Wind turbine generator low voltage ride through implementation system based on direct current energy storage and control method

Abstract

The invention provides a wind turbine generator set low voltage ride through implementation system based on direct current energy storage and a control method. The system comprises a wind turbine generator set and a machine side converter used for being connected with the wind turbine generator set. The grid-side converter is used for connecting a power grid; the machine-side converter and the grid-side converter are connected through a direct-current bus, and a set of bidirectional charge-discharge controllable energy storage unit is connected in parallel to the direct-current bus of the wind power converter. In the low voltage period and after the voltage is recovered, the wind turbine generator has better grid-connected characteristics, the low voltage ride through performance is more excellent, and the technical advantages are more remarkable. The method can be well popularized in a wind power direct current side energy storage scheme in the future, and the application prospect is wide.

Description

technical field [0001] The invention relates to the application field of wind power grid-connected technology, in particular to a low-voltage ride-through realization system and control method for wind turbines based on DC energy storage. Background technique [0002] As the proportion of wind power in my country's power grid is getting higher and higher, its impact on the stable operation of the power system cannot be ignored. This requires large-scale grid-connected wind turbines to have good grid adaptability, especially low-voltage ride-through capabilities. If this capability is not available, when the grid voltage is disturbed or faulty, the sudden drop in grid voltage will cause the wind turbines to be cut off in a short time, resulting in a large change in the system power flow, resulting in aggravated fluctuations in grid voltage and frequency, and worsening grid faults. It may even cause a large-scale power outage. [0003] The volatility of wind power generation...

AI Technical Summary

Problems solved by technology

However, there are the following problems in this traditional prior art: 1) During the period of low voltage ride through, the energy released by the frequent short circuit of the resistor will cause the DC bus voltage to fluctuate frequently, which will cause the output power of the grid-side converter to the grid to fluctuate accordingly. It is beneficial to the stability of the grid power; 2) During the period of low voltage ride through, the release resistor consumes most of the energy of the DC bus, and the DC bus only transmits a small part of the power to the grid-side converter, and the active power of the grid is short; when the voltage recovers, The energy of the DC bus is not enough to support the rapid recovery of the output power of the grid-side converter, let alone the excess output of active power, and cannot support the rapid recovery of the active power of the grid; The speed decreases; after the voltage is restored, the generator speed cannot quickly recover to the rated speed, and its output power cannot quickly recover to the rated output power, resulting in a slow recovery of the output power of the wind turbine, which cannot support the rapid recovery of the active power of the grid

4) During the period of low voltage ride through, the traditional DC side energy release scheme causes absolute loss of energy on the DC bus side due to the energy consumption of the energy release resistor, which is not conducive to the rapid recovery and excess output of the wind turbine output power after the voltage recovery

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