CN102723740B - Stable MPPT (Maximum Power Point Tracking) control system and method of single-stage photovoltaic inverter - Google Patents

Stable MPPT (Maximum Power Point Tracking) control system and method of single-stage photovoltaic inverter Download PDF

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CN102723740B
CN102723740B CN201210243296.0A CN201210243296A CN102723740B CN 102723740 B CN102723740 B CN 102723740B CN 201210243296 A CN201210243296 A CN 201210243296A CN 102723740 B CN102723740 B CN 102723740B
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mppt
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solar panel
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CN102723740A (en
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宁华宏
姜碧光
杨亲成
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ZHEJIANG EIFESUN ENERGY TECHNOLOGY Co Ltd
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ZHEJIANG EIFESUN ENERGY TECHNOLOGY Co Ltd
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    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

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Abstract

The invention provides a stable MPPT (Maximum Power Point Tracking) control system and method of a single-stage photovoltaic inverter. The stable MPPT control system comprises a solar panel, a photovoltaic inverter, a power grid and an MPPT controller, wherein the solar panel, the photovoltaic inverter and the power grid are sequentially connected with one another; and the MPPT controller is respectively connected with the solar panel and the photovoltaic inverter. According to the stable MPPT control method, a novel voltage ring controller is adopted and comprises a proportional integral (PI) control module, a pole compensation module and a notching filter module, and the voltage ring controller and a current ring controller adopt a same control period, thus ensuring the operation stability of a single-stage inversion system and guaranteeing the single-stage inversion system to output electric energy with good quality; and an MPPT (Maximum Power Point Tracking) variable-step voltage disturbance method is adopted, a proportional coefficient is regulated to guarantee better dynamic response and steady-state performance of MPPT, and thus the use efficiency of the solar panel is improved.

Description

Single-stage photovoltaic inverter stablizes MPPT control system and method
Technical field
The invention belongs to technical field of photovoltaic power generation, be specifically related to a kind of single-stage photovoltaic inverter and stablize MPPT control system and method.
Background technology
In solar grid-connected electricity generation system, solar cell is a kind of semiconductor device luminous energy being directly changed into electric energy, under certain luminous energy, how effectively to increase the power output of solar cell, thus making full use of solar energy, the generating efficiency improving whole solar grid-connected electricity generation system is significant.
By studying solar cell characteristics of output power, find that solar cell power output P is relevant with intensity of illumination W and ambient temperature T, as shown in Figure 1, be the P-U characteristic curve under the different W of identical T, wherein, U is solar cell output voltage; Fig. 2 is the P-U characteristic curve under the different T of identical W.As can be seen from Figure 1, solar cell peak power output strengthens with intensity of illumination and becomes large, and, there is unique peak power output point under same photoenvironment.On the left of peak power output point, power output rises in approximately linear ascendant trend with solar cell output voltage; After arriving peak power output point, power output starts quick decline, and decrease speed is much larger than the rate of climb.In Fig. 2, the total variation tendency of solar cell power output is similar to Fig. 1.
Therefore, solar cell power output and intensity of illumination and ambient temperature in close relations, when external environment condition changes, solar cell power output also can produce larger change, how photovoltaic generating system is controlled, making solar cell working near peak power output point, is the effective means improving solar battery efficiency.
MPPT (Maximum Power Point Tracking, MPPT maximum power point tracking) be adopt more a kind of solar cell power points control strategy at present, by changing the operating state of grid-connected system in real time, the peak power output point of tracking solar battery, thus realize solar cell maximum power output.Concrete, by changing controlled quentity controlled variable, the output voltage of solar cell is changed, by power output before and after change to the difference of output voltage, judge the position of present operating point on P-U characteristic curve, and then judge the variation pattern of next step controlled quentity controlled variable, thus make solar cell working point close to peak power output point gradually.
