RU2159477C1 - Three-phase on-load tap-changing transformer - Google Patents

Abstract

FIELD: on-load tap-changing transformers with rather high control percentage. SUBSTANCE: phase-by-phase and simultaneous modes of operation of on- load tap-changing devices of transformer are used in turn. Step voltage is lower during entrance in control zone than at initial point of control range. Transfer from phase-by-phase to simultaneous mode of voltage control provides for leveling voltage step within entire control range. EFFECT: reduced variation in step voltage throughout entire control range. 1 dwg

Description

 The invention relates to the field of electrical engineering, namely to transformers with integrated voltage regulation under load with a relatively large regulation depth, when the requirements of a small variation in the voltage level of a stage are put forward over the entire regulation range.

 Known 3-phase transformer with built-in on-load tap-changer, containing a network and connected in series with it an adjustment winding with n steps, one three-phase device [1]. The disadvantage of this transformer with a large depth of regulation and a small value of the step is the large number of branches (steps) of the control winding and a switching device with a large number of switching positions, as well as the voltage difference of the control stage, reaching, for example, at 50% regulation depth three times the first and the last positions of the adjustment winding of the full range.

 All this complicates and increases the cost of the product as a whole and reduces its technical level.

 Known 3-phase transformer with on-load tap changer, containing a network and connected in series with it an adjustment winding with n steps; three single-phase switching devices (one for each phase) with position sensors and their output circuits performing phase switching in turn (ABC - switching) [2].

 Thanks to this, it is possible to use an adjusting winding with three times less branch number and switching devices having three times less number of positions due to receiving three steps between the two adjacent branches of the regulating winding according to the voltage of the transformer.

 However, in the options considered (analog and prototype) there is a drawback, namely: the difficulty of ensuring an equal value of the stage in the entire range of voltage regulation. This is due to the hyperbolic (non-linear) dependence of the required number of turns of the step of the adjustment winding on the depth of regulation for the case when voltage regulation is carried out by changing the number of turns from the side of the network winding.

 The aim of the present invention is to provide a transformer with a small variation in the voltage level of the stage, regardless of the position of the switching device of the adjustment winding.

 This goal is achieved by the fact that in a three-phase transformer with voltage regulation under load, containing phase-shifting devices with position sensors and their output circuits, the control circuits “ABOVE” and “BELOW”, it is proposed that voltage control by switching devices be performed using logical elements AND, NOT, with the position sensor circuits connected to the inputs of the I1 element, and the output of the I1 element connected to one of the I2 inputs, the control circuits ABOVE, BELOW connected to the second I2 input, the I2 output connected to swing of NOT and control circuits "simultaneously", and the output element is not connected to the switching device control circuit "per phase".

 The need and sufficiency of these distinguishing features to achieve the goal is confirmed by the following.

 The proposed interaction of logical elements AND, NOT, control signals, switching devices and regulating windings of the transformer allows from a given position of the switching devices of the branches of the regulating winding to switch from the phase-by-phase control mode of the switching devices to the simultaneous control mode.

 With such a change of control modes (control), the voltage of the control step increases, i.e. the passage of the second part of the transformer regulation range will occur in steps three times larger than with phase-by-phase regulation.

, либо после прохождения переключающим устройством заданного ответвления регулировочной обмотки.Thus, when entering the regulation zone, when the voltage level of the stage becomes noticeably lower than the voltage level of the stage at the beginning of the regulation range, the transition of the transformer voltage regulation mode from phase-to-phase to simultaneous solves the problem of equalizing the voltage of the stage within the entire regulation range. Depending on the depth of regulation of the connection circuit of the network windings, the position of the switching device at which the position sensor should operate can be combined with either switching on the coarse stage or switching on the network winding with the range switch PARALLEL, SEQUENTLY, or by switching the network winding from Δ to

or after the switching device passes the specified branch of the adjustment winding.

 The drawing shows a diagram of the inventive transformer.

 Three-phase transformer 1 with voltage regulation under load, phase switching devices - 2 with position sensors - 3 with their output circuits - 4, 5, 6, they are input elements I1, circuit 7 - output of element I1 and first input of element I2, circuits controls 8 ABOVE, BELOW and the second input of the I2 element, circuit 9 - the output of the I2 element, the input of the element NOT and the control circuit SIMULTANEOUSLY, the output of the element NOT - the control circuit of the switching devices.

 When the transformer is operating, when the phase voltage values become lower than the set value during phase-by-phase regulation, position 3 sensors are activated, the appearance of three signals in circuits 4, 5, 6 at the input of element I1 provides a signal through circuit 7, which is fed to one of the inputs of element I2 , and after giving the command ABOVE or BELOW on chain 8, a second signal is supplied to the input of the I2 element. The output signal on the circuit 9 of the I2 element through the element DOES NOT prohibit the phase-by-phase regulation (PHASE) and allow the signal to pass SIMULTANEOUSLY, with the help of which the switching devices are switched simultaneously during voltage regulation. The transition to simultaneous switching increases the value of the voltage of the stage three times and allows for voltage regulation in the entire range by more equal voltage steps.

Sources of information
1. Ya.L. Fishler, R.N. Urmanov, L.M. Pestryaeva. "Transformer equipment for converting installations", M., Energoizdat, 1989, pp. 51-53.

 2. The same, p. 67.

Claims (1)

 Three-phase transformer with voltage regulation under load, containing phase switching control branch tap devices with position sensors and their output circuits, phase control circuits with switching devices and control circuits “ABOVE”, “BELOW”, characterized in that the output circuits of the position sensors are connected to the inputs of the I1 element, the output of the I1 element is connected to one of the inputs of the I2 element, the control circuits “ABOVE”, “BELOW” are connected to the second input of the I2 element, the output of the I2 element is connected to the input of the element NOT to the control circuits of the switching devices in the "SIMULTANEOUS" mode, and the output from the element is NOT connected to the control circuits of the switching devices in the "SIMPLE" mode.