ELECTRONICALLY CONTROLLED POWER TRANSFORMER (ECPT) FOR ELECTRIC TRANSMISSION LINE TO CONSUMER WITH VARIABLE LOAD

摘要

FIELD: electricity.;SUBSTANCE: electronically coltrolled power transformer (ECPT) for electric transmission lines to consumer with variable load is proposed, comprising commutating pairs of anti-parallely connected thyristors, connected to the secondary winding of the power transformer, which is distinctive in that the secondary winding is made multitapped, various taps of which through the mentioned pairs of thyristors separately commutate to the electric transmission line via the current measurement unit in the latter, varying with the load change in consumer, the current measurement unit output in the electric transmission line and lead from the line beginning are connected to the automatic control system, controlling the work of electronic switch of switching unit of the corresponding pair of thyristors, the number of which is equal to the number of secondary winding leads of the power transformer, wherein commutation selection of the secondary winding lead of the power transformer to the electric transmission line is carried out in the system of automatic control by comparing transfer voltage U_O=rl, where r is a known resistance of the electric transmission line, corresponding to the average current I of the load R_H of the consumer, with the current value of voltage falling in the electric transmission line rl(α), where l(α)=l/α is the current value of the load current R_H(α)=αR_H of the consumer at the coefficient αof the current load value spreading more or less then one; wherein the stabilised voltage in the end of the electric transmission line U₂ and the voltage at its beginning U₁(α) are related by the ratio U₂=U₁(α)-rI(α) and the voltage U₂=αR_HI/α=R_HI in consumer is maintained unchanged with absolute error not exceeding a pitch ΔU between the voltaged in adjacent power transformer secondary winding leads equidistantly distributed by voltage. The device comprises an automatic control system ECPT from two independent control loops which output signals are summed and the resulting control signal is fed to the input of an analog-to-digital converter connected to a decoder which N outputs out of a total 2^mN number of its outputs are connected respectively to the N switching units of the corresponding power thyristor pairs. The first control loop comprises a series-connected signal conditioner rI(α), a subtraction circuit on the first operational amplifier between the signals - reference 2U_O and the current rI(α), and the second control loop comprises a series-connected subtracter, which two inputs are fed with signals proportional to the values of U₁(α) and rI(α), an integrator on the second operational amplifier, which inputs are fed with signals proportional to the difference U₁(α)-rI(α) and U₂, and a bipolar threshold device - a base limiter with limit thresholds U_THR≈(+/-)1.5ΔU, where ΔU is the voltage difference between adjacent secondary winding leads of the power transformer. Each of the N thyristor pairs entering the automatic control system contains an optron pair, LEDs of which are connected in series with the control transistor to the power source, the transistor base is connected to the corresponding output of the decoder. Optothyristors of optrons are connected to the control electrodes of power thyristors and two separate power sources used for all N pairs of optrones. The considered autoregulation system can be successfully used when building a network of consumers from one TS with redistribution of energy flows to different consumers with varying loads in them while maintaining stable electric line voltages. In this case, only one power transformer with a power which provides for all consumers must be used.;EFFECT: automatic maintenance of constant voltage for all consumers connected with the transformer substation by electric transmission lines, regardless of the variation of the load values in consumers, as well as reducing energy losses and providing an undistorted form of the sinusoidal voltage of the network supplied to the consumer.;3 cl, 3 dwg