RU137641U1 - CAPACITOR UNIT FOR AUTOMATIC COMPENSATION OF REACTIVE POWER - Google Patents

Abstract

A capacitor installation for automatic reactive power compensation, comprising a current transformer, reactive power regulator, n reactive power compensation control steps, a charge-discharge device, the reactive power control being connected to each reactive power compensation control step, which is connected to phases A, B, C power supply, characterized in that introduced additional charge-discharge devices, chokes, semiconductor current switches, each / n stupa s current reactive power compensation regulation is formed by semiconductor switch, the inputs of which are connected to the respective phases A, B, C and a power supply to the corresponding semiconductor inverter outputs, wherein the semiconductor power switch outputs are connected through a charging-discharging device with a capacitor formed three-phase; and each of the other 1/2 n stages of regulation of reactive power compensation is formed by current chokes connected by one output to phases A, B, C of the power source, and other outputs - by the input of a semiconductor current switch connected through a charge-discharge device with a three-phase capacitor, forming a triangle diagram.

Description

The proposed utility model relates to electrical engineering, in particular to electrical distribution equipment, and serves to compensate automatically the reactive power of an inductive nature under variable loads in order to maintain the reactive power level in a given range of values, suppress the harmonic components of voltage and current and improve the quality of electricity.

The prior art capacitor installation for automatic compensation of reactive power type UKM (Operation manual DIAF. 673820.015 RE, 1990, Installation capacitor type UKM. 28 s, p. 13, 14), consisting of a current transformer, reactive power regulator, electromagnetic starters , regulation steps, and the first input of the current transformer is connected to the linear wire of phase A of the power source, and the second input of the current transformer is connected to the linear wire of phase A of the load. The known device allows you to automatically change the total capacitance of the capacitors when changing the magnitude of the inductive component of the reactive power of the load by sequentially connecting and disconnecting individual stages of regulation using magnetic starters.

Its disadvantages include: a high level of switching interference when connecting and disconnecting individual stages, increased wear of contact groups of magnetic starters, large values of charge-discharge currents flowing through capacitors when connecting and disconnecting, which reduces the service life of the latter. The inertia of the magnetic starters, which are used as switching nodes in this device, does not make it possible to compensate for rapid changes in the magnitude of the inductive component of the reactive power of the load. In addition, the device has increased weight and size characteristics (three semiconductor switches in each stage and an additional two current transformers), reactive power compensation for each phase gives a good result, but is rarely used due to the high cost. All main inductive loads are evenly distributed in phases and there is no need to apply phase compensation.

A known capacitor installation for automatic compensation of reactive power (RU 96670 U1, published 10.08.2010), consisting of a current transformer, reactive power regulator, electromagnetic starters, regulation steps, and the input of the current transformer is connected to the linear wire of phase A of the power source, and the other input of the current transformer is connected to the linear phase A wire of the load.

The disadvantages of the analogue are: a high level of switching noise when connecting and disconnecting individual stages, increased wear of contact groups of magnetic starters, large values of charge-discharge currents flowing through capacitors when connecting and disconnecting, which reduces the service life of the latter. The inertia of the magnetic starters, which are used as switching nodes in this device, does not make it possible to compensate for rapid changes in the magnitude of the inductive component of the reactive power of the load. In addition, the circuit features of the known device do not allow it to be effectively used to compensate for the inductive component of reactive power with an asymmetric load. The inertia of the magnetic starters with a rapid change in load, the coil does not have time to react.

The closest analogue to the claimed utility model adopted as a prototype is a capacitor unit for automatic compensation of reactive power (RU 2467448 C1, published November 20, 2012), consisting of a current transformer, reactive power regulator, electromagnetic starters, regulation steps, the first input the current transformer is connected to the linear wire of phase A of the power source, and the second input of the current transformer is connected to the linear wire of phase A of the load, further comprises a charge-discharge device a compensation function of the leakage currents of capacitors, two additional transformer current instead of electromagnetic actuators apply controlled bidirectional semiconductor switches, which control inputs connected to respective outputs of the reactive power regulator allowing the phases separate branches switching control steps.

The disadvantage of the prototype is the low range of compensated reactive power, affecting the quality of electricity.

The technical result of the utility model is an increase in the range of compensated reactive power and the accuracy of compensation of inductive reactive power of the load.

The technical result is achieved in that in a capacitor unit for automatic reactive power compensation, comprising a current transformer, a reactive power regulator, n reactive power compensation control steps, a charge-discharge device, the reactive power control is connected to each reactive power compensation control step, which connected to phases A, B, C of the power source, additional charge-discharge devices, chokes, semiconductor current switches introduced a (triacs), each ½ n step of regulation of reactive power compensation is formed by a semiconductor current switch, the inputs of which are connected to the corresponding phases A, B, C of the power source and to the corresponding outputs of the semiconductor inverter, while the outputs of the semiconductor current switch are connected through a charge-discharge a device with a three-phase capacitor; and each other ½ n step of regulation of compensation of reactive power is formed by current chokes connected by one output with phases A, B, C of the power source, and other outputs with the input of a semiconductor switch connected through a charge-discharge device with a three-phase capacitor, forming a triangle circuit.

