The Research On An Expert System About On-line Verifying Of Relay Setting

The relay system plays an important role in the power system, and a malfunction in it will lead to huge loss. It's necessary to have rapid and right relays. Now, the EMS system is applied abroad, it meets the demands of on-line verification.This thesis uses the knowledge of power system and computer science to carry out the expert system of on-line verification, and puts forward a mathematics model to accelerate the short-circuit calculation.The method based on the symmetrical components runs well in the conventional symmetrical system, but with the three-phase unbalanced lines and loads appear in the ultra-voltage power system, the phase components operates well. This paper presents an amended way to calculate the fault: separates the network into symmetrical parts and unsymmetrical parts, uses sequence components to simplify the network and phase components to calculate unsymmetrical parts.Because the zero-sequence current relay in the ultra-voltage power system is flimsy when the network is changed, the software is designed to verify the zero-sequence current settings. Under the Visual Basic 6.0 development circumstance, utilizing the ACCESS 2000, the expert system can identify the relay settings quickly when the network is changed. The expert system includes three modules: network parameter database module, network short-circuit calculation module, relay setting value verify module.The third part of the thesis refers the fault calculation method. This part also introduces the interface between the VC and VB. The forth part explains the knowledge base of the expert system, the kb is formed of ACCESS tables. The fifth part introduces the reasoning mechanism, and uses the coordination rules to verify the settings. The part introduces the ADO technology too.The thesis is based on the actual demand of power system. In our country, when the network topology is going to be changed, the dispatch center needs the relay department to calculate and verify the settings, then the operator produce sheets. The process is slow and tends to have mistakes.The software forms the human-machine interface to inform the operator with visualized results, the software is able to secure the operation of power system.