A method and system for transient simulation of an AC excited variable speed system

Abstract

The application discloses an AC excitation variable-speed system transient simulation method and system, comprising the following steps: constructing an AC excitation variable-speed system stator and grid-side converter double-port independent grid-connection interface model; constructing a doubly-fed asynchronous motor simulation model; constructing an electromechanical transient phase-locked loop model based on grid positive sequence voltage; constructing an AC excitation system rotor-side dynamic model; constructing an AC excitation system rotor-side converter outer loop control strategy set under a vector control framework; constructing an AC excitation system grid-side dynamic model; constructing a voltage ride-through logic independent model; constructing a shaft system model; and establishing an AC excitation variable-speed system simulation model based on the grid-connection interface model, the doubly-fed asynchronous motor simulation model, the electromechanical transient phase-locked loop model, the rotor-side dynamic model, the grid-side dynamic model, the voltage ride-through logic independent model, the shaft system model and the rotor-side converter outer loop control strategy set, and performing simulation calculation based on the AC excitation variable-speed system simulation model.

Description

Technical Field

[0001] This invention relates to the field of power system simulation technology, and more specifically, to a transient simulation method and system for an AC excitation variable speed system. Background Technology

[0002] With the advancement of the "dual-carbon" strategy, the proportion of doubly-fed induction generator (DFIG) wind turbines and variable-speed pumped storage units in the power system has increased dramatically. Both types of equipment adopt rotor AC excitation technology, featuring bidirectional power flow, variable-speed operation, and asynchronous generators in their electrical components. The rotor side achieves rapid adjustment of operating status through back-to-back converters, and they can be collectively referred to as AC-excited DFIG variable-speed units. The high degree of consistency in their operating mechanisms provides a physical basis for breaking the fragmented "one machine, one model" approach. Establishing a unified AC-excited variable-speed system model can comprehensively cover the high-order electrical dynamics and mechanical shaft coupling of wind turbines and pumped storage units, avoiding redundant maintenance, significantly improving simulation efficiency, and meeting the urgent need of new power systems for cross-equipment, easily maintainable simulation tools.

[0003] In existing electromechanical transient simulations of power systems, power electronic equipment is typically simplified. For motors and their AC excitation systems, a reduced-order simplification is usually used, neglecting the effects of phase-locked loops, inner current loops, DC capacitors, and grid-side converter control. Doubly fed wind turbines and AC-excited variable-speed pumped-storage units are modeled independently. The standard electromechanical transient simulation step size used in electromechanical transient simulations is typically 10ms.

[0004] Therefore, there is an urgent need for a unified and high-precision electromechanical transient simulation modeling method for AC excitation variable speed systems. Summary of the Invention

[0005] This invention proposes a transient simulation method and system for AC excitation variable speed systems to solve the problem of how to determine and achieve unified and refined simulation of AC excitation variable speed systems.

[0006] To address the aforementioned problems, according to one aspect of the present invention, a transient simulation method for an AC excitation variable speed system is provided, the method comprising: The AC excitation control system and the asynchronous motor are identified as unified modeling objects. A dual-port independent grid-connected interface model of the stator and grid-side converter of the AC excitation variable speed system is constructed, and the stator-side power and grid-side converter power are allocated based on power flow. Construct a simulation model of a doubly-fed asynchronous motor that considers the operating characteristics of Crowbar protection; Construct an electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid; A dynamic model of the rotor side of an AC excitation system, including a Crowbar protection circuit, a converter, and a converter inner loop control, is constructed, taking into account the modulation ratio saturation characteristics. Under the vector control framework, an outer loop control strategy set for the rotor-side converter of the AC excitation system, which includes different operating modes and different types of equipment, is constructed. Construct a grid-side dynamic model of an AC excitation system that includes a Chopper protection circuit, a converter, and a DC capacitor, taking into account the converter's outer loop control. Construct a voltage ride-through logic-independent model that considers multiple control strategies; Construct an shaft system model containing blocks of different masses; Based on the aforementioned grid-connected interface model, doubly-fed asynchronous motor simulation model, electromechanical transient phase-locked loop model, rotor-side dynamic model, grid-side dynamic model, voltage ride-through logic independent model, shaft system model, and rotor-side converter outer loop control strategy set, an AC excitation variable speed system simulation model is established. Iterative calculations are performed based on the stator-side power and grid-side converter power distribution to determine the final stator and rotor-side voltage, current, and power. Simulation calculations are then performed based on the aforementioned AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power.

[0007] Preferably, the simulation model of the doubly fed asynchronous motor includes: equivalent rotor voltage equation, stator voltage equation, and electromagnetic torque equation considering the influence of Crowbar protection action characteristics; When modeling the generator, the rotor voltage equation is: , When modeling the motor, the rotor voltage equation is: , , , in, and These are the equivalent transient potentials along the d-axis and q-axis, respectively; For stator leakage reactance; and These are the currents along the d-axis and q-axis of the stator, respectively. For rotor leakage reactance; For excitation reactance; For worsening; and These represent the flux linkages along the d-axis and q-axis of the rotor, respectively. and These represent the voltages along the d-axis and q-axis of the rotor, respectively. For rotor resistance; The signal for enabling Crowbar protection can only be 0 or 1. 0 means that Crowbar protection is not enabled, and 1 means that Crowbar protection is enabled. The resistor is for the Crowbar protection circuit; This is the equivalent time constant.

[0008] Preferably, the electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid includes: The real and imaginary parts of the input grid positive-sequence voltage are transformed into xy-dq coordinates to obtain the dq-axis positive-sequence voltage and the q-axis voltage. The input is given to the PI controller to output the angular frequency deviation. The angular frequency deviation is input to the integrator and output to obtain the phase-locked angle for electromechanical transient simulation. The phase-locked loop (PLL) angle is the voltage relative angle; the PLL output angle is the angle used for coordinate transformation between the dq axis and the xy axis, satisfying the following: , in, and These are the real and imaginary parts of the positive sequence voltage, respectively. and These are the positive sequence voltages for the d-axis and q-axis coordinates, respectively.

[0009] Preferably, when the Crowbar protection is activated... The dynamic model of the rotor side of the AC excitation system includes: , When the Crowbar protection signal is activated The dynamic model of the rotor side of the AC excitation system includes: , in, , It is the dq-axis voltage on the AC side of the rotor-side converter; It is a DC voltage; , It is the dq-axis modulation voltage of the rotor-side converter; This refers to the DC-side current of the converter. and These are the currents along the d-axis and q-axis of the rotor, respectively. , These are the reference values ​​for the rotor's d-axis and q-axis currents, respectively. , For the proportional and integral coefficients of the d-axis PI controller in the inner loop control; , For the proportional and integral coefficients of the q-axis PI controller in the inner loop control; , , , , , These represent the output values, minimum and maximum values ​​of the PI controllers controlling the d-axis and q-axis of the inner loop, respectively; Vmax is the maximum modulation ratio. , It is the limiting value of the modulation voltage along the dq axis; , The cross-compensation terms for the inner loop control of the dq axes are specified separately. The equivalent coefficient is... , For rotor leakage reactance; For excitation reactance; For worsening; For stator leakage reactance; , These represent the stator dq axis flux linkages, respectively. , These are the voltages along the d-axis and q-axis of the stator, respectively. , These are the currents along the d-axis and q-axis of the stator, respectively. This is the stator resistance.

