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INVENTION
Patent of the Russian Federation RU2056692
TRANSFORMER-TIRISTOR COMPENSATOR OF REACTIVE CAPACITY
The name of the inventor: Klimash Vladimir Stepanovich
The name of the patent holder: Klimash Vladimir Stepanovich; Komsomolsk-on-Amur Polytechnic Institute
Address for correspondence:
Date of commencement of the patent: 1993.10.21
The invention can be used to stabilize the AC voltage and compensate the reactive power in devices with a smooth adjustment of the amplitude and phase of the load voltage. The compensator contains a transformer, an inverter, a reversible rectifier, reactive current or network power sensors and load voltages, a subtractor. SUMMARY OF THE INVENTION: The driving signal and the signal from the load voltage sensor are applied to the subtractor inputs. A difference signal is fed to the inventory management system. By varying the control angle of the thyristors of the inventory, the amplitude of the generalized stress vector of the load is regulated. The signal from the reactive component of the current or network power goes to the pulse-phase control system of the reversing rectifier, and by changing the control angle of the rectifier thyristors, regulates the reactive power consumed from the network. This allows for power compensation with a given stable load voltage independent of the external characteristic of the network, but also on the magnitude and nature of the load.
DESCRIPTION OF THE INVENTION
The invention relates to electrical engineering, in particular to reactive power compensation devices, and can be used to create power units of industrial and agricultural facilities with high efficiency of use and consumption of electricity and stable voltage.
A transformer-thyristor regulating device [1] is known which includes a first three-phase transformer including a primary, one control and two secondary windings, a second three-phase transformer including a primary, control and secondary winding, and a thyristor commutator. The primary windings of the transformers are connected in series and connected to the load, and the two secondary windings of the first transformer are interconnected, connected to the mains and the secondary winding of the second transformer, and the control windings of both transformers are closed by a thyristor commutator.
The device provides an interconnected control of the amplitude and phase of the output voltage. In this case, one can only purposefully influence one of these parameters, while the nature of the change of the other is determined by the circuit of winding inclusion.
Major drawbacks of the device include large weight and dimensions, installed capacity and cost of transformers. The device requires special transformers of complex design, which complicates its production.
A transformer-thyristor device for regulating reactive power is known [2] containing two three-phase transformers and two thyristor commutators with control systems. The primary windings of both transformers are connected in series and are connected between the network and the load, and the secondary windings are combined through the first thyristor commutator, while the second thyristor switch switches only the secondary winding sections of the first three-phase transformer. This device is designed to regulate the phase of the load voltage relative to the mains voltage.
However, this device also has drawbacks, among which are the large weight and dimensions, installed capacity and cost of transformers, and the need to design and manufacture special transformers.
The known transformer-thyristor reactive power compensator, taken for the prototype [3], contains two three-phase transformers, two inverters with control systems and a rectifier. The primary windings of both transformers are connected in series to the load circuit, and the secondary windings are connected to the star and connected respectively to the first and second inverters whose inputs are combined and connected via a rectifier to the mains or to the load. The synchronizing inputs of the control systems of the first and second inverters are connected to the network, and their control inputs, respectively, to the output of the reactive power sensor of the network and to the output of the subtractor. The subtractor inputs are respectively connected to the master signal block and the voltage sensor output.
The device provides full compensation of the input reactive power and stabilization of the effective value of the output voltage, regardless of the external characteristics of the network, but also on the magnitude and nature of the load.
However, it also has drawbacks, which include, first of all, the need to use special transformers that require development work, but also the large weight, dimensions and installed capacity of transformers, which increases the cost of both the development and production of such devices. These shortcomings are caused by two circumstances. First, these transformers with rapid control of reactive power and the effective value of the output voltage are prone to unilateral bias due to the large amplitude of the phase of the output voltage of the first and second inverters and to exclude saturation at the required speed require the use of magnetic cores with a calculated induction of about 20-25% those. The next dimension of the standard series. Secondly, the device uses two transformers.
The purpose of the invention is to improve the weight and dimensions and reduce the installed capacity of transformer equipment and, as a consequence, reduce the cost of the device while maintaining speed and functionality.
The goal is achieved by the fact that other terminals of the primary winding of the transformer are connected to the mains and as a rectifier a reversible rectifier is used, which includes a valve block, an output inductive capacitive filter, and a pulse-phase control system synchronized with the voltage at the output terminals of the rectifier, The system of pulse-phase control is connected to the output of the reactive power (reactive current) sensor of the network.
The advantage of the device is that, while maintaining speed, it requires less expenses for transformer equipment both in design and production. It can be applied to a widespread dry transformer transformer of protected or unprotected design with a transformation ratio of 1/1 / 
, In which the device provides full compensation for the average power factor value of industrial and agro industrial enterprises. In the proposed device, one inverter is released and it is possible to use a standard recuperative thyristor converter with a DC link, which is related to lower costs for such products. Due to the change in the method of the amplitude-phase formation of the voltage of the booster, the magnetization of the transformer is eliminated and its installed power is reduced, and as a result, the mass-dimensions parameters of the device as a whole are improved.
