CN104578144A - Anti-sagging control method for photovoltaic inverter in microgrid - Google Patents

Abstract

The invention relates to the technical field of photovoltaic power generation and aims at providing an anti-sagging control method for a photovoltaic inverter in a microgrid. The method comprises the following steps: realizing the whole anti-sagging control process through a photovoltaic inverter anti-sagging controller; calculating the frequency and the voltage of an alternating current bus of the microgrid by an anti-sagging control module to obtain an active power instruction and an inactive power instruction; sampling and fitting the output direct-current current value of a photovoltaic battery and the capacitance and voltage values of a direct current bus by a photovoltaic power-voltage curve fitting module to obtain a photovoltaic power-voltage curve; carrying out closed-loop control by the anti-sagging control module, and controlling the inverter by a current inner ring controller and a space vector pulse width modulation circuit through the proportion and integral action of a voltage/inactive closed-loop control module. The anti-sagging control method adopts a uniform control structure and can work in the grid connection and islanding two states of the microgrid. The schedulability of the photovoltaic power generation unit is enhanced in the grid connection state. The photovoltaic power generation unit can run in a maximum power point tracking mode in the islanding state.

Description

Photovoltaic DC-to-AC converter inverse dip control method in micro-capacitance sensor

Technical field

The present invention relates to technical field of photovoltaic power generation in micro-capacitance sensor, particularly, relate to a kind of inverse dip control method of photovoltaic DC-to-AC converter.

Background technology

In the last few years, because the exhausted problem of World Environment Problems and non-renewable energy resources is more and more serious, new forms of energy are developed rapidly as a kind of clean, regenerative resource, especially photovoltaic generation.Micro-capacitance sensor, as the mode of a kind of effective integration, efficiency utilization generation of electricity by new energy unit, receives the concern of national governments.Photovoltaic generally operated in MPPT maximum power point tracking (MPPT) pattern in the past, under this pattern, the power output of photovoltaic is very large by the such environmental effects such as illumination, temperature, the schedulability of photovoltaic generation unit is poor, and very large fluctuation will be caused to the voltage of micro-capacitance sensor, frequency in the micro-capacitance sensor that capacity is little, affect the quality of power supply of micro-capacitance sensor.In this external micro-grid system, micro battery type is complicated, and load variations is large, only maintained the frequency and voltage of micro-capacitance sensor by droop control by energy storage, energy storage is frequent discharge and recharge by the Rapid Variable Design because of the environmental factor such as load variations, light and temperature, and service life reduction, cost is raised.In recent years, photovoltaic is determined power technology and is paid attention to, and document " Power control strategy for photovoltaic system based on the newtonquadratic interpolation " give a kind of photovoltaic constant dc power control technology based on newton's quadratic interpolation; And it is technical at this, document " A New Frequency Regulation Strategy for Photovoltaic Systems Without EnergyStorage " gives a kind of method that photovoltaic generation supports mains frequency, but the method does not solve active power reference instruction P well _oselect permeability, more reckon without photovoltaic and there is output reactive power to regulate the ability of micro-capacitance sensor voltage.These obviously fully do not excavate the potentiality of photovoltaic generation, are unfavorable for the efficiency utilization of photovoltaic generation and further develop.

Summary of the invention

The problem to be solved in the present invention is, overcomes deficiency of the prior art, proposes photovoltaic DC-to-AC converter inverse dip control method in a kind of micro-capacitance sensor.The method, by strengthening the schedulability of photovoltaic generation unit, strengthens the supporting role of the frequency and voltage to micro-capacitance sensor, improves the stability of micro-capacitance sensor.

For achieving the above object, the technical solution used in the present invention is:

A kind of photovoltaic DC-to-AC converter inverse dip controller for micro-capacitance sensor is provided, is connected with micro-capacitance sensor ac bus; This controller comprises: inverse dip control module, photovoltaic power-voltage curve fitting module, power coordination controller, Voltage-Reactive Power closed loop control module, current inner loop controller and space vector pulse width modulation circuit; Described inverse dip control module is connected to micro-capacitance sensor ac bus, and its output is connected to photovoltaic power-voltage curve fitting module and power coordination controller respectively; The output of photovoltaic power-voltage curve fitting module and power coordination controller is connected to a PI controller separately, two PI controller composition Voltage-Reactive Power closed loop control modules; Voltage-Reactive Power closed loop control module, current inner loop controller and space vector pulse width modulation circuit connect successively.