[0010] Preferably, the circuit model of the Crowbar protection circuit retains only the control logic portion; Among them, when the rotor current amplitude or DC voltage When the threshold value exceeds the threshold for each type of Crowbar protection, the Crowbar protection activation signal is activated. When the rotor current amplitude or DC voltage When the value is less than the respective threshold for exiting Crowbar protection, or when the time for engaging Crowbar protection exceeds the preset delay time, the Crowbar protection engagement signal is activated. .

[0011] Preferably, the grid-side dynamic model of the AC excitation system includes: , in, This is the current flowing through the DC capacitor; It is a DC capacitor; It is a DC voltage; It outputs active power to the rotor side; To output active power to the grid-side converter; It is a resistor for Chopper protection configuration; This is a signal that Chopper protection has been activated; , This refers to the dq-axis current on the AC side of the grid-side converter. DC voltage control reference value; This is a reference value for reactive power control. This refers to the reactive power of the grid-side converter. , The proportional and integral coefficients of the PI controller are used to control the DC voltage. , For reactive power control, the proportional and integral coefficients of the PI controller are used. , , , These represent the maximum and minimum values ​​of the active and reactive reference currents of the outer loop output dq axis, respectively. It turned worse.

[0012] Preferably, for the Chopper protection circuit, when the DC voltage When the value exceeds the threshold for activating Chopper protection, the Chopper protection activation signal... When DC voltage When the threshold for exiting Chopper protection is less than the threshold, the Chopper protection activation signal is activated. .

[0013] Preferably, wherein The outer loop control strategy set for the rotor-side converter of the AC excitation system includes: active power-related control and reactive power-related control; wherein, the active power-related control includes: constant power control, torque control, speed control, power-speed coordinated control, and power open-loop control; the reactive power-related control includes: reactive power control, constant voltage control, and reactive power open-loop control; different control modes are set with flag bits to enable free switching of control modes according to the operating mode and equipment type.

[0014] Preferably, the method further includes: When starting the simulation calculation, the parameter variables of the simulation model are initialized based on the final stator and rotor side voltage, current and power, and the simulation step size of the model is adaptively corrected during the simulation initialization according to the actual motor parameters and control loop gain. The minimum simulation step size is calculated based on the motor parameters and the gain of the control loop. If the current simulation step size is set Greater than the minimum simulation step size The actual simulation step size is then corrected to the minimum simulation step size. If the current simulation step size is set Less than or equal to the minimum simulation step size The actual simulation step size will then follow the currently set simulation step size. implement.

[0015] According to another aspect of the present invention, a transient simulation system for an AC excitation variable speed system is provided, the system comprising: The grid connection interface construction unit is used to determine the AC excitation control system and the asynchronous motor as unified modeling objects, construct a dual-port independent grid connection interface model of the AC excitation variable speed system stator and grid-side converter, and allocate stator-side power and grid-side converter power based on power flow. The doubly-fed asynchronous motor simulation model building unit is used to build a doubly-fed asynchronous motor simulation model that considers the Crowbar protection action characteristics. The electromechanical transient phase-locked loop model construction unit is used to construct an electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid. The rotor-side dynamic model building unit is used to build a rotor-side dynamic model of an AC excitation system that considers modulation ratio saturation characteristics and includes a Crowbar protection circuit, converter, and converter inner loop control. The control strategy set construction unit, under the vector control framework, constructs an outer loop control strategy set for the rotor-side converter of the AC excitation system, which includes different operating modes and different types of equipment; The grid-side dynamic model building unit is used to build a grid-side dynamic model of the AC excitation system, including the Chopper protection circuit, the converter, and the DC capacitor, taking into account the converter outer loop control. Voltage ride-through logic model building unit, used to build independent voltage ride-through logic models that consider multiple control strategies; Shaft system model building unit, used to build shaft system models containing different mass blocks; The simulation calculation unit is used to establish an AC excitation variable speed system simulation model based on the grid-connected interface model, doubly-fed asynchronous motor simulation model, electromechanical transient phase-locked loop model, rotor-side dynamic model, grid-side dynamic model, voltage ride-through logic independent model, shaft system model, and rotor-side converter outer loop control strategy set. It performs iterative calculations based on the stator-side power and grid-side converter power of the power flow distribution to determine the final stator and rotor-side voltage, current, and power. It also performs simulation calculations based on the AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power.

[0016] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the steps in a transient simulation method for an AC excitation variable speed system.

[0017] According to another aspect of the present invention, the present invention provides an electronic device, comprising: The aforementioned computer-readable storage medium; and One or more processors for executing a program in the computer-readable storage medium.

[0018] This invention provides a transient simulation method and system for an AC excitation variable speed system, comprising: determining the AC excitation control system and the asynchronous motor as unified modeling objects; constructing a dual-port independent grid-connected interface model of the stator and grid-side converter of the AC excitation variable speed system, and allocating stator-side power and grid-side converter power based on power flow; constructing a simulation model of the doubly-fed asynchronous motor considering the Crowbar protection action characteristics; constructing an electromechanical transient phase-locked loop model based on the positive sequence voltage of the grid; constructing a dynamic model of the rotor side of the AC excitation system considering the modulation ratio saturation characteristics, including the Crowbar protection circuit, the converter, and the converter inner loop control; constructing an outer loop control strategy set for the rotor side converter of the AC excitation system, including different operating modes and different types of equipment, under a vector control framework; and constructing a model considering... A grid-side dynamic model of the AC excitation system, including the Chopper protection circuit, converter, and DC capacitor, is constructed for the converter outer loop control. A voltage ride-through logic independent model considering multiple control strategies is constructed. A shaft system model containing different mass blocks is constructed. Based on the grid-connected interface model, doubly-fed asynchronous motor simulation model, electromechanical transient phase-locked loop model, rotor-side dynamic model, grid-side dynamic model, voltage ride-through logic independent model, shaft system model, and rotor-side converter outer loop control strategy set, an AC excitation variable speed system simulation model is established. Iterative calculations are performed based on the stator-side power and grid-side converter power distribution to determine the final stator and rotor-side voltage, current, and power. Simulation calculations are then performed based on the AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power. This invention can simultaneously meet the electromechanical transient simulation requirements of doubly-fed wind turbines, AC-excited variable-speed pumped-storage motors, and excitation systems. It establishes a complete and refined electromechanical transient simulation framework, which adopts modular division, making it convenient for other motor systems with similar structures to expand and reuse their functions on this basis. It lays the foundation for establishing a unified model for photovoltaic, energy storage, direct-drive wind turbines, full-power variable-speed pumped-storage, and other equipment, provides technical reference, comprehensively improves simulation modeling efficiency, and greatly saves development and maintenance workload. Attached Figure Description

