SU1474793A1 - Device for automatic control of voltage by compensating devices and taps of three-winding transformer at power supply center - Google Patents

Abstract

The invention relates to devices for controlling and maintaining voltage cuts and reactive power mode in a predetermined range in electrical distribution networks, where in the center of the power supply three-winding power transformers with voltage regulation under load are installed. The purpose of the invention is to improve the quality and speed of regulating the voltage deviations in the center of the power supply, to achieve the optimum reactive power mode established by the power system. This is achieved by the fact that the device is equipped with a voltage sensor on the high side of power transformer 2, active and reactive power sensors at medium and low voltages of distribution network 4-7, analog-to-digital converter 9, analog switch 8, synchronous motor excitation control unit 11, the control unit of the sources of reactive power 12 and the block module of the automatic controller 10, which contains a microprocessor, a persistent storage device, a control unit. 5 il.

Description

The invention relates to devices for controlling and maintaining voltage deviations and reactive power modes in a predetermined range in electrical distribution networks, where voltage-controlled power three-winding transformers are installed in the center of the power supply. nor under load.

The aim of the invention is to improve the quality and speed of controlling the voltage deviation at the center of the power supply and to achieve the optimum reactive power mode established by the power system.

Figure 1 shows the block diagram of the proposed automatic voltage control device by compensating devices and tapes of three-winding transformers in the center of the power supply; Fig. 2 is a block diagram of an automatic controller module; on fig.Z - the general algorithm about 0

The address of the address signal from the module of the automatic controller generates a signal to the analog-to-digital converter 9, which converts the analog signals from the analog switch to digital form and outputs to the input of the module-module of the automatic controller. The automatic regulator module module 10, the AND control unit for synchronous motor excitation control provide for changing the LED mode over the excitation current to compensate for the reactive power in the electrical distribution network, a LED thyristor excitation regulator is used; unit 12 for controlling reactive power sources (IRM) discretely changes the process of generating reactive power for IRM, uses thyristor keys for controlling IRM, Block 13 for controlling the drive of transformer taps, produces two signals Add, Increases

a process for regulating deviations of the direction according to which they originate in the center of the food; Fig. 4 illustrates an algorithm for the procedure of increasing voltage levels to an acceptable range in the center of the power supply system; Fig. 5 a, b shows the algorithm for the procedure for reducing the voltage to the allowable range in the center of the power supply (beginning and end).

In FIGS. 4, 5 a, b, the numbers indicate the sequence of signals passing.

The device contains a three-winding transformer 1, a voltage sensor 2 on the high side of the transformer to control the effects of voltage fluctuations on the side of the power system, a voltage sensor 3 on the low side of the distribution network, the active power sensor 4 on an average voltage of the distribution network, reactive power sensor 5 at medium voltage of the distribution network, low voltage active power sensor 6, reactive power sensor 7

at low voltage distribution network. Active and reactive power sensors provide monitoring of changes in active and reactive power flows in the power supply system.

Analog switchboard (AK) 8 organizes the reception and output of informational analog signals from all measurement sensors, and when the transformer spikes arrive.

At the same time, the outputs of all measuring sensors are connected to the inputs 0 of an analog switch connected via an analog-to-digital converter to the input of a block module of an automatic controller; the first output of which is connected to the input of the excitation control unit of synchronous electric motors, the second output is connected to the entrance of the control room of the source of reactive power, the third output is connected to the input of the control unit for the drive of the transformer taps.

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The fourth and fifth outputs, which provide control signals, are connected respectively to the input of the analog-digital converter and the input of the analog switch, which has two more inputs for information feedback: one of them is connected to the second output of the synchronous electric drives excitation control unit, the first output of which affects the change in the excitation current regime of synchronous motors; the other, to the second output of the power control unit of the sources of reactive power, the first output of which affects on discrete change of power sources of reactive power.

31474793

Block modulator 10 automatic

controller is made on the elements of microprocessor technology and consists of. from input-output (SW) 14 - organizes the reception and output of input and output signals by command; block 15 of the permanent storage device (GOU) - organizes the recording of the program; a random access memory (RAM) unit 16, a control flowchart 17 (SU), a microprocessor 18 (ML), a readiness and reset flowchart 19 (SGT and CC), and a sync pulse shaping circuit 20. The microprocessor is connected to the ROM, RAM, and ACU via a bi-directional data bus 21 (1HD) and through the output address bus 22 (ША). The microprocessor, through the control circuit unit, acts on its output bus 23 of the control unit and activates one of the blocks of RAM, ROM, and UVB.

