RU2074494C1 - Stabilizer control method for three-phase sinusoidal voltage - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: method includes additive voltage making by rectifier and transformer inverters using with simultaneous two coordinates control both amplitude and phase Besides when voltage deviations are significant amplitude control is predominant but in case when deviations are small phase control is more active and among case both control way are operating. Method can be useful both in monophase low power transistor stabilizers and more powerful three phase transistor stabilizers for power net using. EFFECT: better output voltage shaping, less aperture installed power. 2 dwg

Description

 The invention relates to electrical engineering, in particular to converter technology, and can be used for narrow-range regulation or stabilization of three-phase voltage in power supply systems of industrial facilities, agriculture, cultural and domestic purposes.

 A known method of controlling a three-phase sinusoidal voltage stabilizer according to copyright certificate N 1636833, 1991. The stabilizer contains a three-phase boost transformer and a phase converter with a DC link based on an inverter and a rectifier with two-way energy exchange. The transformer reduces the phase-controlled voltage at the inverter output and adding it to the input voltage of the stabilizer forms a voltage of a given value with a leading shift of the first harmonic on the load. In the voltage adding mode, the energy through the rectifier is directed from the network to the DC link, and in the voltage subtraction mode, vice versa from the DC link to the network.

 The disadvantages of the method include the deterioration of the shape of the output voltage curve when it is formed with a shift of the first harmonic and the need to increase the overall power of the transformer due to the occurrence of one-side magnetization of the magnetic circuit during fast regulation of the voltage-addition phase with a large amplitude value.

 The purpose of the invention is the reduction of the overall power of the transformer while maintaining the required speed and improving the sinusoidality of the output voltage.

 This goal is achieved by isolating the difference signal module from which the second control signal is generated and, acting on the inverter or rectifier, change the effective value of the voltage at the inverter output from the maximum possible value to the minimum specified, and changing the effective value of the inverter output voltage within the specified limits, it is performed when the difference signal changes over the entire range, and the phase of the inverter output voltage changes only in the region of small values values of the difference signal.

 The stabilizer control method includes the steps of measuring the output voltage of the stabilizer, comparing it with a voltage of a given level, generating the first control signal obtained from the difference signal and generating a second control signal received from the difference signal module. The first control signal changes the phase, and the second amplitude of the first harmonic of the voltage at the inverter output, which converts the rectified input or output voltage of the stabilizer into a variable of the same frequency, but with amplitude-phase control depending on the first and second control signals. The voltage from the inverter output is supplied to the input of the boost booster unit. A feature of the method is that the impact on the change in the amplitude of the first harmonic of the inverter output voltage with the lower limit is limited in the entire range of the difference signal, and the impact on the phase change only in the region of small values of the difference signal.

In FIG. 1 shows a block diagram of a device that implements a method for controlling a three-phase sinusoidal voltage stabilizer; in FIG. 2 dependences of the amplitude U _{m (1)} and phase α of the first harmonic of the inverter output voltage as a function of the difference signal U _p , explaining the method of amplitude-phase control of the stabilizer and the operation of the device implementing it.

 The device contains a three-phase booster unit 1, which is a three-phase booster transformer and connected between the input and output terminals of the stabilizer, a rectifier 2 with two-sided power transmission, the input of which is connected to the output (or input) terminals of the stabilizer, and the output is connected to the supply terminals of the inverter 3. Rectifier 2 control system 4, which performs the function of controlling a two-sided energy pass while maintaining a constant voltage at the inverter input and does not exclude The ability to take on the function (connecting the control input by a dashed line with the comparison element) to form the second control signal to change the effective voltage value at the output of the inverter 3, is connected to the control input of the rectifier 2 by its output. Inverter 3 control system 5, in which the first and the second control signal for regulating, respectively, the phase and the actual voltage value at the output of the inverter 3 when the difference signal changes, with its two outputs respectively connected to the control inputs (for controlling the phase and amplitude of the first harmonic) of the inverter 3. To the output terminals of the stabilizer is also connected to the output of the output voltage sensor 6, the output of which is connected to the first input of the comparison element 7, the other input is connected to the reference voltage source, and the output to the input of the control system 5 of the inverter 3 and with the non-excluded possibility of connecting also to the input of the control system 4 of the rectifier 2. The primary winding 8 of the transformer three-phase booster unit 1 is connected to the output of the inverter 3 and the secondary winding of the transformer 9 is connected between the input and output terminals of the stabilizer.

 The device operates as follows.

