SU440741A1 - Method for automatic control of a compensating installation of an intermediate long-distance power transmission station - Google Patents

Description

one

The invention relates to the management of long-distance power transmission modes and can be used to construct devices of regime automatics for controlling transverse compensating installations KU (shunt reactors, static capacitors and synchronous compensators) of intermediate points of the AC long-distance power lines AC.

Known methods of controlling compensating plants and devices based on them use either voltage at the point of connection of the capacitor, or signs of power failure as a control parameter.

The voltage of the PP DEP, which is used as a control parameter in the KU automation devices, is an indirect sign of the compensated linpi. The change in voltage at any SP DEP depends on the balance of reactive powers at some other of its points, which, with the inevitable inertia of control equipment, can lead to periodic fluctuations in the voltage along the DEP lines and the stability of the system.

Voltage control of KU does not allow to maintain in intermediate points the optimal balance of reactive power and to limit the flow of reactive power along the AEP under any load and power transmission.

The purpose of the invention is to ensure the nominal voltage level at intermediate points and the minimum reactive power fluxes along the long-distance power line at any value of transmitted active power and any composition of the DEP lines. This is achieved by measuring the reactive power consumed by the system connected to the wearer and the active powers of the ends of the line sections adjacent to the intermediate point. Depending on the position of the switches adjacent to the intermediate point, the measured active powers are converted into reactive powers and, in the case of a disturbance of the reactive power balance at the intermediate point, they control the compensating installation by a signal proportional to the indicated imbalance.

On fng. 1 is a schematic diagram of the far transmission power with a block diagram of the device for carrying out the proposed

way; in fig. 2 - dependences between the value of the transmitted active power and the generated portions of the DEP lines reactive powers, which are used in the power conversion units of the device.

The block diagram of the automatic device, which implements the proposed control method for the AC, contains sensors 1 of three-phase active power, measuring the power of the AEF sections adjacent to this intermediate point; three phase reactive power sensor 2 for measuring the power consumed by the intermediate power system; blocks 3 of information about the composition of the lines, consisting of logical elements "AND," NOT, "NO," OR, perceiving information about line outages (or their individual phases), performing automatic switching of the outputs of these blocks to those power conversion units in which the characteristics shown in FIG. 2, constructed for a certain composition of lines L-1, L-2; Power conversion blocks 4, P 0, in which the nonlinear dependencies shown in FIG. 2, calculated on the assumption of a terminal voltage level along a far power transmission; The unit 5 of the sum, in which the following equation of the balance of reactive power is realized at an intermediate point:

QI-Q2-Qnp.c-QKy 0

The output voltage of this unit is proportional to the required reactive power of the compensating installation, which must be connected to an intermediate point in order to maintain a voltage equal to the rated voltage, as well as to limit the flow of reactive power along the far power transmission.

If shunt reactors (capacitors) without continuous regulation are used as means of lateral compensation, the block diagram should be supplemented with logic block 6, in which the required number of reactors (disconnecting) ).

If synchronous compensators or reactive power sources with smooth regulation are used for this purpose, the output voltage of summing unit 5 should be directly used in the control system of the synchronous compensator to determine the degree of excitation and, therefore, the magnitude of its reactive power.

In various situations on the DEP, the device operates as follows. A large change in the magnitude of the transmitted active power according to the DCT, while its composition remains unchanged and the reactive power consumed by the intermediate system.

At the same time, the output signals of sensors 1 vary depending on the degree of change in the transmitted power. Then the output signals of blocks 4 will be more (less), since the dependencies are approximated in them,

shown in FIG. 2. According to the balance equation of reactive power, which is implemented by block 5, the output signal of the latter, proportional to the required reactive power of the compensating unit, will therefore become larger (smaller), which will require to maintain the nominal connection voltage at an intermediate point reactive power KU.

When one furnace of the L-1 (L-2) line is disconnected, while the transmitted active power and the reactive power consumed by the intermediate power system are unchanged

unit 3 will receive information about disconnecting one circuit (for example, through existing devices via TV channels), on the basis of which it will automatically switch its output to the conversion unit 4 in which the dependence is approximated, similar to those shown in FIG. 2, but calculated with the presence of one circuit on L-1 (L-2). The magnitude of the generated reactive power lines DEP with a decrease in the number of circuits

decreases, therefore, the dependences (P) under the condition of the nominal voltage level are located below. This will cause a decrease in the output signal of block 4, therefore, a decrease in the output signal of the block

5 due to a change in the balance of reactive powers at the PP. Thus, the situation that has arisen causes a decrease in the connected reactive power of the KU PP.

In the case of the interruption of the intermediate power system with the constant composition of the DEP lines and the transmitted active power, for example, in the absence of active power consumption

off), the outputs of block 4 remain unchanged, while the output of block 2 becomes zero. According to the balance equation of reactive powers at the PP, this will cause an increase in the output voltage of unit 5 and, thus, the connection of additional (greater) reactive power to the capacitor.

At rupture of DEP, for example shutdown

switches L-2, at PP 2, when transmitting a large amount of active power and disconnected intermediate power system No. 1, the output signals of power sensors 1 and the input signals of blocks 4 will be equal

zero (sensor 2 output is zero, since the intermediate system is disabled). Then the output values of the blocks 4 will take their maximum possible values, which will cause the output voltage of the summing block to also increase to the maximum. Thus, with a complete rupture of the DEP (one-way or two-way simultaneous disconnection of two circuits of the L-2 line), the device that implements the proposed method will ensure the connection of additional, maximum possible reactive power to the capacitor, which prevents dangerous overvoltages.

Subject invention

A method of automatically controlling a compensating installation of an intermediate long-distance transmission center, characterized in that, in order to maintain the required voltage level and limit reactive power flows, the reactive power consumed by the system connected to the intermediate point and the active power of the ends of the lines adjacent are measured. to an intermediate point; depending on the position of the switches adjacent to the intermediate point, the measured active powers are converted into reactive power and, in case of disturbance of the reactive power balance at the intermediate point, they control the compensating installation by a signal proportional to the imbalance.

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