At present, the existing controller of MPPT control strategy is adopted to use the peak power output point of voltage disturbance method tracking solar battery, there is disturbance following rate lower, and easily there is deviation and cause incorrect polarity in this bat calculated with the solar panel output voltage difference Δ u of last bat, the i.e. positive and negative mistake of Δ u, effectively cannot ensure that solar panel steady operation is near peak power output point, and the photoenvironment that change is violent cannot be followed the tracks of fast, thus reduce solar panel service efficiency.
Summary of the invention
For the defect that prior art exists, the invention provides a kind of single-stage photovoltaic inverter and stablize MPPT control system and method, voltage controller is based on DC capacitor voltage and the modeling of outputting inductance electric current, voltage and electric current loop adopt identical control cycle, adopt novel Voltage loop controller, comprise: proportional integral PI controls, adds pole compensation and notch filter combination, thus ensure that the stable operation of single-stage inversion system is in the solar panel P-U characteristic curve maximum power point left and right sides, stops direct voltage avalanche problem; In addition, adopt the variable step voltage disturbance method of Mppt, by resize ratio coefficient, good dynamic response and the steady-state behaviour of MPPT maximal power tracing can be ensured, thus improve solar panel service efficiency.
The technical solution used in the present invention is as follows:
The invention provides a kind of single-stage photovoltaic inverter and stablize MPPT control system, comprise solar panel, photovoltaic DC-to-AC converter, electrical network and MPPT controller; Described solar panel, described photovoltaic DC-to-AC converter are connected in turn with described electrical network; Described MPPT controller is connected with described solar panel and described photovoltaic DC-to-AC converter respectively.
Preferably, described photovoltaic DC-to-AC converter comprises the three-phase inverting circuit of series connection, filter circuit and transforming circuit; And/or described MPPT controller is dsp controller.
The invention provides and a kind ofly apply the method that above-mentioned single-stage photovoltaic inverter stablizes MPPT control system, said method comprising the steps of:
S1, described MPPT controller gathers the actual output voltage u of described solar panel dcwith actual output current i pv, through the process of voltage disturbance ring, export the voltage given u as voltage control loop dc_ref;
S2, described MPPT controller is by the Voltage Feedback u of described solar panel dc_fbwith u dc_refexport to described voltage control loop, through described voltage control loop process, export as the given i of current regulator d shaft current d_ref;
S3, described MPPT controller gathers the current grid-connected three-phase current i of described photovoltaic DC-to-AC converter a, i band i c, based on PARK and CLARK shift theory, three-phase static coordinate system abc is converted to two-phase rest frame α β, more described two-phase rest frame α β is converted to two-phase rotating coordinate system dq, calculate d shaft current i dwith q shaft current i q;
S4, the i that S2 is obtained d_refwith the i that S3 obtains ddifference export to described current regulator, export d shaft voltage u m_d; Described controller is set to pure active power and exports, the given i of reactive current q_ref=0, with i qdifference export to described current regulator, export q shaft voltage u m_q;
S5, described controller carries out coordinate system inversion conversion, is converted to two-phase rest frame α β by two-phase rotating coordinate system dq, then two-phase rest frame α β is converted to three-phase static coordinate system abc, by u m_dand u m_qbe converted to three-phase control voltage u m_a, u m_band u m_c; Then adopt SVPWM space vector pulse width modulation to obtain three-phase modulations ripple PWM, export the pipe module I GBT of described photovoltaic DC-to-AC converter to.