Invention further provides photovoltaic DC-to-AC converter inverse dip control method in micro-capacitance sensor, realize whole inverse dip control procedure by photovoltaic DC-to-AC converter inverse dip controller: inverse dip control module gathers frequency f and the voltage V of micro-capacitance sensor ac bus, by it and rated frequency f ₀with rated voltage V ₀differ from, difference is added to after being multiplied by inverse dip Coefficient m, n respectively meritorious, reactive power reference instruction P ₀, Q ₀on, to be gained merit, reactive power instruction P _ref, Q _ref; Wherein meritorious, reactive power reference instruction P _o, Q ₀obtain via power coordination controller; Photovoltaic power-voltage curve fitting module exports direct current by sampling photovoltaic cell and the matching of dc-link capacitance magnitude of voltage obtains photovoltaic power-voltage curve, finds the active power instruction P meeting inverse dip control module and obtain _refwith MPPT maximum power point tracking enable signal EN _mpptthe photovoltaic DC busbar voltage reference value V of two conditions _dcref; The reactive power instruction Q that inverse dip control module obtains _refwith photovoltaic DC busbar voltage reference value V _dcrefcarry out closed-loop control together, obtain electric current d axle reference value i through the ratio of Voltage-Reactive Power closed loop control module, integral action _drefwith electric current q axle reference value i _qref; Again by current inner loop controller and space vector pulse width modulation circuit realiration to the control of inverter.

In the present invention, the operating procedure of described photovoltaic power-voltage curve fitting module comprises: input active power instruction P _ref, photovoltaic cell average anode current i _pv, photovoltaic DC bus capacitor voltage V _pvwith MPPT maximum power point tracking enable signal EN _mppt; Through fixed cycle T _samplesample, calculate photovoltaic output direct current power P _pvwith photovoltaic DC bus capacitor voltage V _pv, get up-to-date kth-2, k-1, k time three sampling calculated values compositions carry out matching and obtain photovoltaic power-voltage curve; On this curve, search out the maximum power point performance number P that kth is secondary _mpptwith magnitude of voltage V _mppt; Kth+1 sampling calculated value replace in turn or reset three groups of sampling calculated values that composition is new carry out matching, constantly update iteration thus, matching obtains new photovoltaic power-voltage curve; On new curve, constantly search out maximum power point performance number P _mpptwith magnitude of voltage V _mppt; As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, if active power instruction P _refbe greater than P _mppt, then by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern; If active power instruction P _refbe less than P _mppt, then on this curve, active power instruction P is searched out _refcorresponding magnitude of voltage; Owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 0, represent that photovoltaic is in and determine power tracking pattern.

In the present invention, described power coordination controller operating procedure comprises: the maximum photovoltaic power point power P obtained by photovoltaic power-voltage curve matching _mpptwith photovoltaic DC-to-AC converter capacity S _invtry to achieve and maximumly send reactive power with P _mpptbe multiplied by meritorious inverse dip dot factor k _pdroopobtain islands active power reference instruction P ₀', with Q _maxbe multiplied by idle inverse dip dot factor k _qdroopobtain isolated island reactive power reference instruction Q ₀'; The active power instruction P dispatched by micro-capacitance sensor central controller _mggcwith reactive power instruction Q _mggcgrid-connected active power reference instruction P is obtained through saturation element ₀ ^*with grid-connected reactive power reference instruction Q ₀ ^*, meritorious saturation limiting scope is 0 ~ P _mppt, idle saturation limiting scope is-Q _max~ Q _max; If grid-connected signal IF _{grid_tied}be zero, then meritorious, reactive power reference instruction P _o, Q ₀with islands active, reactive power reference instruction P ₀', Q ₀' equal; If grid-connected signal IF _{grid_tied}be 1, then meritorious, reactive power reference instruction P _o, Q ₀with grid-connected meritorious, reactive power reference instruction P ₀ ^*, Q ₀ ^*equal; Wherein, meritorious inverse dip dot factor k _pdrooprepresent the economy of photovoltaic generation and the compromise of frequency enabling capabilities, the economy and the frequency enabling capabilities that consider generating carry out value, and span is between 0 ~ 1; Meritorious inverse dip dot factor k _pdroopthe utilance of the less photovoltaic generation of numerical value is lower, and economy is poorer, but supports stronger to the frequency of microgrid, and this factor v larger photovoltaic generation utilance is larger, and economy is better, but more weak to microgrid frequency enabling capabilities; Idle inverse dip dot factor k _qdrooprepresent the economy of photovoltaic generation and the compromise of voltage support ability, the economy and the voltage support ability that consider generating carry out value, and span is between-1 ~ 1; Idle inverse dip dot factor k _qdroopthe utilance of absolute value less photovoltaic residual capacity is lower, and economy is poorer, but stronger to the voltage support of microgrid, and the utilance of this absolute coefficient larger photovoltaic residual capacity is larger, and economy is better, but more weak to microgrid voltage support ability.

