CN201188542Y - Apparatus for dynamically adjusting current quality - Google Patents

Abstract

The utility model relates to a current quality dynamic adjusting device, which belongs to the technical field of the electric-energy quality control of the electric power system. The dynamic adjusting device comprises a dc voltage control lopper (4), a direct-current horizontal wave capacitance (5), a three-phase inverter (6) and an output filter (7). The dc voltage control lopper (4) comprises a super capacitance energy storage element (8), a protecting diode (9), a connecting reactor (10), a charge switch (11) and a discharge switch (12); a main circuit is three-phase bridge type inverter topology, and energy storage equipment and a chopper circuit for controlling the dc voltage are arranged on the direct current generatrix of the inverter. The utility model has the advantages that the current quality dynamic adjusting device operates in parallel connection with a non-linear load, and through the supporting functions of the active filtering, the reactive power and negative-sequence compensation and short-time active power, the quality of the load current achieve the condition of ideal load when seen from the system side; the stable sinusoidal current without harmonic waves is absorbed; the three-phase power is balanced; impact inrush current or large starting current does not exist; the power factor is 1, so the target for improving the quality of the electric energy is realized.

Description

Current quality dynamic adjustment device

technical field

The utility model belongs to the field of electric energy quality control in electric power systems, and in particular provides a dynamic adjustment device for electric current quality.

Background technique

The load current quality problem, that is, the load power quality problem is very common in the power system. For example, harmonic problems are mainly caused by nonlinear loads, and the application of a large number of power electronic devices has caused the harmonic level of the power grid to increase year by year; Industrial rolling mills, winches, electric traction locomotives and other electrical equipment; some voltage sags are caused by the start-up of large-capacity impact loads. These power quality problems are directly or indirectly caused by the load operating characteristics, that is, the load current quality. Obviously, improving the load current quality is one of the effective means to solve the power quality problem.

Contents of the invention

The purpose of this utility model is to provide a current quality dynamic adjustment device, which operates in parallel with the load, and realizes the functions of active filtering, reactive power and negative sequence compensation, and short-term active power support, so that the load current quality can be seen from the system side. The conditions of the load, that is, the load (1) absorbs a stable, harmonic-free sinusoidal current, (2) three-phase power balance, (3) no inrush current or large starting current, (4) the power factor is 1, so as to achieve The goal of improving power quality.

The utility model is a power electronic device based on insulated gate bipolar transistor device (IGBT) and pulse width modulation control technology, comprising: DC voltage control chopper 4, DC smoothing capacitor 5, three-phase inverter 6, output filter device7. The two output terminals of the DC voltage control chopper 4 are respectively connected to the two poles P and N of the DC smoothing capacitor 5. The DC smoothing capacitor is formed by connecting two capacitors in series to withstand a higher voltage level. The three-phase inverter 6 The two terminals of the DC bus are respectively connected to the two poles P and N of the DC smoothing capacitor 5, and the three AC output lines of the three-phase inverter 6 are respectively connected to the three filter reactor inputs of the three-phase output filter 7 terminal, the output terminal of the filter reactor is divided into two circuits, one is connected to the filter capacitor, and the other is connected in parallel to the nonlinear load 2.

The main circuit is a three-phase bridge inverter topology, and the DC bus of the inverter is equipped with an energy storage device and a chopper circuit for controlling the DC voltage. The load current quality regulator and the load operate in parallel, through the functions of active filtering, reactive power and negative sequence compensation, short-term active power support, etc., the load current quality from the system side can reach the ideal load condition.

The DC control chopper is used as the energy storage control link of the load regulator. When the load absorbs power suddenly decreases, the unbalanced power between the system and the load is absorbed and stored in the super capacitor in a short time; when the load absorbs power suddenly When increasing, power will be released for a short time to compensate for the unbalanced power between the system and the load.

