Study On Adaptive Protection Considering Wide-area Information

Protective relays are indispensable measures for power system’s safe and steadyoperating. With the fast development of the power industry, the scale of power gird isbecoming larger and larger with more complex structure and the system operation statechanges constantly. The value of traditional protective relays are usually calculated basedon a single measurement point information off-line, which make traditional protection cannot achieve their best performance under various operation states and even fail to protectpower system from accidents. The rise and development of wide-area measurementtechnology provides a new favorable opportunity for solving the problem of using pre-setprotection settings to deal with changing operating environment. With quick access toglobal information of power system, researching on how to improve the adaptability,real-time and reliability performance of protection is a meaningful issue.This paper firstly describes the basic setting calculation principles of conventionalthree-section current protection and distance protection, which indicates that theirreliability and selectivity are achieved by the complex coordination of value and timebetween different sections. As a result, the increasing complex power network may makeconventional protective relays lose their function and even cause a chain of improper trips.Based on the analysis of this problem, the adaptive protection based on wide-areainformation is proposed as an effective solution.Then the paper studies the adaptive protection system from the following two aspects:one is to minimize the computational burden of power system calculation and increasecomputing speed at the same time to ensure real-time, including sensitivity constraintmethod for determining the influence domain, large change sensitivity based powernetwork equivalent decomposition and parallel short circuit calculation method; the otheris to improve the setting rules of protective relay to have better cover range and sensitivityby tracking the change of system states, including adaptive setting algorithms for boththree-section current protection and distance protection. Simulation results verify theeffectiveness of the proposed method.At last, the fault tolerance problem of adaptive protection system in case of data missing is studied, representative data technique is proposed to rebuild the missed datausing wide-area information, and on this basis the priority tripping strategies are proposed,which can improve system reliability by clearing fault accurately and quickly. Simulationanalysis verifies the effectiveness of the proposed method.