RU154310U1 - STEP-BY-STEP SWITCH MANAGEMENT SYSTEM OF A PHASE-TURNING DEVICE SHUNT TRANSFORMER - Google Patents

Abstract

A control system for phased switching the windings of a shunt transformer of a phase-shifting device using a thyristor switch, comprising a switching route selection unit, the first input of which is connected to the output of the unit for setting the desired state of the phase-shifting device, the second input is for the output of the unit for setting the characteristics of the selected switching route, and the third input is for the first the output of the thyristor switch control unit, and the output to the first input of the thyristor switch control unit, while the second output d of the control unit is connected to the thyristor switch, the thyristor switch phase current sensor and the data block on the parameters of the power components of the phase-shifting device, characterized in that a current monitoring unit is introduced into the control system, the first input of which is connected to the thyristor switch phase current sensor, the second input to the output of the data block on the parameters of the power components of the phase-shifting device, the third input to the third output of the control unit of the thyristor switch, while the output of the current tracking unit It is connected to the second input of the thyristor switch control unit.

Description

Technical field

The invention relates to the field of electrical engineering and electric power industry, and in particular to the control of thyristor phase-shifting devices (FPU). FPU represent a high-voltage electrical complex for changing the phase of the voltage, which is included in series in the power line. FPU can be used in electric networks with a voltage of 110 ... 1150 kV for flexible regulation of active and reactive power flows, increasing the capacity of existing lines and increasing the dynamic stability of the energy system by regulating the voltage at the output of the FPU.

State of the art

Thyristor FPUs are known and incorporate two transformers: serial and shunt, as well as a thyristor switch connected between the shunt and serial transformer [see, for example, US Pat. RU 106060]. Each thyristor switch phase contains a series of thyristor bridges connected in series. The thyristor bridge consists of four bi-directional thyristor keys that carry out the switching (connecting in direct or reverse polarity or disconnecting) the secondary winding of the shunt transformer, which is included in the diagonal of the bridge (hereinafter - the shunt winding). The secondary windings of the series transformer are included in the phase separation of the power line. The voltage and phase shift introduced by them can take on a finite number of values, called regulation steps, depending on the number and polarity of the shunt windings introduced into the primary circuit of the series transformer. Each regulation stage corresponds to a specific connection of shunt windings and a specific set of key states of the thyristor switch bridges. The transition from a previously set initial stage of regulation to a newly set (final) stage can be carried out both immediately (in one stage) and through intermediate stages (in several stages). In the general case, such a transition is phased with the number of stages 1 or more and is provided by the corresponding phased switching of shunt windings with thyristor bridges. The sequence of switching between steps that the FPU goes through when switching from the initial stage to the final one is called the switching route. Each switching path is characterized by the initial state of the thyristor switch bridge keys, the final state, and a number of intermediate states.

As a prototype of the claimed utility model, the well-known “Phase-shifting winding shunt transformer winding control system and phase-shifting device with such a control system” is adopted [RF patent for utility model 122814, IPC H03M 7/18, published December 10, 2012, bull. No. 34]. The prototype contains a thyristor switch, a shaper of allowed switching intervals, a block for determining the set of allowable switching, voltage sensors on the switched windings of the shunt transformer and current sensors of thyristor bridges included in the thyristor multibridge switch, a thyristor switch control unit, a switching route selection block, a unit for setting the required phase-rotation state devices, a unit for specifying the characteristics of a selectable switching route, a data block on the parameters of power comp FPU circuit elements, the first and second inputs of the shaper of allowed switching intervals and the block for determining the set of allowable switching are designed to connect to voltage sensors on the windings of the shunt transformer and at least one current sensor through the bridges of the thyristor switch, respectively, and the outputs to - the first input of the thyristor switch control unit and to the first input of the switching route selection unit, respectively, to the second and third inputs of the switching route selection unit the outputs of the unit for setting the required state of the phase-shifting device and the unit for specifying the characteristics of the selected switching route are turned on, respectively, while the thyristor switch control unit is equipped with an output connected to the fourth input of the switching route selection unit, and the generator of allowed switching intervals is equipped with a third input to which the data unit is connected parameters of the power components of the phase-shifting device circuit.

The disadvantage of the prototype is the incomplete controllability of the FPU in various modes of operation of the power system. The control of the FPU from the prototype system does not allow you to immediately switch the FPU to the desired final state for small values of the phase shift between the current and voltage in the thyristor switch, which is determined by the values of active and reactive power flowing in the power system line with the installed FPU.

