CN104466963A - Power induction and regulation filtering device and control method thereof - Google Patents

Abstract

The invention discloses a power induction and regulation filtering device and a control method of the power induction and regulation filtering device. The filtering device comprises a three-phase power grid and a voltage sensor. The three-phase power grid is connected with the voltage sensor in series. The power induction and regulation filtering device further comprises a rectifier transformer. The primary side of the rectifier transformer is connected with the voltage sensor, the secondary side of the rectifier transformer is of an extended triangular connection structure, and an extended winding of the rectifier transformer sequentially passes through a current sensor and a rectifier to be connected with a nonlinear load. A tuning branch circuit is connected to the intersection point of the extended winding of the rectifier transformer and the secondary side of the rectifier transformer. The tuning branch circuit and a voltage source inverter are connected to form a filtering branch circuit. The control end of a switching device of the voltage source inverter is connected with the control output end of a controller, and the control input end of the controller is connected with the voltage sensor and the current sensor. According to the power induction and regulation filtering device and the control method of the power induction and regulation filtering device, the rectifier is used for dynamically adjusting the impedance value of the rectifier transformer, the impedance on the medium voltage side of the rectifier transformer can reach zero under the specific subharmonic frequency, and the purpose of dynamically filtering out harmonics is achieved.

Description

A kind of eletric power induction regulation and control filter and control method thereof

Technical field

The present invention relates to a kind of can the eletric power induction regulation and control filter of real-time tracking harmonic wave change and the control method of voltage source inverter.

Background technology

Due to power electronic device unintentional nonlinearity characteristic, it is when electric power system and industrial distribution system are applied, and inevitably causes that harmonic pollution is serious, power factor is low, the power quality problem such as voltage flicker and imbalance.At present, the method improving the quality of power supply mainly contains multiple rectifying technology, passive filtering, active power filtering, mixing active power filtering and induction filtering.

Multiple technology is mainly applied to high-power industrial rectifier power system.It is mainly connect (12 pulse waves, 18 pulse waves, 24 pulse waves etc.) by the multiplex of converter, the characteristic harmonic current of the predominant amount produced by each converter bridge is cancelled out each other by phase shift effect at the river outlet of grid side, thus reduces the harmonic content of grid side.This filtering mode needs the series/parallel coordinated operation of multiple converter bridge, can produce loss, and this filtering mode can only make specific subharmonic reduce, and still there will be the situation of harmonic excess in the complex working condition of reality between converter bridge due to circulation.

Passive filtering is because apparatus structure is fairly simple, design and manufaction ratio is easier to, and initial investment cost is lower, is widely used in electric power system and industrial distribution system.But passive filter is merely able to suppress specific subharmonic, when electric power networks structure or load change, the change of resonance frequency can be caused, now the ability of passive filter harmonic inhabitation can reduce, and even likely produces resonance, affects electric power system stability.In addition, passive filtering has amplification to low-order harmonic, and capacitor parameters passing in time easily changes, and this can cause tuned frequency to offset, thus the filtering performance that impact is actual.

Active power filtering with mix the mode of Active Power Filter Technology by real-Time Compensation harmonic current and fundamentally can solve above-mentioned passive filtering Problems existing, but existing wholly-controled device capacity is less than normal and problem that is selling at exorbitant prices limits the propagation and employment of these two kinds of filtering techniques.In addition, Active Power Filter Technology can to electrical network Injection Current, if be directly connected with rectifier likely to cause thyristor generation commutation failure, this makes the application of active power filtering mainly rest on the less field of mesolow constant power at present, rarely has application needing the very large electrolysis industry of supply current and the high pressure field (particularly high-voltage dc transmission electrical domain) very high to safety requirements.

