CN202872365U - Hybrid electric filter device based on third harmonic active power filter - Google Patents

Abstract

The utility model discloses a hybrid electric filter device based on a third harmonic active power filter. The hybrid electric filter device based on the third harmonic active power filter comprises a hybrid third harmonic electric active power filter 1, a fifth LC passive power filter bank 2, a seventh LC passive power filter bank 3, a power supply side voltage transformer YT, a power supply side current transformer CT1, a load side current transformer CT2 and a hybrid third harmonic electric active power filter 1 side current transformer CT3. The device not only can be used in a three-phase four-line power distribution system, but also can be used in a three-phase three-line power distribution system, is especially suitable for a system with large fifth and seventh harmonics, and an electric field with more three harmonics.

Description

Hybrid power filter based on the triple-frequency harmonics active power filtering

Technical field

The utility model relates to the Hybrid power filter based on the triple-frequency harmonics active power filtering, belongs to the electrical engineering technical field, is not only applicable to three-phase four-wire system, equally also is applicable to the three-phase three-wire system system.

Background technology

Development along with modern power electronics technology; various nonlinear loads are more and more in the electric power system; so that the harmonic pollution of electric power system is day by day serious; it causes power quality obviously to descend; affect the normal operation of various electric equipments, supply line has been produced supplementary load loss, make the capacitor in the electrical network produce resonance; make relaying protection and automatics misoperation occur, and make instrument and electric energy metrical larger error occur.

Harmonic treating apparatus mainly contains two large classes at present: passive filtration unit and active filter.Passive filtration unit is to be made of reactor, capacitor, resistor, it is low to have cost, the characteristics of technology maturation, but because it is to present the purpose that Low ESR or high impedance reach filtering by the harmonic wave to some number of times, therefore exist some obvious defect problems: be subjected to the impact of power system impedance large such as the filter effect on harmonic current; Bad to mains frequency skew and the frequent situation filter effect that changes of Harmonic Conditions; Be connected to the harmonic current that other the non-linear loads in the same electrical network produce and flow into this filter, thereby cause overload; Serial or parallel connection resonance may occur in the system impedance of electrical network and passive filter under some frequency.Active electric filter device has adopted advanced power electronic technology and Digital Signal Processing, it is a kind of novel electric power electric device for dynamically suppressing harmonic wave, compensating reactive power, it can compensate harmonic wave and the idle of variation that big or small and frequency all change, its application can overcome that traditional harmonic wave such as passive filter suppresses and the shortcoming of reactive-load compensation method, realized dynamic tracking compensation, and not only filtering harmonic current but also compensating power.But because active electric filter device exists the cost high price expensive, therefore the problem that actual life is short, is greatly limited in actual applications.And the hybrid power power filter device that the utility model adopts can be good at addressing this problem, for the triple-frequency harmonics filtering part, the sample of signal that the utility model adopts is different from the method that the patent No. 200510022539.8 Chinese invention patents propose with control method.

Chen Binfa is at " the distribution transformer connection is to the analysis of harmonic effects " (6 phase of electric power network technique-calendar year 2001 P55-P58, Beijing Power Supply Bureau of author unit) point out in the literary composition " when transformer connection n0; phase voltage resultant distortion rate exceed standard mainly be 3 subharmonic voltages of zero sequence too high due to; 3 subharmonic voltages are produced by zero sequence 3 subharmonic currents of load, and 3 subharmonic currents of the zero sequence transformer leakage reactance of not flowing through.When flowing through transformer, can only be with the 380V side leakage anti-and zero sequence excitation reactance formation loop (the zero sequence electromotive force in the induction of 10kV side can not be applied to system impedance).When transformer device structure is three-phase three-limb, because three-phase zero sequence magnetic flux equal and opposite in direction, phase place are identical, thereby can not be as positive sequence (or negative phase-sequence) main flux, one phase main flux can form the loop through the iron core of other two-phase, they are forced through dielectric and shell forms the loop, run into very large magnetic resistance.Therefore, the zero sequence excitation reactance of this transformer is considered as finite value, and Xm0 is roughly 0.3～1.0 (being far longer than leakage reactance).3 subharmonic currents will produce larger pressure drop at this zero sequence excitation reactance, be 3 subharmonic voltages, be easy to cause voltage resultant distortion rate to exceed standard.When the transformer connection was, the Transformer Winding of 10kV side formed the loop of 3 subharmonic currents circulation, and this impedance loop is the transformer leakage reactance, much smaller than the zero sequence excitation impedance, thereby can not produce 3 larger subharmonic voltages." as seen; no matter what connection distribution transformer is; because the necessary ground connection of distribution power transformer case; triple-frequency harmonics all can form current path; only impedance magnitude is different; the triple harmonic current that produces varies in size, must consider that therefore triple harmonic current is on the impact of reactive power compensation and filter.Device of the present utility model has well solved this problem.

