CN103715704B - A kind of micro-electrical network common bus Voltage unbalance inhibition method - Google Patents

Abstract

The invention belongs to distributed power source control technology field in micro-grid system, relate to a kind of micro-electrical network common bus Voltage unbalance inhibition method, the method is carried out direct compensation to micro-grid system PCC Nodes bus negative sequence voltage, each distributed power source in micro-electrical network can be from the variation of the micro-electrical network PCC of dynamic response Nodes busbar voltage degree of unbalancedness, self adaptation is adjusted negative sequence voltage compensating controller (UVC), make each distributed power source idle according to its specified negative phase-sequence reactive capability output negative phase-sequence, maintain the balance of voltage degree of PCC Nodes bus. The present invention can make distributed power source in parallel in micro-electrical network have the function that suppresses micro-unbalanced source voltage.

Description

A kind of micro-electrical network common bus Voltage unbalance inhibition method

Technical field

The invention belongs to distributed power source control technology field in micro-grid system, relate to a kind of common bus Voltage unbalance inhibition method based on the parallel connection of many distributed power sources.

Background technology

Being widely used of grid-connected power generation system, makes based on multiple distributed power source, and the micro-grid system of load and energy storage device becomes the elementary cell of intelligent grid. Micro-grid system is generally low-pressure system, and in low-pressure system, single-phase load is extensively to exist, and has caused the asymmetric of three-phase inverter three-phase output voltage, thereby has caused larger energy loss, affects the stability of micro-grid system. Therefore, must take measures to be suppressed, ensure that distributed power source keeps the relative equilibrium of output voltage under unbalanced load.

IEEE and IEC have all made clear and definite regulation to definition, the maximum permissible value etc. of Voltage unbalance degree^[1]. Regulation in standard GB/T/T15543-2008 " quality of power supply imbalance of three-phase voltage " that State Bureau of Technical Supervision of China promulgates, power system points of common connection (PointofCommonCoupling, PCC) normal voltage degree of unbalancedness permissible value is 2%, must not exceed 4% in short-term^[2]. Therefore, micro-unbalanced source voltage compensation is of crucial importance.

The micro-unbalanced power supply voltage compensation of existing low pressure mainly contains two kinds of modes, and one is by series connection electric energy regulator, injects negative sequence voltage realize to circuit; Another is to adopt electric energy regulator in parallel, realizes by injecting negative-sequence current to circuit. The former applies lessly because cost is high and affect line parameter circuit value, and the latter's its negative-sequence current that is input to system in the time that serious imbalance appears in circuit will increase fast, can exceed the output limit of electric energy regulator seriously time, cause the accident. Moreover, these two kinds common imbalance compensation devices only drop in the time that Voltage unbalance occurs, and are inoperative in the time that system is normally moved, and utilization rate of equipment and installations is low, and economic benefit is poor.

Distributed power sources a large amount of in micro-electrical network are by three-phase grid-connected inverter connecting system, structure and the power quality adjusting device of its inverter are similar, and therefore utilizing distributed power source in micro-electrical network to realize that Voltage unbalance suppresses is that a kind of cost-effective quality of voltage improves scheme.

Bibliography

PillayP,ManyageM.Definitionsofvoltageunbalance[J].IEEEPowerEngineeringReview,2001,21(5):50-51.

CNS GB/T15543-2008: quality of power supply imbalance of three-phase voltage [S]. Beijing: China Standards Press, 2008.

Woods the new year, Duan Shanxu, Kang Yong, Chen Jian. the no control interconnection parallel UPS modeling based on droop characteristic control and stability analysis [J]. Proceedings of the CSEE, 2004,24 (2), 34-39.

Bao Wei, Hu Xuehao, Li Guanghui, Bao Weiyu. the improvement droop control [J] based on virtual impedance in the micro-electrical network of self. protecting electrical power system and control, 2013,41 (16), 7-13.

WangX,BlaabjergF,ChenZ.SynthesisofVariableHarmonicImpedanceinInverter-InterfacedDistributedGenerationUnitforHarmonicDampingThroughoutaDistributionNetwork[J].IndustryApplications,IEEETransactionson,2012,48(4),1407-1417.