No matter be passive filtering or active power filtering, be mainly used to solve harmonic wave and the idle harmful effect to electrical network, but for the transformer be connected with electrical network, harmonics and reactive current can free flow, can not get any suppression.Induction filtering solves this problem from root, and it can improve the electromagnetic environment of transformer work in electric power system, reduces supplementary load loss, the noise and vibration of transformer, and adds the stability of a system and operational efficiency.But shortcoming be still cannot resolution system harmonic wave change time-harmonic wave inhibition be deteriorated problem.

Summary of the invention

Technical problem to be solved by this invention is, for above-mentioned the deficiencies in the prior art, provides a kind of eletric power induction to regulate and control the control method of filter and voltage source inverter.

For solving the problems of the technologies described above, the technical solution adopted in the present invention is: a kind of eletric power induction regulation and control filter, and comprise three phase network, voltage sensor, described three phase network is connected with voltage sensor; Also comprise rectifier transformer, the primary side of described rectifier transformer is connected with described voltage sensor, the secondary side of described rectifier transformer adopts extend-triangle wiring construction, and the limit winding that prolongs of described rectifier transformer is connected with nonlinear load by current sensor, rectifier successively; Described rectifier transformer prolongs limit winding and secondary side point of intersection accesses tuning branch road; Described tuning branch road and voltage source inverter connect to form filter branch; The switching device control end of described voltage source inverter is connected with the control output end of controller; The control input end of described controller is connected with described voltage sensor, current sensor.

Described voltage source inverter is connected with DC capacitor.

Present invention also offers a kind of control method of above-mentioned filter, comprise the following steps:

1) detect the three-phase voltage of three phase network side and the three-phase current of nonlinear load side, calculate three-phase voltage and the three-phase current of nonlinear load side;

2) utilize three-phase voltage and the three-phase current of nonlinear load side, calculated instantaneous active power P and the reactive power Q of nonlinear load side by instantaneous reactive power theory;

3) by above-mentioned instantaneous active power P and reactive power Q through high pass filter, the direct current in elimination instantaneous active power P and reactive power Q and low frequency component, reserved high-frequency composition;

4) utilize p, q operation method to calculate the harmonic current flowing into filter branch, simultaneously in order to make voltage source inverter DC-side Voltage Stabilization, q axle component increasing Voltage Feedback and controls, finally calculating the three-phase output current of filter branch;

5) the above-mentioned three-phase output current calculated is multiplied with gain coefficient K, obtains the PWM modulation signal of voltage source inverter, described pwm signal is exported to voltage source inverter and control to export offset current, reach the object of dynamic compensation harmonic wave.

The three-phase output current computing formula of described filter branch is as follows:

$\left\{\begin{array}{c}{I}_{a0h}=(1+k_{32}^{-1})I_{\mathrm{ALh}}-k_{32}^{-1}{I}_{\mathrm{CLh}}\\ I_{b0h}=(1+k_{32}^{-1})I_{\mathrm{BLh}}-k_{32}^{-1}{I}_{\mathrm{ALh}}\\ I_{c0h}=(1+k_{32}^{-1})I_{\mathrm{CLh}}-k_{32}^{-1}{I}_{\mathrm{BLh}}\end{array}\right.;$

In formula, I _a0h, I _b0h, I _c0hfor the three-phase output current of filter branch, k32 is the no-load voltage ratio that rectifier transformer secondary side delta windings and secondary side prolong limit winding; I _aLh, I _bLh, I _cLhfor the harmonic current of nonlinear load side.

In method of the present invention, during K=-1, gain effect is best.