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In Fig. 1 is a schematic diagram of the power part of the transformer-thyristor compensator of reactive power; In Fig. 2 and 3 vector diagrams of the compensator modes.
The compensator comprises a transformer 1, an inverter 2 with a control system 3 synchronized with the network, a reversible rectifier 4 comprising a valve unit 5, an output inductive capacitive filter 6, and a pulse-phase control system 7 synchronized with the voltage at the input terminals of the rectifier. In addition, the compensator comprises a reactive power or network current sensor 8, a load voltage sensor 9, a subtracter 10, and a load 11.
In Fig. 2 and 3 
, 
and 
Respectively, the network voltage, load and inverter; , and Respectively, current consumption of the network, load and rectifier; 
1 and 2 angles between the current and voltage, respectively, of the network and the load; 
In and And control angles of the thyristors, respectively, of the rectifier and inverter; K m is the coefficient of transformation.
The transformer-thyristor reactive power compensator works as follows.
Output voltage of compensator Is formed from the mains voltage And the voltage of inverter 2 Regulated in magnitude and phase, respectively, with angles In and And Voltage at the output of the inverter 2 
(1) where F ( C) the transfer function of the reversing rectifier 4;
K and K n are the voltage transfer coefficients of the rectifier 4 and inverter 2, respectively.
Using the transformer 1, the output voltage of the inverter 2 Decreases in the transformation ratio K m times and is added to the network voltage As a result, the expression for the load voltage 11 Has the form 
(2) where 
Short-circuit resistance of the transformer;
K n = K in K and the voltage transfer coefficient of a thyristor converter with a DC link.
Bearing in mind that for bridge circuits of a rectifier and an inverter with the same number of phases K n ~ 1,
From expression (2) and vector diagrams (Figures 2 and 3) it can be seen that the module and the argument of the load voltage vector Can be adjusted by changing the angle of control of the rectifier In and inverter And In the compensator, changing the angle In is carried out as a function of the deviation of the reactive power of the network from the zero level, and the change in the angle And in the function of the deviation of the load voltage from a given level, for example, equal to the minimum voltage of the network. With active-inductive load and consumption (generation) by the reactive power compensator, the signal from the output of the reactive power (current) sensor 8 of the network goes to the control input of the pulse-phase control system 7 of the reversing rectifier 4 and, decreasing (increasing) the angle of control of the reversing rectifier In performs an increase (decrease) in the effective value of the output voltage of the inverter And accordingly increasing (decreasing) the phase of the vector of the output voltage , The leading vector of the network voltage . In this case, the voltage sensor 9 monitors the change in the load voltage 11 and provides a feedback signal to the first input of the subtracter 10 characterizing the decrement, a signal proportional to a predetermined value of the load voltage, for example corresponding to the rated line voltage of the network, is fed to the second input of the subtracter 10 indicative of the decrease. The difference of these signals from the output of the subtractor 10 is fed to the control input of the control system 3 of the inverter 2 which, by changing the control angle of the thyristors of the inverter 2 
And regulates the phase of the output voltage of the inverter 2 And the effective value of the output voltage . As a result of this amplitude-phase action on the output voltage of inverter 2, the vector of this voltage So it forms its own module and argument, and that the load voltage vector 11 . Is the radius of the given circle.
With active-capacitive load, the compensator works in the same way, but the output voltage of the inverter 2 is formed in the region where this voltage falls behind the mains voltage.
In the process of stabilizing the output voltage with a lowered (increased) value of the mains voltage relative to the set value, for example the nominal value, the reversing rectifier 4 operates in the rectifier (inverter) mode, providing the transformer 1 and the whole device with a boost operation (volt-off) with the additional power consumption from the network (With the recuperation of energy into the network).
During the transition process of the reverse rectifier 4 from the rectifier mode to the inverter mode and vice versa, the energy entering the DC link is accumulated in the filter 6 and then in the booster mode it is discharged through the inverter 2 and the transformer 1 to the load 11, in the volt-off mode through the reversible rectifier 4 Returns to the network.
The use of the compensator makes it possible to fully compensate the reactive power in various AC systems, ensuring the specified stability of the effective value of the output voltage, regardless of the rigidity of the external characteristic of the network, but also on the magnitude and nature of the load.
CLAIM
TRANSFORMER-WIDTH COMPENSATOR OF REACTIVE POWER, comprising a rectifier with input terminals connected to the network or load, an inverter with a synchronized control system, a transformer with a primary winding connected by one terminal to the load and a secondary winding connected to the star and connected to the output of the inverter, , The sensor of the reactive component of the current or network power, which consists of two single-phase current transformers with primary windings included in the break of two phases of the network, a load voltage sensor whose output is connected to the first subtraction input characterizing the decrement, and its second input characterizing the subtrahend , Is connected to the master signal, the output characterizing the difference to the control input of the inverter control system, characterized in that the other terminals of the primary winding of the transformer are connected to the network, as a rectifier, a reversible rectifier is used, which includes a valve block synchronized with the voltage at Input terminals of the rectifier by a pulse-phase control system, and an inductive-capacitive filter is inserted between the rectifier output and the inverter input, the control input of the reverse-phase rectifier control system being connected to the output of the reactive component of the current or network power.
print version
Published on February 15, 2007
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