储能电站并网线路距离保护的性能分析与协调控制改进方法

Abstract The centralized energy storage power stations play an important role in stabilizing the influence of renewable power fluctuations, regulating system voltage, etc. As we know, the protection, which can quickly and selectively identify the fault, is essential for the power system . However, the four-quadrant operation characteristics of energy storage station have a unique impact on the distance protection performance. In this paper, the operation performance of phase-comparison distance protection under four-quadrant operating characteristics of energy storage station is analyzed, and the strict mathematical relationship between the phase comparison result and positive/negative-sequence d - q -axes currents of the energy storage power conversion system (PCS) is derived. In addition, the effects of positive- and negative-sequence q -axes currents on the phase comparison result and system voltage are analyzed. On this basis, a q -axis current optimization injection strategy (QCOIS) for the energy storage PCS (also applicable to other full-rated power electronic devices) after faults is proposed, which can significantly increase the operation reliability and ability against transition resistance of the distance protection, while with no negative effects on system fault ride-through. Finally, the real-time digital simulation (RTDS) tests are carried out, to fully prove the correctness of the theoretical analysis and superiority of the proposed QCOIS in improving the reliable operation range of distance protection. For example, in the tested case, for the faults at 70 % position of the protected line, the protection ability against transition resistance is increased from 1 Ω to 6 Ω (energy storage in charge state) by QCOIS.