those skilled in the art easily understand that the above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for improving the transient performance of an AC excitation phase shifter, characterized in that: The method is applied to a rotor-side converter in an AC excitation phase shifter excitation system, and the method comprises: Based on the mathematical model of the AC excitation phase shifter excitation system, a dual closed-loop control model consisting of an outer power loop and an inner current loop is constructed. Based on the dual closed-loop control model, PI controllers are used on the d and q axes of the power outer loop to output reference values ​​of the d and q axis rotor currents according to reference values ​​of active power and reactive power, and linear active disturbance rejection controllers are used on the d and q axes of the current inner loop to output d and q axis rotor voltages according to the reference values ​​of the d and q axis rotor currents. Generate a pulse width modulation wave according to the d-axis and q-axis rotor voltages, and output it to the AC excitation phase shifter; The method further includes: The linear extended state observer equation is analyzed in the frequency domain to obtain 、 and the d-axis rotor current and the d-axis rotor voltage The relationship between: in, for tracking signal; is the tracking signal of the total disturbance of the system; is the observer bandwidth, is the Laplace operator; According to the linear error state feedback control law and the equation of the disturbance compensation link, and 、 The relationship between the d-axis rotor current and the d-axis rotor voltage is used to generate the transfer function of the linear active disturbance rejection controller outputting the d-axis rotor voltage: Where, , ; in, is the controller gain, is the controller bandwidth, is the reference value of the d-axis rotor current; The induced electromotive force caused by the grid voltage fault on the rotor side , the voltage drop across the rotor impedance is expressed as: ; According to the rotor transfer function of the AC excitation motor under the current inner loop , determine the relationship between the voltage drop on the rotor impedance and the d-axis rotor current: Where, is the leakage inductance coefficient of the motor, is the rotor leakage inductance, is the rotor resistance; Based on the relationship between the voltage drop on the rotor impedance and the d-axis rotor current, as well as the transfer function of the d-axis rotor voltage output by the linear active disturbance rejection controller, the closed-loop transfer function of the d-axis rotor current with respect to the rotor current reference value and the induced electromotive force is extracted: Then, the induced electromotive force disturbance transfer function of the d-axis of the inner current loop under linear active disturbance rejection control is extracted as follows: According to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and phase-frequency characteristics under different controller bandwidths and observer bandwidths are compared to determine the final controller bandwidth and observer bandwidth.

2. The method according to claim 1, characterized in that Outputting a d-axis rotor voltage according to a reference value of the d-axis rotor current using a linear active disturbance rejection controller specifically includes: The linear extended state observer in the linear active disturbance rejection controller is used to track and observe the d-axis rotor current and the corresponding total system disturbance to obtain the observed values ​​of the d-axis rotor current and the total system disturbance. Utilizing the linear error state feedback control law and disturbance compensation link in the linear active disturbance rejection controller, error feedback and disturbance compensation are performed on the total system disturbance according to the observed values ​​of the d-axis rotor current and the total system disturbance, as well as the reference value of the d-axis rotor current, to obtain the d-axis rotor voltage.

3. The method according to claim 2, characterized in that The linear extended state observer and linear error state feedback control law are designed based on the following steps: According to the mathematical model of the AC excitation phase shifter excitation system, the D-axis rotor current is determined and d-axis rotor voltage The relationship between them is used to extract the first-order differential equation of the d-axis rotor current; the d- and q-axis coupling terms are regarded as the total disturbance of the system, and the first-order differential equation of the d-axis rotor current is converted into the mathematical model of the linear active disturbance rejection controller: Where, the controller gain is ; is the total disturbance of the system; According to the mathematical model of the linear active disturbance rejection controller, the equation for designing the linear extended state observer is: Where, is the observer gain, and the parameters of the observer gain are configured according to the bandwidth tuning method: , ; Then the equations for designing the linear error state feedback control law and disturbance compensation link are: Where, , for Initial value.

4. The method according to claim 1, wherein Based on the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and phase-frequency characteristics under different controller bandwidths and observer bandwidths are compared to determine the final controller bandwidth and observer bandwidth. Specifically, the following are performed: Determine the upper limit of the controller bandwidth based on the switching frequency range requirements of the rotor-side converter; According to the induced electromotive force disturbance transfer function, the amplitude-frequency characteristics and phase-frequency characteristics of different controller bandwidths that do not exceed the upper limit are first compared to determine the final controller bandwidth; Then, based on the controller bandwidth, the amplitude-frequency characteristics and phase-frequency characteristics under different observer bandwidths are compared to determine the final observer bandwidth.

5. A system for improving transient performance of AC excitation phase shifter, characterized in that: include: at least one memory for storing a computer program; At least one processor is used to execute the program stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method according to any one of claims 1 to 4.

6. An electronic device, characterized in that: include: at least one memory for storing a computer program; At least one processor is used to execute the program stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method according to any one of claims 1 to 4.

7. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed on a processor, the processor is caused to execute the method according to any one of claims 1 to 4.

8. A computer program product, characterized in that When the computer program product is run on a processor, the processor is enabled to perform the method according to any one of claims 1 to 4.

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