Summary of the invention

The object of the invention is to overcome the above-mentioned deficiency of prior art, provide a kind of and utilize the distributed power source in micro-electrical network to realize Voltage unbalance inhibition, is that a kind of cost-effective quality of voltage improves scheme. Technical scheme of the present invention is as follows:

A kind of micro-electrical network common bus Voltage unbalance inhibition method, it is characterized in that, the method is carried out direct compensation to micro-grid system PCC Nodes bus negative sequence voltage, each distributed power source in micro-electrical network can be from the variation of the micro-electrical network PCC of dynamic response Nodes busbar voltage degree of unbalancedness, self adaptation is adjusted negative sequence voltage compensating controller (UVC), make each distributed power source idle according to its specified negative phase-sequence reactive capability output negative phase-sequence, the balance of voltage degree that maintains PCC Nodes bus, comprises the following steps:

1) step 1, detects the positive sequence voltage of micro-electrical network PCC Nodes bus in real timeAnd negative sequence voltageCalculate the real-time voltage degree of unbalancedness coefficient of micro-electrical network PCC Nodes bus

2) step 2, detects i distributed power source DG in micro-electrical network in real time_iNegative phase-sequence output idle

3) step 3, works as VUB_pccWhile being greater than certain default percentage, drop into negative sequence voltage compensating controller (UVC): establishFor the rated voltage degree of unbalancedness coefficient of micro-electrical network points of common connection (PCC); n_iFor DG_iThe idle distribution coefficient of negative phase-sequence; k_eFor Voltage unbalance degree error proportionality coefficient; k_P，k_IFor proportionality coefficient and integral coefficient that PI controls, DG_iThe negative sequence voltage penalty coefficient of UVC:

${\mathrm{VCR}}_i=(k_P+\frac{k_I}{s})\mathrm{\Δ}{\mathrm{VCR}}_i,$

Wherein, $\mathrm{\Δ}{\mathrm{VCR}}_i=k_e({\mathrm{VUB}}_{\mathrm{pcc}}-{\mathrm{VUB}}_{\mathrm{pcc}}^{*})-n_i{Q}_i^{-};$

4) step 4, by VCR_iWith DG_iThe negative sequence voltage of output multiplies each other and obtains DG_iThe reference value of negative sequence voltage compensation;

5) step 5, obtains DG_iThe reference value of negative sequence voltage compensation after, coordinate its positive sequence meritorious/frequency and REACTIVE POWER/VOLTAGE droop control, virtual impedance control, synthetic DG_iThe reference voltage of control system, through the laggard horizontal pulse width modulated of electric current and voltage dicyclo control.

The present invention is by changing the control system of the distributed power source accessing in micro-electrical network, make distributed power source in parallel in micro-electrical network there is the function that suppresses micro-unbalanced source voltage, each distributed power source is by transmission line parallel connection separately, in the time carrying out the uneven inhibitory control of PCC Nodes busbar voltage between each distributed power source without signal transmssion line. Two independent targets of controlling have been realized: (1) has guaranteed the quality of voltage of micro-electrical network PCC Nodes bus simultaneously; (2) distributed power source in parallel is idle according to the negative phase-sequence of the specified negative sequence compensation capability distribution output of self. The method is not only applicable to the micro-grid system under the mode of being incorporated into the power networks, also be applicable to the micro-grid system of independent operating, strengthen the control ability of distributed power source to micro-grid voltage quality, improved the quality of voltage of micro-electrical network, realized economy and the stable operation of micro-electrical network.

Brief description of the drawings

Fig. 1 is the micro-grid system schematic diagram that contains multiple distributed power sources;

Fig. 2 is primary circuit structure and the control system structure of a distributed power source;

Fig. 3 is PSCAD simulation model schematic diagram;

Fig. 4 is PCC Nodes busbar voltage degree of unbalancedness change curve;

Fig. 5 is two idle curves of distributed power source output negative phase-sequence;

Fig. 6 is PCC voltage curve before negative sequence voltage compensating controller drops into;

Fig. 7 is PCC voltage curve after negative sequence voltage compensating controller drops into.

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention will be described.

