An anti-power theft method for secondary circuit of energy meter current transformer
At present, power theft ways become increasingly subtle and intelligent. Power theft not only has caused a great loss to the nation and the power sector, but also has brought serious security risks to the equipment and personal health. Although the power theft behavior of the energy meter voltage transformer secondary circuit has been well recognized and effectively suppressed, the anti power theft method for the secondary circuit of the energy meter current transformer is still a weak link. Therefore, this paper proposes a transient method based anti power theft method for the secondary circuit of the energy meter current transformer. This method applied the pulse signal to the secondary circuit of the energy meter current transformer first, then obtained the equivalent resistance and inductance parameter of the circuit by measuring the transient value of the circuit response current. Comparing these parameters with the original parameters of the circuit, we can judge the circuit state and power theft way. The simulation results verify the accuracy and reliability of the proposed method, which is a new anti power theft method of the energy meter.
A novel technique of preventing electricity-stealing in current method for electric power measuring equipment
The novel technique proposed modifies the current coupling device in single-phase or three-phase electric power measuring equipment,and adds two high-frequency coupling windings to each.The high-frequency detection signals generated in electric power measuring equipment are injected into current transformer secondary side.At the same time,the advanced ARM microprocessor is adopted for sampling the high-frequency signals coupled back and real-time computation.It can recognize the normal,opened or shorted state of current transformer secondary side circuit correctly and prevents electricity-stealing in current method effectively.
IEC class 0.5 electronic watt–hour meter implemented with first-order sigma–delta converters
Abstract This paper presents a design of a precise electronic watt–hour meter implemented with first-order sigma–delta analog-to-digital converters. An efficient digital signal-processing circuit is introduced into the design where the whole signal processing is performed directly on an oversampled signal, eliminating the necessity for a decimation filter. It is shown that Gaussian noise, added to the input signal of sigma–delta modulators, decorrelates quantization error of first-order sigma–delta modulators and thus substantially reduces measurement error at low-signal amplitudes. The effect of added noise is analyzed by extensive behavioral simulations for various input signal amplitudes and for various input noise levels. The results show that IEC accuracy class 0.5 can be achieved with first-order sigma–delta converters and digital signal processing in the sigma–delta domain.