CN106712023A - Stability control method of APF (Active Power Filter) paralleling system capable of self-adapting negative-proportion voltage feed forward of power grid - Google Patents

Abstract

The invention discloses a stability control method of an APF (Active Power Filter) paralleling system capable of self-adapting negative-proportion voltage feed forward of a power grid. The stability control method is characterized in that after respective delay links e<-sTd> of a feed-forward controller F(s) and a control system, the voltage E'(s) at the PC position of the power grid and the original disturbance gain D(s) are output in an overlapping manner. By self-adaptive adjustment of a negative-proportion feed-forward coefficient, the disturbance gain D(s) is changed, further the admittance frequency-domain characteristic of a current loop is changed, and the purpose of improving the damping characteristic of the frequency-domain gain is realized. The stability control method disclosed by the invention has the advantages that on the premise without influencing the performance of the current loop, the damping characteristic of a high-frequency section of the current-loop admittance can be obviously improved, additional passive devices do not needs to be additionally arranged, and an APF hardware design scheme does not need to be changed, so that the feasibility and the practical value are good.

Description

A kind of APF combining system stability controls of self adaptation negative ratio voltage feed-forward control Method

Technical field

Before a kind of self adaptation negative ratio line voltage in field of power, particularly Power Electronic Technique The APF combining system stability control methods of feedback.

Background technology

Active Power Filter-APF (Active Power filter, abbreviation APF) is highly controllable, quick response excellent with its Gesture, is increasingly becoming the preferred unit for administering harmonic pollution.With being on the increase for nonlinear-load harmonic pollution, using modularization The study hotspot of APF and machine scheme Concetrated control harmonic wave as this area in recent years.The analysis of stability of modularization APF combining systems Analysis and control planning, to the safe and reliable operation of machine system, are the key technology difficulties that overcome of needs.

Combining system resonance point refers to its global admittance Y_totalAll frequencys when () frequency domain gain imaginary part is zero s, now Corresponding each gain value of real part (R_d) damping size of the combining system at each resonance point is can be considered, as the R of all resonance points_d>0 Combining system stabilization, otherwise unstability.Therefore the target of combining system stability control (unsteady repression) is exactly to be reinvented by admittance Make the R at its all resonance point_dFor just.The mode of combining system stability control has two kinds：(1) indirect mode, i.e., by only Change power network passive device circuit carries out admittance and reinvents without the mode of change APF designs so that the resonance point hair of combining system R at changing or resonance point_dBe worth to increase, so as to realize the R of all resonance points of combining system_d>0 target；(2) directly Mode, i.e., carry out admittance and reinvent by way of only changing APF control strategies without changing the existing passive device configuration of power network, makes APF electric current loop admittance harmonic control ring admittance is obtained at least at all resonance points of combining system in just resistive, so as to realize simultaneously The R of all resonance points of machine system_d>0 target.

For direct mode, on the one hand, direct control mode need not change the configuration of the existing passive device of power network, thus more Suitable for the APF combining systems for using have been put into；On the other hand, due to needing to increase control algolithm, increased control system Design difficulty, thus APF combining system stability direct control methods are not perfect, it is necessary to improve prior art at present.

The content of the invention

Goal of the invention：In order to overcome the deficiencies in the prior art, the present invention to provide a kind of self adaptation negative ratio power network The APF combining system stability control methods of electric voltage feed forward, on the basis of electric current loop performance is not influenceed, can be obviously improved electricity Stream ring admittance high band damping characteristic.

A kind of APF combining system stability control methods of self adaptation negative ratio voltage feed-forward control, in combining system, Every APF is configured in accordance with the following methods：Increase feedforward branch circuit, the feedforward branch on the basis of the disturbance gain of primary current ring Road includes：Feedforward controller F (s), control system time delay processVoltage E ' (s) is respectively through feedforward control at power network PCC Device F (s) and control system time delay processOutput with primary current ring disturbance gain D (s) afterwards is superimposed, and forms new electric current loop Disturbance gain D ' (s), is shown below：

Wherein, D (s) is that primary current ring disturbs gain；D ' (s) is new electric current loop disturbance gain；For control system is prolonged Shi Huanjie；K_fpIt is negative ratio feed-forward coefficients；Increase the electric current loop admittance Y'(s after feedforward branch circuit) it is as follows：

Wherein, Y (s) is to increase the electric current loop admittance before feedforward branch circuit；P (s) is electric current loop controlled device；G (s) P (s) is Electric current loop open-loop branch；

The new electric current loop disturbance gain meets following condition：

1. frequency domain gain amplitude is less than 1；

2. between advanced 0 ° to 90 ° of frequency domain gain-phase.

