Constant-speed constant-frequency wind turbine low-voltage riding-through device and control method

Abstract

The invention discloses a constant-speed constant-frequency wind turbine low voltage riding-through device and a control method, wherein the device comprises a network system and access switches connected in series between wind turbines; a contactor and a reactive power compensation module which are connected in series are in parallel connection between one switch and one wind turbine; an active power absorbing loop is connected in parallel between the contactor and the reactive power compensation module; and the switches are electronic switches. When the network system is in voltage sag, the switches are cut off, passages of the wind turbines, for feeding active power to the system, are cut off, the active power absorbing loop absorbs active power sent out by the wind turbines, and the reactive power compensation module compensates reactive power required by normal running of the wind turbines. The invention plays a role of restraining influences brought by voltage sags of the network system to the wind turbines, simultaneously enhances the reliability of power supply of a wind plant, and can reduce conditions that fans in the same wind turbine are forced to be cut off completely due to voltage sag of the network system, the practicability is strong, and great economic benefits are brought.

Description

Technical field: [0001] The invention relates to the field of power systems, in particular to a low-voltage ride-through device and a control method for constant-speed and constant-frequency wind turbines. Background technique: [0002] With the rapid development of wind power technology and the emphasis on renewable energy power generation in policies around the world, wind power has entered a period of rapid development. The unit capacity of wind turbines, the scale of wind farms and the share of wind power in the power system are all gradually increasing. The integration of large-scale wind power into the power grid has a certain impact on the planning, construction, operation scheduling, analysis and control, economic operation and power quality of the power grid. In order to promote the orderly development of wind farms and ensure the safe and stable operation of the power system, some power associations or power grid companies in Europe, North America, Australia and o...

AI Technical Summary

Problems solved by technology

First, the power electronic devices in the normal working state must always work under the rated output current of the wind turbine, so the requirements for the IGBT devices are very high, and the cost will suddenly increase, and this shortcoming cannot be overcome by this series DVR solution; Second, it is not difficult to find out only from the number of applicable power electronic devices that this kind of DVR control scheme uses more full-control devices IGBT, which will inevitably lead to the complexity of the control system and the increase of device costs; third, this This control method requires the converter to establish a stable DC voltage, and the establishment of the DC voltage of the converter requires an independent DC charging circuit or relying on the active power generated by the wind turbine when the grid system fails, the former will greatly increase this. The cost and floor area of ​​the set of equipment, the latter will make the control complicated, and both of them need to suppress the overvoltage through the discharge circuit when the wind turbine feeds active power to the DVR device, and maintain the stability of the DC voltage. The difficulty of pressure control has increased

The above points all show that the low-voltage ride-through device based on the DVR principle has many deficiencies and deficiencies in terms of device cost, control complexity, and difficulty in implementing engineering transformation.

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