SU1561071A1 - Automatic regulator of reactive power of condenser plant - Google Patents

Abstract

The invention relates to electrical engineering and can be used to regulate reactive power in dynamic compensation installations with switching of capacitors on symmetric controlled thyristors-triacs. The purpose of the invention is to simplify the device while ensuring the specified quality of transients. It is essential that the switch be operated as a triac. This allows to simplify the switching algorithm and the regulator consisting of the reactive power measuring unit 1, the synchronization unit 2, the voltage boosting element 3, two control pulse delay delays 5 and 8, and the dynamic trigger 6. With the arrival of the command switching on the section of the capacitor unit at the forward output of the trigger on the front of the clock at the time of the mains voltage passing through zero is recorded a logical "1" and the power triac 7 opens. With the arrival of the command to turn off the section of the capacitor unit, the sync pulse front end of the trigger output 6 records a logical "0" and the power triac 7 closes when the current is zero and the voltage on the capacitor 10 has a positive or negative amplitude value. The inverse output of the trigger 6 provides a sufficiently fast discharge of the capacitor using an additional discharge triac 9 through the resistor 11. The device is ready to receive a new switch-on command. The voltage boosting element 3 is connected to the installation R-input of resetting the trigger to the zero state, which allows disconnecting the capacitor with an unacceptable increase in the mains voltage. Two delay elements 5 and 8 at the information input of the trigger and at its inverse output perform an auxiliary function. The first delay is determined by the discharge time of the capacitor. The second delay is half the period of the mains voltage. The switch-on current does not exceed 40% of the amplitude steady-state value. 2 Il.

Description

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cut resistor 11. The device is ready to receive a new command to turn on. The 3 latching element is raised - “and the voltage is connected to the installation R-input of resetting the trigger to the zero state, which allows disconnecting the capacitor in case of an unacceptable increase in the mains voltage. Two elements 5 and 8 delays

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an auxiliary function is performed at the information input of the trigger and at its inverse output. The first delay is determined by the discharge time of the capacitor. The second delay is half the period of the mains voltage. The switching current does not exceed the amplitude steady-state value of jg. 2 Il.

The invention relates to electrical engineering and can be used to regulate reactive power in dynamic compensated switching capacitor installations of a triac.

The purpose of the invention is to simplify the controller and improve the quality of the transition process.

Fig. 1 shows a structural diagram of the proposed controller in Fig. 2 — timing diagrams of its operation.

The automatic reactive power controller (Fig. 1) contains the Residual Power Transducer 1, the synchronization unit 2 (null comparator), the overvoltage latching element 3, whose inputs are combined and are the regulator output to which it is fed. proportional voltage of the baby. The output of the measuring converter: the reactive power reader 1 is the input of the control unit 4, the output of which is the input of the first Delaying element 5, the output of which is connected to the information D input of the Trigger 6. The output of the synchronization unit 2 is connected to the synchronous C input of the Trigger and its R input is the output of the element 3 of the overvoltage latching. The forward output of flip-flop 6 is the first output of the controller and controls the activation of power Triac 7. The inverse output of flip-flop 6 is connected to the input of the second front delay element 8, the output of which is the second output of the regulator controlling the switching of the low (low-power) triac 9. Power triac 7 provides the switching of the capacitor 10 of the section of the capacitor unit (KU), and the discharge triac 9 provides the discharge of the capacitor 10 through the resistor 11.

The regulator works as follows.

The synchronization unit 2 (null comparator) forms the fronts of rectangular pulses at the moments when the network voltage passes through zero

There are 0 negative values in the region of positive, and slices at the moments of zero crossing in the opposite direction. These pulses are applied to a synchronous C input of a P-flip-flop 6, which records on the front. The reactive power transmitter 1 outputs a signal to the control unit 4, which generates a command to turn on or off

0 КУ, and the front of the signal for switching on the КУ is delayed by the delay element 5 for a time on the order of 1 s, and a cut of this signal (the transition from a single state to a bullet) is transmitted

5 to the information input of the D-flip-flop 6 without delay. The firing command front is formed at some arbitrary time t0 (figure 2) and arrives at the D input of the trigger 6 through t 1c at the time t, when the capacitor 10 (figure 1) of the considered section of the control unit is completely discharged. the command to turn on (1) comes at the moment

5 t when the network voltage passes through zero from the region of negative values to the region of positive (Fig. 2). Triac 7, connected by a control electrode to the direct output, trigger 6 opens as soon as the mains voltage becomes greater than the threshold value of its trigger (usually several volts). In this case, the turn-on current does not exceed 40% of the amplitude value of the KU current in the steady state, which satisfies the requirement of ensuring the specified quality of the transient process.