In the present invention, (1) when micro-capacitance sensor be in and net state time, grid-connected signal IF _{grid_tied}be 1, micro-capacitance sensor central controller scheduling active power instruction P _mggcwith reactive power instruction Q _mggcgained merit through saturation element, reactive power reference instruction P _o, Q ₀, to be gained merit by the superposition of inverse dip part, reactive power instruction P _ref, Q _ref; As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, if active power instruction P _refbe greater than P _mppt, then by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; If active power instruction P _refbe less than P _mppt, then photovoltaic power-the voltage curve obtained in matching searches out active power instruction P _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in inverse dip control model.In addition, and under net state, the frequency f of micro-capacitance sensor ac bus and rated frequency f ₀, the voltage V of micro-capacitance sensor ac bus and rated voltage V ₀difference be all 0, so as micro-capacitance sensor central controller scheduling active power instruction P _mggcand reactive power instruction Q _mggcbe not more than maximum power point power P _mpptreactive power Q is sent with maximum _maxtime, meritorious, reactive power instruction P _ref, Q _refrespectively with P _mggc, Q _mggcequal, namely photovoltaic generation unit operates in and determines power tracking pattern, and the power sent is dispatched by micro-capacitance sensor central controller; Now, if the environmental factor such as illumination, temperature constantly changes, three the power vs. voltage points adopted due to curve are up-to-date three power vs. voltage points of photovoltaic actual motion, and the photovoltaic power-voltage curve of new matching can ensure very high fitting precision.On photovoltaic power-voltage curve that new matching obtains, by search, active power instruction P under new environmental factor can be found _refcorresponding new photovoltaic DC busbar voltage reference value V _dcref, therefore photovoltaic power output can be subject to the such environmental effects such as illumination, temperature hardly, and keep photovoltaic power output equal with the instruction of micro-capacitance sensor central controller schedule power.

(2) when micro-capacitance sensor is in island state, grid-connected signal IF _{grid_tied}be 0, meritorious, reactive power reference instruction P _o, Q ₀with islands active, reactive power reference instruction P ₀', Q ₀' equal, to be gained merit by the superposition of inverse dip part, reactive power instruction P _ref, Q _ref; As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, photovoltaic power-voltage curve that matching obtains searches out active power instruction P _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in inverse dip control model, and the frequency and voltage of photovoltaic power output and micro-capacitance sensor meets inverse dip relation.When load variations, because the frequency and voltage of photovoltaic power output and micro-capacitance sensor meets inverse dip relation, so the frequency and voltage of photovoltaic generation unit to micro-capacitance sensor has supporting role definitely, improve the stability of micro-capacitance sensor.

Technical scheme of the present invention has following beneficial effect:

Photovoltaic DC-to-AC converter in the present invention adopts inverse dip control method, is a kind of unified control structure, can work in the grid-connected of micro-capacitance sensor and isolated island two kinds of states.And under net state, photovoltaic generation unit may operate at MPPT maximum power point tracking pattern, also can run on and determine power tracking pattern, the power output of photovoltaic by the such environmental effects such as illumination, temperature, enhances the schedulability of photovoltaic generation unit hardly.Under island state, photovoltaic generation unit can operate in MPPT maximum power point tracking pattern most, also can run on inverse dip control model; Under inverse dip control model, photovoltaic carrys out Modulating Power according to the frequency and voltage of micro-capacitance sensor and exports, when load variations, also can support definitely the frequency and voltage of micro-capacitance sensor, enhance the supporting role of photovoltaic generation unit to the frequency and voltage of micro-capacitance sensor, improve the stability of micro-capacitance sensor.

Accompanying drawing explanation

Fig. 1 is the micro-capacitance sensor structure described in the preferred embodiment of the present invention;

Fig. 2 is meritorious-frequency inverse dip schematic diagram;

Fig. 3 is idle-voltage inverse dip schematic diagram;

Fig. 4 photovoltaic power-voltage curve matching flow chart;

Fig. 5 is photovoltaic DC-to-AC converter inverse dip control method block diagram.

Reference numeral in Fig. 5: inverse dip control module 1, photovoltaic power-voltage curve fitting module 2, power coordination controller 3, Voltage-Reactive Power closed loop control module 4, current inner loop controller 5, space vector pulse width modulation circuit 6.

Embodiment

Photovoltaic DC-to-AC converter inverse dip control method in micro-capacitance sensor of the present invention, specifically comprises the following steps:

(1) inverse dip control module 1 gathers frequency f and the voltage V of micro-capacitance sensor ac bus, and given rated frequency f ₀, rated voltage V ₀differ from, difference is added to after being multiplied by the inverse dip Coefficient m of setting, n respectively meritorious, reactive power reference instruction P _o, Q ₀on, to be gained merit, reactive power instruction P _ref, Q _ref; Wherein meritorious, reactive power reference instruction P _o, Q ₀divide via power coordination controller portion and obtain.Inverse dip controls to be shown below:

$\left\{\begin{array}{c}{P}_{\mathrm{ref}}=P_0+m\×(f_0-f)\\ Q_{\mathrm{ref}}=Q_0+n\×(V_0-V)\end{array}\right.---\left(1\right)$

M, n wherein can be obtained by following formula:

$\left\{\begin{array}{c}m=-\frac{P_0-P_{\mathrm{mppt}}}{f_0-f_{\min }}\\ n=-\frac{Q_0-Q_{\max }}{V_0-V_{\min }}\end{array}\right.---\left(2\right)$

Wherein, f _minthat micro-capacitance sensor normally runs minimum tolerance frequency; V _minthat micro-capacitance sensor normally runs minimum permission voltage.

