A METHOD OF REACTIVE POWER MEASUREMENT BASED ON HILBERT DIGITAL FILTERING
Zu Yunxiao, Pang Hao, Li Dongxia, Wang Zanji (Tsinghua University, Beijing 100084, China)
A Hilbert digital filtering technique for reactive power measurement is proposed. The method is not only valid in the sinusoidal condition, but also in the non-sinusoidal conditions under certain definition. The reactive power is measured by firstly sampling the voltage and current signals, and then by directly implementing Hilbert digital filtering technique and some simple calculations. The errors introduced by the measurements of the active power and the root-mean-square values of voltage and current in the existing methods can be avoided. In addition, because of the excellent frequency response of the designed Hilbert filter, the high accuracy of the measurement for high harmonics can be guaranteed. Meanwhile, the positive or negative value of the measured reactive power also indicates the load characteristics. Except for A/D conversion from voltage and current signals, all procedures of the algorithm are digitally performed. Hence, the proposed method is simple and easy to be realized. The method has been used in the design of a multi-functional power instrument.