CN-121984087-A - Synchronous operation control method and system for wind turbine group sent out through diode rectification

CN121984087ACN 121984087 ACN121984087 ACN 121984087ACN-121984087-A

Abstract

The application provides a synchronous operation control method of a wind turbine group sent out through diode rectification, which comprises the steps of executing machine side converter control and network side converter control on the wind turbine, carrying out decoupling control on active power and reactive power of a permanent magnet generator in the machine side converter control to enable the generator to work in a maximum wind energy capturing area or a constant rotating speed control area, constructing a reactive-frequency virtual rotor equation in the network side converter control to simulate the active-frequency power angle characteristic of a synchronous generator and carrying out synchronous operation of a plurality of wind turbines.

Inventors

YANG RENXIN
ZHANG JIANWEN
CAI XU
SHI GANG
ZHOU JIANQIAO
ZHUO ZHIYU

Assignees

上海交通大学

Dates

Publication Date: 20260505
Application Date: 20260130

Claims (10)

1. A synchronous operation control method of a wind turbine group sent out through diode rectification is characterized by comprising the following steps: controlling a side converter and a network side converter of the wind turbine generator; In the machine side converter control, decoupling control is carried out on active power and reactive power of a permanent magnet generator, so that the generator works in a maximum wind energy capturing area or a constant rotating speed control area; In the control of the grid-side converter, a reactive-frequency virtual rotor equation is constructed, the active-frequency power angle characteristic of the synchronous generator is simulated, and synchronous operation of a plurality of wind turbines is carried out.
2. The method for synchronously controlling the operation of a wind turbine group sent out by diode rectification according to claim 1, wherein in the machine side converter control, decoupling control is performed on active power and reactive power of a permanent magnet generator, so that the generator works in a maximum wind energy capturing area or a constant rotation speed control area, and the method comprises the following steps: acquiring a rotor magnetic field position angle through an encoder, and performing vector transformation; based on rotor magnetic field directional control, a two-stage linkage control structure is adopted to decouple active power and reactive power of the permanent magnet generator; the two-stage linkage control structure comprises cascade control of an active outer ring or a rotating speed outer ring and a q-axis current inner ring and d-axis current inner ring control; the active outer loop is used for tracking an optimal power set value or a preset power command value in an MPPT stage, and the rotating speed outer loop is used for controlling the generator to operate in a constant rotating speed stage and decoupling active power and reactive power through a decoupling coefficient K_f.
3. A method of controlling synchronous operation of a wind turbine group sent out through diode rectification according to claim 1, wherein said constructing a reactive-frequency virtual rotor equation comprises: the DRU of the diode rectification system is equivalent to a nonlinear resistive load, meanwhile, the capacitive reactive power consumption of the system is equivalent to parallel capacitive reactance and the inductive reactive power consumption is equivalent to series inductive reactance, and an overall equivalent impedance model of the DRU system is established; At least two grid-connected type current source wind turbines are used as units, the association relation between the output reactive power of the wind turbines and the current phase angle difference between the wind turbines is deduced, and the dual relation with the active-frequency power angle equation of the synchronous generator is determined; Simulating mechanical inertia and damping control logic of the synchronous generator, and setting virtual inertia and virtual damping control parameters; And taking the deviation amount of the reactive reference value and the actual output reactive of the wind turbine generator as a driving signal, and combining the virtual inertia, the virtual damping and the Laplacian to construct a reactive-frequency virtual rotor equation taking the output frequency of the wind turbine generator as a control target.
4. A method for controlling synchronous operation of a wind turbine group sent out through diode rectification according to claim 3, wherein the reactive-virtual conversion sub-equation is: ; Wherein Q WT is the reactive power output value of the wind turbine, ω is the output frequency of the wind turbine, J is the virtual inertia, D is the virtual damping, Is a reactive power reference value; the equivalent impedance model The method comprises the following steps: ; In the formula, Is the equivalent resistance component of the system; Is the equivalent reactance component of the system, X C is the capacitive reactance, X L is the inductive reactance, j is the imaginary unit; is the equivalent resistance of the alternating current side of the diode rectifying unit.
5. The method for controlling synchronous operation of wind turbines through diode rectification according to claim 1, wherein in the grid-side converter control, the grid-side converter adopts a current source type control architecture, and the current source type control architecture comprises a direct-current voltage outer ring and a current inner ring; the input of the direct-current voltage outer ring is the difference value between the direct-current voltage reference and the direct-current voltage feedback, and the output is the d-axis component reference value of the current inner ring; And the q-axis component reference value of the current inner loop is set to be 0, and the active power output by the grid-side converter is regulated by a direct-current voltage loop and is used for PWM modulation.
6. The method for controlling synchronous operation of wind turbines through diode rectification according to claim 1, wherein in the synchronous operation of a plurality of wind turbines, a batch starting strategy is adopted for the wind turbines, part of wind turbines are started preferentially, when the started wind turbines meet reactive power requirements of an offshore alternating current system, the rest wind turbines are started sequentially, and the rest wind turbines take power from the alternating current system to finish starting.
7. A system for controlling synchronous operation of a wind turbine group sent out by diode rectification according to any one of claims 1 to 6, comprising an offshore wind farm and a diode uncontrolled rectification sending-out system; The offshore wind farm comprises a wind farm current collecting circuit and a plurality of current source control wind turbines, and each wind turbine comprises a machine side converter and a grid side converter; The machine side converter is integrated with an active power and reactive power decoupling control module and is used for carrying out decoupling control on the active power and the reactive power of the permanent magnet generator so that the generator works in a maximum wind energy capturing area or a constant rotating speed control area; the grid-side converter is integrated with a synchronous control module based on a reactive-frequency virtual rotor equation, and is used for constructing the reactive-frequency virtual rotor equation, simulating the active-frequency power angle characteristic of a synchronous generator and synchronously operating a plurality of wind turbines; The diode uncontrolled rectification sending-out system is used for rectifying electric energy of the offshore wind power plant and then conveying the electric energy to an onshore converter station.
8. A synchronous operation control system for a wind turbine farm sent out through diode rectification as defined in claim 7, further comprising reactive compensation and passive filters; The reactive compensation and passive filter is arranged between the offshore wind farm and the diode uncontrolled rectification sending-out system and is used for balancing reactive power of the system and improving electric energy quality.
9. The synchronous operation control system of a wind turbine group sent out through diode rectification according to claim 7, wherein the diode uncontrolled rectification sending-out system comprises a sending-end diode rectifier, a current limiting reactor, a direct current sea cable and a receiving-end soft direct current converter, wherein the diode rectifier is connected with one end of the direct current sea cable through the current limiting reactor, and the other end of the direct current sea cable is connected to the receiving-end soft direct current converter; The transmitting end diode rectifier can adopt n [1] pulse waves DRU, the direct current submarine cable is configured with a corresponding direct current cable resistor Rdc, and the current limiting reactor is used for limiting fault current.
10. The synchronous operation control system of a wind turbine farm sent out by diode rectification according to claim 9, wherein a relation between an ac side line voltage U pcc of the diode rectifier and an onshore side dc voltage U dc and a wind farm active output P WF is: ; Wherein n is the number of pulse DRU, T dru and X dru are the transformation ratio and leakage reactance of the DRU transformer respectively, and R dc is the resistance of the direct current cable.