The APF combining system stability control methods of the self adaptation negative ratio voltage feed-forward control enter as follows OK：

1. negative ratio feed-forward coefficients value is estimated；

2. according to negative ratio feed-forward coefficients discreet value, and primary current ring disturbance gain, control system time delay process, calculate New electric current loop disturbance gain；

3. new electric current loop disturbance gain frequency domain gain amplitude, phase characteristic is analyzed；If frequency domain gain amplitude, phase characteristic Above-mentioned condition is unsatisfactory for, 1., again return to step estimates negative ratio feed-forward coefficients；

4. gain is disturbed according to new electric current loop, calculates the electric current loop admittance after increasing feedforward branch circuit, and analyze its damping Characteristic；If increase feedforward branch circuit after electric current loop admittance Y'(s) damping characteristic the resonance frequency near gain be it is just resistive, Design terminates and obtains corresponding parameter, on the contrary return to step 1. above-mentioned design process again.

Beneficial effect：

(1) the APF combining system stability control methods of self adaptation negative ratio voltage feed-forward control of the present invention, lead to Cross and estimate-correct self-adaptative adjustment negative ratio feed-forward coefficients, so as to change disturbance gain D (s), and then change electric current loop admittance frequently Domain characteristic, realizes improving its frequency domain gain damping characteristic.Methods described does not influence electric current loop performance, can obviously improve electric current loop and leads Receive high band damping characteristic.

(2) traditional APF combining system stability method for indirectly controlling is compared to, the present invention need not increase passive device Part, without changing APF hardware schemes.

Brief description of the drawings

Fig. 1 is to change APF electric current loops by power network PCC electric voltage feed forward modes to disturb gain schematic diagram；

Fig. 2 is the APF combining system stability control flow charts of self adaptation negative ratio voltage feed-forward control；

Fig. 3 is negative ratio feed-forward coefficients K_fpElectric current loop admittance frequency district characteristic analysis when=- 1.5；

Fig. 4 is negative ratio feed-forward coefficients K_fpElectric current loop admittance frequency district characteristic analysis when=- 1.0；

Fig. 5 is negative ratio feed-forward coefficients K_fpElectric current loop admittance frequency district characteristic analysis when=- 0.5.

Specific embodiment

The present invention is further described below in conjunction with the accompanying drawings.

Fig. 1 show and changes the disturbance gain signal of APF electric current loops by power network points of common connection PCC electric voltage feed forward modes Figure.I is output current；I^*It is instruction current.Be can be seen that by following formula, by changing disturbance gain D (s), thus it is possible to vary electric current loop Admittance frequency domain characteristic, realizes improving its frequency domain gain damping characteristic, while the process has no effect electric current ring property.

The present invention increases feedforward branch circuit on the basis of the disturbance gain of primary current ring.The feedforward branch circuit includes：Feedforward control Device F (s) processed, control system time delay processVoltage E ' (s) is respectively through feedforward controller F at power network points of common connection PCC (s) and control system time delay processOutput with primary current ring disturbance gain D (s) afterwards is superimposed, and forms new electric current loop disturbance Gain D ' (s), is shown below：

Wherein, D (s) is that primary current ring disturbs gain；D ' (s) is new electric current loop disturbance gain；For control system is prolonged Shi Huanjie；K_fpIt is negative ratio feed-forward coefficients；Increase the electric current loop admittance Y'(s after feedforward branch circuit) it is as follows：

Wherein, Y is to increase the electric current loop admittance before feedforward branch circuit；P (s) is electric current loop controlled device；G (s) P (s) is electricity Stream ring open-loop branch；

The new electric current loop disturbance gain meets following condition：

1. frequency domain gain amplitude is tried one's best small and less than 1；

2. frequency domain gain-phase is tried one's best in advance (between 0 ° to 90 °).

