The influence of the operation of voltage transformers of 35/10 kV substations on the errors of the electricity consumption accounting system

Abstract

The work is devoted to the issue of the optimal functioning of electricity consumption accounting systems in the conditions of market relations and the related problem of reliable and rational use of the operating modes of voltage transformers. The possibility of organizing the electricity consumption accounting system in the absence of voltage transformers on the high side of the substation was analyzed and the possible under-accounting of electricity in this case was calculated. The influence of the parameters of power transformers on the operation of the commercial electricity accounting system when current and voltage transformers are installed at different voltage levels is studied. It was determined that the loading of the power transformer and the switching scheme of its windings affects the error value of the measuring channels in the automated systems of control and accounting of electricity. If you use the classic T-shaped transformer replacement scheme, you can get the equation for its full power. After making some mathematical transformations, we get a formula that calculates the underaccounting of electrical energy. As we can see, the shortfall is proportional to the voltage drop in the transformer, which depends on the load power. According to the constructed dependences of electric energy underaccounting on the load for several types of power transformers (ТМН-4000/35, TМН-6300/35, TДН-10000/35), it was found that the underaccounting of electricity increases in proportion to the load. For reactive power, it is about an order of magnitude more than for active power. Thus, the formation of the accounting system at substations according to the scheme (Fig. 1) is unacceptable, due to the underaccounting of active and reactive electricity. For the optimal functioning of the accounting systems at the "upper" level, it is necessary to install a voltage transformer on the high side of the substation.