Fault handling system of doubly-fed wind generator set and generator set structure

Abstract

The invention provides a fault handling system of a doubly-fed wind generator set and a generator set structure. The fault handling system of the doubly-fed wind generator set controls sequential on-off of three-phase electronic switches K1, K2, K3 and K4 according to the condition that common connection points generate drop faults, and meanwhile according to a fault handling logic controller, a mild fault handling controller or an in-depth fault handling controller is selected to work. According to the fault handling system of the doubly-fed wind generator and the generator structure, a hardware circuit is arranged, and a software control strategy is improved so that the doubly-fed wind generator set can achieve different levels of voltage drop fault ride-through; the fault handing system of the doubly-fed wind generator set is additionally arranged to provide reactive power; dynamic overvoltage and overcurrent of a generator side converter control can be effectively inhibited; complex hardware devices are not needed to be added, the control method is easy, and the fault handling system is convenient for engineering practice; harmonic pollution of the 102 alternating current side of a back-to-back PWM converter is reduced, the start-stop number of a doubly-fed wind generator (DFIG) is reduced, and certain technical support is provided for mass application of the doubly-fed wind generator set.

Description

technical field [0001] The invention relates to a structure of a doubly-fed wind turbine, in particular to a fault handling system and a structure of a doubly-fed wind turbine. Background technique [0002] The penetration rate of wind turbines connected to the power system continues to increase, and it is necessary to improve their fault ride-through capability to meet the requirements of the grid safety operation guidelines "Technical Regulations for Wind Farms Connected to Power Systems GB / T19963-2011" promulgated by the State Grid Corporation of China. As one of the main models of variable-speed constant-frequency wind power generation technology, the operation capability (namely, the fault ride-through capability) of the doubly-fed wind turbine using the doubly-fed generator DFIG when the PCC voltage fails at the common connection point needs to be improved. [0003] The fault ride-through capability of the doubly-fed wind turbine is limited by the capacity of the back-...

AI Technical Summary

Problems solved by technology

[0010] 1. Improve the control technology of back-to-back PWM converters, which can only realize the fault ride-through of the doubly-fed wind turbine in a small range, and cannot realize the fault ride-through when the voltage of the common connection point drops deeply.

[0011] 2. Using the crowbar crowbar protection circuit for double-fed wind turbine fault ride-through technology, when the crowbar crowbar protection circuit is put into operation, the back-to-back PWM converters on the rotor side of the double-fed generator DFIG quit working, and the back-to-back PWM converters lose power. The control effect on the doubly-fed generator DFIG cannot provide reactive power support for the voltage recovery of the common connection point

[0012] 3. The method of adding an unloading chopper protection circuit or a super capacitor on the DC side of the back-to-back PWM converter cannot effectively suppress the dynamic overvoltage and overcurrent of the machine-side converter

[0013] 4. The method of installing auxiliary devices on the stator side of the doubly-fed generator DFIG increases the hardware cost, and the problem of coordinated control must also be considered

[0014] 5. Only install three-phase electronic switches between the stator side and the rotor side of the doubly-fed generator DFIG and the AC side of the machine-side converter and the grid-side converter, which will cause the doubly-fed generator when the common connection point voltage fails The frequent start and stop of DFIG is not conducive to the control of doubly-fed generator DFIG. At the same time, back-to-back PWM converters will generate a certain amount of harmonic pollution while generating reactive power.

Images