Compared with prior art, the beneficial effect that the present invention has is: the present invention uses the resistance value of rectifier dynamic conditioning rectifier transformer, the impedance of rectifier transformer medium voltage side can be made to be issued to zero at specific subfrequency, thus to realize the object of dynamic filtering harmonic wave; Control method of the present invention is only relevant to rectifier transformer filtered side, and need not consider the impact of system impedance, also can not produce interference to the normal operation of system; Use inverter can produce the fast-changing offset current of frequency, when nonlinear load side or grid side occurrence frequency rapid fluctuations, offset current can compensate fast to the harmonic wave of assigned frequency, thus ensures the rejection to principal character harmonic current; There is two-way harmonic shielding function, the filter branch energy simultaneously stability that voltage source inverter and induction filter tuning branch road form is from nonlinear load side and the harmonic current from thyristor controlled reactor side, harmonic current is being inhibited near harmonic source place, thus shorten the circulation path of harmonic current, make the harmonic current content of described rectifier transformer first side winding and grid side very little, in good sine; Can in close nonlinear load side, realize the dynamic compensation nearby of reactive power, make the idle component that produced by nonlinear load can not crosstalk to a winding side of described rectifier transformer and grid side, even if nonlinear load fluctuates, the power factor of described rectifier transformer winding side and grid side maintains desired value (more than 0.95) all the time; Due to harmonic wave with idlely all suppressing nearby and compensating near nonlinear load side, this not only lowers the supplementary load loss of described rectifier transformer, temperature rise, noise and vibration, and achieve High Power Factor and the high-efficiency stable operation of whole industrial rectifier power system.

Accompanying drawing explanation

Fig. 1 is the structured flowchart of apparatus of the present invention;

Fig. 2 is the Type Equivalent Circuit Model of middle rectifier transformer of the present invention;

Fig. 3 is voltage source inverter control principle drawing in the present invention.

Embodiment

As shown in Figure 1, the secondary side of rectifier transformer 3 of the present invention adopts the extend-triangle mode of connection, the external rectifier 5 of low-pressure side, and this mode of connection can meet the low-voltage, high-current power demands of industrial DC nonlinear load 6; Medium voltage side (prolonging limit winding and delta windings point of intersection) external Real-Time Filtering system 7; High pressure winding adopts star-connection mode, and is connected with the equivalent AC power 1 (industrial power distribution systems or external electrical network) of grid side.Real-Time Filtering system 7 comprises controller 8, DC bus capacitor 9, voltage source inverter 10 and induction filter tuning branch road 11.Real-Time Filtering system 7 gathers voltage and current signal by voltage sensor 2 and current sensor 4, the switching device work of the driving voltage source type inverter 10 that transmitted control signal by controller 8, generates the control signal of specifying.DC capacitor 9, as direct current and the energy storage device exchanging conversion, can store the harmonic electric energy of each phase on the one hand, galvanic current pressure also can be provided as inverter on the other hand.The voltage that inverter 10 exports is transformed into electric current by filter circuit 11 and sends into transformer, thus realizes the dynamic compensation to each phase harmonic current.

The Type Equivalent Circuit Model of rectifier transformer as shown in Figure 2.Theoretical according to multi winding transformer, the balance of voltage equation of transformer under harmonic wave effect is:

$\left\{\begin{array}{c}{V}_{\mathrm{Aah}}-k_{12}^{-1}{V}_{\mathrm{Agh}}=-k_{12}{I}_{\mathrm{Agh}}{Z}_{h21}-k_{32}{I}_{\mathrm{abh}}{Z}_{2h}\\ V_{\mathrm{Aah}}-k_{32}^{-1}{V}_{\mathrm{abh}}=-k_{32}{I}_{\mathrm{abh}}{Z}_{h23}-k_{12}{I}_{\mathrm{Agh}}{Z}_{2h}\\ V_{\mathrm{Bbh}}-k_{12}^{-1}{V}_{\mathrm{Bgh}}=-k_{12}{I}_{\mathrm{Bgh}}{Z}_{h21}-k_{32}{I}_{\mathrm{bch}}{Z}_{2h}\\ V_{\mathrm{Bbh}}-k_{32}^{-1}{V}_{\mathrm{bch}}=-k_{32}{I}_{\mathrm{bch}}{Z}_{h23}-k_{12}{I}_{\mathrm{bgh}}{Z}_{2h}\\ V_{\mathrm{Cch}}-k_{32}^{-1}{V}_{\mathrm{Cgh}}=-k_{12}{I}_{\mathrm{bch}}{Z}_{h23}-k_{12}{I}_{\mathrm{cah}}{Z}_{2h}\\ V_{\mathrm{Cch}}-k_{32}^{-1}{V}_{\mathrm{cah}}=-k_{32}{I}_{\mathrm{cah}}{Z}_{h23}-k_{12}{I}_{\mathrm{Cgh}}{Z}_{2h}\end{array}\right.---\left(1\right)$

