| 摘要 |
A method and device for sub-synchronous oscillation (SSO) or sub-synchronous resonance (SSR) protection in wind power plants, which includes: detecting and demodulating mode signals with sub-synchronous frequencies from line current, and then calculating amplitude of mode signals; a control module implements protective functions according to the following three criteria: a) trend judgment based on the sub-synchronous mode signal; when the modes are detected to be divergent, instability protection acts; b) definite time protection based on the sub-synchronous mode amplitude, if duration time during which the signal has large amplitude is more than a set time limit, the protection acts; c) calculating positive sequence sub-synchronous current and negative sequence sub-synchronous current to construct inverse protection criterion; the outputs for the three criterions are independent and can activate a trip breaker of transmission line or bypass series compensating capacitors to avoid power transmission systems or wind turbines suffering damage from SSR/SSO. |