[0019] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures: Figure 1 A flowchart of a transient simulation method 100 for an AC excitation variable speed system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the electromechanical transient simulation model framework according to an embodiment of the present invention; Figure 3 A comparison diagram of active power output between the simulation of the present invention and the electromagnetic transient simulation of the doubly fed wind turbine according to an embodiment of the present invention. Figure 4 A comparison diagram of reactive power between the simulation of the present invention and the electromagnetic transient simulation of the doubly fed wind turbine according to an embodiment of the present invention; Figure 5 This is a comparison diagram of rotor current in the simulation and electromagnetic transient simulation of the doubly fed wind turbine according to an embodiment of the present invention; Figure 6 This is a comparison diagram of the modulation voltage in the simulation of the present invention and the electromagnetic transient simulation of the doubly fed wind turbine according to an embodiment of the present invention; Figure 7 This is a comparison chart of the active power of the AC-excited variable-speed pumped-storage unit according to an embodiment of the present invention and the measured curve of the Fengning variable-speed pumped-storage unit. Figure 8 This is a comparison chart of the reactive power of the AC-excited variable-speed pumped-storage unit according to an embodiment of the present invention and the measured curve of the Fengning variable-speed pumped-storage unit. Figure 9 This is a schematic diagram of the transient simulation system 900 of the AC excitation variable speed system according to an embodiment of the present invention. Detailed Implementation

[0020] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0021] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0022] Figure 1 This is a flowchart of a transient simulation method 100 for an AC excitation variable speed system according to an embodiment of the present invention. Figure 1As shown, the transient simulation method for AC excitation variable speed systems provided by the embodiments of the present invention can simultaneously meet the electromechanical transient simulation requirements of doubly-fed wind turbines, AC excitation variable speed pumped storage motors, and excitation systems. It establishes a complete and refined electromechanical transient simulation framework, employing modular division, which facilitates the functional expansion and reuse of other motor systems with similar structures. It lays the foundation for establishing unified models for photovoltaic, energy storage, direct-drive wind turbines, and full-power variable speed pumped storage devices, providing technical references, comprehensively improving simulation modeling efficiency, and significantly saving development and maintenance workload. The transient simulation method 100 for AC excitation variable speed systems provided by the embodiments of the present invention begins at step 101. In step 101, the AC excitation control system and asynchronous motor are determined as unified modeling objects. A dual-port independent grid-connected interface model of the stator and grid-side converter of the AC excitation variable speed system is constructed, and the stator-side power and grid-side converter power are allocated based on power flow.

[0023] In this invention, based on the structural characteristics of doubly-fed turbine units such as doubly-fed wind turbines and AC-excited variable-speed pumped-storage units, a unified module is defined. The AC excitation control system and asynchronous motor are identified as unified modeling objects. A unified and refined electromechanical transient simulation model framework for the AC excitation variable-speed system is established, including the motor body, converter, DC capacitor, control system and protection circuit, and shaft system. Figure 2 As shown. A simulation model is established based on the model framework. One simulation model can meet the requirements of refined electromechanical transient simulation of all doubly-fed induction generator (DFIG) systems, such as doubly-fed wind turbines and AC-excited variable-speed pumped-storage units. The program code is reusable; different devices only need to select appropriate control methods, eliminating the need for repeated modeling. Each component within the simulation framework exists independently, covering existing modules of existing doubly-fed induction generator (DFIG) and AC-excited variable-speed pumped-storage (AC-SGS) electromechanical transient models. Simultaneously, the refined simulation framework can improve existing electromechanical transient simulation modeling, expanding the applicability of electromechanical transient simulation. A dual-port independent voltage source grid-connected interface model for the stator and grid-side converter of the AC-excited variable-speed system is constructed, enabling the stator and grid-side converters to be connected to two different system buses respectively, completing the dual-port topology extension of the model in the electromechanical transient simulation program. Based on power flow calculation, the initial speed is calculated, and the stator-side power and grid-side converter power are pre-allocated according to slip.

[0024] In step 102, a simulation model of a doubly fed asynchronous motor considering the Crowbar protection action characteristics is constructed.

[0025] Preferably, the simulation model of the doubly fed asynchronous motor includes: equivalent rotor voltage equation, stator voltage equation, and electromagnetic torque equation considering the influence of Crowbar protection action characteristics; When modeling the generator, the rotor voltage equation is: , When modeling the motor, the rotor voltage equation is: , , , in, and These are the equivalent transient potentials along the d-axis and q-axis, respectively; For stator leakage reactance; and These are the currents along the d-axis and q-axis of the stator, respectively. For rotor leakage reactance; For excitation reactance; For worsening; and These represent the flux linkages along the d-axis and q-axis of the rotor, respectively. and These represent the voltages along the d-axis and q-axis of the rotor, respectively. For rotor resistance; The signal for enabling Crowbar protection can only be 0 or 1. 0 means that Crowbar protection is not enabled, and 1 means that Crowbar protection is enabled. The resistor is for the Crowbar protection circuit; This is the equivalent time constant.

[0026] In this invention, a simulation model of a doubly fed asynchronous motor that takes into account the Crowbar protection action characteristics is established. The rotor-side voltage equation fully retains the excitation current differential term, while the stator-side current and flux differential terms can be enabled or ignored in reduced order according to the accuracy-speed trade-off. A scalable electrical expression is formed by configuring coefficients.

[0027] The circuit is converted to the stator side, and based on the per-unit principle of the machine capacity and stator voltage, and in accordance with the conventions of generators or motors, the simulation model of the doubly fed asynchronous motor includes the equivalent rotor voltage equation, stator voltage equation and electromagnetic torque equation considering the influence of Crowbar protection operation characteristics.

[0028] When constructing the model according to generator conventions, the equivalent rotor voltage equation considering the influence of Crowbar protection operating characteristics is as follows: , The equivalent stator voltage equation considering automatic order reduction is as follows: in, , , , The electromagnetic torque equation is: , Here, K is a reduction flag, which can only be equal to 1 or 0. If it is equal to 0, it means that only electromechanical transient processes are simulated; if it is equal to 1, it means that electromagnetic transient processes can be simulated. The signal for enabling Crowbar protection can only be 0 or 1. 0 means Crowbar protection is not enabled, and 1 means Crowbar protection is enabled. The resistor is for the Crowbar protection circuit.

[0029] in, , These represent the stator dq-axis voltages, , These represent the stator dq-axis currents, respectively. , These represent the rotor d-axis voltages, respectively. , These represent the rotor d-axis currents, respectively. , These represent the magnetic flux linkages along the rotor's d and q axes, respectively. Represents stator resistance. Represents rotor resistance. Represents stator leakage reactance, Represents rotor leakage reactance, Represents the magnetizing reactance. This indicates a deterioration in the situation.

[0030] When constructing the model according to the conventions for electric motors, the equivalent rotor voltage equation considering the influence of Crowbar protection operating characteristics is as follows: The equivalent stator voltage equation considering automatic order reduction is as follows: , , , The electromagnetic torque equation is: , in, and These are the equivalent transient potentials along the d-axis and q-axis, respectively; For stator leakage reactance; and These are the currents along the d-axis and q-axis of the stator, respectively. For rotor leakage reactance; For excitation reactance; For worsening; and These represent the flux linkages along the d-axis and q-axis of the rotor, respectively. and These represent the voltages along the d-axis and q-axis of the rotor, respectively. For rotor resistance; The signal for enabling Crowbar protection can only be 0 or 1. 0 means that Crowbar protection is not enabled, and 1 means that Crowbar protection is enabled. The resistor is for the Crowbar protection circuit; This is the equivalent time constant.

[0031] In step 103, an electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid is constructed.

