CN202395647U

CN202395647U - Active power filter system for frequency converter

Info

Publication number: CN202395647U
Application number: CN2011205357214U
Authority: CN
Inventors: 束龙胜; 程建洲
Original assignee: ANHUI USEM TECHNOLOGY Co Ltd; Anhui Xinlong Electrical Co Ltd
Current assignee: Anhui Polytron Technologies Inc
Priority date: 2011-12-20
Filing date: 2011-12-20
Publication date: 2012-08-22
Anticipated expiration: 2021-12-20

Abstract

The utility model discloses an active power filter system for a frequency converter. The active power filter system comprises an active power filter and a group of reactors, wherein the active power filer is connected in parallel with the frequency converter; the reactors are connected in series with the frequency converter; wire lead-out ends of the reactors are connected with the frequency converter; and wire lead-in ends of the reactors are connected in parallel with the active power filter and then are connected with the low voltage side of a power transformer. By using the structure, the active power filter is reconstructed. The active power filter system has the advantages that: 1, the filter effect is good, primary filter is performed through the serial reactors, and the harmonic filtering rate is increased by about 10 percent on the basis of the performance of the active power filter; 2, the operation reliability is higher, and the frequency converter and an external power grid can be effectively isolated through the reactors connected in series with the frequency converter; and 3, the economic performance is better, the price of the active power filter is higher, but the harmonic content is reduced through the reactors connected in series with the frequency converter, the demand capacity of the active power filter is correspondingly reduced, the investment is correspondingly reduced, and the investment can be reduced by about 20 percent according to actual condition of a project.

Description

The active power filtering system that is used for frequency converter

Technical field

The utility model relates to the electric filtering field, relates in particular to a kind of active power filtering system that is used for frequency converter.

Background technology

Frequency converter is in the industrial occasions extensive use at present, and converter plant also produces power quality problems such as serious harmonic pollution when improving efficiency, optimizing technology.And often this transient state or transient power quality problem are bigger than traditional problem to the loss that enterprise brings, and the output and the economic benefit of enterprise takes place to influence greatly if any accident.

At present, solve the harmonic problem that frequency converter brings, the way that mainly solves is the installing electric-power filter, specifically can be divided into two kinds of devices of Active Power Filter-APF and passive power filter.Active Power Filter-APF is based on the novel filter apparatus of electronic power inverter, advantages such as response speed is fast, filtering performance is good that it has, and still, Active Power Filter-APF involves great expense, and this has seriously hindered it and has applied.Frequency converter is at present a lot of topmost harmonic sources of industrial applications, and from technological layer, Active Power Filter-APF is to the best harmonic wave control mode of frequency converter; But because the frequency converter harmonic content reaches, if direct using active electric-power filter, the compensation capacity that needs is bigger; Invest very highly, be limited to factors such as fund, technology, the majority that uses at present is a passive power filter; Though can bring into play great role; But it exists volume big, and filter effect receives system parameter variations to influence shortcomings such as bigger, and passive filter also possibly cause the bigger amplification of certain subharmonic under specific circumstances; Thereby influence the safe operation of filter and other power consumption equipments, so limitation is arranged.

The utility model content

The utility model technical problem to be solved is the deficiency to prior art; A kind of active power filtering system that is used for frequency converter is provided; To reach stability and the filtering performance that improves filtering system; Reduce the configuration capacity of Active Power Filter-APF, thereby reduce the cost of active filter system.

For solving the problems of the technologies described above; The technical scheme of the utility model is a kind of active power filtering system that is used for frequency converter; It is characterized in that; It comprises and Active Power Filter-APF and one group of reactor of connecting with frequency converter of frequency converter parallel connection that the leading-out terminal of described reactor is connected with frequency converter, is connected with the power transformer low-pressure side after the end of incoming cables of reactor and the described Active Power Filter-APF parallel connection.

Described Active Power Filter-APF is made up of detecting unit, control unit, current transformer, energy-storage units, charging inrush current prevention circuit and filter circuit; Detection step down side three-phase voltage, load-side three-phase current, Active Power Filter-APF three-phase output current and energy-storage units direct voltage are sent detected signal into control unit and are carried out after the computational analysis current transformer and energy-storage units being controlled.

Described detecting unit is made up of voltage sensor and current sensor; Described control unit is amplified by A/D converter, digital signal processor DSP, signal and electric isolation, drive circuit are formed, and voltage sensor and current sensor carry out the voltage/current signals of gathering to output control signals to current transformer and energy-storage units through signal amplification and electricity isolation, drive circuit after data processing and the computational analysis through A/D converter, digital signal processor DSP.

The three-phase bridge circuit that described current transformer is made up of high-speed power electronic switching device IGBT, described energy-storage units is made up of direct current capacitor, and the output of described three-phase bridge circuit is connected with charging inrush current prevention circuit through filter circuit.

A kind of active power filtering system that is used for frequency converter owing to adopted said structure, has transformed Active Power Filter-APF, through to the frequency converter series reactor, has realized combined filter.Be a system scheme of electric filtering aspect, this active power filtering stability of a system is better, and filtering performance is more excellent.Compare with single Active Power Filter-APF, have following advantage: 1, good wave filtering effect, carry out elementary filtering through series reactor, on the basis of Active Power Filter-APF performance, the harmonic filtration rate improves about 10%; 2, operational reliability is higher, and the reactor of connecting with frequency converter can effectively be isolated frequency converter and extraneous electrical network; 3, economic performance is better, and the Active Power Filter-APF price is higher, but has reduced harmonic content through the reactor of connecting with frequency converter, and the corresponding reduction of demand capacity to Active Power Filter-APF drops into corresponding reduction, and actual according to engineering, investment can reduce about 20%; 4, compare with passive power filter, the utility model belongs to the active power filtering category, overcome many shortcomings of passive power filter, and filter effect is more excellent.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is done further detailed explanation;

Fig. 1 is a kind of active power filtering system block diagram that is used for frequency converter of the utility model;

Fig. 2 is an Active Power Filter-APF circuit theory sketch map shown in Figure 1;

In Fig. 1, Fig. 2,1, Active Power Filter-APF; 2, reactor; 3, detecting unit; 4, control unit; 5, energy-storage units; 6, current transformer; 7, filter circuit; 8, charging inrush current prevention circuit.

