SU1534686A1 - Method of regulation of three-phase ac voltage - Google Patents

Abstract

The invention relates to electrical engineering. The purpose of the invention is to increase reliability by increasing the current efficiency of key elements. Voltage regulation is carried out by changing the magnitude and phase of the additional voltage of the secondary winding 2 of the three-phase auxiliary transformer 1. The voltage on the windings of the three-phase auxiliary transformer 1 is changed by switching the key elements of the unit 5. With increasing voltage at the transition from the circuit at which the additional voltage coincides in phase with the supply voltage, and when the voltage decreases during the transition from the circuit in which the additional voltage does not coincide in phase with the supply voltage on In a hema at which the additional voltage coincides in phase with the supply voltage, key elements are turned on at a phase angle of 110-130 °, and on reverse transitions, key elements are turned on at a phase angle of 20-40 °. 2 Il.

Description

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figure 1

The invention relates to methods for adjusting a three-phase alternating voltage.

The purpose of the invention is to improve the reliability due to the coefficient of use of key elements for current.

In Fig. 1 is a diagram of the device that implements the proposed method; Fig. 2 shows time diagrams of voltages that explain the process of voltage regulation in accordance with the proposed method.

| The device (Fig. 1) contains a three-phase auxiliary transformer 1 with secondary windings 2 and primary windings 3, terminals 4 in the kak-th phase of the primary windings 3, unit 5 of key elements in the form of thyristor keys, unit 6 for synchronizing the moment of transition from one stationary mode in another, control pulse shaping unit 7, control system 8, power supply unit 9, terminals A, B, C for connecting a three-phase mains supply and output ports A, B, C o

Fig. 2 shows: line voltage diagrams 10, Yamma diag. 11 signals for switching on the thyristor keys of block 5, diagram 12 of the phase voltage of the UA, U6, lic network, voltage diagram 13 on the secondary windings 2 UA | I , 4-gram 14 voltage on weekends you- A, B, C.

Voltage regulation at the output terminals A, B1, C1 is performed not only due to the algebraic (longitudinal) addition of the voltages of the secondary windings 2 of the auxiliary transformer 1 and the mains, but also due to their geometric (transverse) addition.

To adjust the output voltage on the output pins A, B, G to the input three-phase supply voltage Uft, U8, Uc Superimposed on the magnitude and phase of the three-phase voltage PD, U BЈ, Uca three-phase auxiliary transformer 1.

The need to change or stabilize the value of the output voltage leads to the need to change the voltage of the auxiliary transformer 1 both in magnitude and phase. To do this with a block

five

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five

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five

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five

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5 change the scheme of connecting the primary winding 3 to the output pins A, B, C by applying control pulses to certain thyristor keys and prohibiting their supply to previously switched on thyristor keys „

The power factor (costf) of the load when adjusting the alternating voltage is limited to a rather narrow interval of change (0.78–0.95), which corresponds to the range of variation of the switching angle of the thyristor switches to 20 eh grades0. Work in another depends on the costp load.

The minimum current overload of the key elements is observed at well-defined switching points of the switching angles of the thyristor switches. When adjusting the voltage in the direction of its increase by switching from the longitudinal regulation scheme to the transverse regulation scheme, this moment of time lies within 110-130 e-e-deg0, and on the reverse transition, respectively, 20-40 eLaGraDo. When the voltage decreases the above way, during the transition from the longitudinal adjustment scheme to the transverse adjustment scheme, the moment of time is within 20-40 e-degrees, and on the reverse transition - 110-130 e-degrees. The starting point is the moment of transition through the zero value of the supply voltage between the input terminals A and B.

The amount of time at which the key elements are switched in block 5 and the connection scheme of the primary winding 3 of the three-phase auxiliary transformer 1 changes with terminals B, C is determined by block 7 0 In turn, block 7 is synchronized with two pulse signals that are generated by block 6 , each of the pulse signals is transmitted through its own control channel. One corresponds to 20–40 electrons, and the other 110–130 e-degrees. AB supply voltage

Claims (1)

Invention Formula The method of regulating a three-phase alternating voltage, which summarizes the additional voltage of a three-phase auxiliary transformer with the supply voltage, changes the magnitude and phase of the additional voltage, changing the connection circuit of the secondary windings of the three-phase auxiliary transformer and the connection diagram primary windings of the booster transformer with the terminals from the middle point and from one third of its turns, which are connected with it. characterized in that, in order to increase reliability by increasing the current efficiency of key elements, while increasing the voltage sh ft transition from a circuit in which the added, eternal voltage coincides in phase with the supply voltage, to a circuit with an additional voltage that does not coincide in phase with the supply voltage, and with a decrease in voltage during the transition from the circuit in which The additional voltage does not coincide in phase with the supply voltage, the circuit in which the additional voltage coincides in phase with the supply voltage, the key elements include at a phase angle of 110-130 °, and at reverse transitions the key phase angle elements include at 20-40 °. ott 20 + W