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.
Function Requirements and Structure Properties Analysis of Bi-directional Smart Meter
In this paper,firstly related standards for multifunctional electricity meter and the enterprise standard Q/GDW 354-2009 i.e.,the Functional Specification for Smart Electricity Meters,specified by State Grid Corporation of China,are researched.Considering the requirement during the development of electricity utilization in smart grid and in allusion to huge amounts of single-phase smart electricity meters,several new functional requiments to smart electricity meters are proposed.Secondly,according to the experiences from making prototype of smart electricity meter and its performance tests,the performance analysis on main components and key elements of smart electricity meter is performed and the problems to be paid attention to during the design and application of the components are summarized.Finally,based on the development trend of the latest technologies,a technical solution that could be applied to smart electricity meter is given.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.