The three-phase inverter 6 can work in the state of high-frequency rectification and inverter, and switch between the two states according to the control command; control the energy storage of the supercapacitor through the charge switch and discharge switch, and effectively control the load current quality regulator The DC bus voltage of the inverter.

The DC voltage control chopper 4 includes: a supercapacitor energy storage element 8 , a protection diode 9 , a connection reactor 10 , a charging switch 11 , and a discharging switch 12 . The supercapacitor energy storage element 8 is connected in parallel with the lower diode of the protection diode 9 composed of two series diodes, and the upper output terminal is divided into two circuits, one is connected to the connection reactor 10, and the other is connected to the anode of the upper diode of the protection diode. The cathode of is connected to the positive pole P of the DC bus. The lower output terminal of the super capacitor energy storage element 8 is connected to the negative pole N of the DC bus. The output terminal of the connection reactor 10 is connected to the connection point of the charging switch 11 and the discharge switch 12. The charging switch 11 is composed of an IGBT and a freewheeling diode in antiparallel connection. The source is connected to the DC bus terminal P, and the drain is connected to the output of the connection reactor 10. terminal and the source of discharge switch 12. The discharge switch 12 is composed of an IGBT and a freewheeling diode, the source is connected to the drain of the charging switch 11 and the output terminal connected to the reactor 10, and the drain is connected to the terminal N of the DC bus. When the power of the nonlinear load 2 fluctuates and the absorbed active power is less than the set power, the DC voltage controls the charging switch 11 of the chopper 4 to act, and the discharging switch 12 is turned off to store the excess active power of the power system 1 in the super In the capacitive energy storage element 8, the power system 1 maintains the original transmission level; when the active power absorbed by the nonlinear load 2 suddenly increases and is greater than a predetermined value, in order to maintain the constant output power of the power system 1, the DC voltage controls the chopper The discharge switch 12 of 4 operates, and the charging switch 11 is turned off, releasing the energy stored in the supercapacitor energy storage element 8 to the nonlinear load 2, and compensating the added transient active power of the load. See Figure 2, the DC voltage control chopper wiring diagram of the load current quality regulator.

The utility model has the advantages that: the provided load current quality regulator and nonlinear load operate in parallel, and through the realization of active filtering, reactive power and negative sequence compensation, and short-time active power support, the load current quality can be seen from the system side. The conditions of the ideal load, that is, (1) absorbing a stable, harmonic-free sinusoidal current, (2) three-phase power balance, (3) no inrush current or large starting current, (4) power factor is 1, so as to achieve improvement Power quality goals.

Description of drawings

Figure 1 is a schematic wiring diagram of the current quality dynamic adjustment device connected to the system. Among them, power system 1, nonlinear load 2, load current quality regulator 3, DC voltage control chopper 4, DC smoothing capacitor 5, three-phase inverter 6, output filter 7; power system 1 includes equivalent power supply and output impedance.

FIG. 2 is a wiring diagram of a DC voltage control chopper of a current quality dynamic adjustment device, including: a supercapacitor energy storage element 8 , a protection diode 9 , a connection reactor 10 , a charging switch 11 , and a discharging switch 12 .

Detailed ways

1 to 3 are a specific embodiment of the present invention. The utility model is a power electronic device based on an insulated gate bipolar transistor device and pulse width modulation control technology. It is connected in parallel to the power system, as shown in Figure 1. The power system 1 includes an equivalent power supply and output impedance. For nonlinear loads 2 In terms of harmonic suppression and reactive power compensation, the active power exchanged between the load current quality regulator 3 and the power system 1 does not pass through the energy storage link, and the control of the DC bus voltage of the inverter is controlled by the trigger command of the given inverter by the load current The mass conditioner 3 absorbs a small amount of system loss of the active power compensation device and active power required for harmonic suppression. When the nonlinear load 2 has a dynamic fluctuation property, the load current quality regulator 3 will compensate the dynamic part of the load fluctuation through the energy storage link, so that the power system 1 only needs to provide stable active power to the load, and the power factor is 1.