In formula, k12 is the no-load voltage ratio of prolonging limit winding of transformer primary side and secondary side, and k32 is the no-load voltage ratio that secondary side delta windings and secondary side prolong limit winding, and voltage, electric current are all the value under the effect of h subharmonic, and its implication is indicated in fig. 2, Z _h21for prolonging the harmonic short circuits impedance between limit winding and source side winding, Z _h23for prolonging the harmonic short circuits impedance between limit winding and delta windings, both can be obtained by short circuit test, equivalent leakage reactance Z _2hcan calculate by following formula:

$Z_{2h}=\frac{1}{2}(Z_{h21}+Z_{h23}-Z_{h13}^{\text{'}})---\left(2\right)$

Formula 3 can be obtained according to transformer magnetic potential balance principle:

$\left\{\begin{array}{c}{I}_{\mathrm{Aah}}+k_{12}{I}_{\mathrm{Agh}}+k_{32}{I}_{\mathrm{abh}}=0\\ I_{\mathrm{Bbh}}+k_{12}{I}_{\mathrm{Bgh}}+k_{32}{I}_{\mathrm{bch}}=0\\ I_{\mathrm{Cch}}+k_{12}{I}_{\mathrm{Cgh}}+k_{32}{I}_{\mathrm{cah}}=0\end{array}\right.---\left(3\right)$

According to kirchhoffs law, corresponding voltage equation and current equation can be obtained such as formula 4, shown in formula 5:

$\left\{\begin{array}{c}{I}_{\mathrm{Aah}}=I_{\mathrm{ALh}}\\ I_{\mathrm{Aah}}=I_{\mathrm{abh}}+I_{a0h}-I_{\mathrm{cah}}\\ I_{\mathrm{Bbh}}=I_{\mathrm{BLh}}\\ I_{\mathrm{Cch}}=I_{\mathrm{CLh}}\\ I_{\mathrm{Cch}}=I_{\mathrm{cah}}+I_{c0h}-I_{\mathrm{bch}}\\ I_{\mathrm{abh}}+I_{\mathrm{bch}}+I_{\mathrm{cah}}=0\\ I_{\mathrm{Aah}}+I_{\mathrm{Bbh}}+I_{\mathrm{Cch}}=0\end{array}\right.---\left(4\right)$

In formula, I _aLh, I _bLh, I _cLhfor the harmonic current of nonlinear load side.

$\left\{\begin{array}{c}{V}_{\mathrm{abh}}=-V_{b0h}+V_{a0h}\\ V_{\mathrm{bch}}=-V_{c0h}+V_{b0h}\\ V_{\mathrm{cah}}=-V_{a0h}+V_{c0h}\\ V_{a0h}=I_{a0h}{Z}_{\mathrm{Fah}}\\ V_{b0h}=I_{b0h}{Z}_{\mathrm{Fbh}}\\ V_{c0h}=I_{c0h}{Z}_{\mathrm{Fch}}\end{array}\right.---\left(5\right)$

In formula, Z _fah, Z _fbh, Z _fchcan be controlled by voltage source inverter.

