SU1665456A1 - Power directional relay for connecting reserve supply of consumers with motor loads - Google Patents

Abstract

The invention relates to electrical engineering and can be used in automatic backup power supply (ATS) devices for synchronous motors. The goal is to increase the selectivity and reliability. The outputs corresponding to the difference of the phase currents of the main input are removed from the outputs of transformers 1 and 2, and the signals corresponding to the linear voltages of the first busbar section are removed from the outputs of transformers 3 and 4. In the normal mode, the angle between the same voltages of two sections of tires usually does not exceed 5 °, even with the starting modes of individual engines. The magnitude of the charging voltage is chosen to be significantly less than the magnitude of the main polarizing voltage of the direct sequence. The peculiarity of the relay is that due to the polarizing voltage supply from the voltage of the second busbar section, the block 13 is turned on even with close three-phase closures on the monitored first busbar section, when the direct sequence voltage decreases to zero. In the event of a short-circuit in the supply line circuit, the inversion of the current in the direct sequence is provided, which leads to the return of the block 13 to the initial state and the ATS is enabled. 2 Il.

Description

The invention relates to electrical engineering and can be used in automatic backup power supply (ATS) devices for synchronous motors.

The purpose of the invention is to increase the selectivity and reliability of the device.

Figure 1 shows the block diagram of the device; figure 2 is a vector diagram of his work,

The device contains the first 1 and second 2 current transformers, the inputs of which are connected to the phase gap of the main input, the first 3 and second 4 transformers with voltage, the inputs of which are connected respectively to the terminals corresponding to the leading OABI and lagging UBCI of the first section , the third voltage transformer 5, the input of which is connected to the terminals corresponding to the linear voltage Ovsp of the second busbar section, connected to the backup input, and the same voltage with the lagging voltage of the first busbar section, the first form Interchangeer 6 of compared values, including adder 7 with two inputs, the first of which is connected to the output of the first current transformer 1 through the first phase-shifting integrating chain 8, and the second input of this adder 7 is connected to the output of the second current transformer 2, the second driver 9 to be compared values, which includes the adder 10 with three inputs, the first of which is connected to the output of the first transformer through the second phase-shifting integrating chain 11, the second is connected to the output of the second transformer 4 torus voltage, and the third input through the phase-shifting differentiating circuit 12 is coupled to the output of the third transformer 5, the voltage block 13 comparing a phase which is triggered by the coincidence (or mismatches) the phase of the compared quantities. The inputs of the block 13 are connected to the outputs of the adders 7 and 10, which are the outputs of the formers b and 9, respectively.

The device works as follows.

In the normal mode of stable operation, synchronous motors operate with a C02 coefficient leading to or close to one. In this case, the signals corresponding to the difference in phase currents AB 1A-1v1vs 1B-io of the main input are removed from the outputs of transformers 1 and 2 (Fig. 1), and the signals corresponding to the first voltage UABI and UBCI are removed from the outputs of transformers 3 and 4

tire sections (see also vector diagrams in figure 2). The former B provides the summation of the secondary voltages of the transformers L1 and 2 and, at the output, forms a voltage EI proportional to the current of the direct sequence li of the main input.

Ei Ki (lABe-J60 + lBc) Ki-3h. where K | - coefficient of proportionality.

0

This summarizes the current signal IAB

with a phase shift of 60 degrees. and a 1cc current signal without phase shift,

The former 7 provides the summation of the secondary voltages of transformers 3-5, forming the voltage Е2 at the output. proportional to the sum of the voltages of the direct sequence of the first section of tires From and the voltage of the supply On from the voltage of the second section of tires: (UA8i e j60 + UBci) + Kuii UBCIIX xeJ30 Kui-3Ui + On,

where Kui, Kii - the coefficients of proportionality,

pp

5 Un Kuii-UBCiie - recharge voltage.

At the same time, the voltage signal OABI with a phase voltage of 60 electr., The voltage signal UBCI without a phase shift of 0 and the voltage signal Ovsp with a leading phase shift of 30 electr.

In normal mode, the angle between the same voltage of two bus sections

5 usually does not exceed 5 ° even with the starting modes of individual engines, so the voltages KurSUi and On almost coincide in phase. In addition, the value of the supply voltage On is chosen to be significantly less than the value of the main polarizing voltage Kui, 3Ui and is approximately 6% of the latter. Due to this, even with weak interconnections, the phase of polarizing voltage Е2 practically coincides with the phase of voltage Ui of the first busbar section, Block 13 of the phase comparison is implemented as follows. that it works when the compared values match, i.e. stress Ei and Ё2.

0

Block 13 may also be such that it is triggered if the compared values are 180 ° out of phase. In this case, it is necessary to form the voltage EI

5 with a rotation of 180 ° (for example, a change in the polarity of the secondary windings in transformers 1 and 2). In any case, in the initial normal mode, the comparison unit 13 is in the on state, and at the output of the device there is a signal

Wow, blocking AVR.

When short circuits occur on the monitored first busbar section, the current phase Ji changes relative to the voltage CJi slightly by an amount not exceeding the pick-up angle in block 13 (for example, 90 °) and therefore this block 13 remains in the on state. A feature of the device is that by energizing the voltage On from the voltage of the second busbar section, the on state of the block 13 is enabled even with close three-phase closures on the monitored first busbar section, when the voltage Ui decreases to zero.

In the event of a short circuit in the supply line (or in the event of a power failure from the main source), the current is inverted (or decreased), which causes the unit 13 to return to its initial state and the ATS is enabled. The setpoint for returning to the initial state is determined by the threshold element in block 13 and can be adjusted by the factor K |.

In the event of short circuits in the second busbar section and the normal operation of the first busbar section, the supply voltage Un is reduced, and unit 8 remains in the on state, blocking the ATS.

Claims (1)

Invention Formula Power direction relays for switching on backup power supply with motor load, containing the first and second current transformers, whose inputs are connected to the main input phase break, the first and second voltage transformers, whose inputs are connected respectively to the terminals corresponding to the leading and lagging linear voltage. first section busbars, first and second drivers of comparable values, the inputs of which are connected to the outputs of current transformers and voltage transformers As well as a phase comparison unit, triggered by the coincidence of the phase of the compared values, the inputs of which are connected to the outputs of the formers, characterized in that, in order to increase selectivity and reliability, it is equipped with a third voltage transformer, the input of which is connected to the terminals, corresponding to the linear voltage of the second busbar section associated with the backup input, and the same with the lagging voltage of the first busbar section, the first driver of the compared values includes an adder with two inputs, the first of which is connected to the output of the first current transformer through the first phase-shifting integrating chain, and the second input of this adder is connected to the output of the second current transformer, the second driver of the compared value includes an adder with three inputs, the first of which through the second phase-shifting integrating chain connected to the output of the first voltage transformer, the second connected to the output of the second voltage transformer, and the third input through the phase-shifting differentiating chain connected to the output th third transformer voltage.