RU2055440C1 - Adaptive voltage regulator - Google Patents

Abstract

FIELD: voltage regulation in electric networks. SUBSTANCE: directional search of various combinations of time delay and dead zone takes place in device due to introducing into voltage regulator on-load tap changer present position detecting unit, regulation efficiency computing unit, and comparison unit with YES and NO outputs for comparing regulation effectiveness with desired value; this procedure occurs by searching optimum regulation parameters. In addition, assembly averaging operation has been replaced by time averaging operation during information processing as it becomes available. EFFECT: improved efficiency of voltage regulator, saved area of microprocessor main storage. 2 dwg

Description

 The invention relates to electrical engineering and can be used to control voltage in electrical networks, in particular, at traction substations of electric railways.

 Known devices for voltage regulation using a switch under the load of a transformer with the so-called on-load tap-changer of a transformer with automation of their work (ARP). The development of an adaptive voltage regulator was a powerful step towards improving the efficiency of the ARPN functioning. Also known is an adaptive voltage regulator of a transformer with a discrete switching device for regulating voltage under load (on-load tap-changer), containing an on-load tap-changer connected to a control signal generating unit, a voltage transformer with a measuring transducer connected to a traction transformer, this regulator is adopted as a prototype.

 The processing of measurement information, the formation of control actions according to a predetermined algorithm is carried out by a microprocessor device, including a voltage monitoring and control unit, blocks for calculating the number of on-load tap-changer switches and voltage dispersion, blocks for increasing and decreasing the time delay and deadband, and comparison blocks with yes and no outputs "the number of on-load tap-changer switches per day with a given value and dead zones with specified values (maximum and minimum).

 The idea of the control algorithm in the prototype is based on the constant formation of arrays of voltages corresponding to certain combinations of different time delays and insensitivity zones to the choice of such combinations for which the voltage dispersion is minimal and the number of ARPH switching does not exceed the permissible value. At the same time, the number of training and work cycles alternates programmatically.

 The disadvantage of this device is the complexity of the control algorithm due to the need to have a large memory of random access memory for processing a large amount of information and periodically transferring the microprocessor device from the monitoring and control mode to the setting calculation mode, in which voltage is not monitored and controlled.

 The purpose of the invention is the simplification and increase the efficiency of the adaptive voltage regulator.

 This goal is achieved by introducing a unit for determining the current position of the on-load tap-changer, a unit for calculating the regulation efficiency, a unit for comparing with the outputs “yes” and “no” the regulation efficiency with a predetermined value and the corresponding connection of the blocks in the device.

 In FIG. 1 is a block diagram of a proposed adaptive voltage regulator; figure 2 diagram of the position determiner switch on-load tap-changer.

 Consider the functional purpose of all elements of the circuit (see figure 1).

 A measuring transducer (IP) 1 converts the effective value of an alternating voltage of 100 V of the secondary winding of a voltage transformer (VT) 2 into a constant voltage of 0-10 V.

{σ²[n-1]-(x[n]+c[n])²}
(1) где c[n] c[n-1]

(c[n-1]-x[n])
σ [n] σ [n-1] среднеквадратическое значение напряжения за n и (n 1) отсчетов;
x[n] текущая реализация измеряемого напряжения;
n число отсчета текущих значений напряжения.The unit for calculating the estimate of the variance of the voltage (D) 3 performs a calculation each time upon receipt of the next voltage value according to the expression
D σ ² [n] σ ² [n-1]

{σ ² [n-1] - (x [n] + c [n]) ² }
(1) where c [n] c [n-1]

(c [n-1] -x [n])
σ [n] σ [n-1] rms voltage value for n and (n 1) samples;
x [n] current implementation of the measured voltage;
n is the reference number of the current voltage values.

(2) где σ_р среднее квадратическое отклонение напряжения при его регулировании;
σ среднее квадратическое отклонение напряжения без регулирования.The unit for calculating the effectiveness of regulation S 4 calculates the effectiveness of regulation in terms of
S

(2) where σ _{p is the} mean square deviation of the voltage when it is regulated;
σ standard deviation of voltage without regulation.

 The voltage transformer TN 2 is connected to the buses of 27.5 kV traction substation, which are powered by a traction transformer T 5 with a PR 6 drive of the switch under the load of the winding branches (RPN).

