Start-up of a Varspeed Group in Pump Mode, Practical Implementations and Tests

The present paper addresses the practical implementation in a test bench of different control strategies for the start-up of a varspeed group in pump mode. In varspeed groups using a double-fed induction machine supplied by back to back voltage source inverters (VSI), the possibility exists of using the rotor side VSI to start up the group. The current paper focuses on the start-up strategy and its implementation in a test bench of 3.3 kVA. After presenting the hardware composing the test bench, two different start-up strategies are detailed, which are the field oriented control and critical torque. Those two strategies are then implemented in practice, tested, measured and compared.