A novel operation mode of synchronous motor used as generator in pump station using four-quadrant variable frequency technology

The pump motor is capable of working at generator mode via using frequency units, but operating at this mode cannot maintain the optimum working efficiency at any time. Using the four-quadrant medium voltage converter, the pump motor can work as a generator at the optimum working efficiency all along, and the surge occurred at the transit from motor mode to generator mode of the pump can be avoided at the same time. In the paper, the topology of four-quadrant medium voltage converter and the working principle of pump at generator mode via using the converter are proposed and analyzed. Simulations also have been done to demonstrate the processes of power generation.