Moreover, the controllability of the FPU under certain modes of operation of the power system may be completely lost, namely, in the cases where when the FPU is in the extreme stages of regulation there will be no allowed time intervals necessary to exit the current extreme stage of regulation.

Utility Model Essence

The technical result of the utility model is to increase the efficiency of regulation of power flows by a phase-shifting device by ensuring full control of the FPU regardless of the operating mode of the power system.

The subject of the invention is a control system for phased switching the windings of a shunt transformer of a phase-shifting device using a thyristor switch, comprising a switching route selection unit, the first input of which is connected to the output of the unit for setting the desired state of the phase-shifting device, the second input is for the output of the unit for setting the characteristics of the selected switching route, the third input - to the first output of the thyristor switch control unit, and output - to the first input of the thyristor control unit m switch, while the second output of the control unit is connected to the thyristor switch, the thyristor switch phase current sensor, a data block on the parameters of the power components of the phase-shifting device and a current tracking unit, the first input of which is connected to the thyristor switch phase current sensor, the second input to the output data block on the parameters of the power components of the phase-shifting device, the third input is to the third output of the thyristor switch control unit, while the output of the current tracking unit is connected to the W the input of the thyristor switch control unit.

Brief Description of the Figures

In FIG. 1 shows a functional diagram of a control system for thyristor switch FPU. In FIG. 2 shows a diagram of one of the thyristor bridges as part of the FPU thyristor switch with a connected secondary winding of the shunt transformer and with a phase current sensor. In FIG. Figure 3 shows the current diagrams and signals generated by the control system in the process of switching one phase of the FPU thyristor switch from an arbitrary initial state to the desired final state.

Implementation of Utility Model FIG. 1 shows a thyristor switch 1, with which a phased switching of the windings of a shunt transformer of a phase-shifting device is carried out under the control of a control system that contains functional units 2-8.

The switching route selection unit 2, with its first input, is connected to the output of the unit 3 for setting the required state of the phase-shifting device, the second input is for the output of the unit 4 for specifying the characteristics of the selected switching route, and the third input is for the first output of the thyristor switch control unit 5. The output of block 2 is connected to the first input of the control unit of the thyristor switch 5, while the second output of block 5 is connected to the thyristor switch. The output of the thyristor switch phase current sensor unit 6 is connected to the first input of the current tracking unit 7, the second input of which is connected to the output of the phase information unit 8 of the phase-shifting device power components, and the third input is connected to the third output of the thyristor switch control unit 5. Block 7 output current monitoring is connected to the second input of the thyristor switch control unit 5.

The control system operates as follows.

In the initial position, block 5 generates control pulses of the switch 1, supporting the state of the FPU thyristor bridges previously set by block 3. In this case, block 2 constantly monitors the input to which a signal is given about the state of the FPU that is set (from the output of block 3) and, if it differs from the previous value, the next switching process begins.

During this process, unit 2 selects a specific switching route for the thyristor bridges of switch 1, which provides a transition from the initial state to the newly defined final one, and block 5 provides the subsequent implementation of the selected route in real time.

Block 2 can be performed, for example, on the basis of a storage device, in the cells of which are stored the set of all switching routes possible for a given FPU, and the data received from blocks 3 and 4 are entered in the corresponding fields of the address register.

The control of the FPU provides transitions of the FPU from a state called the initial one with one phase shift to another state defined by block 3, called the final state, with a different value of the phase shift introduced by the FPU. The change in the phase shift of the FPU is provided by a change in the composition and polarity of the series connection of the secondary windings of the shunt transformer in each phase of the thyristor switch 1 due to the corresponding switching of the thyristor bridges of the switch 1.

Switching thyristor bridges in order to change the connection of each secondary winding of a shunt transformer is carried out by turning on one and turning off the other shoulders of a certain thyristor bridge. Each thyristor bridge has three operating states, differing in the connection of the shunt transformer winding switched by it (see Fig. 2):

- the winding is taken out of operation and does not affect the output voltage of the FPU (thyristors VS1, VS2 or VS3, VS4 are included);

- the winding is turned on according to (thyristors VS 1, VS4 are included);

- the winding is turned on in turn (thyristors VS2, VS3 are turned on).

Any other combinations of switching thyristors of the bridge are inoperative, i.e. never used in a working device.

Switching thyristor bridges is possible by turning off the thyristors in all bridges belonging to one phase of the FPU switch, and then turning on the thyristor bridges of this phase in the required state, according to the switching route that block 2 chose.