The utility model content

The technical solution of the utility model: comprising: 2,7 LC passive filter groups 3 of 1,5 LC passive filter groups of mixed type triple-frequency harmonics active power filter, mains side voltage transformer YT, mains side Current Transmit 1, load-side Current Transmit 2, mixed type triple-frequency harmonics active power filter 1 side Current Transmit 3.

Described mixed type triple-frequency harmonics active power filter 1: comprise the DSP master control circuit board, the IGBT drive circuit of the inverter circuit that is formed by IGBT half-bridge and electric capacity half-bridge, 2 road PWM output and the direct-current switch power supply with metering function of DC power supply is provided for this inverter circuit.

Described 5 LC passive filter groups 2: 5 the LC passive filters by the neutral point tap by many groups of wye connections form, it can not only filtering 5 subharmonic currents, provide suitable reactive power to system, path is provided for the tertiary current of the zero sequence in the three-phase current.

Described 7 LC passive filter groups 3: 7 the LC passive filters by the neutral point tap by many groups of wye connections form, it can not only filtering 7 subharmonic currents, provide suitable reactive power to system, path is provided for the tertiary current of the zero sequence in the three-phase current.

The outlet side Current Transmit 3 of described mains side voltage transformer YT, mains side Current Transmit 1, load-side Current Transmit 2, mixed type triple-frequency harmonics active power filter 1, because the size of current of each side is different, therefore, the no-load voltage ratio of each current transformer is different, will be folded to them on the same benchmark in design is used.

DSP master control circuit board in the described mixed type triple-frequency harmonics active power filter 1: mainly be by DSP, FPGA, ADC transducer; the formations such as communication interface chip; the software function module that can realize has: control system module, data-signal acquisition module, PWM driver module, the control of reactive power compensating module, temperature detecting module, CAN bus communication module, line voltage synchronization phase-locked control module, human-machine interface module, protection and alarm circuit etc., wherein the data-signal acquisition module includes the signal conditioning circuit of band isolation.

3 subharmonic reference signal i of described mixed type triple-frequency harmonics active power filter _F3Be 3 subharmonic currents that the three-phase phase current extracts by bandpass digital filter from the low-voltage distribution system load, and use 3 subharmonic currents that from mains side three-phase phase current, extract to revise, formed a complete closed-loop control system.

Description of drawings

Below the utility model will be further described by drawings and Examples:

Fig. 1 is the utility model theory diagram;

Fig. 2 is three-phase voltage synchronization phase-locked control module;

Fig. 3 is the PWM control method theory diagram of the fixed frequency of triple-frequency harmonics active power filter 1;

Fig. 4 is the theory diagram of idle software model;

Wherein, i _Sa, i _Sb, i _ScThe three-phase current of distribution transformer low-voltage distribution side, i _La, i _Lb, i _LcThe three-phase current of nonlinear load, i _F3jIt is the output current of mixed type triple-frequency harmonics active power filter 1, the upper voltage of dc capacitor CD1, CD2 of UD1, UD2 mixed type triple-frequency harmonics active power filter 1, CONVST is the enabling signal of data-signal acquisition module ADC, and CONVST1 and CONVST2 are space signals.