In this case, the conclusions of the microprocessor

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20

The automatic regulator module module contains a readiness and reset block diagram 19 that generates a reset signal (CBP) for input into the UVB unit and an MP unit; the Ready signal (GT) for input into the MP unit is intended for laying the controller module and consists of two elements NOT, RS-flip-flop, buttons and toggle. A toggle switch (T2) is used to switch from automatic mode to step-by-step, the button to execute the hague program. The sync pulse shaping circuit 20 generates two phase shifted clock pulses C and C and is a known closed phase synchronization circuit and consists of a square pulse generator, a sync pulse generator, and a level converter.

Microprocessor unit 18 performs all logical and arithmetic operations inside the module device.

through the internal address bus of the controller connection 25, work on the pr .ogram, with

The microprocessor inputs are connected to the I / O of the random access memory block, the Permanent Memory block, and the I / O unit with inputs of the random access memory block, the persistent memory block and the control unit. The input of the control unit is directly connected to the output of the microprocessor, and the outputs of the control unit are connected via the control bus to the inputs of the read-only memory block, the operational memory block and the I / O block.

The outputs of the ready and reset blocks, the formation of sync pulses are connected to the external inputs of the microprocessor for debugging and starting the microprocessor. The external input of the I / O unit is connected to the output of an analog-to-digital converter.

Five external outputs of the I / O unit are connected: the first to the input of the control unit of synchronous motors, the second to the input of the control unit of the sources of reactive power, the third to the input of the drive control unit of the transformer taps, and the fourth and fifth, respectively, to the information inputs of the analog switch and analog -digital converter.

l-

0

The automatic regulator module module contains a readiness and reset block diagram 19 that generates a reset signal (CBP) for input into the UVB unit and an MP unit; the Ready signal (GT) for input into the MP unit is intended for laying the controller module and consists of two elements NOT, RS-flip-flop, buttons and toggle. A toggle switch (T2) is used to switch from automatic mode to step-by-step, the button to execute the hague program. The sync pulse shaping circuit 20 generates two phase shifted clock pulses C and C and is a known closed phase synchronization circuit and consists of a square pulse generator, a sync pulse generator, and a level converter.

Microprocessor unit 18 performs all logical and arithmetic operations inside the module device.

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40

Jq

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held in a block permanently storage device.

The control block diagram 17 is designed to activate one of the devices (ESD, RAM, HVM) by the MP unit for the exchange of information. The block 15 of the persistent storage device serves to store the initial program, processing information. It also stores constants characterizing the dependence of voltage levels on active and reactive loads at medium and low voltage of the distribution network. The operative storage unit 16 serves to store intermediate calculation results. The ROM and RAM blocks have a system for addressing content to the data bus. The I / O unit 14 is configured so that the microprocessor refers to it as memory cells. Here, at the request of the MP unit, reading of digital input signals from the ADC unit is organized, and outputting signals to blocks 11–13 and control signals to blocks 8 and 9 are organized through the UVB block.

The control bus 23 is organized by the output signals of the control unit and is designed to control the ROM, RAM, and UVB units upon request of the block 18, the data bus 21, and the address bus 22 for exchanging information between the RAM, REM and UVB blocks and the MP unit.

A voltage control device to maintain voltage deviations from nominal on medium and low voltage buses of three-winding transformers in the optimal range provides for the combined combination of local control means (synchronous

motors and static sources of re-IQ at the command of the SU and MP units coming active power) and centralized (taps of power transformers). Information signals from all measuring sensors 2-7 are fed to the input of block 8 of the analogue switchboard 15. On the output channel of the air-blast unit 14, the MP-18 unit sets the address of the sensor, which is the input for unit 8, and the input of this unit is supplied with the air-blast signal from the ADC. Here, an RFP signal is generated for outputting digital output signals from the MP unit through the SU unit for controlling blocks 11-13, and the control signals for blocks 8 and 9. The GT signal is generated in the SGT block and C is fed to the input MP unit debugging the controller, signal Resetting the CBP from the SGI and C block, gives all the signals from all the sensors. Select 20 seconds on the VC ° D of the MP unit and the air-blast unit for

installation of MP and UVV in the initial state when the power is turned on. Two phase-shifted clock pulses C. and C 1 are formed in FS block 20. The mathematical model of voltage regulation in the center of the power supply is presented in a general form by the regression equation:

The early signal is switched to the ADC block f, the output of which removes the corresponding digital signal to the input channel of the UVB block 14, then sets the address of the next signal, reads the signals from all measurement sensors and writes them to the RAM block 16. After recording all signals unit MP 18 requests the initial calculation program and constants from ROM unit 15. The output signals of the DB and PM microprocessor unit and two signals from the address bus ША 10, ША 13, are input signals for the control unit 17. The input signals of the control unit These are the output signals of the VD, PM microprocessor unit and two signals ША 10, ША 13, with the help of which the VD unit activates one of the ROM, RAM, UVV devices with which the MP exchanges information. The output signals of the SU unit form a psh, n, control, SHU 23, which includes five control signals of the ROM, RAM, and UVB.

The input signals of the REM unit are: the ten address signals coming from the address bus 22, one control signal VM, coming from the control circuit. The eight output data signals on the bus 21 data.

 The input signals of the RAM unit are ten address signals, coming from the address bus, two control signals VM, RAM, ZP RAM from the control circuit unit, output and input signals, eight data signals per data bus. The input signals of the air-blast unit are:

three control signals VM55, ChT55, ZP55 coming from the control circuit of the control system, the CBP signal comes from the reset generation circuit, two signals AO and A1 come from the MP unit, eight input and output data signals from the data bus. In the UVV block, digital input signals are read,

on the command block SU and MP coming

on UVV with ADC. Here, an RFP signal is generated for outputting digital output signals from the MP unit through the SU unit for controlling blocks 11-13, and the control signals for blocks 8 and 9. The GT signal is generated in the SGT block and C is fed to the input MP unit the debugging of the regulator, the signal Resetting the CBP from the SGI and C block is output to the VC ° D block of the MP block and the UVB block for

 about

installation of MP and UVV in the initial state when the power is turned on. Two phase-shifted clock pulses. and C 1 are formed in FS block 20. The mathematical model of voltage regulation in the center of the power supply is presented in a general form by the regression equation:

+ B, U Bk + bc nc + b 5Q HH + b4 cn + + b50CH (1)

coefficients or constants: b0, bf, ..., bЈ - are determined using a regression analysis based on preliminary experimental data and entered into a block of ROM 15.

The variable factors involved in - functional dependence (1) are selected on the basis of the following causal relationships:

(u)

en

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0

five

- the main determining variable factor, this interrelation between the voltage modes in the power supply system (SES) and the power system is needed later to coordinate the operating modes of the ADSU and this local controller, constant monitoring of the voltage levels of UBH is necessary due to the fact that with the inclusion of compensating devices in the SES, a certain optimization of URlt is achieved;

(PHH) - establishes a causal relationship between the operating modes of the main energy-intensive and responsible power consumers — injection plants that determine the final output of the chemical enterprise, the permissible levels of CPU voltage are selected based on an analysis of the parameters of the mode of these plants, adjusted by economic characteristics and on voltage losses in SES elements;

f, (QHH QCH) constant monitoring of these variable factors is necessary to determine the characteristics of the operating modes of the compensating devices at medium and low voltage SES;

(PCH) - establishes the relationship between the active power fluxes at the average SES voltage and the voltage levels on the low side of the SES;

UHH - constant monitoring of the voltage levels on the low side of the SES is necessary for internal diagnostics. after the input of all variable parameters and UHH calculation by the model, the calculated U HW is compared with the actual U WH voltage from the sensor, if the given parameters of the control system coincide, they function normally, if there is a discrepancy

, a malfunction of the regulator, a torus, and a software shutdown of the automatic regulator is triggered, and the executive elements of the on-load tap-changer control system of transformers, DM and IRM operate in an autonomous mode.

The functional dependence of its voltage in the CPU (UHH) with a power three-winding transformer on the voltage USH / UCH / U HH and variable 20 factors is represented by the expression

HJH v.H LiHjLi Ei QfJli5Јi5.

TO

 NN

U

kn

  ) Qcij (.

U

NO

. U

NN

where K is the transformation ratio of the power transformer.