Many distributed power sources of one embodiment of the invention parallel system comprises that several distributed power sources in parallel are connected on same micro-electrical network bus by PCC, and busbar voltage is 400V, as shown in Figure 1. Distributed power source comprises the micro-source of direct current, three-phase full-bridge inverter, LC filter circuit and control system. As shown in Figure 2, the control strategy of every distributed power source comprises positive sequence meritorious/frequency and REACTIVE POWER/VOLTAGE droop control, virtual impedance control and Voltage unbalance inhibitory control. Gain merit/frequency of positive sequence and REACTIVE POWER/VOLTAGE droop control are guaranteed output voltage level and the power level of each distributed power source; Virtual impedance control ensures the control effect of gain merit/frequency of positive sequence and REACTIVE POWER/VOLTAGE droop control by additional impedance in distributed electrical source control system; Voltage unbalance inhibitory control detects the Voltage unbalance degree VUB at PCC place in real time_pcc, work as VUB_pcc>=2% time, start, the Voltage unbalance degree that each distributed power source maintains PCC place by quick adjustment maintains setting level.

1. the Voltage unbalance inhibition method of the many distributed power sources parallel connection in micro-electrical network, comprises the following steps:

(1) as shown in Figure 2, each distributed power source detects the positive sequence voltage of micro-electrical network PCC Nodes bus in real timeAnd negative sequence voltageForm the real-time voltage degree of unbalancedness constant of micro-electrical network PCC Nodes bus

1) the control system collection of distributed power source outlet voltage v_Cabc＝[v_Cav_Cbv_Cc]^TWith outlet current i_Cabc＝[i_Cai_Cbi_Cc]^T. According to symmetrical component method, in three-phase circuit, any asymmetric three-phase voltage or electric current all can resolve into by symmetrical component method the component of three groups of three-phase symmetricals, i.e. positive sequence, negative phase-sequence and zero-sequence component. In phase three-wire three circuit, owing to there is no zero sequence path, therefore do not have zero-sequence current, and residual voltage also can be ignored on the impact of micro-grid system. From instantaneous symmetrical component method, instantaneous voltage positive-sequence componentAnd negative sequence componentCan be expressed as,

$\left\{\begin{array}{c}{v}_{\mathrm{Cabc}}^{+}={\[v_{\mathrm{Ca}}^{+}{v}_{\mathrm{Cb}}^{+}{v}_{\mathrm{Cc}}^{+}\]}^T=T_{+}{\[v_{\mathrm{Ca}}{v}_{\mathrm{Cb}}{v}_{\mathrm{Cc}}\]}^T\\ v_{\mathrm{Cabc}}^{-}={\[v_{\mathrm{Ca}}^{-}{v}_{\mathrm{Cb}}^{-}{v}_{\mathrm{Cc}}^{-}\]}^T=T_{-}{\[v_{\mathrm{Ca}}{v}_{\mathrm{Cb}}{v}_{\mathrm{Cc}}\]}^T\end{array}\right.,$

Transient current positive-sequence componentAnd negative sequence componentCan be expressed as,

$\left\{\begin{array}{c}{i}_{\mathrm{Cabc}}^{+}={\[i_{\mathrm{Ca}}^{+}{i}_{\mathrm{Cb}}^{+}{i}_{\mathrm{Cc}}^{+}\]}^T=T_{+}{\[i_{\mathrm{Ca}}{i}_{\mathrm{Cb}}{i}_{\mathrm{Cc}}\]}^T\\ i_{\mathrm{Cabc}}^{-}={\[i_{\mathrm{Ca}}^{-}{i}_{\mathrm{Cb}}^{-}{i}_{\mathrm{Cc}}^{-}\]}^T=T_{-}{\[i_{\mathrm{Ca}}{i}_{\mathrm{Cb}}{i}_{\mathrm{Cc}}\]}^T\end{array}\right..$

Wherein $T_{+}=\frac{1}{3}\left[\begin{array}{ccc}1& a& a^2\\ a^2& 1& a\\ a& a^2& 1\end{array}\right],$ $T_{-}=\frac{1}{3}\left[\begin{array}{ccc}1& a^2& a\\ a& 1& a^2\\ a^2& a& 1\end{array}\right],$ And $a=e^{j\frac{2}{3}\mathrm{\π}}.$

2) by abc → α β conversion, this output voltage and output current are converted into v_CαβAnd i_Cαβ：

$\left\{\begin{array}{c}{v}_{\mathrm{C\α\β}}={\[v_{\mathrm{C\α}}{v}_{\mathrm{C\β}}\]}^T=T_{\mathrm{abc}\→\mathrm{\α\β}}{\[v_{\mathrm{Ca}}{v}_{\mathrm{Cb}}{v}_{\mathrm{Cc}}\]}^T\\ i_{\mathrm{C\α\β}}={\[i_{\mathrm{C\α}}{i}_{\mathrm{C\β}}\]}^T=T_{\mathrm{abc}\→\mathrm{\α\β}}{\[i_{\mathrm{Ca}}{i}_{\mathrm{Cb}}{i}_{\mathrm{Cc}}\]}^T\end{array}\right.,$ Wherein $T_{\mathrm{abc}\→\mathrm{\α\β}}=\frac{2}{3}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& \sqrt{3}/2\end{array}\right].$

