The development of monitoring and analyzing system of voltage sag

It is necessary to monitor and analyze the power quality firstly in order to solve the power quality problems in power system, and then the possible reforming project can be put forward for improving power supply quality. According to the actual situation in the region, a system approach to voltage sag monitoring and analyzing has been designed and developed. The system and its composition, software design, network architecture and application effects, etc, are detail introduced, analyzed and discussed in this paper. System software, including front-desk program, the background-desk program, analysis software, adopt homemade advanced unary multi-point voltage sag criterion used for giving more voltage sag characteristics, improves the monitoring accuracy¿second-order Butterworth low-pass filters designed to reduce the impact of the voltage harmonics on the voltage sag detection algorithm, so reduces misjudgment rate during the voltage sag detection. The system has taken a series of measures, including signal acquisition, signal isolation module, anti-jamming, that is why it has a good reliability and stability. In the May 1 2007, a load rejection and voltage sag incident occurred in a 110kV substation, the device accurate records provided significant assistance to the accident analysis. The system meets the design requirements, that is, can be online accurately, high-density monitors the measurement system's three-phase bus voltage. Measurement system can accurately record the system operation state, the voltage sag occurs in the system will be accurate and timely recorded, and be able to regularly analyze the overall operation of the system voltage, it is beneficial to make detailed, scientific judgments and analysis for the system voltage sag and incidents.