Blocks D 3 and S 4 are located in the microprocessor device of MU 7. In addition, the MU contains blocks of ODA 8 of the position indicator of the on-load tap-changer regulator, block N 9 for calculating the number of switchings, block N _c <N _q 10 for comparing the daily number N _{with on} -load tap-changer s given N _q , block S> Sq 11 comparing the calculated control efficiency S with a given S _q , blocks (TB t) and (TB + t) respectively decrease 12 and increase 13 time delay.

Here TV is the initial time delay (2-5 min), the stage of change of time delay (1 min). Block Z _n <Z <Z _in (14 compares the current value of the dead zone with the given minimum Z _n and maximum Z _in values, the blocks (Z + + ΔZ) and (Z Δ Z) are connected to its outputs “yes” and “no” accordingly, changes in zone 15 and changes in the sign of the increment Z 16 dead zone.

The control unit BKU 17 receives information about the time delay and dead zones selected as a result of the search by the MU device in the following options:
(TV + t), Z
TV, Z
(TV t), (Z Δ Z)
(TV t), (Z + Δ Z) The input signals of the BKU 17 block are amplified by the FSU 18 control signal generation block.

Figure 2 shows the connection of the ODA unit to the magnetoelectric logometer A of the PR drive, where R ₁ , R ₂ , R _{3 are the} resistance of the logometer, and R _{l is the} resistance of the line. The logometer is powered by a voltage of 12 V. R _p1 and R _{p2 are the} resistance of the displacement sensor. When changing the position of the on-load tap-changer, the position of the contact K changes and, accordingly, the ratio R _p1 / R _p2 and, therefore, U ₁ / U ₂ change. Since each ratio U ₁ / U ₂ corresponds to a specific position of the on-load tap-changer, the ODA unit, calculating the ratio U ₁ / U ₂ , determines the position of the switch.

 The adaptive controller circuit operates as follows.

 Depending on the load conditions in the power system and traction substation, as well as the position of the on-load tap-changer of the traction transformer T 5, the voltage on the 27.5 kV buses is constantly changing. A signal proportional to the voltage on the 27.5 kV buses, with the help of a voltage transformer TN 2 and a measuring transducer IP 1, is fed to the input of the voltage monitoring and control unit BKU 17, which receives information on the values of the dead band and the time delay and issues a command to the FSU 6 increase or decrease voltage. In the initial state, in the BCU block, the control parameters are TV and Z. The FSU block generates control signals for the PR 6 drive, which acts on the on-load tap-changer of the traction transformer 5.

 Block 3 calculates the variance of the voltage coming from IP 1, i.e. tire voltage dispersion of 27.5 kV when regulating it using on-load tap-changer. At the same time, taking into account the position of the on-load tap-changer using the OCR unit 8, in block D, the voltage is reduced to the initial (unchanged) position of the on-load tap-changer, i.e. the voltage is determined by calculation in the absence of regulation and then the variance of this voltage is calculated. MU repeats all calculations with a given frequency (usually 10-60 s).

 The main task of the microprocessor device MU 7 is to search for optimal values of the control parameters (dead band Z and time delay TV). For this, the MU blocks were connected appropriately (see Fig. 1), as a result, an increased or decreased time delay and a dead zone can be applied to the input of the control unit.

The search for the optimal control parameters begins with an estimate of the number of switchings of the controller for the billing period (day) in block N 9. There may be the following situations:
if the daily number of switchings of the controller N _s exceeds the permissible value N _d , which is determined in the block N _c <N _d 10, then a decision is made to increase the time delay in the block (TV + t), 13. As a result, the BCU block works with the control parameters ( TB + t), Z, i.e. only the delay increases;
if the daily number of switchings of the controller N _s does not exceed the permissible N _d , then the calculation of the efficiency of regulation in block S 4 and comparison with the set value S _d in block S> S _d 11 are performed;
if the regulatory efficiency is satisfactory, i.e. the condition S> S _{d is} not fulfilled, then the control parameters remain unchanged, the control unit continues to work with the parameters TV and Z;
if the condition S> S _d is satisfied, i.e. Since the regulatory efficiency is unsatisfactory, a decision is made to reduce the time delay in the unit (TV t) 12 and at the same time change the deadband. For this, in the block Z _n <Z <Z _in ? 14 compares Z with predetermined values of Z _n and Z _in . If the condition is met, then the deadband in the Z + Δ Z block changes by the increment Δ Z 15, otherwise the sign of the deadband increment in the Δ Z Δ Z 16 block changes. Thus, the BCU 17 will work with the parameters (TV t) , (Z + + Δ Z) or (TV t), (Z Δ Z), as well as from TV, Z or from (TV + t), Z.

