CN202285329U

CN202285329U - Active power filter

Info

Publication number: CN202285329U
Application number: CN2011204024581U
Authority: CN
Inventors: 梁冰
Original assignee: Sichuan An Rui Genie Et Environnement
Current assignee: Sichuan An Rui Environment Engineering Co., Ltd.
Priority date: 2011-10-21
Filing date: 2011-10-21
Publication date: 2012-06-27
Anticipated expiration: 2021-10-21

Abstract

The utility model discloses an active power filter which connected between an AC power supply and a load. The active power filter comprises a command current arithmetic circuit and an offset current generating circuit, wherein the offset current generating circuit comprises a main circuit, a drive circuit and a current tracking control circuit; the input end of the command current arithmetic circuit is connected with the power supply input end of the load; the output end of the command current arithmetic circuit is connected with the input end of the current tracking control circuit; the output end of the current tracking control circuit is connected with the input end of the drive circuit; and the output end of the drive circuit is connected with the AC power supply output end after being connected in series with the main circuit. Through the active power filter provided by the utility model, the harmonic wave of the AC power supply can be subjected to dynamic suppression, and the harmonic wave variational in the intensity and frequency and the variational reactive power can be compensated, thereby obtaining an ideal AC power supply.

Description

Active Power Filter-APF

Technical field

The utility model relates to a kind of filter, relates in particular to a kind of idle Active Power Filter-APF that compensates that can suppress and change the harmonic wave that big or small and frequency all change.

Background technology

Along with the extensive use of power electronic equipment, a large amount of harmonic waves are injected into electrical network, cause the quality of power supply of whole electrical network to go from bad to worse.The harm of harmonic current is mainly reflected in the following aspects in the electrical network:

1, harmonic wave makes the equipment that gets in the electrical network produce additional harmonic loss, reduces the service efficiency of electrical network, transmission of electricity and power consumption equipment, increases grid line loss.

2, harmonic wave can produce extra thermal effect, thereby causes the power consumption equipment heating, makes its ageing of insulation, reduces the useful life of equipment.In independent minor scale power net, harmonic current also can make transformer, generator etc. produce supplementary load loss and heating, causes mechanical oscillation and noise, strengthens the electric equipment heating loss greatly, quickens ageing of insulation, influences equipment life; Also can cause the rotor top layer overheated and damage when serious because of kelvin effect.

3, harmonic wave makes easily between electrical network and the compensation condenser resonance takes place, and makes harmonic current amplify several times even tens of times, not only makes capacitor directly impaired, and increases the weight of the threat to other electric equipment.This shows particularly evidently in independent minor scale power net, because its line voltage frequency fluctuation scope is bigger, so just causes resonance more easily.

4, harmonic wave can cause some protection equipment malfunctions works, like relay, fuse etc., also can cause the electrical measuring instrument metering inaccurate simultaneously.In the class grid of oil field, the error in dipping that harmonic wave causes for the well logging appearance might influence the operate as normal of whole oil.

5, harmonic wave can produce near communication system and disturb, and the lighter introduces noise, reduces speech quality, and weight person causes dropout, makes the communication system can't operate as normal.

Summary of the invention

The purpose of the utility model just is to provide in order to address the above problem a kind of humorous idle Active Power Filter-APF that compensates that involves variation that can all change size and frequency.

The utility model is realized above-mentioned purpose through following technical scheme:

The utility model is connected between AC power and the load; Comprise instruction current computing circuit and offset current generation circuit; Said offset current generation circuit comprises main circuit, drive circuit and current tracking control circuit; The input of said instruction current computing circuit is connected with the power input of load; The output of said instruction current computing circuit is connected with the input of said current tracking control circuit, and the output of said current tracking control circuit is connected with the input of said drive circuit, and the output of said drive circuit is connected in series with said main circuit and then is connected with ac power output.

The core of instruction current computing circuit is harmonic wave and the current component such as idle that detects in the target compensation electric current.The command signal of the offset current that offset current generation circuit then draws according to the instruction current computing circuit produces actual offset current.

Particularly, said main circuit comprises circuit breaker, A.C. contactor, inlet wire inductance, PWM current transformer, electrochemical capacitor and filter capacitor.The PWM current transformer is the abbreviation of pulse width modulation current transformer, is to utilize the numeral of microprocessor to export a kind of very effective technology that analog circuit is controlled, and is widely used in from many fields of measurement, the power of communicating by letter control and conversion.