[0032] Preferably, the electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid includes: The real and imaginary parts of the input grid positive-sequence voltage are transformed into xy-dq coordinates to obtain the dq-axis positive-sequence voltage and the q-axis voltage. The input is given to the PI controller to output the angular frequency deviation. The angular frequency deviation is input to the integrator and output to obtain the phase-locked angle for electromechanical transient simulation. The phase-locked loop (PLL) angle is the voltage relative angle; the PLL output angle is the angle used for coordinate transformation between the dq axis and the xy axis, satisfying the following: , in, and These are the real and imaginary parts of the positive sequence voltage, respectively. and These are the positive sequence voltages for the d-axis and q-axis coordinates, respectively.

[0033] In this invention, an electromechanical transient phase-locked loop model is constructed. The real and imaginary parts of the positive-sequence voltage of the power grid are input, and the positive-sequence voltage along the dq axis and the voltage along the q axis are obtained through xy-dq coordinate transformation. The input is given to the PI controller to output the angular frequency deviation. The angular frequency deviation is input to the integrator and output to obtain the phase-locked angle for electromechanical transient simulation. This phase-locked loop (PLL) angle is a voltage-relative angle, which differs from the PLL output angle used in electromagnetic transient simulations. The PLL output angle is the angle used for coordinate transformation between the dq axis and the xy axis, satisfying the following: , in, and These are the real and imaginary parts of the positive sequence voltage, respectively. and These are the positive sequence voltages for the d-axis and q-axis coordinates, respectively.

[0034] In step 104, a dynamic model of the rotor side of the AC excitation system, including the Crowbar protection circuit, converter, and converter inner loop control, is constructed, taking into account the modulation ratio saturation characteristics.

[0035] Preferably, when the Crowbar protection is activated... The dynamic model of the rotor side of the AC excitation system includes: , When the Crowbar protection signal is activated The dynamic model of the rotor side of the AC excitation system includes: , in, , It is the dq-axis voltage on the AC side of the rotor-side converter; It is a DC voltage; , It is the dq-axis modulation voltage of the rotor-side converter; This refers to the DC-side current of the converter. and These are the currents along the d-axis and q-axis of the rotor, respectively. , These are the reference values ​​for the rotor's d-axis and q-axis currents, respectively. , For the proportional and integral coefficients of the d-axis PI controller in the inner loop control; , For the proportional and integral coefficients of the q-axis PI controller in the inner loop control; , , , , , These represent the output values, minimum and maximum values ​​of the PI controllers controlling the d-axis and q-axis of the inner loop, respectively; Vmax is the maximum modulation ratio. , It is the limiting value of the modulation voltage along the dq axis; , The cross-compensation terms for the inner loop control of the dq axes are specified separately. The equivalent coefficient is... , For rotor leakage reactance; For excitation reactance; For worsening; For stator leakage reactance; , These represent the stator dq axis flux linkages, respectively. , These are the voltages along the d-axis and q-axis of the stator, respectively. , These are the currents along the d-axis and q-axis of the stator, respectively. This is the stator resistance.

[0036] Preferably, the circuit model of the Crowbar protection circuit retains only the control logic portion; Among them, when the rotor current amplitude or DC voltage When the threshold value exceeds the threshold for each type of Crowbar protection, the Crowbar protection activation signal is activated. When the rotor current amplitude or DC voltage When the value is less than the respective threshold for exiting Crowbar protection, or when the time for engaging Crowbar protection exceeds the preset delay time, the Crowbar protection engagement signal is activated. .

[0037] In this invention, a dynamic model of the rotor side of an AC excitation system is constructed, including a Crowbar protection circuit, a converter, current inner loop control, and saturation characteristics.

[0038] The Crowbar protection circuit model retains only the control logic portion when determining the rotor current amplitude. or (and) DC voltage When the value exceeds the threshold of each Crowbar, When judging the rotor current amplitude or (and) DC voltage If the threshold for exiting Crowbar protection is less than the respective threshold, or if the Crowbar protection is enabled for a period greater than the delay time, .

[0039] when When considering saturation characteristics, the rotor-side dynamic model of the AC excitation system with converter and inner loop control can be expressed as: , in, The equivalent coefficient is... , It is the dq-axis modulation voltage of the rotor-side converter; , , , , , These represent the output values, minimum and maximum values ​​of the PI controllers controlling the d-axis and q-axis of the inner loop, respectively; Vmax is the maximum modulation ratio. , It is the limiting value of the modulation voltage along the dq axis. This refers to the DC-side current of the converter. , It is the dq-axis voltage on the AC side of the rotor-side converter. , These are the reference values ​​for the rotor's d-axis and q-axis currents, respectively. , The cross-compensation terms for the inner loop control of the dq axes are respectively defined. , These represent the stator dq axis flux linkages, , For the proportional and integral coefficients of the d-axis PI controller in the inner loop control, , These are the proportional and integral coefficients of the q-axis PI controller for the inner loop control. , These represent the stator dq axis flux linkages, respectively. , These are the voltages along the d-axis and q-axis of the stator, respectively. , These are the currents along the d-axis and q-axis of the stator, respectively. This is the stator resistance.

[0040] when When the rotor-side converter is locked, the equivalent dynamic model of the rotor side of the AC excitation control system can be expressed as: .

[0041] In step 105, under the vector control framework, an outer loop control strategy set for the rotor-side converter of the AC excitation system, which includes different operating modes and different types of equipment, is constructed.

[0042] Preferably, the outer loop control strategy set of the rotor-side converter of the AC excitation system includes: active power-related control and reactive power-related control; wherein, the active power-related control includes: constant power control, torque control, speed control, power-speed coordinated control and power open-loop control; the reactive power-related control includes: reactive power control, constant voltage control and reactive power open-loop control; different control modes are set with flag bits to realize free switching of control modes according to the operating mode and equipment type.

[0043] In this invention, under the vector control framework, an outer loop control strategy set for the rotor-side converter of the AC excitation system is established, which includes active power-related control and reactive power-related control.

[0044] This control strategy set integrates all existing equipment control modes: active power related control includes constant power control, torque control, speed control, power-speed coordinated control, and power open-loop control; reactive power related control includes constant reactive power control, constant voltage control, and reactive power open-loop control. The control strategy set is scalable, supporting the addition of control logic without affecting the overall structure, and automatically switching control logic when the operating state changes. Different control modes are set with flags, allowing for free switching based on the operating mode and equipment type. Power and speed references in the control loop can be integrated with the equipment's speed control system and collaborative control system; reactive power and voltage references can be coordinated with upper-level control commands.

[0045] For active power control of doubly fed wind turbine units, speed control, torque control, and power control are typically selected.

[0046] For AC-excited variable speed pumped storage control units, speed control, power control, or power-speed coordinated control can be flexibly switched depending on the power generation and pumping operation modes.

[0047] For ease of testing, active power control usually retains open-loop power control.

[0048] In step 106, a grid-side dynamic model of the AC excitation system, including the Chopper protection circuit, the converter, and the DC capacitor, is constructed, taking into account the converter outer loop control.

[0049] Preferably, the grid-side dynamic model of the AC excitation system includes: , in, This is the current flowing through the DC capacitor; It is a DC capacitor; It is a DC voltage; It outputs active power to the rotor side; To output active power to the grid-side converter; It is a resistor for Chopper protection configuration; This is a signal that Chopper protection has been activated; , This refers to the dq-axis current on the AC side of the grid-side converter. DC voltage control reference value; This is a reference value for reactive power control. This refers to the reactive power of the grid-side converter. , The proportional and integral coefficients of the PI controller are used to control the DC voltage. , For reactive power control, the proportional and integral coefficients of the PI controller are used. , , , These represent the maximum and minimum values ​​of the active and reactive reference currents of the outer loop output dq axis, respectively. It turned worse.

