CN2891438Y

CN2891438Y - Active power filter

Info

Publication number: CN2891438Y
Application number: CNU2005200154773U
Authority: CN
Inventors: 陈识微; 蒋鲁军; 金晓明
Original assignee: ZHEJIANG RONGDA ELECTRIC EQUIPMENT MANUFACTURY CO Ltd
Current assignee: ZHEJIANG RONGDA ELECTRIC EQUIPMENT MANUFACTURY CO Ltd
Priority date: 2005-10-10
Filing date: 2005-10-10
Publication date: 2007-04-18
Anticipated expiration: 2015-10-10

Abstract

Disclosed is an active power filtering device which comprises a loading current sampling unit, a harmonic-reactive current separation unit, a controlling signal producing unit and an output compensation current, wherein the loading current sampling unit, the harmonic-reactive current separation unit, the controlling signal producing unit and the output compensation current are combined into an integrate filtering module, at least two independent modules are in series connected in the systemic power network, the main-sub module control is turned into completely independent series module, each module can work independently and without interaction, thereby the device has the advantages of simple and reasonable configuration, convenient and easy use, test and maintenance. The device is characterized in that it can be effectively and reliably operated for a long term, thereby improving the stability of the power system filtering function and reducing the risk coefficient.

Description

The active power filtering device

Technical field

The utility model relates to a kind of harmonic current and reactive current that can detect the nonlinear load generation in real time, produce and its equal and opposite in direction the active power filtering device of the offset current that direction is opposite fast.

Background technology

In recent years, such as the use of nonlinear loads such as Medium Frequency Induction Heating Furnace, frequency converter, electrolysis electrodeposit equipment, arc furnace, when producing a large amount of reactive powers, also cause the distortion of electrical network waveform in a large number, promptly had voltage and harmonic wave.And the existence of harmonic wave has increased the loss of line loss and subscriber equipment, has reduced the quality of power supply.Of common occurrence by the equipment breakdown that high order harmonic component causes, thereby harmonic wave has become " public hazards " of polluting utility network and harm miscellaneous equipment.For solving above-mentioned harmful " harmonic wave " harm to utility network and miscellaneous equipment, eliminate its harmful effect, adopt the active power filtering device at present, the operation principle of this filter is to detect harmonic current IH and the reactive current IQ that nonlinear load produces in real time, produce and its equal and opposite in direction fast, offset current that direction is opposite and injected system reach the filtering harmonic wave and improve the purpose of power factor.The active power filtering device is eliminated the high order harmonic component that is harmful to other electric equipment, avoiding high order harmonic component that other electric equipment and electricity are died works the mischief, it has the power supply quality of improvement, improve power factor and utilization rate of equipment and installations, multiple functions such as energy savings reduces the wastage, its principle is as follows: active filter is connected in system's electrical network, harmonic current and reactive current by real-time detection nonlinear load generation, produce and its equal and opposite in direction fast, offset current IF and injected system that direction is opposite, reach the filtering harmonic wave and improve the purpose of power factor, as Fig. 1, shown in Figure 2.

At present, the active power filtering device structure contents that adopt as shown in Figure 3 more, it is by in the main control module APF connecting system, finish the load current sampling, and from load current, isolate harmonic current IH and reactive current IQ, produce control signal then to respectively from modules A PF1-APFN, from reverse harmonic current and the reactive current of module output, see shown in Figure 3 by respectively; Thereby the sampling of above-mentioned load current with separate and the generation of control signal is finished by main control module, respectively do not contain these functions from module, and only accept the control signal output current of main control module, its total is formed and is belonged to typical principal and subordinate's modular device, though it has advantages such as with low cost, but, accept the agreement of main control module and coordinate because N module all is subjected to a master control module controls; If one still can be accomplished not influence overall operation from module failure, if in case the main control module fault, N will lose the control and the coordination of main control module from module, will produce inevitable system crash.

Summary of the invention

The purpose of this utility model is to overcome the deficiency of above-mentioned existence, and provides a kind of multimode independently to be connected in the electric power system active power filtering device with harmonic carcellation electric current and reactive current.It includes load current sampling unit, harmonic current and reactive current separative element, produces control signal unit and output offset current unit, it is characterized in that described load current sampling unit, harmonic current and reactive current separative element, produce the control signal unit and a complete filtration module is formed in output offset current unit, have at least two filtration modules independently to be connected in system's electrical network.