(2) photovoltaic power-voltage curve fitting module 2 obtains active power instruction P by step (1) _ref, gather photovoltaic cell average anode current i _pv, photovoltaic DC bus capacitor voltage V _pvwith the MPPT maximum power point tracking enable signal EN of micro-capacitance sensor central controller setting _mppt; Through fixed cycle T _samplesample, calculate photovoltaic output direct current power P _pvwith photovoltaic DC bus capacitor voltage V _pv, get up-to-date kth-2, k-1, k time three sampling calculated values compositions carry out matching and obtain photovoltaic power-voltage curve P _pv(V _dcref).Approximating method is as follows: sorted from small to large according to magnitude of voltage by three power vs. voltage points, without loss of generality, suppose then:

$P_{\mathrm{pv}}\left(V_{\mathrm{dcref}}\right)=a{V}_{\mathrm{dcref}}^2+b{V}_{\mathrm{dcref}}+c---\left(3\right)$

$a=\frac{P_{\mathrm{pv}\left(1\right)}^k}{(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(2\right)}^k}{(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(3\right)}^k}{(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)}---\left(4\right)$

$b=-[\frac{P_{\mathrm{pv}\left(1\right)}^k(V_{\mathrm{pv}\left(2\right)}^k+V_{\mathrm{pv}\left(3\right)}^k)}{(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(2\right)}^k(V_{\mathrm{pv}\left(1\right)}^k+V_{\mathrm{pv}\left(3\right)}^k)}{(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(3\right)}^k(V_{\mathrm{pv}\left(1\right)}^k+V_{\mathrm{pv}\left(2\right)}^k)}{(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)}]---\left(5\right)$

$c=\frac{P_{\mathrm{pv}\left(1\right)}^k{V}_{\mathrm{pv}\left(2\right)}^k{V}_{\mathrm{pv}\left(3\right)}^k}{(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(2\right)}^k{V}_{\mathrm{pv}\left(1\right)}^k{V}_{\mathrm{pv}\left(3\right)}^k}{(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(3\right)}^k{V}_{\mathrm{pv}\left(1\right)}^k{V}_{\mathrm{pv}\left(2\right)}^k}{(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)}---\left(6\right)$

On this curve, search out the maximum power point performance number P that kth is secondary _mpptwith magnitude of voltage V _mppt, meet following relation:

$\left\{\begin{array}{c}{V}_{\mathrm{mppt}}=-\frac{b}{2a}\\ P_{\mathrm{mppt}}=\frac{4a\×c-b^2}{4a}\end{array}\right.---\left(7\right)$

Kth+1 sampling calculated value replace in turn or reset three groups of sampling calculated values that composition is new carry out matching, constantly update iteration thus, matching obtains new photovoltaic power-voltage curve.On new curve, constantly search out maximum power point performance number P _mpptwith magnitude of voltage V _mppt.

As the MPPT maximum power point tracking enable signal EN of micro-capacitance sensor central controller setting _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern.As the MPPT maximum power point tracking enable signal EN of micro-capacitance sensor central controller setting _mpptwhen being 0, if active power instruction P _refbe greater than P _mppt, then by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern; If active power instruction P _refbe less than P _mppt, then on this curve, active power instruction P is searched out _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 0, represent that photovoltaic is in and determine power tracking pattern.V _dcrefvalue can be obtained by following formula:

$V_{\mathrm{dcref}}=\frac{-b-\sqrt{(b^2-4a\×(c-P_{\mathrm{ref}}))}}{2a}---\left(8\right)$

(3) the maximum photovoltaic power point power P that obtained by photovoltaic power-voltage curve matching of the power coordination controller 3 described in step (1) _mpptwith the photovoltaic DC-to-AC converter capacity S in photovoltaic DC-to-AC converter nameplate _invcan try to achieve and maximumly send reactive power p _mpptbe multiplied by the meritorious inverse dip dot factor k of setting _pdroopobtain islands active power reference instruction P ₀', Q _maxbe multiplied by the idle inverse dip dot factor k of setting _qdroopobtain isolated island reactive power reference instruction Q ₀'; Micro-capacitance sensor central controller scheduling active power instruction P _mggcwith reactive power instruction Q _mggcgrid-connected active power reference instruction P is obtained through saturation element _o ^*with grid-connected reactive power reference instruction Q ₀ ^*, meritorious saturation limiting scope is 0 ~ P _mppt, idle saturation limiting scope is-Q _max~ Q _max.If grid-connected signal IF _{grid_tied}be 0, then meritorious, reactive power reference instruction P _o, Q ₀with islands active, reactive power reference instruction P ₀', Q ₀' equal; If grid-connected signal IF _{grid_tied}be 1, then meritorious, reactive power reference instruction P _o, Q ₀with grid-connected meritorious, reactive power reference instruction P ₀ ^*, Q ₀ ^*equal.Wherein, meritorious inverse dip dot factor k _pdrooprepresent the economy of photovoltaic generation and the compromise of frequency enabling capabilities, economy and the frequency enabling capabilities that can consider generating carry out value, and span is between 0 ~ 1.Meritorious inverse dip dot factor k _pdroopthe utilance of the less photovoltaic generation of numerical value is lower, and economy is poorer, but supports stronger to the frequency of microgrid, and this factor v larger photovoltaic generation utilance is larger, and economy is better, but more weak to microgrid frequency enabling capabilities.Idle inverse dip dot factor k _qdrooprepresent the economy of photovoltaic generation and the compromise of voltage support ability, economy and the voltage support ability that can consider generating carry out value, and span is between-1 ~ 1.Idle inverse dip dot factor k _qdroopthe utilance of absolute value numerical value less photovoltaic residual capacity is lower, and economy is poorer, but stronger to the voltage support of microgrid, and the utilance of this absolute coefficient numerical value larger photovoltaic residual capacity is larger, and economy is better, but more weak to microgrid voltage support ability.