Embodiment

As shown in Figure 1, Fig. 1 is the utility model structured flowchart, and it comprises: Active Power Filter-APF 1 and one a group reactor of with frequency converter connecting 2 parallelly connected with frequency converter; The leading-out terminal of the reactor 2 of described and frequency converter series connection is connected with frequency converter, the end of incoming cables of

reactor

2 and 1 parallelly connected then the connection with the power transformer low-pressure side of described Active Power Filter-APF; Be connected with the power transformer low-pressure side after the end of incoming cables parallel connection of described Active Power Filter-APF 1 and described reactor 2.

The reactor 2 of connecting with frequency converter can be a three-phase reactor; Also can be three single-phase reactors; The magnetic flux density of its inductance value and reactor, current density value should be designed by the technical professional, otherwise possibly influence the normal operation of reactor 2 itself and frequency converter.

Referring to Fig. 2, Fig. 2 is the circuit theory sketch map of Active Power Filter-APF.Active Power Filter-APF is made up of detecting unit 3, control unit 4, current transformer 6, energy-storage units 5, charging inrush current prevention circuit 8 and filter circuit 7; Detecting unit 3 detects step down side three-phase voltage, load-side three-phase current, Active Power Filter-APF three-phase output current and energy-storage units direct voltage, detected signal is sent into control unit 4 carry out after the computational analysis current transformer 6 and energy-storage units 5 being controlled; Detecting unit 3 is made up of voltage sensor and current sensor; Control unit 4 is amplified by A/D converter, digital signal processor DSP, signal and electricity is isolated, drive circuit is formed; The three-phase bridge circuit that current transformer 6 is made up of high-speed power electronic switching device IGBT; Described energy-storage units 5 is made up of direct current capacitor; Charging inrush current prevention circuit 8 is made up of contactor J1, J2 and resistance R 1, R2, R3; Filter circuit 6 is composed in series by inductance L, resistance R and capacitor C, the high fdrequency component of output during the work of filtering Active Power Filter-APF.

When Active Power Filter-APF started, charging inrush current prevention circuit 8 was closed with contactor J1 earlier, through resistance R 1, R2, R3 and 5 chargings of 6 pairs of energy-storage units of current transformer; After charging is accomplished; Contactor J2 is closed, and with resistance R 1, R2, R3 excision, Active Power Filter-APF begins normal operation then; Charging inrush current prevention circuit 8 can effectively suppress excessive shoving to the infringement of current transformer 6 and energy-storage units 5 in the starting process.

The utility model is through playing the effect of elementary filtering to the frequency converter series reactor; Play buffer action simultaneously; Can protect load; Carry out depth filtering through Active Power Filter-APF again, filtering performance is more excellent on the whole, and the whole comparable single Active Power Filter-APF of harmonic filtration rate improves about 10%.

Combine accompanying drawing that the utility model has been carried out exemplary description above; Obviously the concrete realization of the utility model does not receive the restriction of aforesaid way; As long as adopted method design of the utility model and the various improvement that technical scheme is carried out; Or directly apply to other occasion without improvement, all within the protection range of the utility model.

Claims

1. active power filtering system that is used for frequency converter; It is characterized in that; It comprises Active Power Filter-APF (1) and one group of reactor of connecting with frequency converter (2) with the frequency converter parallel connection; The leading-out terminal of described reactor (2) is connected with frequency converter, and the end of incoming cables of reactor (2) is connected with the power transformer low-pressure side with described Active Power Filter-APF (1) parallel connection back.

2. the active power filtering system that is used for frequency converter according to claim 1; It is characterized in that described Active Power Filter-APF (1) is made up of detecting unit (3), control unit (4), current transformer (6), energy-storage units (5), charging inrush current prevention circuit (8) and filter circuit (7); Detecting unit (3) detects step down side three-phase voltage, load-side three-phase current, Active Power Filter-APF three-phase output current and energy-storage units direct voltage, detected signal is sent into control unit (4) carry out after the computational analysis current transformer (6) and energy-storage units (5) being controlled.

3. the active power filtering system that is used for frequency converter according to claim 2; It is characterized in that; Described detecting unit (3) is made up of voltage sensor and current sensor; Described control unit (4) is amplified by A/D converter, digital signal processor DSP, signal and electric isolation, drive circuit are formed, and voltage sensor and current sensor carry out the voltage/current signals of gathering to output control signals to current transformer (6) and energy-storage units (5) through signal amplification and electricity isolation, drive circuit after data processing and the computational analysis through A/D converter, digital signal processor DSP.

4. the active power filtering system that is used for frequency converter according to claim 2; It is characterized in that; The three-phase bridge circuit that described current transformer (6) is made up of high-speed power electronic switching device IGBT; Described energy-storage units (5) is made up of direct current capacitor, and the output of described three-phase bridge circuit is connected with charging inrush current prevention circuit (8) through filter circuit (7).