Wind energy caching low voltage ride through and reactive supporting control method for double-feed draught fan

Abstract

The invention discloses a wind energy caching low voltage ride through and reactive supporting control method for a double-feed draught fan and belongs to the technical field of automatic control over wind driven generators. The purpose of reducing the currents of a rotor is achieved by switching electromagnetic torque reference values in a rotor side (RSC) control circuit under grid faults and temporarily storing surplus wind energy captured under the faults into rotor inertia energy. After the voltage recovers, a traditional circuit is switched back by an RSC, after the switch, overcurrent of the voltage recovery segment is avoided by temporarily limiting the electromagnetic torque of the RSC, and energy balance recovers safely. After a cascading feedback type reactive controller is applied, a fan can also provide reactive supporting safely for a grid in the whole low voltage ride through process. Compared with the prior art, the method is high in control strategy speed, new hardware is not introduced in, fault current in the fan can be effectively reduced, grid leaving time is prolonged, and nearby voltage can be obviously stabilized.

Description

technical field [0001] The invention belongs to the technical field of automatic control of wind power generators. More precisely, the invention relates to a low-voltage ride-through and reactive power support control method of a doubly-fed wind turbine for caching wind energy. Background technique [0002] Doubly-fed wind turbines (doubly-fed wind turbines) are widely used because of their high efficiency, variable speed operation, and independent control of active and reactive power. Under normal working conditions, the optimal wind energy capture control (MPPT) method with optimal wind energy capture as the control goal is widely used in the doubly-fed wind turbine control system, and its schematic diagram is as follows: figure 1 shown. [0003] The MPPT method applies a fifth-order dynamic model, and uses the state equation of formula (1) to describe the generator model: [0004] u ds ...

AI Technical Summary

Problems solved by technology

However, such methods are usually complicated, subject to the negative impact of controller time lag on the tracking process (in extreme cases, the peak value of the fault current may be increased), and the reliability of the algorithm is not high, so it is difficult to be applied in industry

At the same time, the above two types of methods do not consider the problem of wind turbines providing reactive power support to the grid under fault conditions.

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