CN113346510B - Controllable reactive power compensation device topology based on IGCT and control method thereof - Google Patents

Abstract

The present invention discloses a controllable reactive power compensation device topology based on IGCT and a control method thereof, wherein the device topology includes: a capacitor module, an inductor and a controllable module; the inductor is connected in series with the capacitor module; the capacitor module includes: a fixed capacitor unit and a controllable capacitor unit connected in series, and the controllable capacitor unit is connected in parallel with the controllable module; when the AC transmission line fault causes the line voltage to decrease, the controllable module bypasses the controllable capacitor unit to increase the reactive power compensation capacity of the compensation device and stabilize the line voltage, and the controllable capacitor unit is re-invested after the AC transmission line fault disappears and the line voltage recovers to the preset upper limit value of the voltage to reduce the reactive power compensation capacity of the compensation device. By utilizing the full control characteristics of IGCT, it can control its opening and closing, and can control the precise time of investing and removing the capacitor in real time, so as to compensate the reactive power demand of the power grid system in real time and stabilize the AC bus voltage.

Description

A controllable reactive power compensation device topology based on IGCT and its control method

Technical Field

The present invention relates to the technical field of power grid operation control, and in particular to a topology of a controllable reactive power compensation device based on IGCT and a control method thereof.

Background Art

In the power supply system, in order to improve the safety and reliability of the power grid, it is usually necessary to add a large number of reactive power compensation devices. The power compensation of the transmission system is mainly to control the voltage, improve the maximum transmission capacity of the transmission network and improve the stability of the power system operation. The power compensation of the distribution system is mostly load compensation, which is mainly to control reactive power, improve the power factor of the load and improve the power quality.

A common way to compensate reactive power is to use thyristor switching capacitors, which is achieved by controlling the conduction of the semi-controlled thyristor device to switch the capacitor on and off. The main disadvantage of this compensation method is that since the thyristor device can only be controlled to be turned on, it cannot be controlled to be turned off (using external voltage to force shutdown), so accurate control of the compensation power cannot be achieved.

Summary of the invention

The purpose of the embodiment of the present invention is to provide a controllable reactive power compensation device topology based on IGCT and a control method thereof. By utilizing the full control characteristics of IGCT, both its opening and closing can be controlled, and the precise time of inputting and removing the capacitor can be controlled in real time to compensate the reactive power demand of the power grid system in real time and stabilize the AC bus voltage. At the same time, the advantages of IGCT such as reduced voltage, low loss, strong di/dt tolerance, and large fault surge current are fully utilized to greatly improve the reliability of the controllable reactive power compensation device.

To solve the above technical problems, a first aspect of an embodiment of the present invention provides a controllable reactive power compensation device topology based on IGCT, comprising: a capacitor module, an inductor and a controllable module;

The inductor is connected in series with the capacitor module;

The capacitor module comprises: a fixed capacitor unit and a controllable capacitor unit connected in series, and the controllable capacitor unit is connected in parallel with the controllable module;

When an AC transmission line fault causes the line voltage to drop, the controllable module bypasses the controllable capacitor unit to increase the reactive power compensation capacity of the compensation device and thus stabilize the line voltage. It also re-activates the controllable capacitor unit after the AC transmission line fault disappears and the line voltage recovers to a preset upper limit value of the voltage to reduce the reactive power compensation capacity of the compensation device.

Furthermore, the IGCT-based controllable reactive power compensation device topology further includes: a protection module;

The protection module is connected in parallel with the capacitor module.

Furthermore, the controllable module comprises: a current limiting resistor, a saturated reactor and an integrated gate-commutated thyristor subunit connected in series.

Furthermore, the gate-commutated thyristor sub-unit comprises: two groups of integrated gate-commutated thyristor sub-units connected in reverse parallel.

Furthermore, the IGCT is a reverse-blocking integrated gate-commutated thyristor.

Accordingly, a second aspect of the embodiment of the invention provides a method for controlling a topology of a controllable reactive power compensation device based on IGCT, which controls any of the above-mentioned topologies of a controllable reactive power compensation device based on IGCT, comprising the following steps:

obtaining a line voltage of an AC transmission line;

Determining whether the line voltage is less than a preset lower voltage limit;

If the line voltage is less than the preset lower limit of the voltage, the controllable capacitor unit is bypassed through the controllable module to increase the reactive power compensation capacity of the compensation device, thereby stabilizing the line voltage;

If the line voltage is greater than or equal to the preset lower limit of the voltage, the controllable module is controlled to maintain the current operating state.

Furthermore, after bypassing the controllable capacitor unit through the controllable module, the method further includes:

Continue to detect the line voltage of the AC power transmission line;

Determining whether the line voltage is greater than or equal to a preset upper voltage limit;

If the line voltage is greater than or equal to the preset upper limit value of the voltage, the controllable module is controlled to re-activate the controllable capacitor unit to reduce the reactive power compensation capacity of the compensation device;

If the line voltage is less than the preset upper limit value of the voltage, the controllable module is controlled to maintain the current operating state.