After appropriate transformations and decomposition of the functional dependence according to the Taylor formula, the weight fraction of the variable factors in the regulation process, limited only to terms of the first order and neglecting the residual term R, defines et 5 s as

ei

7f

Јunn

(R + r °);

- 21С (хс + ХВ

50

UHK I Cr + g V T 2TG Gs + rj) ainn

3QcH

 9lE (xc + xb)

2TG

3UM (L UBH D K 2K1 I

1 + 215

 . K 1

where - | (gjft ... H (fgs + xb) +

NN

(r, + rR) + QNHx

+ PCH (rc + r6) + QCH (xc + xB)

The weight fraction of the input variables is characterized mainly by changes in the corresponding active and reactive resistances, these changes are entered into the mathematical model (1) in the form of constant coefficients of the regression equation b,

The constant coefficients of the regression equation (b) are obtained on the basis of processing experimental and statistical studies using regression analysis methods on a computer using the ANAL-2 program, the regression equation for each particular distribution network should be calculated from characteristic samples of input parameters from the initial array — experimental statistical data - follow.

The mathematical model includes all factors that determine the causes of the occurrence of voltage deviations from normative values. When solving equation (1), changes in any parameter included in the multiparameter model can cause a mismatch between the calculated indo and. empty range and the corresponding software testing of the control functions of the automatic controller by local means of regulating diabetes and IRS. If this control process is insufficient, the on-load tap-changer of the transformers is turned on.

Constant information about variable parameters from control sensors about their change allows us to create the following discrete system for regulating the voltage at the center of the power supply. .

After entering all the information sig - 45 which consists of two sub-steps,

The sensor module 18 calculates, according to the program (1), the required voltage value on the low side of the distribution network, the power supply system, and undergoes a comparison with the signal from sensor 3 if there is no difference between the two voltage values or the minimum and is within the allowable range of voltage deviations in the center of the power supply on the output channel of the UVB block of control signals to blocks 11–13 and there is no after a time interval & t

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The process of determining UHH in block 18 is repeated and, if even after this stage, there is no normalization of deviations of voltage 7 j, then the signal generated in block 18 is output to control block 13 from the output channel of block 14, which produces a signal to Add or Hear This means that, depending on them, the spider of the transformer is switched one by one respectively.

After each stage there is a program check accordingly.

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The process of controlling the input parameters is repeated.

When the voltage on the low side of the distribution network from sensor 3 does not correspond to the calculated value of test voltage and goes beyond the permissible limits of voltage deviations, in block 18, a signal is generated for the SU 17 unit, which activates the UVB 14 unit and generates an RFP signal for output through the output channel of the unit The UVV signal to the block BUU SD 11, which is converted to analog in a digital-to-analog converter and after block 11 using an thyristor device APB, affects the change in the excitation current of a synchronous motor and the corresponding changes of reactive power flows in the power supply system. After this adjustment step through time ut, the readout of signals is repeated, but here the input signal of block 8 is supplied with an information feedback signal from block 11, which is then compared with the signal of block 7, if there is no discrepancy between them, the information signal passes from block 7, if there is a discrepancy due to losses in the elements of the power supply circuit, the signal from block 11 is taken as the reference signal, n the process of calculating the level of eg 20

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low side (UHH) is repeated. If by the previous stage we did not achieve the normalization of voltage deviation levels, then at the next stage, on the output channel of the air-blast unit (14). a control signal is issued to block 12, which two-step changes the reactive power flows by turning on or off the sections of the reactive power sources of block 12. After this step,

which consists of two sub-steps,

The process of determining UHH in block 18 is repeated and, if after this stage there is no normalization of deviations of voltage 7 j, then from the output channel of block 14, the signal generated in block 18 is output to control block 13, which generates a signal to Add or Remove. and depending on them, the transformer taps are switched one step at a time, respectively.

After each stage there is a program check accordingly.

voltage levels on the low voltage side of the transformer permissible range. The process of switching over the transformer taps, depending on the levels of voltage deviations, is repeated until the voltage deviations of the permissible range are reached.