[0050] Preferably, for the Chopper protection circuit, when the DC voltage When the value exceeds the threshold for activating Chopper protection, the Chopper protection activation signal... When DC voltage When the threshold for exiting Chopper protection is less than the threshold, the Chopper protection activation signal is activated. .

[0051] In this invention, a grid-side dynamic model of an AC excitation system, including Chopper protection, the converter, and a DC capacitor, is constructed considering the converter's outer loop control. The Chopper protection, in conjunction with the DC capacitor voltage equation and the active power conservation equation, flexibly achieves dynamic simulation of the DC voltage. The grid-side converter's outer loop control employs PI control to output active and reactive currents, which are then limited to simulate the grid-side dynamic characteristics of the AC excitation system.

[0052] , In this case, converter losses are ignored. For rotor-side output active power, To output active power to the grid-side converter, The current flowing through the DC capacitor. It is a DC capacitor. It is a resistor for Chopper protection configuration. DC voltage control reference value, This is a reference value for reactive power control. , , , These represent the maximum and minimum values ​​of the active and reactive reference currents of the outer loop output dq axis, respectively. , To determine the proportional and integral coefficients of the PI controller for constant DC voltage control, , For reactive power control, the proportional and integral coefficients of the PI controller are used. , This refers to the dq-axis current on the AC side of the grid-side converter.

[0053] For the Chopper protection circuit model section, when the DC voltage... When the threshold for inputting into Chopper is exceeded, DC voltage When the threshold for exiting Chopper is less than 1, .

[0054] In step 107, a voltage ride-through logic-independent model considering multiple control strategies is constructed.

[0055] In this invention, an encapsulated, flexible high and low voltage ride-through logic independent model is constructed. This model dynamically corrects the active and reactive current reference values ​​during grid faults and smoothly exits after the fault is cleared to restore normal control.

[0056] In step 108, a shaft system model containing different mass blocks is constructed.

[0057] Preferably, the shaft system model supports modeling in the form of two mass blocks and a single mass block; When modeling is based on a two-mass block form, the shaft system model includes: , , , When modeling is based on a single mass block, the shaft system model includes: , in, For the rotational transducer of the prime mover module; The mechanical torque of the prime mover; For shaft torque; This refers to the speed of the prime mover; This refers to the generator speed; The moment of inertia of the generator module; This refers to the mechanical torque of the generator; The angle difference between the prime mover and the generator module; It is the stiffness coefficient; The damping coefficient; The inertial time constant; This is the per-unit value of the prime mover's mechanical torque; This is the per-unit value of the generator's mechanical torque; This is the per-unit value for rotational speed.

[0058] In this invention, a shaft system model is constructed that is converted to a high-speed shaft or a low-speed shaft. The shaft system model supports different forms such as two-mass blocks and single-mass blocks, and can also be extended to a multi-mass block form. If the mechanical shaft system of a wind turbine or pumped storage is modeled as an equivalent two-mass block form, including a spring-damped system, the dynamic equations of the speed and torsional angle of the prime mover and generator are written, and coupled with the electromagnetic torque equation of the motor.

[0059] The dynamic equations of the shaft system under a nominal value system are: , , , in, It is the mechanical torque of the prime mover. It is the mechanical torque of the generator. The prime mover speed, For generator speed, It is the rotational transduction of the prime mover module. The moment of inertia of the generator module. It is the angle difference between the prime mover and the generator module.

[0060] If a single-mass block model is used, the elasticity and damping coefficients of the shaft are ignored. A per-unit system modeling method is adopted, using the machine capacity and the equivalent rated speed as the reference values. The moment of inertia is converted into an inertial time constant, and the generator inertial time constant and the prime mover inertial time constant are summed to obtain the total shaft system inertial time constant. The dynamic equation of the shaft system under this per-unit system is: , in, It is the per-unit value of the prime mover's mechanical torque. This is the per-unit value of the generator's mechanical torque. This is the per-unit value of the rotational speed. is the inertial time constant.

[0061] In step 109, an AC excitation variable speed system simulation model is established based on the grid-connected interface model, the doubly-fed asynchronous motor simulation model, the electromechanical transient phase-locked loop model, the rotor-side dynamic model, the grid-side dynamic model, the voltage ride-through logic independent model, the shaft system model, and the rotor-side converter outer loop control strategy set. Iterative calculations are performed based on the stator-side power and grid-side converter power of the power flow distribution to determine the final stator and rotor-side voltage, current, and power. Simulation calculations are then performed based on the AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power.

[0062] Preferably, the method further includes: When starting the simulation calculation, the parameter variables of the simulation model are initialized based on the final stator and rotor side voltage, current and power, and the simulation step size of the model is adaptively corrected during the simulation initialization according to the actual motor parameters and control loop gain. The minimum simulation step size is calculated based on the motor parameters and the gain of the control loop. If the current simulation step size is set Greater than the minimum simulation step size The actual simulation step size is then corrected to the minimum simulation step size. If the current simulation step size is set Less than or equal to the minimum simulation step size The actual simulation step size will then follow the currently set simulation step size. implement.

[0063] In this invention, an AC excitation variable speed system simulation model is established based on the constructed grid-connected interface model, doubly-fed asynchronous motor simulation model, electromechanical transient phase-locked loop model, rotor-side dynamic model, grid-side dynamic model, voltage ride-through logic independent model, shaft system model, and rotor-side converter outer loop control strategy set. The model includes a doubly-fed generator unit or an AC excitation variable speed pumped-storage unit. Iterative calculations are performed based on the stator-side power and grid-side converter power of the power flow distribution to determine the final stator and rotor-side voltage, current, and power. Simulation calculations are then performed based on the AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power.

[0064] The process involves calculating rotor current, voltage, and power based on stator power and voltage. Iteration stops when both rotor-side power and grid-side converter power are below a set threshold, determining the final stator and rotor-side voltage, current, and power. Upon initiating the simulation, model parameters are initialized based on the final stator and rotor-side voltage, current, and power. The simulation step size is then adaptively corrected during initialization based on actual motor parameters and control loop gains.

[0065] Specifically, the minimum simulation step size is calculated based on the motor parameters and the gain of the control loop. If the current simulation step size is set Greater than the minimum simulation step size The actual simulation step size is then corrected to the calculated minimum simulation step size. If the current simulation step size is set Smaller than the minimum simulation step size The actual simulation step size is determined according to the simulation settings. implement.

[0066] The transient simulation method for AC excitation variable speed systems proposed in this invention has the following advantages: (1) It can simultaneously meet the electromechanical transient simulation of doubly fed wind turbine, AC excitation variable speed pumped storage motor and excitation system.

[0067] (2) The electrical description is scalable and detailed motor dynamic model, which has a wider simulation range and can respond to the influence of Crowbar protection. It can accurately simulate the characteristics of asynchronous motor at the moment of fault or when the severe fault protection is activated.