(4) the reactive power instruction Q that in step (1), inverse dip control module 1 obtains _refwith photovoltaic DC busbar voltage reference value V in step (2) _dcrefcarry out closed-loop control by Voltage-Reactive Power closed loop control module 4 together, obtain electric current d axle reference value i through ratio, integral action _drefwith electric current q axle reference value i _qref; Obtain electric current d axle reference value i _drefwith electric current q axle reference value i _qrefafter, then obtain d shaft voltage reference value u by current inner loop controller _dwith q shaft voltage reference value u _q, obtain photovoltaic DC-to-AC converter control signal finally by space vector pulse width modulation circuit.

Micro-capacitance sensor be in and net state time, grid-connected signal IF _{grid_tied}be 1, micro-capacitance sensor central controller scheduling active power instruction P _mggcwith reactive power instruction Q _mggcgained merit through saturation element, reactive power reference instruction P _o, Q ₀, to be gained merit by the superposition of inverse dip part, reactive power instruction P _ref, Q _ref.As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, if active power instruction P _refbe greater than P _mppt, then by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; If active power instruction P _refbe less than P _mppt, then photovoltaic power-the voltage curve obtained in matching searches out active power instruction P _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in inverse dip control model.In addition, and under net state, the frequency f of micro-capacitance sensor ac bus and rated frequency f ₀, the voltage V of micro-capacitance sensor ac bus and rated voltage V ₀difference be all 0, so as micro-capacitance sensor central controller scheduling active power instruction P _mggcand reactive power instruction Q _mggcbe not more than maximum power point power P _mpptreactive power Q is sent with maximum _maxtime, meritorious, reactive power instruction P _ref, Q _refrespectively with P _mggc, Q _mggcequal, namely photovoltaic operates in and determines power tracking pattern, and the power sent can be dispatched by micro-capacitance sensor central controller.Now, if the environmental factor such as illumination, temperature constantly changes, three the power vs. voltage points adopted due to curve are up-to-date three power vs. voltage points of photovoltaic actual motion, and the photovoltaic power-voltage curve of new matching can ensure very high fitting precision.On photovoltaic power-voltage curve that new matching obtains, by search, active power instruction P under new environmental factor can be found _refcorresponding new photovoltaic DC busbar voltage reference value V _dcref, therefore photovoltaic power output can be subject to the such environmental effects such as illumination, temperature hardly, and keep photovoltaic power output equal with the instruction of micro-capacitance sensor central controller schedule power.

When micro-capacitance sensor is in island state, grid-connected signal If _{grid_tied}be 0, meritorious, reactive power reference instruction P _o, Q ₀with islands active, reactive power reference instruction P ₀', Q ₀' equal, to be gained merit by the superposition of inverse dip part, reactive power instruction P _ref, Q _ref.As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, photovoltaic power-voltage curve that matching obtains searches out active power instruction P _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in inverse dip control model, and the frequency and voltage of photovoltaic power output and micro-capacitance sensor meets inverse dip relation.When load variations, because the frequency and voltage of photovoltaic power output and micro-capacitance sensor meets inverse dip relation, so the frequency and voltage of photovoltaic generation unit to micro-capacitance sensor has supporting role definitely, improve the stability of micro-capacitance sensor.

Below by accompanying drawing and preferred embodiment, technical scheme of the present invention is described in further detail.Should be appreciated that this time described preferred embodiment is only for instruction and explanation of the present invention, is not intended to limit the present invention.

Fig. 1 is the micro-capacitance sensor structure described in the embodiment of the present invention, comprises photovoltaic cell, photovoltaic DC bus capacitor, energy storage, photovoltaic DC-to-AC converter, energy storage inverter, LC filter, transformer, load, grid-connected switch and electrical network.Fig. 2,3 is inverse dip schematic diagrames, for setting forth the relation between active power and frequency, between reactive power and voltage.Fig. 4 is photovoltaic power-voltage curve matching flow chart, for setting forth photovoltaic power-voltage curve fitting theory.Fig. 5 is the entire block diagram that photovoltaic DC-to-AC converter inverse dip controls, and comprises inverse dip control module 1, photovoltaic power-voltage curve fitting module 2, power coordination controller 3, Voltage-Reactive Power closed loop control module 4, current inner loop controller 5, space vector pulse width modulation circuit 6.