The two output terminals of the DC voltage control chopper 4 are respectively connected to the two poles P and N of the DC smoothing capacitor 5. The DC smoothing capacitor is formed by connecting two capacitors in series to withstand a higher voltage level. The three-phase inverter 6 The two terminals of the DC bus are respectively connected to the two poles P and N of the DC smoothing capacitor 5, and the three AC output lines of the three-phase inverter 6 are respectively connected to the three filter reactor inputs of the three-phase output filter 7 terminal, the output terminal of the filter reactor is divided into two circuits, one is connected to the filter capacitor, and the other is connected in parallel to the nonlinear load 2.

The DC voltage control chopper 4 includes: a supercapacitor energy storage element 8 , a protection diode 9 , a connection reactor 10 , a charging switch 11 , and a discharging switch 12 . The supercapacitor energy storage element 8 is connected in parallel with the lower diode of the protection diode 9 composed of two series diodes, and the upper output terminal is divided into two circuits, one is connected to the connection reactor 10, and the other is connected to the anode of the upper diode of the protection diode. The cathode of is connected to the positive pole P of the DC bus. The lower output terminal of the super capacitor energy storage element 8 is connected to the negative pole N of the DC bus. The output terminal of the connection reactor 10 is connected to the connection point of the charging switch 11 and the discharge switch 12. The charging switch 11 is composed of an IGBT and a freewheeling diode in antiparallel connection. The source is connected to the DC bus terminal P, and the drain is connected to the output of the connection reactor 10. terminal and the source of discharge switch 12. The discharge switch 12 is composed of an IGBT and a freewheeling diode, the source is connected to the drain of the charging switch 11 and the output terminal connected to the reactor 10, and the drain is connected to the terminal N of the DC bus.

Claims (2)

1. A current quality dynamic adjustment device, characterized in that: comprising: DC voltage control chopper (4), DC smoothing capacitor (5), three-phase inverter (6), output filter (7); The two output terminals of the DC voltage control chopper (4) are respectively connected to the two poles P and N of the DC smoothing capacitor (5). The DC smoothing capacitor is formed by connecting two capacitors in series. The three-phase inverter (6) The two terminals of the DC bus are respectively connected to the poles P and N of the DC smoothing capacitor (5), and the three AC output lines of the three-phase inverter (6) are respectively connected to the three terminals of the three-phase output filter (7). The input end of a filter reactor, the output end of the filter reactor is divided into two circuits, one is connected to the filter capacitor, and the other is connected in parallel to the nonlinear load (2); the main circuit is a three-phase bridge inverter topology, and the DC of the inverter Energy storage equipment and a chopper circuit for controlling DC voltage are arranged on the busbar. 2. The current quality dynamic adjustment device according to claim 1, characterized in that: the DC voltage control chopper (4) includes: a supercapacitor energy storage element (8), a protection diode (9), a connecting reactor (10 ), a charge switch (11), a discharge switch (12); the supercapacitor energy storage element (8) and the lower diode of the protection diode (9) formed by two series diodes are connected in parallel, and the upper output terminal is divided into two circuits, one of which is connected to The reactor (10) is connected, the other is connected to the upper diode anode of the protection diode, and the cathode of this diode is connected to the positive pole P of the DC bus; the lower output terminal of the supercapacitor energy storage element (8) is connected to the negative pole N of the DC bus; Connect the output terminal of the reactor (10) to the connection point of the charging switch (11) and the discharging switch (12), the charging switch (11) is composed of an IGBT and a freewheeling diode in antiparallel connection, and the source is connected to the DC bus terminal P, The drain is connected to the output terminal of the reactor (10) and the source of the discharge switch (12); the discharge switch (12) is composed of an IGBT and a freewheeling diode, and the source is connected to the drain of the charging switch (11) and the reactor ( 10), the drain is connected to the terminal N of the DC bus.

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