[0068] (3) The simulation method of this invention proposes a dynamic model of AC excitation rotor side of phase-locked loop, converter body, converter inner loop and saturation characteristics. It can simulate the coupling characteristics between generator and rotor converter control that are ignored, can simulate the characteristics of 50Hz-200Hz frequency band, can simulate the sub / supersynchronous oscillation problem dominated by current inner loop control, and the current stability problem dominated by current inner loop control and PWM link saturation, and can improve the simulation accuracy of transient overvoltage.

[0069] (4) The simulation method of this invention proposes an AC excitation grid-side dynamic model of DC capacitor, Chopper protection and grid-side converter control, which can simulate the energy buffering process and DC voltage change, as well as the impact of DC voltage dynamic process and grid-side converter control on the transient characteristics of the system.

[0070] (5) The simulation method of the present invention includes the simulation of Crowbar protection, which can simulate the characteristics of the unit after the serious fault hardware protection is put into operation, and accurately reflect the impact of the equipment’s own capacity constraints on the transient characteristics of the system.

[0071] (6) The simulation method of the present invention proposes an adaptive simulation step size correction method, which avoids the problem that the simulation cannot be performed normally due to the mismatch between the set simulation step size and the model, resulting in the distortion of the calculated values.

[0072] In embodiments of the present invention, electromechanical transient simulations are performed on doubly-fed wind turbine generators and AC-excited variable-speed pumped-storage generators according to the above technical route. For example... Figure 3 and 4 The figures shown are comparisons of active and reactive power in the simulation results of this invention and the electromagnetic transient simulation results of the doubly-fed induction generator (DFIG) wind turbine. Figure 5 and 6 The figures shown are comparisons of rotor current and modulation voltage in the simulation results of this invention and the electromagnetic transient simulation results of the doubly-fed induction generator (DFIG) wind turbine. The simulation results show that, under short-circuit fault conditions, excluding the high-frequency characteristics unique to electromagnetic transient simulation, within the electromechanical transient simulation frequency band, considering the high-low voltage surge strategy, the two simulation results not only maintain consistent external power characteristics, but also largely match the simulation results of internal characteristics such as rotor current and modulation voltage.

[0073] like Figure 7 and 8 The figures shown are comparisons of the active and reactive power of the AC-excited variable-speed pumped-storage unit simulation results and the measured curves of the Fengning variable-speed pumped-storage unit. The simulation results show that the simulation results of the AC-excited variable-speed pumped-storage unit are in good agreement with the measured curves. The method proposed in this invention can simultaneously meet the electromechanical transient simulation requirements of both doubly-fed induction generators (DFIGs) and AC-excited variable-speed pumped-storage units.

[0074] Figure 9This is a schematic diagram of the transient simulation system 900 for an AC excitation variable speed system according to an embodiment of the present invention. Figure 9 As shown, the transient simulation system 900 for AC excitation variable speed system provided in this embodiment of the invention includes: a grid-connected interface construction unit 901, a doubly-fed asynchronous motor simulation model construction unit 902, an electromechanical transient phase-locked loop model construction unit 903, a rotor-side dynamic model construction unit 904, a control strategy set construction unit 905, a grid-side dynamic model construction unit 906, a voltage ride-through logic model construction unit 907, a shaft system model construction unit 908, and a simulation calculation unit 909.

[0075] Preferably, the grid connection interface construction unit 901 is used to determine the AC excitation control system and the asynchronous motor as unified modeling objects, construct a dual-port independent grid connection interface model of the AC excitation variable speed system stator and grid-side converter, and allocate stator-side power and grid-side converter power based on power flow.

[0076] Preferably, the doubly fed asynchronous motor simulation model building unit 902 is used to build a doubly fed asynchronous motor simulation model that takes into account the Crowbar protection action characteristics.

[0077] Preferably, the simulation model of the doubly fed asynchronous motor includes: equivalent rotor voltage equation, stator voltage equation, and electromagnetic torque equation considering the influence of Crowbar protection action characteristics; When modeling the generator, the rotor voltage equation is: , When modeling the motor, the rotor voltage equation is: , , , in, and These are the equivalent transient potentials along the d-axis and q-axis, respectively; For stator leakage reactance; and These are the currents along the d-axis and q-axis of the stator, respectively. For rotor leakage reactance; For excitation reactance; For worsening; and These represent the flux linkages along the d-axis and q-axis of the rotor, respectively. and These represent the voltages along the d-axis and q-axis of the rotor, respectively. For rotor resistance; The signal for enabling Crowbar protection can only be 0 or 1. 0 means that Crowbar protection is not enabled, and 1 means that Crowbar protection is enabled. The resistor is for the Crowbar protection circuit; This is the equivalent time constant.

[0078] Preferably, the electromechanical transient phase-locked loop model construction unit 903 is used to construct an electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid.

[0079] Preferably, the electromechanical transient phase-locked loop model construction unit 903 constructs an electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid, including: The real and imaginary parts of the input grid positive-sequence voltage are transformed into xy-dq coordinates to obtain the dq-axis positive-sequence voltage and the q-axis voltage. The input is given to the PI controller to output the angular frequency deviation. The angular frequency deviation is input to the integrator and output to obtain the phase-locked angle for electromechanical transient simulation. The phase-locked loop (PLL) angle is the voltage relative angle; the PLL output angle is the angle used for coordinate transformation between the dq axis and the xy axis, satisfying the following: , in, and These are the real and imaginary parts of the positive sequence voltage, respectively. and These are the positive sequence voltages for the d-axis and q-axis coordinates, respectively.

[0080] Preferably, the rotor-side dynamic model building unit 904 is used to build a rotor-side dynamic model of an AC excitation system that considers modulation ratio saturation characteristics and includes a Crowbar protection circuit, a converter, and converter inner loop control.

[0081] Preferably, when the Crowbar protection is activated... The dynamic model of the rotor side of the AC excitation system includes: , When the Crowbar protection signal is activated The dynamic model of the rotor side of the AC excitation system includes: , in, , It is the dq-axis voltage on the AC side of the rotor-side converter; It is a DC voltage; , It is the dq-axis modulation voltage of the rotor-side converter; This refers to the DC-side current of the converter. and These are the currents along the d-axis and q-axis of the rotor, respectively. , These are the reference values ​​for the rotor's d-axis and q-axis currents, respectively. , For the proportional and integral coefficients of the d-axis PI controller in the inner loop control; , For the proportional and integral coefficients of the q-axis PI controller in the inner loop control; , , , , , These represent the output values, minimum and maximum values ​​of the PI controllers controlling the d-axis and q-axis of the inner loop, respectively; Vmax is the maximum modulation ratio. , It is the limiting value of the modulation voltage along the dq axis; , The cross-compensation terms for the inner loop control of the dq axes are specified separately. The equivalent coefficient is... , For rotor leakage reactance; For excitation reactance; For worsening; For stator leakage reactance; , These represent the stator dq axis flux linkages, respectively. , These are the voltages along the d-axis and q-axis of the stator, respectively. , These are the currents along the d-axis and q-axis of the stator, respectively. This is the stator resistance.

[0082] Preferably, the circuit model of the Crowbar protection circuit retains only the control logic portion; Among them, when the rotor current amplitude or DC voltage When the threshold value exceeds the threshold for each type of Crowbar protection, the Crowbar protection activation signal is activated. When the rotor current amplitude or DC voltage When the value is less than the respective threshold for exiting Crowbar protection, or when the time for engaging Crowbar protection exceeds the preset delay time, the Crowbar protection engagement signal is activated. .

