On-line Monitoring System Of The Complete Equipment Of Capacitors

Shunt capacitors are important reactive power compensation equipments, which are widely used in electricity transmission and distribution system.they can improve the power factor of the system effectively, and improve the utilization of the equipments. But the high voltage shunt capacitors are fully loaded and the rated current is heavy while they are running. The capacitive elements are prone to age and damage, then the capacitance value will change. The objective of this paper is to develop a set of on-line monitoring system of the complete equipment of capacitors, in order to realize the condition monitoring of the electricity capacitors. When the fault of the capacitors is detected, the system can tell the reason and the position of the fault.The principle of the on-line monitoring system is that AC voltage and AC current signals are connected to the A/D sampling board through conditioning circuit, then synchronize the sampled data by shifting linear interpolation algorithm, using the FFT algorithm in the digital signal processing can do harmonic analysis. With the RMS of fundamental voltage and fundamental current, the capacitance value of the capacitor at the current time can be obtained. It can be definitely judged that whether the current capacitor is faulted or not with the help of capacitor fault diagnosis algorithm.The control system is based on TI’s OMAP-L138processor, including an ARM9CPU core and a C6748core. The C6748core supports floating-point arithmetic, and it has a strong arithmetic ability. The ARM9processor core provides a high degree of flexibility for developers, with the help of embedded Linux operating system, it can manage the file system easily, and complete the task scheduling.Qt GUI design makes the condition display intuitive, and the human-computer interaction is also very friendly.The monitoring system remains to be further tested and validated to put it into field, but in the laboratory environment, the basic measurement of electrical parameters has reached the requirements of on-line monitoring.