Described filtration module includes current sensor and 50 Ω resistance and the follower 1 that is connected in the CT secondary side at least, is connected to a quadravalence low pass filter after voltage signal LDOU who is directly proportional with load current of its generation and standard cosine signal COS multiply each other and produces a size to be the direct current signal IPJ of load active current; The direct voltage setting is connected pi regulator respectively with the direct voltage feedback, and PI is regulated output and IPJ adder addition, multiply by COS again, obtains load active power IP; In that voltage signal LDOU and load active power IP are inserted subtracter 1, obtain the instruction current IQH that module need be followed the tracks of output.

The value of feedback FBOU of described instruction current IQH and module output current carries out obtaining difference IDT and inserting a hysteresis loop comparator 1 behind the subtraction with subtracter 2, and by this hysteresis loop comparator 1 output DRS upset.

Described DRS signal produces two switch controlling signal DR12, DR23 after inserting a dead-time control circuit that is combined by resistance R 58, C14 and comparator and two NAND gate; These two switch controlling signal DR12, DR23 insert the IGBT main circuit respectively through four photoelectric coupled circuit output four IGBT drive signal DR1, DR2, DR3, DR4.

Described IGBT main circuit is made up of IGBT module, capacitor C 9, inductance L 6, L8, capacitance-resistance C18, R44, the Z1 of inside modules, Z4 and Z2, two pairs of brachium pontis conductings in succession of Z3, the direct voltage on the C9 and the difference of system voltage are connected to the two ends of L6, L8, produce follow current, and go into system, and offset with harmonic current and reactive current by system's AN termination.

The utility model belongs to a kind of improvement to prior art, it changes principal and subordinate's module controls of device into module fully independently in parallel, and each module all includes the sampling of load current, separate harmonic current and reactive current, produce complete functions such as control signal and output offset current, each module all can work alone, unaffected mutually, thereby have simple in structure, rationally, easy to use, debugging and maintenance are easier and convenient, each module is unaffected mutually, make the device can be effective, chronically, reliability service, the filtering performance of electric power system is stable, characteristics such as risk factor reduction.

Description of drawings

Fig. 1 is the structure principle chart of active power filtering device.

Fig. 2 is the structure principle chart of the active power filtering device of existing principal and subordinate's module controls.

Fig. 3 is the logic diagram of the active power filtering device of existing principal and subordinate's module controls.

Fig. 4 is a structure principle chart of the present utility model.

Fig. 5 is a logic diagram of the present utility model.

Fig. 6 is the sampling of load current of the present utility model and separates circuit theory diagrams such as harmonic current and reactive current.

Fig. 7 is the circuit theory diagrams of IGBT main circuit of the present utility model.

Embodiment

Below in conjunction with accompanying drawing the utility model is described in detail: shown in Figure 4, the utility model is connected to a plurality of independently filtration module APF in the electric power pool, each filtration module APF has included load current sampling unit, harmonic current and reactive current separative element 1, has produced control signal unit 2 and output offset current unit 3, sees shown in the accompanying drawing 5.

A complete filtration module is formed in described load current sampling unit, harmonic current and reactive current separative element, generation control signal unit and output offset current unit, and a plurality of complete filtration module APF independently are connected in system's electrical network.

Shown in Figure 6, described filtration module APF includes current sensor and 50 Ω resistance and the follower 1 that is connected in the CT secondary side at least, is connected to a quadravalence low pass filter after voltage signal LDOU who is directly proportional with load current of its generation and standard cosine signal COS multiply each other and produces a size to be the direct current signal ipj of load active current; The direct voltage setting is connected pi regulator respectively with the direct voltage feedback, and PI is regulated output and ipj adder addition, multiply by COS again, obtains load active power ip; In that voltage signal LDOU and load active power ip are inserted subtracter 1, obtain the instruction current IQH that module need be followed the tracks of output.Described COS is and the fixed ampllitude standard cosine signal of line voltage same-phase with frequency.The effect of described pi regulator is to stablize the C9 dc voltage value.As everyone knows, load current i=active current ip+ reactive current ip+ harmonic current ih, detect IQH=reactive current ip+ harmonic current ih=I-ip, can realize IQH=LDOU-ip with subtracter 1, IQH is exactly the instruction current that module need be followed the tracks of output, FBOU is the value of feedback of module output current, as long as FBOU follows the tracks of IQH within the specific limits, just can reach the purpose of harmonic carcellation.