[0083] Preferably, the control strategy set construction unit 905, under the vector control framework, constructs an outer loop control strategy set for the rotor-side converter of the AC excitation system, which includes different operating modes and different types of equipment.

[0084] Preferably, the outer loop control strategy set of the rotor-side converter of the AC excitation system includes: active power-related control and reactive power-related control; wherein, the active power-related control includes: constant power control, torque control, speed control, power-speed coordinated control and power open-loop control; the reactive power-related control includes: reactive power control, constant voltage control and reactive power open-loop control; different control modes are set with flag bits to realize free switching of control modes according to the operating mode and equipment type.

[0085] Preferably, the grid-side dynamic model construction unit 906 is used to construct a grid-side dynamic model of the AC excitation system that includes the Chopper protection circuit, the converter, and the DC capacitor, taking into account the converter outer loop control.

[0086] Preferably, the grid-side dynamic model of the AC excitation system includes: , in, This is the current flowing through the DC capacitor; It is a DC capacitor; It is a DC voltage; It outputs active power to the rotor side; To output active power to the grid-side converter; It is a resistor for Chopper protection configuration; This is a signal that Chopper protection has been activated; , This refers to the dq-axis current on the AC side of the grid-side converter. DC voltage control reference value; This is a reference value for reactive power control. This refers to the reactive power of the grid-side converter. , The proportional and integral coefficients of the PI controller are used to control the DC voltage. , For reactive power control, the proportional and integral coefficients of the PI controller are used. , , , These represent the maximum and minimum values ​​of the active and reactive reference currents of the outer loop output dq axis, respectively. It turned worse.

[0087] Preferably, for the Chopper protection circuit, when the DC voltage When the value exceeds the threshold for activating Chopper protection, the Chopper protection activation signal... When DC voltage When the threshold for exiting Chopper protection is less than the threshold, the Chopper protection activation signal is activated. .

[0088] Preferably, the voltage ride-through logic model building unit 907 is used to build an independent voltage ride-through logic model that considers multiple control strategies.

[0089] Preferably, the shaft system model construction unit 908 is used to construct a shaft system model containing different mass blocks.

[0090] Preferably, the shaft system model supports modeling in the form of two mass blocks and a single mass block; When modeling is based on a two-mass block form, the shaft system model includes: , , , When modeling is based on a single mass block, the shaft system model includes: , in, For the rotational transducer of the prime mover module; The mechanical torque of the prime mover; For shaft torque; This refers to the speed of the prime mover; This refers to the generator speed; The moment of inertia of the generator module; This refers to the mechanical torque of the generator; The angle difference between the prime mover and the generator module; It is the stiffness coefficient; The damping coefficient; The inertial time constant; This is the per-unit value of the prime mover's mechanical torque; This is the per-unit value of the generator's mechanical torque; This is the per-unit value for rotational speed.

[0091] Preferably, the simulation calculation unit 909 is used to establish an AC excitation variable speed system simulation model based on the grid-connected interface model, the doubly-fed asynchronous motor simulation model, the electromechanical transient phase-locked loop model, the rotor-side dynamic model, the grid-side dynamic model, the voltage ride-through logic independent model, the shaft system model, and the rotor-side converter outer loop control strategy set. Iterative calculations are performed based on the stator-side power and grid-side converter power of the power flow distribution to determine the final stator and rotor-side voltage, current, and power. Simulation calculations are then performed based on the AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power.

[0092] Preferably, the simulation calculation unit 909 is further configured to: initialize the parameter variables of the simulation model based on the final stator and rotor side voltage, current and power when starting the simulation calculation, and adaptively correct the simulation step size of the model during the simulation initialization according to the actual motor parameters and control loop gain. The minimum simulation step size is calculated based on the motor parameters and the gain of the control loop. If the current simulation step size is set Greater than the minimum simulation step size The actual simulation step size is then corrected to the minimum simulation step size. If the current simulation step size is set Less than or equal to the minimum simulation step size The actual simulation step size will then follow the currently set simulation step size. implement.

[0093] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the steps in a transient simulation method for an AC excitation variable speed system.

[0094] According to another aspect of the present invention, the present invention provides an electronic device, comprising: The aforementioned computer-readable storage medium; and One or more processors for executing a program in the computer-readable storage medium.

[0095] The transient simulation system 900 of the AC excitation variable speed system in an embodiment of the present invention corresponds to the transient simulation method 100 of the AC excitation variable speed system in another embodiment of the present invention, and will not be described again here.

[0096] According to another aspect of the present invention, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the steps in a transient simulation method for an AC excitation variable speed system.

[0097] According to another aspect of the present invention, the present invention provides an electronic device, comprising: The aforementioned computer-readable storage medium; and One or more processors for executing a program in the computer-readable storage medium.

[0098] The present invention has been described with reference to a few embodiments. However, it will be apparent to those skilled in the art that other embodiments besides those disclosed above fall equivalently within the scope of the present invention.

[0099] Generally, all terms used in this invention are interpreted according to their ordinary meaning in the art, unless otherwise expressly defined herein. All references to “a / the / the [device, component, etc.]” ​​are openly interpreted as at least one instance of said device, component, etc., unless otherwise expressly stated. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless explicitly stated otherwise.

[0100] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. The invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0101] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0102] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0103] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the present invention.

Claims

1. A transient simulation method for an AC excitation variable speed system, characterized in that, The method includes: The AC excitation control system and the asynchronous motor are identified as unified modeling objects. A dual-port independent grid-connected interface model of the stator and grid-side converter of the AC excitation variable speed system is constructed, and the stator-side power and grid-side converter power are allocated based on power flow. Construct a simulation model of a doubly-fed asynchronous motor that takes into account the influence of the Crowbar protection action characteristics; Construct an electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid; A dynamic model of the rotor side of an AC excitation system, including a Crowbar protection circuit, a converter, and a converter inner loop control, is constructed, taking into account the modulation ratio saturation characteristics. Under the vector control framework, an outer loop control strategy set for the rotor-side converter of the AC excitation system, which includes different operating modes and different types of equipment, is constructed. Construct a grid-side dynamic model of an AC excitation system that includes a Chopper protection circuit, a converter, and a DC capacitor, taking into account the converter's outer loop control. Construct a voltage ride-through logic-independent model that considers multiple control strategies; Construct an shaft system model containing blocks of different masses; Based on the aforementioned grid-connected interface model, doubly-fed asynchronous motor simulation model, electromechanical transient phase-locked loop model, rotor-side dynamic model, grid-side dynamic model, voltage ride-through logic independent model, shaft system model, and rotor-side converter outer loop control strategy set, an AC excitation variable speed system simulation model is established. Iterative calculations are performed based on the stator-side power and grid-side converter power distribution to determine the final stator and rotor-side voltage, current, and power. Simulation calculations are then performed based on the aforementioned AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power.