The APF combining system stability control methods of the self adaptation negative ratio voltage feed-forward control enter as follows OK：

1. negative ratio feed-forward coefficients value is estimated；

2. according to negative ratio feed-forward coefficients discreet value, and primary current ring disturbance gain, control system time delay process, calculate New electric current loop disturbance gain；

3. new electric current loop disturbance gain frequency domain gain amplitude, phase characteristic is analyzed；If frequency domain gain amplitude, phase characteristic Above-mentioned condition is unsatisfactory for, 1. return to step, resets negative ratio feed-forward coefficients discreet value；

4. gain is disturbed according to new electric current loop, calculates the electric current loop admittance after increasing feedforward branch circuit, and analyze its damping Characteristic；If increase feedforward branch circuit after electric current loop admittance Y'(s) damping characteristic the resonance frequency near gain be it is just resistive, Design terminates and obtains corresponding parameter, on the contrary return to step 1. above-mentioned design process again.

When the grid-connected Interface designs of APF are reactance, primary current ring disturbs gain D (s)=1, then with negative ratio feedforward control Device F (s) forms new electric current loop and disturbs gain D ' (s), is shown below.

It is target to improve electric current loop admittance damping characteristic, the new electric current that designed feedforward controller F (s) is formed is disturbed Dynamic gain D ' (s) should have following frequency domain characteristic：(1) frequency domain gain amplitude should try one's best it is small and less than 1, so as to reduce High-frequency Interference Effect of signals and electric current loop start output overshoot；(2) frequency domain gain-phase should try one's best in advance (between 0 ° to 90 °), compensate electric current The delayed phase of ring admittance frequency domain gain, so that it is resistive to increase its frequency domain gain.

Fig. 2 is the APF combining system stability control flow charts of self adaptation negative ratio voltage feed-forward control.

Electric current loop admittance frequency district characteristic analysis when Fig. 3 to Fig. 5 is using different negative ratio feed-forward coefficients.Wherein, TOP is marked Amplitude frequency curve is represented, mark BOT represents phase frequency curve；Grid-connected reactance：Inductance L=0.2mH, resistance R=0.01 Ω；Electric current loop control Device processed：VPI (Vector PI, vector scale integration)；Zero pole offsets the inductance L '=0.1mH of setting, resistance R '=0.01 Ω； Each resonator equivalent point COEFFICIENT K is 2 π 20；The resonator frequency is respectively 5,7 and 11 times, fundamental frequency 50Hz.Set in Fig. 3 Put K_fp=-1.5；K is set in Fig. 4_fp=-1.0；K is set in Fig. 5_fp=-0.5.In Fig. 3, it can be seen that new current disturbing gain D ' (s) frequency domains gain amplitude is basic near 0db, but frequency domain gain-phase be lead compensation angle by 180 ° be decremented to 90 ° it is attached Closely, make electric current loop admittance Y ' (s) the frequency domain gain-phase overcompensation after increase feedforward branch circuit, capacitive is changed into from perception；In Fig. 4, The frequency domain gain amplitude of new current disturbing gain D ' (s) increases to 1.414 by 0, and phase is decremented to 45 ° by 90 °, increases feedforward branch The damping characteristic of electric current loop admittance Y ' (s) full frequency band behind road be improved significantly, but the phase overcompensation near the resonance frequency； In Fig. 5, the frequency domain gain amplitude of new current disturbing gain D ' (s) is basic near 0db, and phase is first incremented by successively decreases (by 0 ° afterwards Increase to 20 ° and reduce to 15 ° again), increase the damping characteristic near the resonance frequency of electric current loop admittance Y ' (s) after feedforward branch circuit and do not obtain Improve, but high band damping characteristic outside the resonance frequency be improved significantly, and full frequency band phase is without overcompensation.