Blocks 14, 15 and 16 form a “shuttle” of zone Z: from Z _n to Z _in (with positive Δ Z) and then from Z _in to Z _n (at Δ Z Δ Z), then again from Z _n to Z _in etc. As a result, all the values of the zones Z within Z _n -Z _{c are} viewed.

 Thus, in the process of searching for optimal control parameters, directional enumeration of various combinations of time delays and dead zone (within the specified values) occurs, which simplifies the implementation of optimal voltage regulation; due to the transition from a complete enumeration of all acceptable combinations of time delay and deadband (as in [7]) to directional enumeration with control of the standard deviation of the voltage; due to the fact that there is no longer a need to periodically transfer the microprocessor from the control and management mode to the mode of calculating control settings when the mode is not controlled. By replacing the averaging operation over the set with an averaging operation over time when processing information as it arrives, which saves the memory of the microprocessor random access memory.

 The initial selection of control parameters is made directly at the traction substation.

The adaptive regulator operates at the traction substation Mukhtolovo of the Gorky Railway, where it was assumed that
N _d 15, Z _n 1.3 kV, Z _at 2 kV,
Δ Z 0.05 kV, t 1 min, S _d 0.2 Initial values Z 1.65 kV, TV 4 min.

 Operational results: the average daily number of switchings of the regulator is 7-10, the regulation efficiency is S 0.7-0.79.

 The technical and economic effect of the adaptive controller is that the reliability of the on-load tap-changer of the transformer is increased by reducing the number of switching operations, as well as the reliability and efficiency of the electric rolling stock and the power supply system as a whole by reducing voltage fluctuations.

Claims (1)

 ADAPTIVE VOLTAGE REGULATOR, comprising an on-load tap-changer drive with a control signal generating unit, a voltage transformer with a voltage measuring transducer, a microprocessor device that switches off the voltage monitoring and control unit, on-load tap-changer and voltage dispersion calculation blocks, time delay increase and decrease blocks, zone change and changes in the sign of the increment of the deadband of the voltage regulation, comparison blocks with the outputs "Yes" and "No" of the number of on-load tap-changer switches per day from the given m value and dead zones with set values, characterized in that the blocks for determining the current position of the on-load tap-changer, the block for calculating the regulation efficiency and the comparison unit with outputs “Yes” and “No” for the regulation efficiency with the set value are input, and the input of the block for determining the current switch position The on-load tap-changer is connected to the on-load tap-changer, and its first and second outputs are connected respectively to the input of the on-load tap-changer calculation unit and the first input of the voltage dispersion calculation unit, the first and second the moves of the control efficiency calculation unit are connected respectively to the output of the voltage dispersion calculation unit and the “Yes” output of the on-load tap-changer comparison unit per day with the set value, and its output is connected to the input of the control efficiency comparison unit with the set value, the “Yes” output of which is connected to the input of the unit for reducing the time delay, the input of the unit for comparing the number of on-load tap-changers per day with a valid value is connected to the output of the unit for calculating the number of on-load tap-changers, and the output "No" is connected to the unit uve time delay, the input of the dead band comparison unit with the set values is connected to the output of the time delay reduction unit, and its outputs "Yes" and "No" are connected respectively to the first input of the dead band change unit and to the input of the change sign block of the increment of the dead band of the voltage regulation the output of which is connected to the second input of the deadband change unit, the output of the measuring transducer is connected to the input of the voltage dispersion calculation unit and to the first input control and control unit, the output of which is connected to the input of the control signal generation unit, the second input of the control and control unit is connected to the output of the time delay increase unit, with the output "No" of the unit for comparing the control efficiency with the set value and the output of the deadband unit.

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