2. The method according to claim 1, characterized in that, The simulation model of the doubly fed asynchronous motor includes: the equivalent rotor voltage equation, stator voltage equation, and electromagnetic torque equation considering the influence of Crowbar protection action characteristics. When modeling the generator, the rotor voltage equation is: ， When modeling the motor, the rotor voltage equation is: ， ， ， in, and These are the equivalent transient potentials along the d-axis and q-axis, respectively; For stator leakage reactance; and These are the currents along the d-axis and q-axis of the stator, respectively. For rotor leakage reactance; For excitation reactance; For worsening; and These represent the flux linkages along the d-axis and q-axis of the rotor, respectively. and These represent the voltages along the d-axis and q-axis of the rotor, respectively. For rotor resistance; The signal for enabling Crowbar protection can only be 0 or 1. 0 means that Crowbar protection is not enabled, and 1 means that Crowbar protection is enabled. The resistor is for the Crowbar protection circuit; This is the equivalent time constant.

3. The method according to claim 1, characterized in that, Construct an electromechanical transient phase-locked loop model based on the positive-sequence voltage of the power grid, including: The real and imaginary parts of the input grid positive-sequence voltage are transformed into xy-dq coordinates to obtain the dq-axis positive-sequence voltage and the q-axis voltage. The input is given to the PI controller to output the angular frequency deviation. The angular frequency deviation is input to the integrator and output to obtain the phase-locked angle for electromechanical transient simulation. The phase-locked loop (PLL) angle is the voltage relative angle; the PLL output angle is the angle used for coordinate transformation between the dq axis and the xy axis, satisfying the following: ， in, and These are the real and imaginary parts of the positive sequence voltage, respectively. and These are the positive sequence voltages for the d-axis and q-axis coordinates, respectively.

4. The method according to claim 1, characterized in that, When the Crowbar protection signal is activated The dynamic model of the rotor side of the AC excitation system includes: ， When the Crowbar protection signal is activated The dynamic model of the rotor side of the AC excitation system includes: ， in, , It is the dq-axis voltage on the AC side of the rotor-side converter; It is a DC voltage; , It is the dq-axis modulation voltage of the rotor-side converter; This refers to the DC-side current of the converter. and These are the currents along the d-axis and q-axis of the rotor, respectively. , These are the reference values ​​for the rotor's d-axis and q-axis currents, respectively. , For the proportional and integral coefficients of the d-axis PI controller in the inner loop control; , For the proportional and integral coefficients of the q-axis PI controller in the inner loop control; , , , , , These represent the output values, minimum and maximum values ​​of the PI controllers controlling the d-axis and q-axis of the inner loop, respectively; Vmax is the maximum modulation ratio. , It is the limiting value of the modulation voltage along the dq axis; , The cross compensation terms for the inner loop control of the dq axes are specified separately. The equivalent coefficient is... , For rotor leakage reactance; For excitation reactance; For worsening; For stator leakage reactance; , These represent the stator dq axis flux linkages, respectively. , These are the voltages along the d-axis and q-axis of the stator, respectively. , These are the currents along the d-axis and q-axis of the stator, respectively. This is the stator resistance.

5. The method according to claim 1, characterized in that, The circuit model of the Crowbar protection circuit retains only the control logic part; Among them, when the rotor current amplitude or DC voltage When the threshold value exceeds the threshold for each type of Crowbar protection, the Crowbar protection activation signal is activated. When the rotor current amplitude or DC voltage When the value is less than the respective threshold for exiting Crowbar protection, or when the time for engaging Crowbar protection exceeds the preset delay time, the Crowbar protection engagement signal is activated. .

6. The method according to claim 1, characterized in that, The grid-side dynamic model of the AC excitation system includes: ， in, This is the current flowing through the DC capacitor; It is a DC capacitor; It is a DC voltage; It outputs active power to the rotor side; To output active power to the grid-side converter; It is a resistor for Chopper protection configuration; This is a signal indicating the activation of Chopper protection; , This refers to the dq-axis current on the AC side of the grid-side converter. DC voltage control reference value; This is a reference value for reactive power control. This refers to the reactive power of the grid-side converter. , The proportional and integral coefficients of the PI controller are used to control the DC voltage. , For reactive power control, the proportional and integral coefficients of the PI controller are used. , , , These represent the maximum and minimum values ​​of the active and reactive reference currents of the outer loop output dq axis, respectively. It turned worse.

7. The method according to claim 1, characterized in that, For the Chopper protection circuit, when the DC voltage... When the value exceeds the threshold for activating Chopper protection, the Chopper protection activation signal... When DC voltage When the threshold for exiting Chopper protection is less than the threshold, the Chopper protection activation signal is activated. .

8. The method according to claim 1, characterized in that, The outer loop control strategy set for the rotor-side converter of the AC excitation system includes: active power-related control and reactive power-related control; wherein, the active power-related control includes: constant power control, torque control, speed control, power-speed coordinated control, and power open-loop control; the reactive power-related control includes: reactive power control, constant voltage control, and reactive power open-loop control; different control modes are set with flag bits to enable free switching of control modes according to the operating mode and equipment type.

9. The method according to claim 1, characterized in that, The method further includes: When starting the simulation calculation, the parameter variables of the simulation model are initialized based on the final stator and rotor side voltage, current and power, and the simulation step size of the model is adaptively corrected during the simulation initialization according to the actual motor parameters and control loop gain. The minimum simulation step size is calculated based on the motor parameters and the gain of the control loop. If the current simulation step size is set Greater than the minimum simulation step size The actual simulation step size is then corrected to the minimum simulation step size. If the current simulation step size is set Less than or equal to the minimum simulation step size The actual simulation step size will then follow the currently set simulation step size. implement.

10. A transient simulation system for an AC excitation variable speed system, characterized in that, The system includes: The grid connection interface construction unit is used to determine the AC excitation control system and the asynchronous motor as unified modeling objects, construct a dual-port independent grid connection interface model of the AC excitation variable speed system stator and grid-side converter, and allocate stator-side power and grid-side converter power based on power flow. The doubly-fed asynchronous motor simulation model building unit is used to build a doubly-fed asynchronous motor simulation model that considers the Crowbar protection action characteristics. The electromechanical transient phase-locked loop model construction unit is used to construct an electromechanical transient phase-locked loop model based on the positive sequence voltage of the power grid. The rotor-side dynamic model building unit is used to build a rotor-side dynamic model of an AC excitation system that considers modulation ratio saturation characteristics and includes a Crowbar protection circuit, converter, and converter inner loop control. The control strategy set construction unit, under the vector control framework, constructs an outer loop control strategy set for the rotor-side converter of the AC excitation system, which includes different operating modes and different types of equipment; The grid-side dynamic model building unit is used to build a grid-side dynamic model of the AC excitation system, including the Chopper protection circuit, the converter, and the DC capacitor, taking into account the converter outer loop control. Voltage ride-through logic model building unit, used to build independent voltage ride-through logic models that consider multiple control strategies; Shaft system model building unit, used to build shaft system models containing different mass blocks; The simulation calculation unit is used to establish an AC excitation variable speed system simulation model based on the grid-connected interface model, doubly-fed asynchronous motor simulation model, electromechanical transient phase-locked loop model, rotor-side dynamic model, grid-side dynamic model, voltage ride-through logic independent model, shaft system model, and rotor-side converter outer loop control strategy set. It performs iterative calculations based on the stator-side power and grid-side converter power of the power flow distribution to determine the final stator and rotor-side voltage, current, and power. It also performs simulation calculations based on the AC excitation variable speed system simulation model and the final stator and rotor-side voltage, current, and power.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-9.

12. An electronic device, characterized in that, include: The computer-readable storage medium as described in claim 11; as well as One or more processors for executing a program in the computer-readable storage medium.

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