3) utilize v_CαβAnd i_CαβCalculate respectively fundamental positive sequence output voltageFirst-harmonic negative phase-sequence output voltageFundamental positive sequence output currentFirst-harmonic negative phase-sequence output currentWherein,

$\left\{\begin{array}{c}{v}_{\mathrm{C\α\β}}^{+}={\[v_{\mathrm{C\α}}^{+}{v}_{\mathrm{C\β}}^{+}\]}^T=T_{\mathrm{abc}\→\mathrm{\α\β}}{v}_{\mathrm{Cabc}}^{+}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{+}{v}_{\mathrm{Cabc}}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{+}{T}_{\mathrm{abc}\→\mathrm{\α\β}}^T{v}_{\mathrm{C\α\β}}\\ v_{\mathrm{C\α\β}}^{-}={\[v_{\mathrm{C\α}}^{-}{v}_{\mathrm{C\β}}^{-}\]}^T=T_{\mathrm{abc}\→\mathrm{\α\β}}{v}_{\mathrm{Cabc}}^{-}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{-}{v}_{\mathrm{Cabc}}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{-}{T}_{\mathrm{abc}\→\mathrm{\α\β}}^T{v}_{\mathrm{C\α\β}}\end{array}\right.,$

$\left\{\begin{array}{c}{i}_{\mathrm{C\α\β}}^{+}={\[i_{\mathrm{C\α}}^{+}{i}_{\mathrm{C\β}}^{+}\]}^T=T_{\mathrm{abc}\→\mathrm{\α\β}}{i}_{\mathrm{Cabc}}^{+}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{+}{i}_{\mathrm{Cabc}}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{+}{T}_{\mathrm{abc}\→\mathrm{\α\β}}^T{i}_{\mathrm{C\α\β}}\\ i_{\mathrm{C\α\β}}^{-}={\[i_{\mathrm{C\α}}^{-}{i}_{\mathrm{C\β}}^{-}\]}^T=T_{\mathrm{abc}\→\mathrm{\α\β}}{i}_{\mathrm{Cabc}}^{-}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{-}{i}_{\mathrm{Cabc}}=T_{\mathrm{abc}\→\mathrm{\α\β}}{T}_{-}{T}_{\mathrm{abc}\→\mathrm{\α\β}}^T{i}_{\mathrm{C\α\β}}\end{array}\right..$

4) positive sequence voltage of PCC Nodes bus $V_{\mathrm{pcc}}^{+}=\sqrt{{\left(v_{\mathrm{C\α}}^{+}\right)}^2+{\left(v_{\mathrm{C\β}}^{+}\right)}^2}$ , negative sequence voltage $V_{\mathrm{pcc}}^{-}=\sqrt{{\left(v_{\mathrm{C\α}}^{-}\right)}^2+{\left(v_{\mathrm{C\β}}^{-}\right)}^2}$ . The real-time voltage degree of unbalancedness coefficient of micro-electrical network PCC Nodes bus

(2) detect in real time i distributed power source DG in micro-electrical network_iNegative phase-sequence output idle

$Q_i^{-}=v_{\mathrm{C\α}}^{-}{i}_{\mathrm{C\β}}^{-}-v_{\mathrm{C\β}}^{-}{i}_{\mathrm{C\α}}^{-}.$

(3) work as VUB_pcc>=2% time, drop into UVC. IfFor the rated voltage degree of unbalancedness coefficient of micro-electrical network PCC Nodes bus; n_iFor DG_iThe idle distribution coefficient of negative phase-sequence; k_eFor Voltage unbalance degree error proportionality coefficient; k_P，k_IFor proportionality coefficient and the integral coefficient of PI control. DG_iThe negative sequence voltage penalty coefficient of UVC:

${\mathrm{VCR}}_i=(k_P+\frac{k_I}{s})\mathrm{\Δ}{\mathrm{VCR}}_i,$ Wherein $\mathrm{\Δ}{\mathrm{VCR}}_i=k_e({\mathrm{VUB}}_{\mathrm{pcc}}-{\mathrm{VUB}}_{\mathrm{pcc}}^{*})-n_i{Q}_i^{-}.$

In the time that system enters stable state,Due to the VUB of each DG_pccWithCorresponding same PCC node, and k_eFor fixed constant, therefore(subscript i, j represents respectively two distributed power source DG different in micro-electrical network_iAnd DG_j), according to DG_iSpecified negative phase-sequence reactive capability n is set_i, any two different distributed power sources will be according to the proportional output negative phase-sequence of specified negative phase-sequence reactive capability is idle separately.