In Fig. 1-5, the implication of each symbol is: f. micro-capacitance sensor ac bus frequency, f ₀. micro-capacitance sensor ac bus rated frequency, V. micro-capacitance sensor ac bus voltage, V ₀. micro-capacitance sensor ac bus rated voltage, θ. synchronous rotation transformation angle, m. active power inverse dip coefficient, n. reactive power inverse dip coefficient, P _o. active power reference instruction, Q ₀. reactive power reference instruction, P _ref. active power instruction, Q _ref. reactive power instruction, Q. photovoltaic output reactive power, i _pv. photovoltaic cell average anode current, V _pv. photovoltaic DC bus capacitor voltage, MPPT. MPPT maximum power point tracking, EN _mppt. MPPT maximum power point tracking enable signal, V _mppt. maximum power point voltage, IF _mppt. MPPT maximum power point tracking mode signal, V _dcref. photovoltaic DC busbar voltage reference value, i _dref. electric current d axle reference value, i _qref. electric current q axle reference value, i _d. photovoltaic DC-to-AC converter AC d shaft current, i _q. photovoltaic DC-to-AC converter AC q shaft current, u _d.d shaft voltage reference value, u _q.q shaft voltage reference value, P _mppt. maximum power point power, s _inv. photovoltaic DC-to-AC converter capacity, Q _max. maximumly send reactive power, IF _{grid_tied}. grid-connected signal, k _pdroop. meritorious inverse dip dot factor, k _qdroop. idle inverse dip dot factor, P ₀'. the instruction of islands active power reference, Q ₀'. the instruction of isolated island reactive power reference, P ₀ ^*. grid-connected active power reference instruction, Q ₀ ^*. grid-connected reactive power reference instruction, P _pv. photovoltaic exports direct current power, P _mggc. the instruction of microgrid central controller scheduling active power, Q _mggc. the instruction of microgrid central controller scheduling reactive power, C _pv. photovoltaic DC bus capacitor, L _pv. photovoltaic filter inductance value, C _lpv. photovoltaic filtering capacitance, i _pvabc. photovoltaic filter inductance electric current, V _pvabc. photovoltaic filter capacitor voltage, V _busabc. micro-capacitance sensor ac bus voltage, L _store. energy storage filter inductance value, C _store. energy storage filtering capacitance, SVPWM. space vector pulse width modulation, T _sample. the sampling time, the 1st, the 2nd, the 3rd the photovoltaic output direct current power sampled point that kth is secondary, the 1st, the 2nd, the 3rd the photovoltaic DC bus capacitor voltage sample point that kth is secondary, the 1st, the 2nd, the 3rd photovoltaic that kth is+1 time exports direct current power sampled point, the 1st, the 2nd, the 3rd the photovoltaic DC bus capacitor voltage sample point that kth is+1 time, a. matched curve secondary power coefficient, b. matched curve first power coefficient, c. matched curve constant term, P _pv(V _dcref). photovoltaic power-voltage matched curve.

In complete micro-capacitance sensor, as shown in Figure 5, concrete steps are as follows for photovoltaic DC-to-AC converter inverse dip control method:

(1) inverse dip control module 1 gathers micro-capacitance sensor ac bus voltage V _busabc, calculate micro-capacitance sensor ac bus frequency f and voltage V; Respectively with given micro-capacitance sensor ac bus rated frequency f ₀(generally getting 50Hz) and micro-capacitance sensor ac bus rated voltage V ₀(generally getting perunit value 1) is poor, and difference is added to after being multiplied by the inverse dip Coefficient m of setting, n respectively meritorious, reactive power reference instruction P _o, Q ₀on, to be gained merit, reactive power instruction P _ref, Q _ref, P _ref, Q _refwith the relation of f, V as shown in Figure 2,3.Wherein, meritorious, reactive power reference instruction P _o, Q ₀divide via power coordination controller portion and obtain.Inverse dip controls to be shown below:

$\left\{\begin{array}{c}{P}_{\mathrm{ref}}=P_0+m\×(f_0-f)\\ Q_{\mathrm{ref}}=Q_0+n\×(V_0-V)\end{array}\right.---\left(9\right)$

M, n wherein can be obtained by following formula:

$\left\{\begin{array}{c}m=-\frac{P_0-P_{\mathrm{mppt}}}{f_0-f_{\min }}\\ n=-\frac{Q_0-Q_{\max }}{V_0-V_{\min }}\end{array}\right.---\left(10\right)$

Wherein, f _minthat micro-capacitance sensor normally runs minimum tolerance frequency, such as 49.5Hz; V _minthat micro-capacitance sensor normally runs minimum permission voltage, such as perunit value 0.95.