In FIG. shows a block diagram of a capacitor unit for automatic reactive power compensation, where the following notation is accepted:

1 - input three-phase four-wire bus power supply;

2 - output three-phase load bus (semiconductor inverter, motor, etc.);

3 - current transformer;

4 - reactive power regulator;

5 - stages of regulation of reactive power compensation;

6 - semiconductor current switch (for example, triac);

7 - three-phase capacitor;

8 - charge-discharge device;

9 - connector;

10 - throttle;

A, B, C - phase power supply;

N is the neutral wire of the power source.

A capacitor unit for automatic reactive power compensation contains an input three-phase (A, B, C) four-wire bus (1) for connecting a power source Ν to a neutral wire, an output three-phase load bus (2) (for connecting a load), a current transformer (3), reactive power regulator (4), n steps for regulating reactive power compensation, 1/2 n of which consists of a choke (10), a semiconductor current switch (6) and three-phase capacitors connected by a triangle circuit (7) (used in the second otype) of a charge-discharge device (8) with the function of compensating the leakage currents of three-phase capacitors (7). The other 1/2 n reactive power control stages consist of a semiconductor current switch (6) and three-phase capacitors (7), a charge-discharge device (8). The first input of the current transformer (3) is connected to phase A of the input three-phase four-wire bus 1 of the power source, the second input of the current transformer (3) is connected to phase A of the output three-phase four-wire bus (2) so that the current consumed by the load completely passes through the primary windings of the transformer current (3). The outputs of the current transformer (3) are also connected to the input of the reactive power controller (4). The control inputs of n reactive power compensation regulation steps (5) are connected to the outputs of the reactive power regulator (4), the power inputs of the semiconductor current switches (6) are connected to the chokes (10) connected to phases A, B and C of the output three-phase four-wire bus (2) ) The power outputs of the semiconductor current switch (6) are connected to the inputs of the three-phase capacitors (7) of the triangle circuit, and the capacitances of the capacitors belonging to the control stage under number k are determined by the formula (1):

where C1 denotes the capacitance of the capacitors of the first control stage, a charge-discharge device (8) with a function for compensating leakage currents, the reactive power compensation control steps (5) are connected in the same way, with the exception of chokes (10) for filtering harmonics.

The control signals for switching on the corresponding switches are supplied when the linear voltage is reached, under which a particular capacitor is connected to a three-phase (7) amplitude value, while the potential difference on the semiconductor current switch (6) at the time of switching on is close to zero. The disconnection of a specific three-phase capacitor (7) also occurs when the linear voltage is reached under which the corresponding three-phase capacitor (7) is connected to the amplitude value, while the current flowing through the semiconductor switch is close to zero (6). The described algorithm for switching three-phase capacitors (7) with semiconductor switches (6) allows to minimize switching surges of currents and voltages. The choice of the type of reactive power compensation control steps (5) occurs automatically depending on the presence of higher harmonic components. At a constant inductive load, the steps for regulating reactive power compensation operate, including semiconductor current switches (6), and when harmonics appear, the steps for regulating reactive power compensation with chokes (10) are turned on.

Thus, the claimed utility model allows to increase the range of compensated reactive power and the compensation accuracy of the inductive reactive power of the load, in other words, to minimize switching surges of currents and voltages and compensate for the inductive reactive power of the load symmetrically in each phase by automatically switching the number of reactive power control stages and selection of the type of reactive power control stages depending on the nature of the reactive power of the loads and. Semiconductor current switches respond quickly to changing load parameters. The accuracy of reactive power compensation is determined by the value of the capacitance of three-phase capacitors of the first control stage, and the control range depends on the number n of reactive power control steps.

The claimed technical solution, in its implementation is intended for use in the field of industrial electrical distribution equipment.

Claims (1)

A capacitor installation for automatic reactive power compensation, comprising a current transformer, reactive power regulator, n reactive power compensation control steps, a charge-discharge device, the reactive power control being connected to each reactive power compensation control step, which is connected to phases A, B, C power supply, characterized in that the introduced additional charge-discharge devices, inductors, power semiconductor switches, wherein each _^half n Art stump regulating reactive power compensation current is formed by semiconductor switch, the inputs of which are connected to the respective phases A, B, C and a power supply to the corresponding semiconductor inverter outputs, wherein the semiconductor power switch outputs are connected through a charging-discharging device with a capacitor formed three-phase; and each of the other 1/2 n stages of regulation of reactive power compensation is formed by current chokes connected by one output to phases A, B, C of the power source, and other outputs - by the input of a semiconductor current switch connected through a charge-discharge device with a three-phase capacitor, forming a triangle diagram.

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