Embodiment

The theory diagram of the device that the utility model proposes as shown in Figure 1, at first, three-phase voltage signal U _a, U _b, U _cBy the line voltage synchronization phase-locked control module that is consisted of by FPGA and phase-locked loop pll chip, produce respectively a digitlization 10 frequency be the ADC enabling signal CONVST and two space signal CONVST1, CONVST2 (guaranteeing the reliably working of ADC and DSP fully) (seeing Fig. 2) that function is consistent of 1024 times of fundamental frequencies, ADC chip on the master control circuit board has had just to begin constantly to sample behind the enabling signal CONVST and has kept and conversion, sends the transformation result that eoc signal notice DSP reads ADC behind the EOC.Like this, the three-phase current i on the mains side Current Transmit 1 _Sa, i _Sb, i _ScWith the three-phase current i on the load-side Current Transmit 2 _La, i _Lb, i _LcAnd the current i on the Current Transmit 3 _F3jThrough delivering to the input of corresponding ADC transducer behind the corresponding signal conditioning circuit, convert corresponding digital quantity to through ADC, and read by DSP respectively.Then, as shown in Figure 3, DSP adopts the IIR digital filtering technique according to the transformation result of ADC, can calculate respectively 3 subharmonic current i of load-side _S3a, i _S3b, i _S3c, 5 subharmonic current i _S5a, i _S5b, i _S5cWith 7 subharmonic current i _S7a, i _S7b, i _S7c, and 3 subharmonic current i of mains side _L3a, i _L3b, i _L3c, 5 subharmonic current i _L5a, i _L5b, i _L5cWith 7 subharmonic current i _L7a, i _L7b, i _L7c, so just can obtain mixed type triple-frequency harmonics active power filter 1 needed 3 subharmonic reference signal: i _F3=i _L3a+ i _L3b+ i _L3cBecause also there are 3 a small amount of subharmonic currents in 3 subharmonic currents of mixed type triple-frequency harmonics active power filter 1 impossible absolutely complete filtering load-side at mains side; For 3 subharmonic currents that make mains side are as far as possible few, the feedback that 3 subharmonic currents by mains side of having induced one in DSP control software consist of; Such 3 subharmonic reference signal i of mixed type triple-frequency harmonics active power filter 1 _F3Be 3 subharmonic currents that the three-phase phase current extracts by digital filter from the low-voltage distribution system load, and use the 3 subharmonic current i that from mains side three-phase phase current, extract _F3kRevise, formed a complete closed-loop control system.

The feedback signal that is produced by 3 subharmonic of mains side is: i _F3k=i _S3a+ i _S3b+ i _F3c

The revised reference signal of process: K in the formula ₁For less than 1 coefficient.

Error signal

This error signal Δ i _CMultiply by after the gain A pwm signal that has just obtained driving IGBT after comparing with a triangular wave of deciding frequency.The theory diagram of its PWM control method as shown in Figure 3.It adopts the PWM control method of fixed frequency, and amplifier A has ratio or proportional integral characteristic, and its parameter directly affects the tracking characteristics of mixed type triple-frequency harmonics active power filter 1.In this method, the switching frequency of device for power switching is certain, namely equal carrier frequency, be conducive to like this switching harmonics on filtering output current or the voltage, the contained harmonic wave of output current is less, be usually used in harmonic wave and the strict occasion of noise requirements, but slow than instantaneous value manner of comparison of current response.In fact the control of 1 couple of dc bus capacitor CD1 of mixed type triple-frequency harmonics active power filter, the upper voltage of CD2 requires is not very strict, in order to guarantee the reliably working of direct-current switch power supply, need to the maximum output current of direct-current switch power supply be limited.

