SU1576979A1 - Device for power supply with compensation for distortions of currents and voltage of power supply system - Google Patents

Abstract

The invention relates to electrical engineering. The aim of the invention is to improve the control accuracy at the final power and non-sinusoidal voltages and currents. New is the division of the process of compensating for distortions into separate components. When compensating for the current consumed from the generators, the form of the current must coincide with the form of the generator voltage. In fact, the task of compensating for the energy consumed by the generator is divided into two tasks: the compensation of current distortions and the compensation of voltage distortion. For this, the instantaneous voltage values at the output terminals of the converter and / or the load are measured. The frequency of the output voltage of the generator is measured. The period of the generator output voltage is determined. The partial current converter and / or load and generator voltage are determined, the non-sinusoidal generator voltage from the first voltage sensor and the output of the sample memory circuit are multiplied. A reference signal proportional to the input voltage of the converter and / or the load on the period of operation is stored in the memory block. In accordance with the signal from the synchronization circuit, the required value of the voltage from the memory unit is selected, the current value of the output voltage of the converter and / or the load over which the output voltage of the longitudinal part of the compensator is formed is determined. The instantaneous values of the voltages at the output of the transverse part of the compensator and / or the load in the common circuit are summed up. 1 il.

Description

The invention relates to the field of electrical engineering, in particular, to the compensation of current and voltage distortions in systems by compensating for the phase angle shift between the first harmonics and the current and voltage harmonics in general industrial and autonomous electrical networks using static valve compensated DOM.

The purpose of the invention is to improve the accuracy of regulation in the system of final power and non-sinusoidal voltages and currents.

The drawing shows a diagram of the device.

The device contains a generator 1 voltage, choke 2, valves, filter 7, capacitor 8, valves 9-12, filter 13, load 14, sensors

15 generator generator sensor

16th load, sensor 17 and

18 current, divider 19, integrator 20, sampling circuit 21, sample multiplier 22, adder 23, frequency sensor 2k, synchronization circuit 25, control circuit 26, adders 27 and 28, first delay lag unit 29, comparator 30 with hysteresis, driver pulse control device 31, sampling device 32, memory unit 33, digital-to-analog converter 34L adders 35 and 36, first-order delay unit 37, comparator 38 with hysteresis, driver control pulse generator 39.

In the power device with

by compensating for distortions connected in parallel with voltage generator 1 and load 14, the first four controlled valves 3-6 are connected in a bridge circuit, one diagonal includes choke 2, and the nodes of the second diagonal through the first output filter 7 are connected in parallel with voltage generator 1, in the second group of four controllable valves, the valves are connected by a bridge circuit, in one diagonal of which are included a capacitor 8, and the nodes of the second diagonal are connected in series with the load 14 through the second output filter 13, current sensors 17 and 18 respectively, connected in series with the output terminals of the first filter 7 and the load 14, the output terminals of the divider 19 are connected to the outputs of the generator voltage sensor 15 and the first current sensor 18, and the output terminal of the divider 19 is connected via an integrator 20 to the output terminal of the sampling circuit 21 By recalling the samples, the output of which is connected to the first input of the multiplier 22, in which the second input is connected to the output terminal of the generator voltage sensor 15, the output terminal of the multiplier 22 is connected to the non-inverting input of the adder 23, which rtiruyuschy input Con

Jq 20

25

50 55

thirty

35

40

45

It is connected to the output of the first current sensor 18, the output terminal of the frequency sensor 24 is connected to the output terminal of the generator voltage sensor 15, and the output terminal of the frequency sensor is connected via a synchronization circuit 25 to a control circuit 26, the output terminals of which are connected to the regulating inputs of the integrator 20 and circuit 21 sampling with memorization of samples, the output terminal of the adder 23 is connected to the non-inverting input of the second adder 27, in which the inverting input is connected to the output of the second current sensor 17, and the output is connected to non-inverted The input of the third adder 28, in which the output terminal through the first delay unit 29 of the first order is connected to the input terminal of the first comparator 30 with a hysteresis, the output of which is connected to the non-inverting input of the third adder 28 and the input of the first driver 31 of the valve control pulses, the output terminal which is connected to the control electrodes of the first four controlled valves, the input terminal of the sampling device 32 connected to the memory block 33 is connected to the output of the synchronization circuit 25, and the output terminal is 32 samples through a digital-to-analog converter 34 is connected to a non-inverting input of a fourth adder 35, whose inverting input is connected to the output of a load voltage sensor 16, and the output is connected to a non-inverting input of a fifth adder 36, whose output terminal is through the second block 37 of the first time delay This is connected to the input terminal of the second comparator 38 with a hysteresis, the output of which is connected to the non-inverting input of the fifth adder 36 and the input of the second driver 39 of the valve control pulses, the output Lemma which is connected to the control electrodes of the second group of four valves actuated.

