Research On Electric Energy Metering In The Syestem Of Multi-harmonic Source

The electric energy is the main energy of the national economy and people’s lives, it plays a very important role to the development of the country. The measurement data involves the tripartite economic benefits of generating electricity, supplying power and using. It is also important bases that a lot of technical indicators are calculated. At present, with a large amount of application in non-linear loads, such as electric and electronic devices etc. The voltage, current wave form is often deviated from sine wave. So the harmonic receives the general concern of each side to the research of measuring influence of electric energy.On the base of the existing research results of subject, the influence of harmonic is analyzed correctly in this text from electric energy measure accuracy and electric energy measure rationality two angles. A lot of work have been done in this paper, explain it as follows in detail.Energy metering devices consist of energy meters and its accompanying devices such as voltage transformer and current transformer. This paper introduces the structure and principle of energy metering devices, and analyzes the causes of errors produced in the harmonic conditions on this basis. The result shows that: The error frequency characteristic curves of inductive energy meter present a descendant trend, so it can measure the fundamental power and part of the harmonic power; frequency characteristic curves of the electronic energy meter are much flatter than those of inductive energy meter, showing a broadband response characteristic, therefore, it can measure the fundamental power and all the harmonic energy; when distorted current and voltage signal pass through the transformer, the conversion ratio of each harmonic component is inconsistent, and signals entering the meters will deviate from practical values, resulting in the increase of error from the measurement results.Starting from the flow direction of the harmonic energy, the paper points out the unreasonableness of the existing energy metering mode by deducing the electrical consumption of linear load and nonlinear load on the basis of multi-harmonic source. MATLAB/SIMULINK simulation is carried out under different backgrounds and harmonic conditions, and the different harmonic emission levels of nonlinear load are obtained by changing the angle of the rectifier circuit. The paper discusses the harmonic power direction of linear load and nonlinear load under various situations, and further analyzes the effect of harmonic trend on reasonableness of various metering mode, with relevant conclusions drawn. Finally, an energy metering mode based on the non-linearity degree is recommended to avoid additional losses of linear load caused by measurement of power harmonic.On the other hand, for non-linear load charges will not be reduced because of the measurement of negative harmonic power, and corresponding punishment will be given. And consumers should be forced to take some measure to reduce the harmonic injected into the grid by effectively giving some economic means.