Algorithms for the general regulation of voltage deviations in the center of the power supply. When the voltage drops below the optimum level, the control sequence is as follows; by increasing the excitation current, the generation of reactive power by synchronous motors increases, then with an insufficient increase in voltage, static sources of reactive power are connected and, finally, the voltage is increased by switching the transformer taps under load. When the voltage rises above the optimum level, the control sequence is as follows: decreasing the excitation current reduces the reactive power generation of synchronous motors, then, if the voltage is not sufficiently reduced, static sources of reactive power are turned off, and finally, the voltage of the transformer taps under load decreases. At the same time, the increase or decrease in reactive power from local sources (synchronous electric motors and static sources of reactive power) is carried out within the limits established in accordance with the reactive power mode specified by the power system. In cases when the use of one or two local control means is impossible due to systemic limitations on reactive power, these steps return to their original state after checking compliance with the reactive power mode, are programmatically blocked and proceed to the next voltage control step. nutrition centers. The permissible levels of voltage deviations in the center of the power are set on the basis of a preliminary analysis of the nature of the change in the levels of voltage deviations from the load parameters on the side of the medium and low voltages of the center of the power supply, taking into account voltage losses and power

in the distribution network elements of the power supply system

U. Ј U

CPU

 U

1 g

where U. and U2 are the boundary values of voltage variation levels.

The adjustment of the initial control program taking into account the voltage losses in the elements of the power supply circuit allows us to establish the optimal range of voltage deviations at all distribution points of the power supply system according to the mathematical model of the form:

UHH.p..Ug. + b3QH) r + b4PCH +

(2)

+ bcQ.u t Lee

)

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0

five

0

five

0

five

where is the voltage loss in the elements of the power supply system to this RP.

Equation (2) determines the optimal range, if necessary, of voltage deviations at this distribution point, where local means of regulation are installed, using information and feedback signals on reactive power at these distribution points.

The detuning of the voltage regulator in the process of regulation from deep landings and voltage surges occurs due to the fact that the verification of compliance with specified conditions is carried out discretely in time through ut ,. The sampling interval Јt1 is sufficient for restoring reactive power sources and re-activating the drive of transformer taps, and also provides software blocking from landings, emissions, and voltage fluctuations by magnitude and duration.

Protection against tampering of transformers to extreme positions (the most severe mode for the normal functioning of transformer taps) is programmed by continuously taking into account the steps of adjusting the taps of transformers, for example, by condition

п п п п reg

: P

n

n,

where nu is the initial step

transformers;

final step otpaek

transformers.

When developing an algorithm for regulating the voltage deviation levels in the center of the power supply, methods and means of structural programming are used.

The proposed device is a tracking system for adjusting

voltages in the center of the power when the active and reactive loads vary widely. The use of the servo system and control over voltage variation levels (OI) for all inputs and parameters improves the quality and speed of the process of voltage variation control on low and medium voltage buses of the power supply system of the power supply system.

The use of local voltage regulators (DM and IRM) and centralized in one automatic regulator improves the quality of the regulation process and eliminates the mutual influence of each other on each other during the step-wise regulation process. Maintaining the OP levels of the required quality in the power center while ensuring the necessary compensation of reactive power in the power supply system reduces the overall power consumption of the enterprise. The implementation of an automatic control system based on microprocessor technology improves the speed of the control process, provides for the expansion and improvement of functionality and application.

Claims (1)

Invention Formula Device for automatic voltage regulation by compensating devices and tap-off triple-winding five 0 five 0 five 0 five 0 transformer in the center of the power supply, containing a voltage sensor on the low side of the power transformer, an automatic voltage regulator module and an actuator control unit for transformer taps, affecting the switching of transformer taps, with the aim of improving the quality and the speed of regulating the voltage rtclone in the center of the power supply and achieving the optimal mode of reactive power installed by the power system, it is equipped with a voltage sensor on the high side of the power transformer, active and reactive power sensors at medium and low voltages of the distribution network, analog-digital converter, analog switch, automatic regulator module block, the algorithm of which is shown in figures 4,5a, 56, synchronous electric field excitation control unit control unit of reactive power sources, while the outputs of all measuring sensors are connected to the inputs of an analog switch5 connected through an analog-to-digital converter with an input The automatic regulator module module, the first output of which is connected to the input of the excitation control unit of synchronous electric motors, the second output - to the input of the control unit of reactive power sources, the third output - to the input of the drive unit of the tamper transformer, the fourth and fifth control outputs are connected respectively to the input of the analog-digital converter and the input of the analog switch; two inputs for information backhaul are connected to the second output of the control unit in zbuzhdeniem synchronous motors and a second output reactive power sources, the power control unit accordingly. Fia. fa the end uii i i- Compiled by 0.Nakazna & “& Editor S.Patrusheva Tehred L. Serdyukova. Proofreader S. Shekmar Order 1906/54 Edition 605 Subscription VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. D. 4/5