(4) by the VCR calculating in step (3)_iWith DG_iThe negative sequence voltage of output multiply each other obtain negative sequence voltage compensation reference value (by VCR_iWith DG_iThe negative sequence voltage of output multiplies each other and ensures DG_iThe reference value of negative sequence voltage compensation consistent with the phase place of the actual negative sequence voltage of micro-grid system PCC Nodes bus):

$v_{\mathrm{C\α\β}}^{-*}={\mathrm{VCR}}_i\·v_{\mathrm{C\α\β}}^{-}.$

(5) obtain after the reference value of negative sequence voltage compensation, coordinate positive sequence to gain merit/frequency and REACTIVE POWER/VOLTAGE droop control [3], virtual impedance control [4], the reference voltage of synthetic inverter, through interior loop voltag double current loop modulation^[5]Laggard horizontal pulse width modulated.

1) positive sequence of gain merit/frequency of positive sequence and REACTIVE POWER/VOLTAGE droop control is meritorious with the idle method for solving of positive sequence is:

$\left\{\begin{array}{c}{P}_i^{+}=v_{\mathrm{C\α}}^{+}{i}_{\mathrm{C\α}}^{+}+v_{\mathrm{C\β}}^{+}{i}_{\mathrm{C\β}}^{+}\\ Q_i^{+}=v_{\mathrm{C\α}}^{+}{i}_{\mathrm{C\β}}^{+}-v_{\mathrm{C\β}}^{+}{i}_{\mathrm{C\α}}^{+}\end{array}\right..$

Obtained the meritorious and positive sequence of positive sequence idle after, the control method of meritorious/frequency and REACTIVE POWER/VOLTAGE droop control is:

$\left\{\begin{array}{c}{\mathrm{\ω}}_i^{*}={\mathrm{\ω}}_0-m_{\mathrm{pi}}{P}_i^{+}\\ E_i^{*}=E_0-n_{\mathrm{qi}}{Q}_i^{+}\end{array}\right.,$

Wherein,For reference value and the amplitude reference value of DGi output positive sequence voltage; ω₀And E₀For DG_iRated frequency and rated voltage amplitude; m_piAnd n_qiBe respectively meritorious and idle sagging coefficient. Obtain DG_iThe reference value of output positive sequence voltageWith amplitude reference valueAfter, obtain DG by abc → α β conversion_iThe reference value of output positive sequence voltage

2) virtual impedance control ensures the control effect of positive sequence voltage, frequency droop control by additional impedance in distributed electrical source control system, and its control method is:

$\left\{\begin{array}{c}{v}_{\mathrm{Cf\α}}=i_{\mathrm{C\α}}{R}_{\mathrm{vi}}-i_{\mathrm{C\β}}{\mathrm{\ω}}_i^{*}{L}_{\mathrm{fi}}\\ v_{\mathrm{Cf\β}}=i_{\mathrm{C\β}}{R}_{\mathrm{vi}}+i_{\mathrm{C\α}}{\mathrm{\ω}}_i^{*}{L}_{\mathrm{fi}}\end{array}\right.,$

Wherein, v_Cfαβ=[v_Cfαv_Cfβ]^TFor the output reference value of virtual impedance control, R_viAnd L_fiFor the equivalent output resistance and the outputting inductance value that fictionalize in controlling unit.