The above technical solution of the embodiment of the present invention has the following beneficial technical effects:

By utilizing the full control characteristics of IGCT, it is possible to control both its opening and closing, and to control the precise time of inputting and removing capacitors in real time, so as to compensate the reactive power demand of the power grid system in real time and stabilize the AC bus voltage. At the same time, by making full use of the advantages of IGCT such as reduced voltage, low loss, strong di/dt tolerance, and large fault surge current, the reliability of the controllable reactive power compensation device is greatly improved, and the maximum transmission capacity of the transmission network and the stability of the power system are further improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the topology principle of a controllable reactive power compensation device based on IGCT provided in an embodiment of the present invention;

FIG2 is a flow chart of a topology control method for a controllable reactive power compensation device based on IGCT provided in an embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

FIG1 is a schematic diagram of the topology principle of a controllable reactive power compensation device based on IGCT provided in an embodiment of the present invention.

Please refer to Figure 1. The first aspect of an embodiment of the present invention provides a controllable reactive power compensation device topology based on IGCT, including: a capacitor module, an inductor and a controllable module. The inductor is connected in series with the capacitor module. The capacitor module includes: a fixed capacitor unit C1 and a controllable capacitor unit C2 connected in series, and the controllable capacitor unit C2 is connected in parallel with the controllable module. When the AC transmission line fault causes the line voltage to decrease, the controllable module bypasses the controllable capacitor unit C2 to increase the reactive power compensation capacity of the compensation device and stabilize the line voltage. It also re-activates the controllable capacitor unit C2 after the AC transmission line fault disappears and the line voltage recovers to the preset upper limit value of the voltage to reduce the reactive power compensation capacity of the compensation device.

The above technical solution can control both the opening and closing of IGCT by utilizing the full control characteristics of IGCT, and can control the precise time of inputting and removing capacitors in real time, so as to compensate the reactive power demand of the power grid system in real time and stabilize the AC bus voltage. At the same time, it makes full use of the advantages of IGCT such as reduced voltage, low loss, strong di/dt tolerance, and large fault surge current, greatly improving the reliability of the controllable reactive power compensation device, and further improving the maximum transmission capacity of the transmission network and the stability of the power system.

Specifically, the topology of the controllable reactive power compensation device based on IGCT also includes: a protection module. The protection module is connected in parallel with the capacitor module. When an overvoltage occurs in the AC bus, the lightning arrester in the protection module will present a low impedance characteristic, limit the overvoltage level of the bus, and play a role in protecting the capacitor body, inductor and control module.

In a specific implementation of the embodiment of the present invention, the controllable module includes: a current limiting resistor R, a saturated reactor L and an integrated gate-commutated thyristor sub-unit connected in series.

Optionally, the gate-commutated thyristor sub-unit comprises: two groups of integrated gate-commutated thyristor sub-units connected in reverse parallel.

Specifically, the above-mentioned IGCT is a reverse resistance type integrated gate commutated thyristor.

As shown in Figure 1, the specific working process of the topology of the controllable reactive power compensation device based on IGCT is as follows:

When the power grid is operating normally and the AC bus voltage is stable, the integrated gate-commutated thyristor unit IGCT1 and the integrated gate-commutated thyristor unit IGCT2 in the controllable module are in a locked state, and the fixed capacitor unit C1 and the controllable capacitor unit C2 are both put into the power grid system; the lightning arrester in the protection module is in a high impedance state and basically does not absorb energy. When a fault occurs in the power grid and the AC bus voltage drops, the integrated gate-commutated thyristor unit IGCT1 and the integrated gate-commutated thyristor unit IGCT2 in the controllable module are controlled to be in a conductive state, and the controllable capacitor unit C2 discharges to the integrated gate-commutated thyristor unit IGCT through a resistor. Since the resistance of the current limiting resistor R is small, the voltage on the capacitor C2 can be instantly reduced to zero. At the same time, the current limiting resistor R can limit the high-frequency oscillation between the controllable part capacitor C2 and the control module loop stray inductance when the integrated gate-commutated thyristor unit IGCT is turned on, so as to avoid the integrated gate-commutated thyristor unit IGCT from being damaged due to excessive loop oscillation voltage. The saturated reactor L can limit the current rise rate of the integrated gate commutated thyristor unit IGCT at the moment of opening, and ensure the safe conduction of the integrated gate commutated thyristor unit IGCT. Since the integrated gate commutated thyristor unit IGCT is in the on state, the controllable module plays the role of bypassing the controllable capacitor unit C2, and only the fixed capacitor unit C1 in the capacitor module is put into the power grid system, achieving the effect of increasing the reactive power compensation capacity.

When the AC system fault disappears and the bus voltage returns to stability, the controllable capacitor unit C2 can be put back into the grid by locking the integrated gate commutated thyristor unit IGCT in the controllable module. Since the integrated gate commutated thyristor unit IGCT is a turn-off device, the switching of the controllable capacitor unit C2 can be controlled at any time, ultimately achieving the effect of precise control of reactive power compensation.