на входе и соответственно снижении напряжения

на выходе стабилизатора уменьшается сигнал на выходе датчика 6 напряжения, что приводит к увеличению разностного сигнала U_p (фиг. 2), который снимается с выхода элемента 7 сравнения и подается на управляющий вход системы 4 управления выпрямителем 2 и (или) на управляющий вход системы 5 управления инвертором 3. С первого выхода системы 5 управления снимают первый управляющий сигнал, которым, воздействуя на инвертор 3, изменяют фазу α (фиг. 2) выходного напряжения инвертора 3, а с второго выхода системы 5 управления инвертором 3 (или с выхода системы 4 управления выпрямителем 2) снимают второй управляющий сигнал, которым, воздействуя на инвертор 3 (или выпрямитель 2), изменяют амплитуду U_m(1) (фиг. 2) первой гармоники выходного напряжения инвертора 3; получающего питание от выпрямителя 2. В зависимости от величины разностного сигнала U_p различают три области (фиг. 2):
1 регулированию подлежит только фаза a;
2 одновременно регулируется и фаза α и амплитуда U_m(1);
3 регулированию подлежит только амплитуда U_m(1) выходного напряжения инвертора 3.With a decrease in voltage

at the input and, accordingly, voltage reduction

the output of the stabilizer decreases the signal at the output of the voltage sensor 6, which leads to an increase in the difference signal U _p (Fig. 2), which is removed from the output of the comparison element 7 and fed to the control input of the control system 4 of the rectifier 2 and (or) to the control input of the system 5 control the inverter 3. From the first output of the control system 5, the first control signal is removed, which, acting on the inverter 3, changes the phase α (Fig. 2) of the output voltage of the inverter 3, and from the second output of the control system 5 of the inverter 3 (or from the system output 4 Board rectifier 2) remove the second control signal, which, acting on the inverter 3 (or the rectifier 2), the amplitude change U _{m (1)} (Figure 2) of the first harmonic of the output voltage of the inverter 3.; receiving power from the rectifier 2. Depending on the value of the differential signal U _{p there} are three areas (Fig. 2):
1 only phase a is subject to regulation;
2, both the phase α and the amplitude U _{m (1) are} simultaneously regulated;
3, only the amplitude U _{m (1) of the} output voltage of the inverter 3 is subject to regulation.

вторичной обмотки 9 трансформатора, складывается с напряжением U₁ на входе и увеличивает напряжение

на выходе стабилизатора до требуемого уровня. Аналогично происходит работа устройства и при увеличении напряжения на входе выше требуемого уровня. В этом случае разностный сигнал U_p отрицательный (фиг. 2) и в зависимости от его величины также происходит амплитудное, фазовое или смешанное амплиудно-фазовое управление устройством.The inverter output voltage 3 U _{m (1)} • e ^jα is supplied to the primary winding 8 of the transformer of the booster unit 1. As a result, the voltage reduced by the transformation coefficient K _T times

secondary winding 9 of the transformer, is folded with voltage U ₁ at the input and increases the voltage

at the output of the stabilizer to the desired level. Similarly, the operation of the device occurs when the input voltage increases above the required level. In this case, the difference signal U _{p is} negative (Fig. 2) and, depending on its magnitude, amplitude, phase or mixed amplitude-phase control of the device also occurs.

 It should be noted that the influence of the second control signal on the rectifier 2 (in Fig. 1 cm, dashed line) gives the best result in ensuring the sinusoidality of the output voltage, and the effect of the second control signal on the inverter 3 has improved speed, both in that and in in other cases, a decrease in the overall power of the booster unit 1 is achieved.

Claims (1)

 A method of controlling a three-phase sinusoidal voltage stabilizer containing a three-phase boost booster connected between the input and output terminals and the control input connected to the inverter output, the input of which is connected to the input and output terminals through a rectifier with two-sided energy pass, which consists in measuring the output voltage of the stabilizer , compare it with the voltage of a given level and form a difference signal, and also form the first control signal and it, acting on and the inverter, they change the phase of the voltage at the inverter output within 0-π rad. in the direction of advancing relative to the input voltage of the stabilizer, characterized in that a second control signal is formed from the differential signal and, acting on the inverter or rectifier, they change the effective voltage value at the inverter output from the maximum possible value to the minimum specified, which when exposed to the second control the signal to the inverter for pulse-width control of its output voltage, respectively, set the maximum pulse width of the output voltage the inverter is equal to the switching period and the minimum fixed pulse duration, and when the second control signal is applied to the rectifier for amplitude control of the inverter output voltage, respectively, the minimum possible control angle and the maximum fixed angle of the pulse-phase control of the rectifier are set, while changing the effective value of the output voltage the inverter within the specified limits is produced when the difference signal changes over the entire range, and the phase change voltage at the inverter output only in the region of small values of the difference signal due to the formation of the first control signal from the amplified and limited at a given level differential signal, and the level of limitation of the amplified difference signal is not less than the value of the difference signal at which the effective voltage value at the inverter output reaches its minimum limit limit.

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