Timing diagrams of FIG. 3 illustrate the process of switching bridges of one phase of the thyristor switch 1. To organize the switching, the thyristor switch control unit 5 removes control pulses from the bridges of one phase of the switch 1 and generates a signal to turn off the control pulses of this phase in the current monitoring unit 7.

Block 7 monitoring the current by a signal from block 5 removes from its output a enable signal for thyristors, which goes to block 5, receives a signal about the instantaneous current value in the switched phase of the thyristor switch from the output of current sensor 6 and determines the time when the current flowing through thyristor bridges the phase of the switch FPU becomes equal to zero.

To ensure reliable shutdown of the thyristors, it is necessary to introduce time delays calculated on the basis of the parameters of the FPU power circuit, which are fed to the input of block 7 from the output of block 8, the data block on the parameters of the power components of the phase-shifting device circuit. These parameters are:

- time off the thyristors in the switch 1;

- errors of real devices that are in the circuit for transmitting information about the instantaneous current value in the thyristor switch (phase shift generated by the current sensor 6, possibly analog-to-digital conversion devices, etc.).

The introduction of these delays is necessary due to the fact that in the case when the thyristors are switched at a moment close to the current passing through a zero value, short circuits of the secondary winding of the shunt transformer may occur. This is due to the fact that in this case, thyristors, de-energized, but not having time to restore their ability to hold voltage, are under positive (direct) voltage, which leads to their spontaneous inclusion. If the error in the measuring equipment of the power circuit is underestimated, premature supply of control pulses to the power devices is possible, which can also lead to the formation of a short circuit of the secondary winding of the shunt transformer.

To ensure trouble-free switching of bridges of the switched phase of switch 1, the current tracking unit 7 detects the presence of zero current in the switched phase of the thyristor switch during the time interval tz (see Fig. 3), equal to the sum of the thyristor recovery time and the delay time introduced due to the instrumental error current sensors 6 and the circuit for processing information about the instantaneous current value. After the time t3 expires, block 7 generates a thyristor enable signal to block 5, and block 5 supplies control pulses to other thyristors of the bridges of the same phase of switch 1 in accordance with the required control step of the FPU.

After switching one phase, the thyristor switch control unit 5 takes control pulses from the thyristors of the next phase of switch 1 and repeats the considered sequence of actions until all phases of the thyristor switch are transferred to the next intermediate or final state, according to the switching path. After completing each step of switching the selected route, i.e. after sequential switching of the three phases of switch 1, block 5 gives to block 2 a signal to complete the switch, allowing you to start the next switching step in accordance with the selected route, until the required control step of the FPU is reached.

Unlike the prototype, the control system under consideration will switch the secondary windings of the shunt transformer at any phase ratio of currents and voltages in the line, since the successful completion of the switching does not depend on the phase shift between the current and voltage in the bridges of thyristor switch 1.

The selected permissible sequence of step-by-step switching of shunt windings (the switching route selected by block 2) must satisfy the specified signal from the output of block 4 of the restrictions, at least by the value of the output voltage of the FPU during the step-by-step switching.

The choice of a route with the required properties is carried out by placing possible routes stored in the memory cells of block 2 at the addresses in accordance with the previously calculated value of the limited parameter. Block 2, using the information coming from blocks 3 and 4 in the corresponding address field, selects a route that satisfies the given restrictions, which include limiting the value of the output voltage of the FPU during the phased switching of the windings. In addition, block 4 can set block 2 with other restrictions, for example, on the number of switching shunt transformer windings, on the switching sequence, on the rate of change of the output phase shift.

Block 2 selection of the switching route, it is advisable to perform in such a way that, as a result of taking into account all the requirements set, he unambiguously selected from the set of switching routes stored in his memory a single (specific) switching route intended for working out by blocks 5 and 7.

Claims (1)

A control system for phased switching the windings of a shunt transformer of a phase-shifting device using a thyristor switch, comprising a switching route selection unit, the first input of which is connected to the output of the unit for setting the desired state of the phase-shifting device, the second input is for the output of the unit for setting the characteristics of the selected switching route, and the third input is for the first the output of the thyristor switch control unit, and the output to the first input of the thyristor switch control unit, while the second output d of the control unit is connected to the thyristor switch, the thyristor switch phase current sensor and the data block on the parameters of the power components of the phase-shifting device, characterized in that a current monitoring unit is introduced into the control system, the first input of which is connected to the thyristor switch phase current sensor, the second input to the output of the data block on the parameters of the power components of the phase-shifting device, the third input to the third output of the control unit of the thyristor switch, while the output of the current tracking unit It is connected to the second input of the thyristor switch control unit.

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