2,7 LC passive filter groups 3 of 1,5 LC passive filter groups of mixed type triple-frequency harmonics active power filter are to be controlled by DSP main control circuit and the auxiliary controller synthesis that consists of.After mixed type triple-frequency harmonics active power filter 1 was started working, DSP opened the locking passage of 5 LC passive filter groups 2 and 7 LC passive filter groups 3 by software operation IO mouth.That maximum reactive requirement and maximum harmonic wave situation according to real system designs at the group number of 5 LC passive filter groups 3 shown in Fig. 1 and 7 LC passive filter groups 4 and every pool-size.The idle software model of DSP the inside can determine the switching of each LC passive filter according to System Reactive Power and 5 at that time, the situation of 7 subharmonic currents when LC passive filter switching.Therefore, can be good at realizing the reactive power compensation target of 3,5,7 subharmonic filtering and system.

The reactive power of load is calculated software block diagram as shown in Figure 4 among the DSP, the three-phase voltage signal U of low-voltage distribution system _a, U _b, U _cThree-phase current i with nonlinear load _La, i _Lb, i _LcCan calculate respectively the U of A phase by three FFT software modules _A1, I _L1a,

I _L5a, I _L7a, the U of B phase _B1, I _L1b,

I _L5b, I _L7b, the U of C phase _C1, I _L1c,

I _L5c, I _L7c, then can be in the hope of the power factor of three-phase by the sine and cosine table of looking into the dsp software the inside

The reactive power that so just can obtain the A phase is

The reactive power of B phase is

The reactive power of C phase is

The reactive power of 5 LC passive filter groups 2 and 7 LC passive filter groups 3 is to distribute according to the 5 subharmonic currents size of load-side and the ratio of 7 subharmonic current sizes, and computing formula is as follows:

The three phase reactive power of 5 LC passive filter groups 2: $\left\{\begin{array}{c}{W}_{5a}=\frac{I_{l5a}}{I_{l5a}+I_{l7a}}{W}_a\\ W_{5b}=\frac{I_{l5b}}{I_{l5b}+I_{l7b}}{W}_b\\ W_{5c}=\frac{I_{l5c}}{I_{l5c}+I_{l7c}}{W}_c\end{array}\right.$

The three phase reactive power of 7 LC passive filter groups 3 $\left\{\begin{array}{c}{W}_{7a}=\frac{I_{l7a}}{I_{l5a}+I_{l7a}}{W}_a\\ W_{7b}=\frac{I_{l7b}}{I_{l5b}+I_{l7b}}{W}_b\\ W_{7c}=\frac{I_{l7c}}{I_{l5c}+I_{l7c}}{W}_c\end{array}\right.$

After having determined the three phase reactive power of the three phase reactive power of 5 LC passive filter groups 2 and 7 LC passive filter groups 3, the Reactive Power Control module of DSP inside determines separately switching branch road situation according to the actual capacity of the actual packet number of 5 LC passive filter groups 2 and 7 LC passive filter groups 3 and each branch road respectively, 5, the group number of No. 7 passive filters and capacity can be configured according to the needs of real system, also can divide phase control to 5,7 LC passive filters.

Claims (4)

1. Hybrid power filter based on the triple-frequency harmonics active power filtering, it is characterized in that, comprising: mixed type triple-frequency harmonics active power filter (1), 5 LC passive filter groups (2), 7 LC passive filter groups (3), mains side voltage transformer (YT), mains side current transformer (CT1), load-side current transformer (CT2), mixed type triple-frequency harmonics active power filter (1) side current transformer (CT3).

2. device according to claim 1 is characterized in that, 3 subharmonic reference signal (i of mixed type triple-frequency harmonics active power filter (1) _F3) be 3 subharmonic currents that the three-phase phase current extracts by bandpass digital filter from the low-voltage distribution system load, and use 3 subharmonic currents that from mains side three-phase phase current, extract to revise, formed a complete closed-loop control system.

3. device according to claim 1, it is characterized in that, mixed type triple-frequency harmonics active power filter (1), 5 LC passive filter groups (2), 7 LC passive filter groups (3) are to be controlled by DSP main control circuit and the auxiliary controller synthesis that consists of, therefore, can be good at realizing the reactive power compensation target of 3,5,7 subharmonic filtering and system.

4. device according to claim 1 is characterized in that, 5, the group number of No. 7 passive filters and capacity can be configured according to the needs of real system, also can divide phase control to No. 5,7 passive filters.

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