Preferably, in S1, described voltage disturbance ring processing procedure is specially:
S11, sets the voltage given u of described voltage control loop dc_refinitial value and meet variable sign;
S12, setting sample frequency, gathers the actual output voltage u of the solar panel of current bat by this sample frequency dc(k) and actual output current i pvk (), then calculates the power output P (k) of the solar panel of current bat, wherein, and P (k)=u dc(k) × i pv(k);
S13, obtains the direct voltage set-point u of the power output P (k-1) of the solar panel that front 1 claps, front 1 solar panel clapped dc_refand the front 2 direct voltage set-point u of solar panels clapped (k-1) dc_ref(k-2); Then Δ P and Δ u is calculated, wherein, Δ P=P (k)-P (k-1), Δ u=u dc_ref(k-1)-u dc_ref(k-2);
S14, judges whether Δ P equals 0, if judged result is yes, then sign assignment 0, then performs S17; If judged result is no, then perform S15;
S15, judge whether further to meet Δ P > 0 and the condition of Δ u < 0, if judged result is yes, then sign assignment 1, then performs S17; If judged result is no, then perform S16;
S16, judge whether further to meet Δ P < 0 and the condition of Δ u > 0, if judged result is yes, then sign assignment 1, then performs S17; If judged result is no, then sign assignment-1, then performs 17;
S17, calculates the current voltage given u clapping the described voltage control loop needing output according to formula (1) dc_ref(k);
U dc_ref(k)=u dc_ref(k-1)-sign × u step× (K mppt× Δ P) formula (1)
Wherein, u step---voltage disturbance step value, K mppt---proportionality coefficient;
S18, when arriving the sampling period that next is clapped, making k=k+1, repeating S12-S17.
Preferably, described voltage control loop processing procedure is specially:
Through the process of described voltage disturbance ring, the given u of output voltage dc_ref, u dc_refwith Voltage Feedback u dc_fbsubtract each other, obtain difference through proportional controller K pcalculate, ratio exports pr out, through integral controller calculate, integration exports in out; Pr outwith in outbe added, export pi out; Pi outthrough 1 limit process, exports as sys out; Carry out the feedforward compensation of solar panel output current again, output valve is again through secondary notch filter G notchs () processes, export as the given i of current regulator d shaft current d_ref; Wherein, when for 50Hz electrical network, ω=100 π rad/s.
Preferably, after S2, also comprise:
Through the process of described voltage disturbance ring, the given u of output voltage dc_ref, u dc_refwith Voltage Feedback u dc_fbsubtract each other, obtain difference through Voltage loop controller D v_alls (), exports i d_refgiven as electric current loop d shaft current; i d_refi is fed back with inductance d shaft current ddifference through current loop controller D is (), exports u m_d; u m_dthrough hardware inductor module export actual d shaft current i d; i dwith i pvdifference, export actual capacitance i dc; Again through hardware capacitance module export u dc.
Preferably, described voltage control loop is identical with the control cycle of described current regulator.
Beneficial effect of the present invention is as follows:
Single-stage photovoltaic inverter provided by the invention stablizes MPPT control system and method, there is following innovation: (1) is based on inverter DC capacitor voltage and the modeling of outputting inductance electric current, Voltage loop control system by adopting control cycle identical with current regulator, thus improves voltage control dynamic response.(2) novel Voltage loop controller is adopted, comprise: proportional integral PI controls, adds pole compensation and notch filter combination, thus ensure that the stable operation of single-stage inversion system is in the solar panel P-U characteristic curve maximum power point left and right sides, stops direct voltage avalanche problem.Therefore, ensure that single-stage inverter maximal power tracing stability and the highest tracking efficiency and good electric energy export.(3) adopt the variable step voltage disturbance method of Mppt, by resize ratio coefficient, good dynamic response and the steady-state behaviour of MPPT maximal power tracing can be ensured.
Accompanying drawing explanation
Fig. 1 is the solar panel P-U characteristic curve in prior art under equivalent environment temperature different illumination intensity;
Fig. 2 is the solar panel P-U characteristic curve in prior art at identical intensity of illumination varying environment temperature;
Fig. 3 is the overall structure schematic diagram that single-stage photovoltaic inverter provided by the invention stablizes MPPT control system;
Fig. 4 is the process chart of voltage disturbance ring provided by the invention;
Fig. 5 is the structural representation of voltage control loop provided by the invention;
Fig. 6 is the structural representation of electric current and voltage control ring provided by the invention;
Fig. 7 is solar panel power output Pdc and the inverter output power Pacc curve chart that inverter applications MPPT control system provided by the invention is run a day;
Fig. 8 is the solar cell panel voltages applied in Fig. 7 and the change curve of time.