(2) photovoltaic power-voltage curve matching flow process as shown in Figure 4.By fixed cycle T _samplesampling photovoltaic cell exports direct current i _pvwith dc-link capacitance magnitude of voltage V _dc, get up-to-date kth-2, k-1, k time three sampling calculated values compositions carry out matching and obtain photovoltaic power-voltage curve P _pv(V _dcref).Approximating method is as follows: sorted from small to large according to magnitude of voltage by three power vs. voltage points, without loss of generality, suppose then:

$P_{\mathrm{pv}}\left(V_{\mathrm{dcref}}\right)=a{V}_{\mathrm{dcref}}^2+b{V}_{\mathrm{dcref}}+c---\left(11\right)$

$a=\frac{P_{\mathrm{pv}\left(1\right)}^k}{(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(2\right)}^k}{(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(3\right)}^k}{(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)}---\left(12\right)$

$b=-[\frac{P_{\mathrm{pv}\left(1\right)}^k(V_{\mathrm{pv}\left(2\right)}^k+V_{\mathrm{pv}\left(3\right)}^k)}{(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(2\right)}^k(V_{\mathrm{pv}\left(1\right)}^k+V_{\mathrm{pv}\left(3\right)}^k)}{(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(3\right)}^k(V_{\mathrm{pv}\left(1\right)}^k+V_{\mathrm{pv}\left(2\right)}^k)}{(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)}]---\left(13\right)$

$c=\frac{P_{\mathrm{pv}\left(1\right)}^k{V}_{\mathrm{pv}\left(2\right)}^k{V}_{\mathrm{pv}\left(3\right)}^k}{(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)(V_{\mathrm{pv}\left(1\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(2\right)}^k{V}_{\mathrm{pv}\left(1\right)}^k{V}_{\mathrm{pv}\left(3\right)}^k}{(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(2\right)}^k-V_{\mathrm{pv}\left(3\right)}^k)}+\frac{P_{\mathrm{pv}\left(3\right)}^k{V}_{\mathrm{pv}\left(1\right)}^k{V}_{\mathrm{pv}\left(2\right)}^k}{(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(1\right)}^k)(V_{\mathrm{pv}\left(3\right)}^k-V_{\mathrm{pv}\left(2\right)}^k)}---\left(14\right)$

On this curve, search out maximum power point performance number P _mpptwith magnitude of voltage V _mppt, meet following relation:

$\left\{\begin{array}{c}{V}_{\mathrm{mppt}}=-\frac{b}{2a}\\ P_{\mathrm{mppt}}=\frac{4a\×c-b^2}{4a}\end{array}\right.---\left(15\right)$

Kth+1 sampling calculated value replace in turn or reset three groups of sampling calculated values that composition is new carry out matching, constantly update iteration thus, matching obtains new photovoltaic power-voltage curve.On new curve, constantly search out maximum power point performance number P _mpptwith magnitude of voltage V _mppt.

As the MPPT maximum power point tracking enable signal EN of micro-capacitance sensor central controller setting _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern.As the MPPT maximum power point tracking enable signal EN of micro-capacitance sensor central controller setting _mpptwhen being 0, if active power instruction P _refbe greater than P _mppt, then by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern; If active power instruction P _refbe less than P _mppt, then on this curve, active power instruction P is searched out _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 0, represent that photovoltaic is in and determine power tracking pattern.V _dcrefvalue can be obtained by following formula:

$V_{\mathrm{dcref}}=\frac{-b-\sqrt{(b^2-4a\×(c-P_{\mathrm{ref}}))}}{2a}---\left(16\right)$

(3) by maximum photovoltaic power point power P that photovoltaic power-voltage curve matching obtains _mpptwith the photovoltaic DC-to-AC converter capacity s in photovoltaic DC-to-AC converter nameplate _invcan try to achieve and maximumly send reactive power Q _max, meet following relation:

$Q_{\max }=\sqrt{(S_{\mathrm{inv}}^2-P_{\mathrm{mppt}}^2)}---\left(17\right)$

Maximum photovoltaic power point power P _mpptbe multiplied by the meritorious inverse dip dot factor k of setting _pdroop(can be taken as 0.7) obtains islands active power reference instruction P ₀', maximumly send reactive power Q _maxbe multiplied by the idle inverse dip dot factor k of setting _qdroop(can be taken as 0) obtains isolated island reactive power reference instruction Q ₀'; Micro-capacitance sensor central controller scheduling active power instruction P _mggcwith reactive power instruction Q _mggcgrid-connected active power reference instruction P is obtained through saturation element ₀ ^*with grid-connected reactive power reference instruction Q ₀ ^*, meritorious saturation limiting scope is 0 ~ P _mppt, idle saturation limiting scope is-Q _max~ Q _max.If grid-connected signal IF _{grid_tied}be 0, then meritorious, reactive power reference instruction P _o, Q ₀with islands active, reactive power reference instruction P ₀', Q ₀' equal; If grid-connected signal IF _{grid_tied}be 1, then meritorious, reactive power reference instruction P _o, Q ₀with grid-connected meritorious, reactive power reference instruction P ₀ ^*, Q ₀ ^*equal.

(4) reactive power instruction Q is obtained by step (1) _refphotovoltaic DC busbar voltage reference value V is obtained with step (2) _dcrefafter, then carry out closed-loop control by Voltage-Reactive Power closed loop control module.Electric current d axle reference value i is obtained through ratio, integral action _drefwith electric current q axle reference value i _qref.Photovoltaic output reactive power Q in Fig. 4 is by the photovoltaic filter capacitor voltage V collected _pvabcwith photovoltaic filter inductance current i _pvabccalculate through instantaneous power and obtain after low-pass filtering.