Shown in Figure 7, described DRS signal produces two switch controlling signal dr14, dr23 after inserting a dead-time control circuit that is combined by resistance R 58, C14 and comparator and two NAND gate; These two switch controlling signal dr14, dr23 insert the IGBT main circuit respectively through four photoelectric coupled circuit output four IGBT drive signal dr1, dr2, dr3, dr4; Described dr1, dr2, dr3, dr4 are the drive signal of IGBT.

IGBT main circuit described in the utility model is made up of IGBT module, capacitor C 9, inductance L 6, L8, capacitance-resistance C18, R44, the Z1 of inside modules, Z4 and Z2, two pairs of brachium pontis conductings in succession of Z3, the direct voltage on the C9 and the difference of system voltage are connected to the two ends of L6, L8, produce tracking and compensating current, and go into system, and offset with harmonic current and reactive current by a of system and n termination.C18, R44 form high pass filter filtering switching frequency electric current, make that the offset current of injected system is the electric current of relative clean.Z1, Z4 are controlled by DR1, DR4 respectively, and Z2, Z3 are controlled by dr2, dr3 respectively.

IQH described in the utility model and FBOU carry out difference IDT behind the subtraction as the input of hysteresis loop comparator 1, hysteresis band is by R1 and R2 decision, when IDT arrives the upper lower limit value of hysteresis band, hysteresis loop comparator 1 output DRS upset, offset current is oppositely increased, the result is that FBOU centers on IQH and fluctuates up and down, has realized the function of offset current trace command electric current I QH.

The synchronization criterion COS signal that the utility model is used, the alternating voltage zero-crossing testing circuit that its phase-detection is used is realized, alternating voltage is inserted filtering High-frequency Interference behind the low pass filter, export lock-out pulse with hysteresis loop comparator again, offer the COS signal generating circuit.

The utility model can also dispose underloading protection, DC over-voltage protection, startup protection and IGBT failure protection function, and specifically: F0 provides fault-signal for IGBT inside, produces the FAILER signal after light-coupled isolation; DEL is the time delayed signal during the electrifying startup, and purpose is the charging interval of crossing capacitor C 9 when powering on, during this period of time the enclosed switch control signal; IPJO is the underloading signal, but when the load underloading stopcock control signal, when load reaches a certain amount of, start blower fan and give device radiation; DCMP is a direct voltage overvoltage signal; lockout switch control signal when producing this signal; produce the drB signal by optocoupler simultaneously; make the Z7 conducting; direct voltage discharges by R45; direct voltage reopens switch controlling signal after descending, and above guard signal is combined on dr14, the dr23 through a series of or door, to realize underloading protection, DC over-voltage protection, startup protection and IGBT failure protection function.

Claims

1, a kind of active power filtering device, it includes load current sampling unit, harmonic current and reactive current separative element, produces control signal unit and output offset current unit, the incoming end that it is characterized in that described load current sampling unit is connected in system's electrical network, picking out end links to each other with the reactive current separative element with harmonic current, and link to each other with output offset current unit and, have at least two filtration modules independently to be connected in system's electrical network by complete filtration module of composition by producing the control signal unit.

2, active power filtering device according to claim 1, it is characterized in that described filtration module includes current sensor and 50 Ω resistance and the follower 1 that is connected in the CT secondary side at least, after joining, it and standard cosine signal COS input be connected to a quadravalence low pass filter again, one tunnel process direct voltage feedback of this quadravalence low pass filter is connected in pi regulator with the direct voltage setting, another road is directly exported with pi regulator and is joined, link to each other with an adder again, join with standard cosine signal COS input, the output behind follower 1 is connected on the subtracter 1 again.

3, active power filtering device according to claim 2, the output that it is characterized in that described subtracter 1 inserts a subtracter 2 with the compensation current feedback of module output current, inserts a hysteresis loop comparator 1 again.

4, active power filtering device according to claim 3, the output that it is characterized in that described hysteresis loop comparator 1 inserts one by resistance R 58, C14 and comparator and two dead-time control circuits that NAND gate combines, it produces two switch controlling signal dr12, dr23 outputs and connects four photoelectric coupled circuit, exports four IGBT drive signal dr1, dr2, dr3, dr4 and inserts the IGBT main circuit respectively.

5, active power filtering device according to claim 4, it is characterized in that the IGBT main circuit is made up of IGBT module, capacitor C 9, inductance L 6, L8, capacitance-resistance C18, R44, the Z1 of inside modules, Z4 and Z2, two pairs of brachium pontis conductings in succession of Z3, the direct voltage on the C9 and the difference of system voltage are connected to the two ends of L6, L8, produce follow current, and go into system, and offset with harmonic current and reactive current by A of system and N termination.