SU1197006A2 - Device for compensating reactive power - Google Patents

Abstract

DEVICE FOR COMPENSATION OF REACTIVE POWER according to author. sv.SSR No. 1070644, characterized in that, in order to increase reliability, it is equipped with a bridge rectifier, an analog signal multiplier and a level converter, the threshold elements are supplemented with means for changing the response threshold, the bridge terminals being connected to the terminals for connecting the supply network, the output connected to the inputs of the analog signal multiplier, the output of which is connected via a level converter to the inputs of the means for changing the threshold of the threshold elements e and to the input of the digital-analogue terminal logical unit reformer. (/)

Description

. . The invention relates to electrical engineering, in particular, to devices for automatic control of the reactive power of electrical networks. with the help of cosine capacitor batteries and is an improvement in the aut. St. No. 107064 The purpose of the invention is to increase reliability. The drawing shows a functional diagram of a device for compensating reactive power. The device contains p sections of compensator batteries 1.1 - 1.p, blocks 2..1 - 2.p switching, sensor 3 re. Active power, threshold elements 4.1 and 4.2, comparators 5.1 and 5.2, inverting integral repeater 6 , inverter 7, mismatch circuit 8, time delay element 9, two-input circuits 10.1 and 10.2 coincidence; circuit OR 11, circuit 12 strobirrvani, digital-analogue converter 13, which specifies. generator 14, three-input coincidence circuit 15 ,, reversing binary counter 16,; direct account limiting circuit 17, scheme -18. Inverse counting limit, decoder 19, switch .20 mode, operation, driver 21 of turn-on signals capacitor bank sections (KB), shaper 22 of the KV sections disconnect signals, bridge rectifier 23, multiplier 24 analog signals and level converter 25. The device works as follows. Suppose that in the initial state all sections 1.1 - 1.P are disabled. At the output of the reactive power sensor 3 (FDM) there is a signal IR ;, proportional to the reactive power. These three-phase networks, which are supplied to the information inputs. Downstream elements 4.1 and 4.2. Simultaneously, with the indicated signal, at the output of the bridge rectifier 23, a signal is generated that is proportional to the voltage of the three-phase network. The rectified voltage goes to the inputs: multiply 24 analog signals, realizing the function of the quad, the output of which has a signal proportional to the square of the external voltage and through the converter. The 25 level goes to the inputs of the means for determining the threshold values of threshold elements 4.1 and 4.2 and the digital analog converter (DAC) 13. from 6.6. Consequently, the voltage values determining the thresholds for switching on and off the threshold elements of the device ( proportional reactive power of the minimum step KB), as well as the reference voltages TsA1T synchronously. treason - at voltage deviations in the network from the nominal value .. -. . Assume that the mains voltage is equal to the nominal values, And there is a deficit of reactive power Q in the network, causing a signal to the output. de DRM, exceeding switching thresholds. threshold elements (PE). 4.1 and 4.2. Threshold elements are triggered and through circuit 8 start. Element 9 time delay, which produces a signal that allows current pulses to pass through Scheme 15 to start reversing counter 16 and D / A IX -, Suppose DAL 13 generates three stages. And output voltage DRM 3. This triggers the comparator 5 and through the circuit. IDI 1.1 prohibits the passage of clock pulses. .RDS 16. Stops the counting of pulses, and a state is recorded in its upper bits, respectively. connection of the three stages of the KB. Simultaneously, a gating circuit .12 is launched, and the signal generated by it resets the ATP 13. To the zero state and allows the information to pass through the switch 20 of the operating mode to the circuits; 21 and 22. The device is switching three stages of the battery block, the deficit of reactive power is reduced, and the signal from the HLR 3 goes to the dead zone of the device between g, OTHA Threshold, element 4 is set to its original position. Suppose that all stages of the switchgear are disconnected, the initial reactive power has not changed and is equal to Q, the voltage of the network is greater than the nominal (,,), and the threshold voltages on 8M.V on the output voltage Uon „„ remain the same network. The process takes place in the device, and is similar to that described, and since the PD has changed, DAI still counts the three steps of the CB required for compensation, however, due to the fact that it is actually reactive; Since the power of QB Q becomes narrower and equal (1 + uUp, then after connecting three levels of KB to the network, overcompensation occurs, the signal from the HF becomes lower than the threshold of PE 4.1 and 4.2, and additional switching occurs in the device to disconnect the excess levels of KB. .... Consider the case when the network voltage is lower than the nominal, and the initial reactive power levels Q of the threshold voltage are the same as in the cases considered. In the device, as before, it is defined.

There is a need to connect. three steps of kb, however due to the fact

that the step power is already less and equal to the nom total reactive power of the three steps

It is not enough to compensate for the lack of reactive power of the network. The nfj signal (does not get below the turn-on threshold, and... In the device, additional commutations occur by connecting the missing KB stages.

. Consider the operation of the device. in the case when the initial level of reactive power has not changed and is equal to Q, the network voltage is greater than the nominal

and proportionally

Nome

deviation of network voltage increased voltage thresholds Uoj, cm

and and

, and also values

QP. Kbps

This increases and. the size of the steps formed by the DAC

by an amount proportional to the square of the deviation of the network voltage, i.e. synchronously with the change in the real reactive power levels KB.

The threshold elements 4.1 and 4.2 are triggered even with a large value of the signal U а p and the required number of KB stages is determined by the DAC 13 taking into account the increase in the actual reactive stage KB for a given network voltage value, i.e. The number and combination of KB stages is determined at the time the comparator 5 is triggered, will be sufficient to compensate for the reactive power, and the signal is received. immediately c. deadband / device. At the same time, there is no undesirable overcompensation occurrence and no additional UPS commutations are required to disconnect excess reductions in KB. The device works similarly in the case when the network voltage is below nominal. At. This reduces U, Ugn off and Uflf, as well as the step size generated by the DAC 13. There is no shortage of sensation and there is no need for additional commutation to connect the missing KB stages. The reliability of the device in general age em. . ,

The use of the invention makes it possible to create reliable devices for reactive power compensation, in which additional commutation of sections of a CB in automatic control mode is excluded.

Claims (1)

DEVICE FOR COMPENSATION OF REACTIVE POWER by ed. St. USSR # 1070644, characterized in that, in order to increase reliability, it is equipped with a bridge rectifier, an analog signal multiplier and a level converter, the threshold elements are supplemented with means for changing the threshold, and the inputs of the bridge rectifier are connected to the terminals for connecting the mains, output connected to the inputs of the analog signal multiplier, the output of which through a level converter is connected to the inputs of the means for changing the threshold of threshold elements and to the input of the digital-analog the forming logical block. 1 1197006