Hybrid LVRT Control of Doubly-Fed Variable Speed Pumped Storage to Shorten Crowbar Operational Duration

Crowbar is the most widely used low voltage ride-through (LVRT) solution for doubly-fed variable speed pumped storage (VSPS) unit. However, the conventional crowbar solution suffers from excessive crowbar activation period when applied to large-scale VSPS unit, which leads to the disadvantages of high reactive power absorption and huge electromagnetic torque oscillation. To solve the issue, this article analyzes the condition of crowbar release from the perspective of system controllability. Based on it, a hybrid LVRT control strategy combining crowbar and dynamic demagnetizing control is proposed. In this strategy, the crowbar operational duration can be minimized by optimizing the demagnetizing coefficient dynamically. Moreover, the objective of reactive power support or electromagnetic torque oscillation suppression can be achieved to enhance the transient performance of VSPS unit. Finally, the proposed hybrid LVRT control method is validated by the experiments.