To describe the process of compensating for generator current distortions, consider a parallel connection of an equivalent EMF - e (t) and non-stationary (instantaneous) conductivities gn (t) and gK (t), which simulate respectively electromagnetic processes in series connection of load with

the longitudinal part of the compensation device, distortion and the transverse part of the compensation device.

Since, when using the distortion compensator, the generator current ir (t) must be identical in shape with the generator voltage Ur (t), i.e. Ur (t) / ir (t) const, then the total conductivity relative to the output nodes of generator 1 should be constant:

U Sn (t) + 8R (0 gjt) +

+ gnjt) + gK (t) g0 const,

+ gKj: t)

-

ten

15

Generator voltages are related to the fact that the proposed distortion compensation device is intended for systems with converters with final power and non-sinusoidal generator voltages. For such systems, in general, it is impossible to determine the period duration, as the duration of the time interval bounded by two consecutive transitions of the function U (() through zero.

The algorithms in accordance with which the generator current distortion is compensated are as follows.

Determining the duration of the period

where gn (t), gK (t), gn. (t), g KJt) are the constant (variable) components of the instantaneous conductivity values of the series connection of the load and the longitudinal part of the device

compensation, as well as the transverse clock. 25 Formation of a current iK (t) by means of

These devices are compensation.

The distortion compensator cannot generate active energy, i.e. The constant value gK- (t) of the conductivity of the compensator gK (t) cannot be negative. If we assume that the energy losses in the compensator are negligible and can be neglected, then the equality g - (t) 0 is true. Then, in accordance with (1), to satisfy the condition of optimal energy consumption

t S0 8n (t) Y Sn (t) dt

(2)

gK (t) g

(t) -gn / - (t).

Distortion compensator current iK (t) is equal to iK (t) Ur (t) gK (t) Un (t)

()) ur (t) (- 8n (t) + 8e)

 in (t) + g0Ur (t). (3

Thus, if the transverse part of the distortion compensator generates a current iK (t) into the system, which is determined in accordance with expressions (2) and (3), then the current consumed from the generator coincides in form with the voltage of the generator generators

Introduction of measuring the frequency of the output voltage of the generator and determining the period of the output

Measurement of values in (t) and Ur (t). The calculation of g0 (t) from the expression (2), the calculation of the current of the transverse part of the compensator in accordance with the expression (3).

. a2) 40

modulation signal throttle transverse part of the compensator. For tracking the current value of the current of the distortion compensator iK (t) with respect to the reference (reference) value of this current, a closed control system is applied.

To describe the compensation of load voltage distortions with the help of the longitudinal part of the compensator, instantaneous current and reference (reference) voltage functions on the load UH (t) and U (t) on are used. The work of the longitudinal part of the compensating device should be organized

3)

and in addition, the voltage of the longitudinal part of the compensator UnK (t) satisfies the condition Ur (t) - (t) Urt (t), where U (t) - U (t), ЈX) d5 is a predetermined real number, accuracy of tracking function U (t) on.

The need to introduce instantaneous compensation operations

The 50 parts of the generator voltage supplied to the load input are caused by the possibility of generator voltage variations in the limits exceeding the allowable voltage variation limits on the converter, as well as by generating a voltage whose form does not satisfy the required voltage form on the load. The value of the reference signal is entered into

memory block. At the same time, the possible set of changes in the voltages Ur (t),), as well as the allowable set of changes in the parameters of the load circuit and their modes are divided into subsets, for each of which the required reference voltage on the load UH (t ) on ,, The selection of the required value of the number of the i-th table of the given function UH (t) ol is made in advance on the basis of a priori information.