Can obtain transformer primary side current expression formula by formula 1 ~ 5 is:

$\left\{\begin{array}{c}{I}_{\mathrm{Agh}}=-\frac{k_{12}(Z_{3h}+3Z_{\mathrm{Fh}})+k_{12}{k}_{32}{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{ALh}}+\frac{k_{12}{k}_{32}{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{2h}}{I}_{\mathrm{BLh}}\\ I_{\mathrm{Bgh}}=-\frac{k_{12}(Z_{3h}+3Z_{\mathrm{Fh}})+k_{12}{k}_{32}{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{BLh}}+\frac{k_{12}{k}_{32}{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{2h}}{I}_{\mathrm{CLh}}\\ I_{\mathrm{Cgh}}=-\frac{k_{12}(Z_{3h}+3Z_{\mathrm{Fh}})+k_{12}{k}_{32}{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{CLh}}+\frac{k_{12}{k}_{32}{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{2h}}{I}_{\mathrm{ALh}}\end{array}\right.---\left(6\right)$

In like manner, also can obtain Circuit Fault on Secondary Transformer current expression is:

$\left\{\begin{array}{c}{I}_{\mathrm{abh}}=-\frac{k_{32}{Z}_{1h}-Z_{12}^2{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{ALh}}-\frac{k_{12}^2{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{BLh}}\\ I_{\mathrm{bch}}=-\frac{k_{32}{Z}_{1h}-Z_{12}^2{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{BLh}}-\frac{k_{12}^2{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{CLh}}\\ I_{\mathrm{cah}}=-\frac{k_{32}{Z}_{1h}-Z_{12}^2{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{CLh}}-\frac{k_{12}^2{Z}_{\mathrm{Fh}}}{k_{12}^2(Z_{3h}+3Z_{\mathrm{Fh}})+k_{32}^2{Z}_{1h}}{I}_{\mathrm{ALh}}\end{array}\right.---\left(7\right)$

From formula 6, ideally, Z is worked as _3hand Z _fhwhen meeting the following conditions, the harmonic current of net side is zero.

I.e. Z _3h=Z _fh=0 (8)

The electric current that can be obtained circulation novel rectifying transformer secondary winding by formula 4,7 and 8 is:

$\left\{\begin{array}{c}{I}_{\mathrm{abh}}=-k_{32}^{-1}{I}_{\mathrm{Aah}}\\ I_{\mathrm{bch}}=-k_{32}^{-1}{I}_{\mathrm{Bbh}}\\ I_{\mathrm{cah}}=-k_{32}^{-1}{I}_{\mathrm{Cch}}\end{array}\right.---\left(9\right)$

The magnetic potential of this time-harmonic wave visible reaches balance in the secondary of transformer and filter branch, therefore again to primary side, namely can not net side and have an impact, namely prevent harmonic current to scurry into electrical network and pollute electrical network.

In order to realize dynamic filter, Real-Time Filtering system 7 needs the change of real-time tracking load-side harmonic current, calculating should flow into the harmonic content of filter branch, then dynamically output current is changed, thus change the impedance of filter branch, harmonic current is sucked filter branch, thus reaches the object of dynamic filtering harmonic wave.

As shown in Figure 3, concrete control procedure is as follows for the control system of voltage source inverter:

First the three-phase voltage of checking network side and the three-phase current of load-side, indirect calculation goes out the three-phase voltage of nonlinear load side, utilize the nonlinear load side three-phase voltage and three-phase current that calculate, calculated instantaneous active power P and the reactive power Q of nonlinear load side by instantaneous reactive power theory.After high pass filter, the direct current in elimination instantaneous active power P and instantaneous reactive power Q and low frequency component, reserved high-frequency and harmonic components.Cut-off frequency is set to 100Hz.Then utilize p, q operation method to calculate the harmonic current flowing into filter branch, simultaneously in order to make voltage source inverter DC-side Voltage Stabilization, needing on q axle component, increase Voltage Feedback and controlling.Finally calculate the three-phase output current of filter branch.The electric current flowing into filter branch can obtain according to formula 4 and 7:

$\left\{\begin{array}{c}{I}_{a0h}=(1+k_{32}^{-1})I_{\mathrm{ALh}}-k_{32}^{-1}{I}_{\mathrm{CLh}}\\ I_{b0h}=(1+k_{32}^{-1})I_{\mathrm{BLh}}-k_{32}^{-1}{I}_{\mathrm{ALh}}\\ I_{c0h}=(1+k_{32}^{-1})I_{\mathrm{CLh}}-k_{32}^{-1}{I}_{\mathrm{BLh}}\end{array}\right.$

In formula, I _a0h, I _b0h, I _c0hfor filter branch harmonic current size, k ₃₂for secondary side delta windings and secondary side prolong the no-load voltage ratio of limit winding.I _aLh, I _bLh, I _cLhfor the harmonic current of nonlinear load side.