By above-mentioned analysis, for adjustment line voltage negative ratio feed-forward coefficients, following some qualitative conclusions can be drawn：1) Work as K_fp<When -1, new current disturbing gain D ' (s) leading phase (offset angle) is decremented to 90 ° by 180 °, makes increase feedforward branch Electric current loop admittance Y ' (s) phase overcompensation behind road, actual conditions are not allowed；2) K is worked as_fpWhen=- 1, new current disturbing gain D ' (s) offset angles are decremented to 45 ° by 90 °, increase electric current loop admittance Y ' (s) the full frequency band damping characteristic after feedforward branch circuit and obtain It is obviously improved, but during practical application, K_fpCan not possibly definitely be equal to -1, when occur deviation less than -1 when, can cause increase feedover Electric current loop admittance Y ' (s) phase overcompensation after branch road；3) when 0>K_fp>When -1, new current disturbing gain D ' (s) offset angle By 0 ° increase to maximum α (<90 °) be decremented to again β (>0 °), K_fpAbsolute value and α are directly proportional, and increase the electric current loop after feedforward branch circuit Admittance Y ' (s) damping characteristic near the resonance frequency does not improve, but high band damping characteristic outside the resonance frequency is substantially changed It is kind, and full frequency band phase is without overcompensation.

The above is only the preferred embodiment of the present invention, it should be pointed out that：For the ordinary skill people of the art For member, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications also should It is considered as protection scope of the present invention.

Claims (1)

1. APF combining system stability control methods of a kind of self adaptation negative ratio voltage feed-forward control, it is characterised in that：Simultaneously In machine system, every APF is configured in accordance with the following methods：Increase feedforward branch on the basis of primary current ring disturbs gain D (s) Road, the feedforward branch circuit includes：Feedforward controller F (s) and control system time delay processElectricity at power network points of common connection PCC Pressure E ' (s) is successively by feedforward controller F (s) and control system time delay processAfterwards with primary current ring disturbance gain D (s) Output superposition, forms new electric current loop and disturbs gain D ' (s)；Above-mentioned parameter is designed determination in accordance with the following steps：

1. negative ratio feed-forward coefficients K is estimated_fp；

2. according to the negative ratio feed-forward coefficients K for estimating_fpAnd primary current ring disturbs gain D (s), control system time delay process Calculate new electric current loop and disturb gain D ' (s)：

$\left\{\begin{array}{c}{D}^{\&prime;}\left(s\right)=D\left(s\right)+F\left(s\right)e^{-{\mathrm{sT}}_d}\\ \begin{array}{cc}F\left(s\right)=K_{fp}& (K_{fp}<0)\end{array}\end{array}\right.$

3. following 2 conditions are set：Condition 1, frequency domain gain amplitude are less than 1；Advanced 0 ° to 90 ° of condition 2, frequency domain gain-phase it Between；

Whether the frequency domain gain amplitude and phase characteristic of new electric current loop disturbance gain D ' (s) of analysis can meet 2 conditions of the above, If meet then entering step 4.；If can not meet, 1., again return to step estimates negative ratio feed-forward coefficients；

4. gain D ' (s) is disturbed according to new electric current loop, calculates the electric current loop admittance Y'(s after increasing feedforward branch circuit)：

$\left\{\begin{array}{c}{Y}^{\&prime;}\left(s\right)=D^{\&prime;}\left(s\right)Y\left(s\right)\\ Y\left(s\right)=\frac{D\left(s\right)P\left(s\right)}{1+G\left(s\right)P\left(s\right)}\end{array}\right.$

Wherein：Y (s) is to increase the electric current loop admittance before feedforward branch circuit；P (s) is electric current loop controlled device；G (s) P (s) is electric current Ring open-loop branch；

Analysis increase feedforward branch circuit after electric current loop admittance Y'(s) damping characteristic, if increase feedforward branch circuit after electric current loop lead Receive Y'(s) damping characteristic near the resonance frequency gain be just resistive, then design terminates and obtains corresponding parameter, otherwise returns Return step 1. above-mentioned design process again.