The compensation of the distortion of the currents and voltages of the power supply systems using the proposed device, the block diagram of which is shown in the drawing, is performed as follows.

Using voltage sensors 15 and 16 and currents 17 and 18, galvanic isolation, matching the levels of energy circuits and the measuring part of the device, as well as measuring instantaneous generator voltages) voltage at the input of load 1A, load current in ( t) and the current value of the compensator current at the filter 13 output- The output voltage of the generator voltage sensor 15 UBt ,, x, (t) proportional to the measured voltage U Xt) tUBMXl (t) o (MUr (t) 3) is supplied to the second input of the divider 19, the sensor 2k frequency, multiplier 22. Output nap The second current sensor UeMX (t), proportional to the output current of the first filter 7, enters the input of the first closed control circuit by the deviation of the adders 27 and 28, the first-order delay unit 29, and the comparator 30 with giteresis. load voltage sensor UeMX (t), proportional to the voltage at the input of the load 14, is fed to the input of the second closed control circuit for the deviation containing the adders 35 and 36, the first-order delay block 37 and the comparator 38 with hysteresis.

The first input of the divider 19 receives the output voltage of the first sensor 18 of the current U fibix (t), proportional to the measured load current DW4 (t) o (ilin (t) J, which also simultaneously goes to the inverting input of the adder GZ. At the output

divider 19 as a result of dividing two signals UB4fXi (t) and Ueb, M (t) will be a signal proportional to g (t)

e ft) - -in (tl

  Kn ur (t)

The output from the 19 Cgpg (t) divider is fed to the input of the integrator 20. The beginning and end of the integration by the integrator 20 of the input signal are determined by the control pulses from the control circuit 26. As a result of integrating the input signal at the output of the integrator 20, the signals are proportional to the value of g0: t

1

Kjt

Bn (t) clt.

5 oh

five

0

five

When integration is complete, the output of the integrator 20 is supplied to the circuit.

The sampling memory is sampled and then the integrator output is reset to zero. The output of sampling memory sampling circuit 21 remains constant (a signal proportional to g) during the next period of the frequency spectrum.

The moments of change of the output signal of the block 21 are set by signals from the control circuit 26. The moments of issuing control pulses by control circuit 26 (two sequences of pulses, the repetition period of which is equal to T) are specified by synchronization circuit 25, which, based on information from the output of the frequency sensor 2k, determines the output voltage period of the generator ur (t).

Since the two inputs of the multiplier

22 signals are proportional to the values of g0 and Uf (t), the output of the multiplier 22 generates a signal proportional to the product g0 Ur (t), which is fed to the non-inverting input of the adder 23. If we consider that

the inverting input of the adder 23 receives a signal proportional to in (t), then the output of the adder has an instantaneous reference (reference) current value of the compensator i (t) dn (circuit realization of expression (3).

The non-inverting input of the adder 27 receives the signal i (t) on, and the inverting input of the adder 27 is CHI-i (t) T. The output of this adder is proportional to

Ai (t) i (t) on - i (t) T, is fed to the inverting input of the adder 28, the inverting input of which receives a signal from the output of the comparator 30 with hysteresis. At the output of the comparator 30, a signal is generated, which is the control for the driver 31 of the control pulses of the valves. To implement a closed current distortion control system, the output signal from the adder 28 is fed to the input of the first order delay unit 29, and from there to the input of the comparator with hysteresis, due to the relay characteristic of the comparator 30 with hysteresis and feedback to the inverting input of the adder 28 Continuous current tracking of the transverse part of the comparator i (t) T of the reference value

on

i (t)

To effect pulse-width modulation, the control signals from block 31 control the operation of four gates, the inclusion of which by a bridge circuit allows the instantaneous function of the transverse part of the compensator to be formed. When this signal passes through the first output filter 7, a harmonic signal is filtered from it, the frequency of which is equal to the modulation frequency of the output signal.

The summation of the currents ip (t) and i | (t) in the common node allows, at the output of generator 1, to obtain a current ir (t) proportional to the voltage Ur (t).

