Method for braking in series for frequency-conversion speed-regulating wind power generation water pumping system

Abstract

The invention relates to a method for braking in series for a frequency-conversion speed-regulating wind power generation water pumping system. A braking unit which is composed of a braking resistor and an electronic switch in parallel is connected to the positive electrode of a direct current bus in a frequency-conversion controller, and is connected with the flat wave capacitor of the direct current bus in series; a control unit in the frequency-conversion controller detects the voltage Udc1 of the input end of the direct current bus, the voltage Udc2 of the output end of the direct currentbus and the operation state of a water pump; when the water pump operates at a full speed, and the voltage Udc1 of the input end is greater than a limited value ULtd, the control unit regulates the on-state duty ratio Don of the electronic switch so as to further regulate the power ad pressure drop of the braking unit, thus the voltage Udc2 of the output end is stable at the limited value ULtd; and at the same braking capacity, the wind power generation water pumping system adopting the serial braking method provided by the invention has greater safe operation region, and the water pumping system can keep normal operation at a greater wind speed.

Description

technical field [0001] The invention relates to a frequency-variable speed-regulating wind power generation water lifting system, in particular to a braking method applied to a frequency conversion speed regulating wind power water lifting system under high wind speed conditions, and belongs to the technical field of wind power generation. Background technique [0002] Wind water pumping is widely used in drinking water for humans and animals, irrigation of agriculture, forestry and pastures, seawater salt production and breeding, desert control, etc. It is one of the earliest forms of wind energy utilization and has a long history. The construction and development of my country's remote areas without electricity, as well as the control and management of large deserts, urgently need to solve the water problem. Compared with erecting a power grid or using a photovoltaic water pumping system, the wind power water pumping system is easy to construct, occupies less land, and has...

AI Technical Summary

Problems solved by technology

[0023] The parallel braking method can effectively control the braking power, realize low-speed operation of the wind turbine under high wind speed by suppressing the speed of the wind turbine, and prevent overvoltage. In direct proportion, a small increase in wind speed will lead to a rapid increase in output power, so the brake circuit must have a large enough capacity

On the other hand, the speed of the permanent magnet synchronous generator remains unchanged but the output power increases, which means that the output current increases proportionally, and overcurrent can easily cause permanent demagnetization of the permanent magnet in the generator.

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