Research On Novel Adaptive Reginal Protection Scheme

Relay protection is the first defense line for power sysetm, and its accurate and quick action is very important to ensure the safety of power grid. For the blackouts happened in the domestic and overseas in recent years, the unreasonable operation of relay is one of the main causes for accident and spread, which eventually becomes a help to prompt the collapse of power grid. In this paper, by applying the idea of strengthening the local protection and simplifing the regional protection, the adaptive primary distance protection and backup distance protection schemes are put forward. On the basis, the regional protection is realized based on adaptive distance protection operating information. The work and results are shown as belows.1) An adaptive primary distance protection scheme based on voltage phase comparison is proposed. The internal fault is distinguished from the external fault is by comparing the angles of fault voltage and compensation voltage. The proposed scheme is immune to system operation modes and transition resistance, and its operation time and setting value error both meet the demand of protection technology. Besides, it has the potential to be applied in real power system because of small computation amount.2) An adaptive backup distance protection scheme based on the impedance complex plane is proposed. The internal fault is distinguished from the external fault by determing whether the fault adaptive protection measured value falls in the operation zone of distance protection. The proposed scheme is immune to fault type, and has good immunity to the transition resistance, which can effectively solve the problem of mal-operation or miss operation of distance protection caused by transition resistance.3) A regional backup protection scheme based on fault idtification fuction is proposed. The fault line is identified by comparing the values of fault idtification fuction of transmission lines in protection area. The proposed scheme is with low requirement of information synchronization by using the adaptive distance protection operating information, and can determine the fault line accurately in the case of some information missing or wrong.The simulation results verify the correctness and effectiveness of the proposed schemes in this paper.