To form the required voltage waveform at the input terminals of load 1, information about the values of the reference signal UH (t) onj is initially written into the memory block. . On a command from the sampling device 32, whose operation is synchronized by signals from the synchronization circuit 25, the value of the reference signal UH (t) 0fl | over the entire period T of load 1 through the sampling device 32 itself enters the input of the digital-to-analog converter 3, which converts the value of the reference signal UH (t) OP |, - from digital to analog form. This signal is fed to the non-inverting input of the adder 35 to the second input of which a signal U (t) is received from the output of the load voltage sensor 16. The operation of the second closed control circuit for the deviation is carried out analogously

five

0

five

0

five

0

five

0

five

As the operation of the first closed control circuit for the deviation is operating, the units 35-38 continuously monitor the current value of the voltage U (t) T of the reference value u (t) onii.

The monitoring of the voltage U (t) itself is carried out by changing the voltage at the output of the longitudinal part of the compensator. For this, the signal from the output of the comparator 38 with a hysteresis is fed to the second driver 39 of the control pulses, the operation of which is similar to that of the driver 31. The control signals from block 39 control the operation of four valves, the inclusion of which, by means of a bridge circuit, forms a voltage on the capacitor 8 U (t) r is the voltage of the longitudinal part of the compensator, the summation of which in the common circuit with the output voltage of the voltage generator 1 leads to the formation of a load 14 at the input minutes shape voltage UH (t). When the signal from the output of blocks 8-12 passes through the second output filter 13, a harmonic signal is generated from it, the frequency of which is equal to the modulation frequency of the output signal.

Compensation of current and voltage distortion of the power supply system using the proposed device allows increasing the efficiency and efficiency of controlling the operation of the power system with valve converters by bringing the generator consumed current form to its output voltage, as well as the reference input voltage. ) voltage.

Claims (1)

Invention Formula A power supply device with compensation for distortion of currents and voltages of the power supply system, containing four controllable valves connected in a bridge circuit, in one diagonal of which a choke is connected, and the nodes of the second diagonal are connected via a first output filter in parallel to a voltage generator, terminals for connecting to the load, a generator voltage sensor, two current sensors, one of which is connected in series to the output load circuit, and the other in series with the output terminals of the first output filter, the integrator whose output is connected to the first input of the multiplier through which the second input is connected to the input of the first voltage sensor, the control circuit whose first output impulses are generated and the end of the period, and a pulse is formed at the second output corresponding to the end of the period, the first output of the control circuit is connected to the integrator control input, and the second output is connected to the control input sampling circuit with sample memory, the multiplier output is connected to the non-inverting input of the first adder, the inverting input of which is connected to the output of the second current sensor, and the output is connected to the non-inverting input of the second adder, whose inverting input is connected to the output of the second current sensor, and the output connected with a non-inverting input of the third adder, the output of which through the first delay unit of the first order is connected to the input terminal of the first comparator with a hysteresis, the output of which is not connected the inverting input of the third adder and connected to the input of the first driver control pulse generator; the outputs of the first driver control pulse generator are connected to the control electrodes of four controllable valves, in order to improve the control accuracy in the final power system and non-sinusoidal voltage and currents, a load voltage sensor, four controllable valves, a capacitor, a second output filter, a divider, a frequency sensor, a synchronization circuit, an installed five 0 five 0 five 0 sampling array, memory unit, digital-analog converter, fourth and fifth adders, second first-order delay unit, second comparator with hysteresis, second fan control pulse generator, four entered controlled valves included in a bridge circuit, into one the diagonal of which is connected to a capacitor, and the nodes of the second diagonal are connected in series with the voltage generator and terminals for connecting the load through the second output filter, the first input of the divider is connected to the output of the second sensor and the second divider input is with the generator voltage sensor output, the divider output is connected to the integrator input, the frequency sensor input is connected to the generator voltage sensor output, and the frequency sensor output terminal is connected to the control circuit input through the synchronization circuit, the control output the synchronization circuit is connected to the control input of the sampling device, which is connected to the memory unit, as well as to the input of the digital-to-analog converter, the output of which is connected to the non-inverting input of the fourth adder, An expensive inverting input is connected to the output of a load voltage sensor, and the output is connected to a non-inverting input of a fifth adder, the output of which is connected via a second delay unit of the first order to the input of a second comparator with a hysteresis, the output of which is connected to a non-inverting input of the fifth adder and connected to the input of the second pulse generator of control of the valves, in which the output is connected with the control electrons of the sorts of four controllable gates introduced.