Preventive Control Considering Stability Constraints for Repeated Low Voltage Ride Through Events

Abstract

With the continuous increase in renewable energy penetration, power systems are facing two major challenges: first, the reduction in system voltage stability margin and significantly weakened resilience to disturbances; second, although grid-integration control strategies such as low voltage ride-through (LVRT) in renewable energy units are increasingly critical to system stability, their inherent control limitations introduce new dynamic stability issues that seriously threaten the secure operation of power systems. To address these challenges, this paper proposes a preventive control method that incorporates short-term voltage stability constraints to enhance system stability margins. First, an equivalent model for grid-connected wind power was developed to analyse the mechanism of voltage instability at the point of common coupling (PCC) post-disturbance, summarizing the impact of wind turbine generators on system voltage stability. Furthermore, the system was partitioned based on the admittance matrix, and short-term voltage stability assessment indices suitable for different regions were established. Subsequently, considering the system short-circuit ratio (SCR), static voltage stability constraints, and short-term voltage stability constraints, an optimal preventive control strategy was derived using a particle swarm optimization (PSO) algorithm, with the objective of minimizing control costs. Finally, the proposed preventive control method was validated through three simulation case studies. In the 10-machine 39-bus system and a 100-bus test system, the truncated mean of the voltage deviation index reduction rate reached 61.26% and 47.52%, respectively. Compared to conventional methods, the proposed approach generated more favourable power flow optimization outcomes, effectively enhanced the system's ability to withstand transient disturbances, and provided an engineering-feasible control strategy for future power systems.This paper proposes a preventive control method that considers short-term voltage stability constraints under new power system scenarios. The proposed method effectively enhances the system's capability to mitigate short-term voltage risks and improves voltage stability margins.