When Fig. 9 is for the generating of actual measurement photovoltaic DC-to-AC converter, direct voltage and output current wave.
Embodiment
As shown in Figure 3, single-stage photovoltaic inverter provided by the invention stablizes MPPT control system, it is characterized in that, comprises solar panel, photovoltaic DC-to-AC converter, electrical network and MPPT controller; Described solar panel, described photovoltaic DC-to-AC converter are connected in turn with described electrical network; Described MPPT controller is connected with described solar panel and described photovoltaic DC-to-AC converter respectively.Wherein, described photovoltaic DC-to-AC converter comprises the three-phase inverting circuit of series connection, filter circuit and transforming circuit; And/or described MPPT controller is dsp controller.
Apply above-mentioned single-stage photovoltaic inverter and stablize MPPT control system, single-stage photovoltaic inverter provided by the invention is stablized MPPT control method and is comprised the following steps:
S1, described MPPT controller gathers the actual output voltage u of described solar panel dcwith actual output current i pv, through the process of voltage disturbance ring, export the voltage given u as voltage control loop dc_ref;
As shown in Figure 4, be the process chart of voltage disturbance ring provided by the invention, voltage disturbance ring processing procedure is specially:
S11, sets the voltage given u of described voltage control loop dc_refinitial value and meet variable sign;
Wherein, variable sign is met only with by tax three kinds of values: 0,1 and-1.
S12, setting sample frequency, gathers the actual output voltage u of the solar panel of current bat by this sample frequency dc(k) and actual output current i pvk (), then calculates the power output P (k) of the solar panel of current bat, wherein, and P (k)=u dc(k) × i pv(k);
S13, obtains the direct voltage set-point u of the power output P (k-1) of the solar panel that front 1 claps, front 1 solar panel clapped dc_refand the front 2 direct voltage set-point u of solar panels clapped (k-1) dc_ref(k-2); Then Δ P and Δ u is calculated, wherein, Δ P=P (k)-P (k-1), Δ u=u dc_ref(k-1)-u dc_ref(k-2);
In this step, in calculating voltage difference, use u dc_refreplace u dc, that is: the direct voltage set-point u of front 1 solar panel clapped is made dc_ref(k-1) with the direct voltage set-point u of front 2 solar panels clapped dc_ref(k-2) poor, can avoid causing Δ u value deviation or incorrect polarity when there is larger voltage ripple by voltage sample deviation or direct current, and then affect accuracy and the stability of disturbance operation.
S14, judges whether Δ P equals 0, if judged result is yes, then sign assignment 0, then performs S17; If judged result is no, then perform S15;
S15, judge whether further to meet Δ P > 0 and the condition of Δ u < 0, if judged result is yes, then sign assignment 1, then performs S17; If judged result is no, then perform S16;
S16, judge whether further to meet Δ P < 0 and the condition of Δ u > 0, if judged result is yes, then sign assignment 1, then performs S17; If judged result is no, then sign assignment-1, then performs 17;
S17, calculates the current voltage given u clapping the described voltage control loop needing output according to formula (1) dc_ref(k);
U dc_ref(k)=u dc_ref(k-1)-sign × u step× (K mppt× Δ P) formula (1)
Wherein, u step---voltage disturbance step value, K mppt---proportionality coefficient;
S18, when arriving the sampling period that next is clapped, making k=k+1, repeating S 12-S17.