Description

Synchronous operation control method and system for wind turbine group sent out through diode rectification Technical Field The application relates to the technical fields of offshore wind power, direct current transmission and power electronics, in particular to a method and a system for controlling synchronous operation of wind turbines sent out through diode rectification. Background With the increasing worldwide climate change and energy crisis, the development of clean, renewable energy has become an important strategic goal for sustainable development across countries of the world. The offshore wind power has the remarkable advantages of abundant wind energy resources, stable wind speed, small occupied area, low environmental influence and the like, and is an important direction of wind energy development at present. The flexible direct current transmission technology has the advantages of independent and controllable active and reactive power, no reactive power compensation, low transmission loss and the like, and has more engineering application in offshore wind power transmission in recent years. However, as the grid-connected capacity of the offshore wind farm breaks through GW level and the voltage level rises to +/-500 kV, the offshore converter station becomes a key bottleneck for restricting the economy of soft and direct delivery of the deep offshore wind power. Under the current mainstream technical scheme, the marine converter adopts modularization multi-level topology (Modular Multilevel Converter, MMC), and its submodule quantity is numerous, and submodule electric capacity is huge, leads to the construction cost of marine converter station high. In addition, the complex power modularized structure of MMC and the precise control system not only increase the fault probability, but also significantly increase the operation and maintenance cost of the whole life cycle. Under the background, based on the characteristic that the offshore converter station is in a rectification operation mode for a long time, a diode rectification unit (Diode Rectifier Unit, DRU) is used for replacing MMC, and the construction of an offshore wind power-diode rectification and transmission system (Diode Rectifier Unit High Voltage Direct Current, DRU-HVDC) with low cost and high reliability becomes a current research hot spot. However, DRU cannot establish the voltage of the wind farm collector system, and cannot provide stable phase references for the wind turbines for synchronous operation. In the prior art, the application publication number is CN 114825431A, a grid-connected system is sent out from a wind farm through diode rectification, a plurality of full-power conversion wind turbines are collected in parallel at a sending end converter station based on a diode rectifier, the sending end converter station is connected with an on-shore receiving end converter station, an energy storage device is connected to a converter direct current bus of a part of full-power conversion wind turbines, an alternating current breaker for a collecting line is arranged on an alternating current collecting line between the full-power conversion wind turbines, the sending end station alternating current breaker is arranged on an alternating current side of the sending end converter station, a current limiting reactor is arranged on a direct current side of the on-shore receiving end converter station, and the alternating current side of the on-shore receiving end converter station is connected with an on-shore power grid through a transformer and a receiving end station alternating current breaker. According to the technical scheme, because the electric distance between the wind turbine generators is relatively short, the grid-structured control also faces challenges such as stable operation of multiple parallel machines, transient fault current limiting and the like. In order to make up the defects, research at home and abroad is mainly developed from two technical routes, and the first is to add auxiliary networking equipment, such as a small-capacity MMC, to establish the voltage of a current collecting system so as to realize the synchronous operation of the black start and the phase locking of a fan, but the use of the auxiliary equipment can lead to great economic loss. And secondly, the grid-structured wind turbine generator is adopted to cooperatively establish the voltage of the current collecting system, and an energy storage system or a diesel generator is arranged on part of the wind turbine generator to realize the black start function. However, the control strategy of the grid-connected voltage source type wind turbine generator is not fully mature, and compared with the existing grid-connected current source type wind turbine generator, the control structure of the grid-connected voltage source type wind turbine generator needs to be greatly adjusted, and the control strategy relates to multiple aspects of mec