3) positive sequence of comprehensive every distributed power source meritorious/frequency and REACTIVE POWER/VOLTAGE droop control, virtual impedance control and Voltage unbalance inhibitory control, obtain the input reference of outer voltage

$U_{\mathrm{\α\β}}^{*}=v_{\mathrm{C\α\β}}^{+*}-v_{\mathrm{Cf\α\β}}-v_{\mathrm{C\α\β}}^{-*}.$

4) control of electric current and voltage dicyclo has adopted ratio resonant controller (PR),And v_CαβBy PR controller, obtain the current reference value under static coordinateDeduct i_Lαβ, through PR controller, obtain the PWM control inputs signal U under rest frame_PWMαβ；U_PWMαβThrough α β → abc, conversion obtains the PWM control inputs signal U under three phase coordinate systems_PWMabc, input value PWM generation unit carries out pulse width modulation. The transfer function that PR controls is:

$G\left(s\right)=k_{\mathrm{PRp}}+\frac{{2k}_{\mathrm{PRr}}{\mathrm{\ω}}_{c}s}{s^2+{2\mathrm{\ω}}_{c}s+{\left({\mathrm{\ω}}_i^{*}\right)}^{2}s},$

Wherein, k_PRpAnd k_PRrRespectively proportionality coefficient and the resonance gain that PR controls, ω_cFor cut-off frequency.

2. in order to verify the correctness of institute of the present invention extracting method, with reference to Fig. 3, on PSCAD emulation platform, build the micro-grid system that contains two distributed power sources, system voltage is 400V, load is one and is connected on the 10 Ω resistance between mutually of A phase and B on PCC bus, and degree of unbalancedness is 2.5%. The systematic parameter of two distributed power sources is identical, controls parameter and loading condition as shown in table 1. In the time of t=0.5 second, add negative sequence voltage compensating controller. Carrier frequency is made as 12.8kHz. As seen from the figure, after adding negative sequence voltage compensating controller, Voltage unbalance degree is reduced to the idle ratio of negative phase-sequence of 1.6%, two distributed power source outputContrary with the ratio of the idle distribution coefficient of negative phase-sequence, prove the validity of institute of the present invention extracting method. Table 1 control system parameter:

Claims (2)

1. a micro-electrical network common bus Voltage unbalance inhibition method, is characterized in that, the method is to micro-grid system points of common connection (PCC)Place's bus negative sequence voltage carries out direct compensation, and each distributed power source in micro-electrical network can be from the micro-electrical network points of common connection of dynamic response (PCC)The variation of place's busbar voltage degree of unbalancedness, self adaptation is adjusted negative sequence voltage compensating controller (UVC), makes each distributed power source according to its volumeDetermine negative phase-sequence reactive capability output negative phase-sequence idle, maintain points of common connection (PCC) and locate the balance of voltage degree of bus, comprise the following steps:

1) step 1, detects micro-electrical network points of common connection (PCC) and locates the positive sequence voltage of bus in real timeAnd negative sequence voltageCalculate micro-Electrical network points of common connection (PCC) is located the real-time voltage degree of unbalancedness coefficient of bus

2) step 2, detects i distributed power source DG in micro-electrical network in real time_iNegative phase-sequence output idle

3) step 3, works as VUB_pccWhile being greater than certain default percentage, drop into negative sequence voltage compensating controller (UVC): establishForMicro-electrical network points of common connection (PCC) is located the rated voltage degree of unbalancedness coefficient of bus; n_iFor DG_iThe idle distribution coefficient of negative phase-sequence; k_eFor electricityPress degree of unbalancedness error proportionality coefficient; k_P，k_IFor proportionality coefficient and integral coefficient that PI controls, DG_iNegative sequence voltage compensating controller(UVC) negative sequence voltage penalty coefficient:

${\mathrm{VCR}}_i=(k_P+\frac{k_I}{s}){\mathrm{\ΔVCR}}_i,$

Wherein, ${\mathrm{\ΔVCR}}_i=k_e({\mathrm{VUB}}_{pcc}-{\mathrm{VUB}}_{pcc}^{*})-n_i{Q}_i^{-};$

4) step 4, by VCR_iWith DG_iThe negative sequence voltage of output multiplies each other and obtains DG_iThe reference value of negative sequence voltage compensation;

5) step 5, obtains DG_iThe reference value of negative sequence voltage compensation after, coordinate its positive sequence meritorious/frequency and REACTIVE POWER/VOLTAGE droop control,Virtual impedance control, synthetic DG_iThe reference voltage of control system, through the laggard horizontal pulse width modulated of electric current and voltage dicyclo control.

2. micro-electrical network common bus Voltage unbalance inhibition method according to claim 1, is characterized in that, works as VUB_pcc>=2% time, drop intoNegative sequence voltage compensating controller (UVC).