When the three-phase output current of filter branch is I _a0h, I _b0hand I _c0htime, the compensation of the harmonic wave of load-side can be realized.According to the size of amount of calculation adjustment gain coefficient K, make output valve and carrier waveform coupling, obtain the PWM modulation signal of voltage source inverter.Finally generation pwm signal is exported to voltage source inverter to control to export offset current, reach the object of dynamic compensation harmonic wave.

Claims (5)

1. an eletric power induction regulation and control filter, comprise three phase network, voltage sensor, described three phase network is connected with voltage sensor; It is characterized in that, also comprise rectifier transformer, the primary side of described rectifier transformer is connected with described voltage sensor, the secondary side of described rectifier transformer adopts extend-triangle wiring construction, and the limit winding that prolongs of described rectifier transformer is connected with nonlinear load by current sensor, rectifier successively; Described rectifier transformer prolongs limit winding and secondary side point of intersection accesses tuning branch road; Described tuning branch road and voltage source inverter connect to form filter branch; The switching device control end of described voltage source inverter is connected with the control output end of controller; The control input end of described controller is connected with described voltage sensor, current sensor.

2. eletric power induction regulation and control filter according to claim 1, it is characterized in that, described voltage source inverter is connected with DC capacitor.

3. a control method for filter described in claim 1 or 2, is characterized in that, comprises the following steps:

1) detect the three-phase voltage of three phase network side and the three-phase current of nonlinear load side, calculate three-phase voltage and the three-phase current of nonlinear load side;

2) utilize three-phase voltage and the three-phase current of nonlinear load side, calculated instantaneous active power P and the reactive power Q of nonlinear load side by instantaneous reactive power theory;

3) by above-mentioned instantaneous active power P and reactive power Q through high pass filter, the direct current in elimination instantaneous active power P and reactive power Q and low frequency component, reserved high-frequency composition;

4) utilize p, q operation method to calculate the harmonic current flowing into filter branch, simultaneously in order to make voltage source inverter DC-side Voltage Stabilization, q axle component increasing Voltage Feedback and controls, finally calculating the three-phase output current of filter branch;

5) the above-mentioned three-phase output current calculated is multiplied with gain coefficient K, obtains the PWM modulation signal of voltage source inverter, described pwm signal is exported to voltage source inverter and control to export offset current, reach the object of dynamic compensation harmonic wave.

4. control method according to claim 3, is characterized in that, the three-phase output current computing formula of described filter branch is as follows:

$\left\{\begin{array}{c}{I}_{a0h}=(1+k_{32}^{-1})I_{\mathrm{ALh}}-k_{32}^{-1}{I}_{\mathrm{CLh}}\\ I_{b0h}=(1+k_{32}^{-1})I_{\mathrm{BLh}}-k_{32}^{-1}{I}_{\mathrm{ALh}}\\ I_{c0h}=(1+k_{32}^{-1})I_{\mathrm{CLh}}-k_{32}^{-1}{I}_{\mathrm{BLh}}\end{array}\right.;$

In formula, I _a0h, I _b0h, I _c0hfor the three-phase output current of filter branch, k32 is the no-load voltage ratio that rectifier transformer secondary side delta windings and secondary side prolong limit winding; I _aLh, I _bLh, I _cLhfor the harmonic current of nonlinear load side.

5. control method according to claim 3, is characterized in that, K=-1.