Concrete, composition graphs 1 or Fig. 2, point following three kinds of briefings:
(1) as Δ P=0, show that solar panel work at present is at maximum power point (mpp), so, sign is made to be 0, make current bat need the voltage given of the voltage control loop exported equal with the last voltage given clapping the voltage control loop exported, that is: do not change this bat solar panel operating state;
(2) when satisfying condition 1: Δ P > 0 and Δ u < 0; Or condition 2: Δ P < 0 and Δ u > 0 time, show the right side of solar panel work at present at maximum power point (mpp), therefore, sign assignment is 1, current bat is made to need the voltage given of the voltage control loop exported to be less than the last voltage given clapping the voltage control loop exported, the power output of solar panel is namely made to move to left, and gradually near maximum power point (mpp);
(3) as Δ P/ Δ u > 0, show the left side of solar panel work at present at maximum power point (mpp), therefore, sign assignment is-1, current bat is made to need the voltage given of the voltage control loop exported to be greater than the last voltage given clapping the voltage control loop exported, the power output of solar panel is namely made to move to right, and gradually near maximum power point (mpp).
In this step, adopt the variable step voltage disturbance method of Mppt, by resize ratio coefficient, good dynamic response and the steady-state behaviour of MPPT maximal power tracing can be ensured.
S2, described MPPT controller is by the Voltage Feedback u of described solar panel dc_fbwith u dc_refexport to described voltage control loop, through described voltage control loop process, export as the given i of current regulator d shaft current d_ref;
As shown in Figure 5, be the structural representation of voltage control loop provided by the invention, voltage control loop processing procedure is specially:
Through the process of described voltage disturbance ring, the given u of output voltage dc_ref, u dc_refwith Voltage Feedback u dc_fbsubtract each other, obtain difference through proportional controller K pcalculate, ratio exports pr out, through integral controller calculate, integration exports in out; Pr outwith in outbe added, export pi out; Pi outthrough 1 limit process, exports as sys out; Carry out the feedforward compensation of solar panel output current again, output valve is again through secondary notch filter G notchs () processes, export as the given i of current regulator d shaft current d_ref; Wherein, when for 50Hz electrical network, ω=100 π rad/s.
In this step, pi outcan ensure that direct voltage is without clean poor tracking; The disposal in singular point act as: by high-frequency signal filtering, can eliminate and inject high frequency harmonic components to current regulator under stable state.Have suffered Cheng Zuowei Voltage loop control system D v_all(s), Voltage loop control system is by adopting and the same control cycle of current regulator, improve voltage control dynamic response, by designing good controller parameter, ensure that single-stage inverter Absorbable organic halogens runs on the left and right sides of cell panel power voltage PV curve maximum power point, algorithm makes pole compensation and filter simultaneously, under ensure that stable state, only inject small harmonic wave to current regulator, substantially on the no impact of actual current harmonic wave.Therefore, ensure that single-stage inverter maximal power tracing stability and the highest tracking efficiency and good electric energy export.
As shown in Fig. 6, after S2, also comprise: through the process of described voltage disturbance ring, the given u of output voltage dc_ref, u dc_refwith Voltage Feedback u dc_fbsubtract each other, obtain difference through Voltage loop controller D v_alls (), exports i m_d; i m_dwith solar panel output current i pvbe added, export i d_ref; i d_refi is fed back with inductance d shaft current ddifference through current loop controller D is (), exports u m_d; u m_dthrough hardware inductor module export actual d shaft current i d; i dwith i pvdifference, export actual capacitance i dc; Again through hardware capacitance module export u dc.