FIG2 is a flow chart of a topology control method for a controllable reactive power compensation device based on IGCT provided in an embodiment of the present invention.

Accordingly, referring to FIG. 2 , a second aspect of an embodiment of the invention provides a method for controlling a topology of a controllable reactive power compensation device based on IGCT, which controls any of the above-mentioned topologies of a controllable reactive power compensation device based on IGCT, comprising the following steps:

S200: Obtain a line voltage of an AC transmission line.

S400, determining whether the line voltage is less than a preset lower limit of the voltage.

S600, if the line voltage is less than the preset lower limit of the voltage, the controllable capacitor unit C2 is bypassed through the controllable module to increase the reactive power compensation capacity of the compensation device, thereby stabilizing the line voltage.

S800: If the line voltage is greater than or equal to the preset lower limit of the voltage, the controllable module is controlled to maintain the current operating state.

Furthermore, after the controllable capacitor unit C2 is bypassed by the controllable module, the method further includes:

S710, continue to detect the line voltage of the AC transmission line.

S720, determining whether the line voltage is greater than or equal to a preset upper voltage limit.

S730, if the line voltage is greater than or equal to the preset upper limit of the voltage, the controllable module is controlled to re-activate the controllable capacitor unit C2 to reduce the reactive power compensation capacity of the compensation device.

S740: If the line voltage is less than the preset upper limit of the voltage, the controllable module is controlled to maintain the current operating state.

The embodiment of the present invention aims to protect a controllable reactive power compensation device topology based on IGCT and its control method, including: a capacitor module, an inductor and a controllable module; the inductor is connected in series with the capacitor module; the capacitor module includes: a fixed capacitor unit and a controllable capacitor unit connected in series, and the controllable capacitor unit is connected in parallel with the controllable module; when the AC transmission line fault causes the line voltage to drop, the controllable module bypasses the controllable capacitor unit to increase the reactive power compensation capacity of the compensation device and stabilize the line voltage, and it also re-activates the controllable capacitor unit after the AC transmission line fault disappears and the line voltage returns to a preset value to reduce the reactive power compensation capacity of the compensation device. The above technical solution has the following effects:

By utilizing the full control characteristics of IGCT, it is possible to control both its opening and closing, and to control the precise time of inputting and removing capacitors in real time, so as to compensate the reactive power demand of the power grid system in real time and stabilize the AC bus voltage. At the same time, by making full use of the advantages of IGCT such as reduced voltage, low loss, strong di/dt tolerance, and large fault surge current, the reliability of the controllable reactive power compensation device is greatly improved, and the maximum transmission capacity of the transmission network and the stability of the power system are further improved.

It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims (4)

1. The topology control method of the controllable reactive power compensation device based on the IGCT is characterized by comprising the following steps of: a capacitance module, an inductance and a controllable module; the inductor is connected with the capacitor module in series; the capacitive module includes: a fixed capacitance unit and a controllable capacitance unit connected in series, the controllable capacitance unit is connected with the controllable module in parallel; the controllable module bypasses the controllable capacitance unit when the line voltage is reduced due to the fault of the alternating current transmission line so as to increase the reactive power compensation capacity of the compensation device and further stabilize the line voltage, and the controllable capacitance unit is put into the device again after the fault of the alternating current transmission line disappears and the line voltage is restored to the preset upper limit value of the voltage so as to reduce the reactive power compensation capacity of the compensation device; the controllable module comprises: a current limiting resistor, a saturable reactor, and a gate commutated thyristor subunit connected in series, the gate commutated thyristor subunit comprising: two groups of integrated gate commutated thyristor subunits connected in anti-parallel; the control method comprises the following steps:

Acquiring line voltage of an alternating current transmission line;

Judging whether the line voltage is smaller than a preset lower limit value of the voltage;

If the line voltage is smaller than the preset lower limit value of the voltage, bypassing the controllable capacitance unit through a controllable module to increase the reactive power compensation capacity of the compensation device so as to stabilize the line voltage;

and if the line voltage is greater than or equal to the preset lower limit value of the voltage, controlling the controllable module to keep the current running state.

2. An IGCT-based controllable reactive power compensation device topology control method as recited in claim 1, further comprising, after said bypassing said controllable capacitive unit by a controllable module:

Continuing to detect the line voltage of the alternating current transmission line;

judging whether the line voltage is greater than or equal to a preset upper limit value of the voltage;

if the line voltage is greater than or equal to the preset upper limit value of the voltage, the controllable module is controlled to throw the controllable capacitance unit back in so as to reduce the reactive power compensation capacity of the compensation device;

and if the line voltage is smaller than the preset upper limit value of the voltage, controlling the controllable module to keep the current running state.

3. An IGCT-based controllable reactive power compensator topology control method as recited in claim 1, wherein the IGCT-based controllable reactive power compensator topology further comprises: a protection module;

The protection module is connected with the capacitance module in parallel.

4. An IGCT-based controllable reactive power compensation device topology control method of claim 1, characterized in that,

The IGCT is a reverse resistance type integrated gate commutated thyristor.