Analysis of load rejection transient process based on static efficiency factor for hydraulic unit security assessment

Abstract

Hydraulic units often come across condition changes such as start-up, normal stop and load rejection. Load rejection transient process (LRTP) is one of the running conditions which make the unit and water diversion system in worst operation state. It has great influence on the safety and stability of hydraulic units. A new method called SE-ICNA which is based on Internal Characteristic Numerical Algorithm (ICNA) and static efficiency (SE) iteration is proposed. The analysis of rotating speed rising ratio (RS-RR) and pressure rising ratio (P-RR) in LRTP is mainly discussed for hydraulic unit security assessment. The correctness and rationality of SE-ICNA can be verified by means of Transient Process (TP) analysis on medium and small units within the scope of different water levels. Verification examples proved that this method has an excellent performance for hydraulic unit security assessment in low water level conditions. A conclusion is made that the proposed SE-ICNA method can well assess the security of small hydraulic units in low head conditions.