S3, described MPPT controller gathers the current grid-connected three-phase current i of described photovoltaic DC-to-AC converter a, i band i c, based on PARK and CLARK shift theory, three-phase static coordinate system abc is converted to two-phase rest frame α β, more described two-phase rest frame α β is converted to two-phase rotating coordinate system dq, calculate d shaft current i dwith q shaft current i q;
S4, the i that S2 is obtained d_refwith the i that S3 obtains ddifference export to described current regulator, export d shaft voltage u m_d; Described controller is set to pure active power and exports, the given i of reactive current q_ref=0, with i qdifference export to described current regulator, export q shaft voltage u m_q;
S5, described controller carries out coordinate system inversion conversion, is converted to two-phase rest frame α β by two-phase rotating coordinate system dq, then two-phase rest frame α β is converted to three-phase static coordinate system abc, by u m_dand u m_qbe converted to three-phase control voltage u m_a, u m_band u m_c; Then adopt SVPWM space vector pulse width modulation to obtain three-phase modulations ripple PWM, export the pipe module I GBT of described photovoltaic DC-to-AC converter to.
Adopt space vector pulse width modulation SVPWM strategy, have the following advantages 1) improve direct voltage utilance, ensure to adapt to wider DC voltage range; 2) greatly can reduce the harmonic current (as 3,6,9... subharmonic) of 3 multiples, can reduce the wastage and ensure to provide better electric energy to electrical network.
In addition, in the present invention, voltage control loop is identical with the control cycle of current regulator, has illustrated that the control cycle of voltage control loop and the control cycle of current regulator are 100us, improve voltage control dynamic response in Fig. 3.It should be noted that, in the present invention, control cycle refers to that the voltage to the digital signals format received of voltage control loop or current regulator or current signal carry out the cycle of s operation control, such as: every 100us makes 1 signal sampling, namely the sampling period is 100us, the every 100us of control ring does a controller computing, then control cycle is 100us.
Apply single-stage photovoltaic inverter provided by the invention and stablize MPPT control system and method, carry out actual test to photovoltaic DC-to-AC converter, Fig. 7 shows solar panel power output P dcwith inverter output power Pac curve, wherein, 1 represents solar panel power output P dcwith the change curve of time, 2 represent inverter output power P acwith the change curve of time; Fig. 8 shows the change curve of solar cell panel voltages and time.When Fig. 9 is for the generating of actual measurement photovoltaic DC-to-AC converter, direct voltage and output current wave.Composition graphs 7, Fig. 8 and Fig. 9 can find out, apply after single-stage photovoltaic inverter of the present invention stablizes MPPT control system and method, solar panel direct voltage and power output are all highly stable.
In sum, single-stage photovoltaic inverter provided by the invention stablizes MPPT control system and method, there is following innovation: (1) adopts the variable step voltage disturbance method of Mppt, by resize ratio coefficient, can ensure good dynamic response and the steady-state behaviour of MPPT maximal power tracing.(2) Voltage loop control system is by adopting and the same control cycle of current regulator, improve voltage control dynamic response, by designing good controller parameter, ensure that single-stage inverter Absorbable organic halogens runs on the left and right sides of cell panel power voltage PV curve maximum power point, algorithm makes pole compensation and filter simultaneously, small harmonic wave is only injected to current regulator, substantially on the no impact of actual current harmonic wave under ensure that stable state.Therefore, ensure that single-stage inverter maximal power tracing stability and the highest tracking efficiency and good electric energy export.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should look protection scope of the present invention.