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The KU's output at the time t at the D input of the trigger 6 without delay is set O, and this new information is recorded at the time t4 on the front of the square pulse at the C input (FIG. 2). Thus, at the time t, at the first output of the regulator, there is O and pulses are removed from the control electrode of the power triac 7, permitting its open state. However, the triac 7 is closed in the case under consideration only when the current of the capacitor 10 becomes zero, and the voltage on the capacitor 10 reaches the amplitude positive value of the mains voltage. Delay element 8 provides a command at the second output of the regulator that enables the forced discharge of the capacitor 10, in the order of 10 ms in time t (FIG. 2). This delay is introduced so that the opening of the triac 9 can only open after closing the main power simistor 7 (figure 1). The discharge triac 9 with its control electrode is connected to the second output of the controller. This means that at the time tg, the energy stored in capacitor 10 will begin to discharge at resistor 11 with a constant time, which is determined by the product T. For example, let R 200 Ohm, CK 1000 µF, then T 0.2 s, time full yes capacitor t ".. The initial value of the discharge current through the discharge triac 7 in order of 2A at

UH-GH. 400 V. In the next production (| |

the free moment t0 immediately after the moment t or after several periods the control unit 4 (Fig. 1) forms the front of the command to turn on the AC section; then at time tr after 1s, defined by delay element 5, the information D input of the trigger 6 is fed 1 , recorded on the front of the synchronization unit pulse at the moment tg. In this case, the capacitor 10 is completely discharged, the discharge triac 9 is closed and the capacitor unit is again connected to the mains voltage. When the network voltage rises above the allowable value, the overvoltage latching element 3 (Fig. 1) generates a single signal arriving at the R input of the trigger 6 installation to the zero state. Thus, at the first output of the regulator,

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O is cast and pulses are forced forcibly removed from the control power triac 7 allowing its natural commutation. Snimistor 7

closes when the current passes through zero, and the discharge of the capacitor 10 through the resistor 11 begins, since 10 ms after being set to AC. the first output O at the second controller output is set to a single state allowing opening of the triac 9,

The proposed automatic regulator of reactive power of a KU on a triac in the circuit solution is much simpler than the known one, since instead of two complex amplitude discriminators one simple

Q is a null comparator (synchronization unit 2 in FIG. 1), instead of two triggers, one, instead of two oppositely connected power thyristors, one triac, which makes it possible to reduce the weight, size and cost indicators of contactless semiconductor switches almost twice (mass and size cost indicators of an additional discharge triac with a resistor are disproportionately less than those of a single power thyristor or triac). At the same time, the specified quality of the transient process is ensured when the switch-on current does not exceed 40% of the amplitude of the VALUE of a steady-state value, which is the best indicator for the known switching circuits of discharged capacitors with the help of two back-to-back power thyristors.

Claims (1)

Claims An automatic reactive power capacitor control regulator containing a reactive power measuring transducer, a synchronization unit, an overvoltage latching element, whose inputs are combined and are the regulator input 0, the reactive power transducer output connected to the control unit input connected with a trigger, to the C input of which the synchronization unit is connected, its R input is connected to the overvoltage latching element, the trigger output is connected to the input of the switch, characterized in that, in order to simplify the controller 0 U network Editor A. Lezhnin Compiled by O. Nakazna Tehred L. Oliynyk Proofreader M. Kucher va Order 977 Circulation 649 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and publishing plant Patent, Uzhgorod, st. Gagarin, 101 FIG. 2 Subscription