Further; Said instruction current computing circuit comprises CPLD, DSP single-chip microcomputer and D/A change-over circuit; The FPDP of said CPLD is connected with the FPDP of said DSP single-chip microcomputer; The signal port of said CPLD and said DSP single-chip microcomputer is connected with said D/A change-over circuit, and said D/A change-over circuit is connected with said current tracking control circuit.CPLD (Complex Programmable Logic Device), CPLD is the device that develops out from PAL and GAL device, and scale is big comparatively speaking, and complex structure belongs to the large scale integrated circuit scope.It is a kind of user according to needs separately and the digital integrated circuit of constitutive logic function voluntarily.

Further, said CPLD also is connected with protection and I/O circuit.

The beneficial effect of the utility model is:

Can dynamically suppress harmonic wave to AC power through the utility model, and can humorous the idle of variation that involve that size all changes with frequency be compensated, final arrive desirable AC power, avoid or reduce the harm of mains by harmonics.

Description of drawings

Fig. 1 is the integrated circuit block diagram of the utility model;

Fig. 2 is the circuit block diagram of instruction current operator circuit in the utility model.

Embodiment

Below in conjunction with accompanying drawing the utility model is described further:

As shown in Figure 1; The utility model is connected between AC power and the load; Comprise instruction current computing circuit and offset current generation circuit; Offset current generation circuit comprises main circuit, drive circuit and current tracking control circuit, and the input of instruction current computing circuit is connected with the power input of load, and the output of instruction current computing circuit is connected with the input of current tracking control circuit; The output of current tracking control circuit is connected with the input of drive circuit, and the output of drive circuit is connected in series with main circuit and then is connected with ac power output.In conjunction with Fig. 1, main circuit comprises circuit breaker, A.C. contactor, inlet wire inductance, PWM current transformer, electrochemical capacitor and filter capacitor (physical circuit of main circuit is not shown, for conventional convertor assembly, repeats no more at this).

As shown in Figure 2; The instruction current computing circuit comprises CPLD, DSP single-chip microcomputer and D/A change-over circuit; The FPDP of said CPLD is connected with the FPDP of said DSP single-chip microcomputer; The signal port of CPLD and DSP single-chip microcomputer is connected with the D/A change-over circuit, and the D/A change-over circuit is connected with said current tracking control circuit; CPLD also is connected with protection and I/O circuit.The DSP single-chip microcomputer adopts TMS320F2812.Among Fig. 2; The instruction current computing circuit is the digital circuit part; Current tracking control circuit and protection and I/O circuit are artificial circuit part, between current tracking control circuit and the CPLD, all carry out the conversion of digital signal and analog signal between current tracking control circuit and the DSP single-chip microcomputer through the D/A change-over circuit.

In conjunction with Fig. 1; The instruction current computing circuit at first detects harmonic wave and the current component such as idle among the load input current iL (being the target compensation electric current); Obtain concrete offset current component ic ', and this signal is transferred to the current tracking control circuit, the current tracking control circuit sends control signal through calculating and change the back to drive circuit; PWM current transformer action in the driving circuit drives main circuit; Produce actual offset current ic, the current i s that AC power is exported compensates stack, obtains desirable load input current iL at last.Because the instruction current computing circuit is monitored, is detected load input current iL incessantly all the time; So as long as load input current iL harmonic excess at any time occurs; Will be at once by the compensation corrigendum, reach and remain the purpose that load input current iL is desirable electric current.

Claims

1. Active Power Filter-APF; Be connected between AC power and the load; It is characterized in that: comprise instruction current computing circuit and offset current generation circuit; Said offset current generation circuit comprises main circuit, drive circuit and current tracking control circuit, and the input of said instruction current computing circuit is connected with the power input of load, and the output of said instruction current computing circuit is connected with the input of said current tracking control circuit; The output of said current tracking control circuit is connected with the input of said drive circuit, and the output of said drive circuit is connected in series with said main circuit and then is connected with ac power output.

2. Active Power Filter-APF according to claim 1 is characterized in that: said main circuit comprises circuit breaker, A.C. contactor, inlet wire inductance, PWM current transformer, electrochemical capacitor and filter capacitor.

3. Active Power Filter-APF according to claim 1; It is characterized in that: said instruction current computing circuit comprises CPLD, DSP single-chip microcomputer and D/A change-over circuit; The FPDP of said CPLD is connected with the FPDP of said DSP single-chip microcomputer; The signal port of said CPLD and said DSP single-chip microcomputer is connected with said D/A change-over circuit, and said D/A change-over circuit is connected with said current tracking control circuit.

4. Active Power Filter-APF according to claim 3 is characterized in that: said CPLD also is connected with protection and I/O circuit.