Claims (2)

1. apply the method that single-stage photovoltaic inverter stablizes MPPT control system, it is characterized in that, single-stage photovoltaic inverter stablizes MPPT control system, comprises solar panel, photovoltaic DC-to-AC converter, electrical network and MPPT controller; Described solar panel, described photovoltaic DC-to-AC converter are connected in turn with described electrical network; Described MPPT controller is connected with described solar panel and described photovoltaic DC-to-AC converter respectively; Wherein, described photovoltaic DC-to-AC converter comprises the three-phase inverting circuit of series connection, filter circuit and transforming circuit; And/or described MPPT controller is dsp controller;
Said method comprising the steps of:
S1, described MPPT controller gathers the actual output voltage u of described solar panel dcwith actual output current i pv, through the process of voltage disturbance ring, export the voltage given u as voltage control loop dc_ref;
S2, described MPPT controller is by the Voltage Feedback u of described solar panel dc_fbwith u dc_refexport to described voltage control loop, through described voltage control loop process, export as the given i of current regulator d shaft current d_ref;
S3, described MPPT controller gathers the current grid-connected three-phase current i of described photovoltaic DC-to-AC converter a, i band i c, based on PARK and CLARK shift theory, three-phase static coordinate system abc is converted to two-phase rest frame α β, more described two-phase rest frame α β is converted to two-phase rotating coordinate system dq, calculate d shaft current i dwith q shaft current i q;
S4, the i that S2 is obtained d_refwith the i that S3 obtains ddifference export to described current regulator, export d shaft voltage u m_d; Described MPPT controller is set to pure active power and exports, the given i of reactive current q_ref=0, with i qdifference export to described current regulator, export q shaft voltage u m_q;
S5, described MPPT controller carries out coordinate system inversion conversion, is converted to two-phase rest frame α β by two-phase rotating coordinate system dq, then two-phase rest frame α β is converted to three-phase static coordinate system abc, by u m_dand u m_qbe converted to three-phase control voltage u m_a, u m_band u m_c; Then adopt SVPWM space vector pulse width modulation to obtain three-phase modulations ripple PWM, export the pipe module I GBT of described photovoltaic DC-to-AC converter to;
Wherein, in S1, described voltage disturbance ring processing procedure is specially:
S11, sets the voltage given u of described voltage control loop dc_refinitial value and meet variable sign;
S12, setting sample frequency, gathers the actual output voltage u of the solar panel of current bat by this sample frequency dc(k) and actual output current i pvk (), then calculates the power output P (k) of the solar panel of current bat, wherein, and P (k)=u dc(k) × i pv(k);
S13, obtains the direct voltage set-point u of the power output P (k-1) of the solar panel that front 1 claps, front 1 solar panel clapped dc_refand the front 2 direct voltage set-point u of solar panels clapped (k-1) dc_ref(k-2); Then Δ P and Δ u is calculated, wherein, Δ P=P (k)-P (k-1), Δ u=u dc_ref(k-1)-u dc_ref(k-2);
S14, judges whether Δ P equals 0, if judged result is yes, then sign assignment 0, then performs S17; If judged result is no, then perform S15;
S15, judge whether further to meet Δ P>0 and the condition of Δ u<0, if judged result is yes, then sign assignment 1, then performs S17; If judged result is no, then perform S16;
S16, judge whether further to meet Δ P<0 and the condition of Δ u>0, if judged result is yes, then sign assignment 1, then performs S17; If judged result is no, then sign assignment-1, then performs S17;
S17, calculates the current voltage given u clapping the described voltage control loop needing output according to formula (1) dc_ref(k);
U dc_ref(k)=u dc_ref(k-1)-sign × u step× (K mppt× Δ P) formula (1)
Wherein, u step---voltage disturbance step value, K mppt---proportionality coefficient;
S18, when arriving the sampling period that next is clapped, making k=k+1, repeating S12-S17;
Wherein, in S2, described voltage control loop processing procedure is specially:
Through the process of described voltage disturbance ring, the given u of output voltage dc_ref, u dc_refwith Voltage Feedback u dc_fbsubtract each other, obtain difference through proportional controller K pcalculate, ratio exports pr out, through integral controller calculate, integration exports in out; Pr outwith in outbe added, export pi out; Pi outthrough 1 limit process, exports as sys out; Carry out the feedforward compensation of solar panel output current again, output valve is again through secondary notch filter G notchs () processes, export as the given i of current regulator d shaft current d_ref; Wherein, when for 50Hz electrical network, ω=100 π rad/s.
2. method according to claim 1, is characterized in that, described voltage control loop is identical with the control cycle of described current regulator.
CN201210243296.0A 2012-07-13 2012-07-13 Stable MPPT (Maximum Power Point Tracking) control system and method of single-stage photovoltaic inverter Active CN102723740B (en)

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