(5) electric current d axle reference value i is obtained _drefwith electric current q axle reference value i _qrefafter, then obtain d shaft voltage reference value u by current inner loop controller _dwith q shaft voltage reference value u _q, obtain photovoltaic DC-to-AC converter control signal finally by space vector pulse width modulation circuit.Photovoltaic DC-to-AC converter AC d shaft current i in Fig. 4 _dwith photovoltaic DC-to-AC converter AC q shaft current i _qby the photovoltaic filter inductance current i collected _pvabcobtain through synchronous rotation transformation, after synchronous rotation transformation angle θ is multiplied by 2 π by micro-capacitance sensor ac bus frequency f in step (1), integration obtains.

Finally should be noted that: above embodiment is only for above embodiment, only in order to technical scheme of the present invention to be described but not to be limited, although with reference to above-mentioned execution mode to invention has been detailed description, those of ordinary skill in the field are to be understood that: still can modify to the specific embodiment of the present invention or equivalent replacement, and not departing from any amendment of spirit and scope of the invention or equivalent replacement, it all should be encompassed in the middle of right of the present invention.

Claims (5)

1., for the photovoltaic DC-to-AC converter inverse dip controller of micro-capacitance sensor, be connected with micro-capacitance sensor ac bus; It is characterized in that, this controller comprises: inverse dip control module, photovoltaic power-voltage curve fitting module, power coordination controller, Voltage-Reactive Power closed loop control module, current inner loop controller and space vector pulse width modulation circuit; Described inverse dip control module is connected to micro-capacitance sensor ac bus, and its output is connected to photovoltaic power-voltage curve fitting module and power coordination controller respectively; The output of photovoltaic power-voltage curve fitting module and power coordination controller is connected to a PI controller separately, two PI controller composition Voltage-Reactive Power closed loop control modules; Voltage-Reactive Power closed loop control module, current inner loop controller and space vector pulse width modulation circuit connect successively.

2. photovoltaic DC-to-AC converter inverse dip control method in micro-capacitance sensor, it is characterized in that, realize whole inverse dip control procedure by photovoltaic DC-to-AC converter inverse dip controller: inverse dip control module gathers frequency f and the voltage V of micro-capacitance sensor ac bus, by it and rated frequency f ₀with rated voltage V ₀differ from, difference is added to after being multiplied by inverse dip Coefficient m, n respectively meritorious, reactive power reference instruction P ₀, Q ₀on, to be gained merit, reactive power instruction P _ref, Q _ref; Wherein meritorious, reactive power reference instruction P ₀, Q ₀obtain via power coordination controller; Photovoltaic power-voltage curve fitting module exports direct current by sampling photovoltaic cell and the matching of dc-link capacitance magnitude of voltage obtains photovoltaic power-voltage curve, finds the active power instruction P meeting inverse dip control module and obtain _refwith MPPT maximum power point tracking enable signal EN _mpptthe photovoltaic DC busbar voltage reference value V of two conditions _dcref; The reactive power instruction Q that inverse dip control module obtains _refwith photovoltaic DC busbar voltage reference value V _dcrefcarry out closed-loop control together, obtain electric current d axle reference value i through the ratio of Voltage-Reactive Power closed loop control module, integral action _drefwith electric current q axle reference value i _qref; Again by current inner loop controller and space vector pulse width modulation circuit realiration to the control of inverter.

3. method according to claim 2, is characterized in that, the operating procedure of described photovoltaic power-voltage curve fitting module comprises: input active power instruction P _ref, photovoltaic cell average anode current i _pv, photovoltaic DC bus capacitor voltage V _pvwith MPPT maximum power point tracking enable signal EN _mppt; Through fixed cycle T _samplesample, calculate photovoltaic output direct current power P _pvwith photovoltaic DC bus capacitor voltage V _pv, get up-to-date kth-2, k-1, k time three sampling calculated values compositions carry out matching and obtain photovoltaic power-voltage curve; On this curve, search out the maximum power point performance number P that kth is secondary _mpptwith magnitude of voltage V _mppt; Kth+1 sampling calculated value replace in turn or reset three groups of sampling calculated values that composition is new carry out matching, constantly update iteration thus, matching obtains new photovoltaic power-voltage curve; On new curve, constantly search out maximum power point performance number P _mpptwith magnitude of voltage V _mppt; As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, if active power instruction P _refbe greater than P _mppt, then by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 1, represent that photovoltaic is in MPPT maximum power point tracking pattern; If active power instruction P _refbe less than P _mppt, then on this curve, active power instruction P is searched out _refcorresponding magnitude of voltage; Owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _daref, MPPT maximum power point tracking mode signal IF simultaneously _mpptbe set to 0, represent that photovoltaic is in and determine power tracking pattern.

4. method according to claim 2, is characterized in that, described power coordination controller operating procedure comprises: the maximum photovoltaic power point power P obtained by photovoltaic power-voltage curve matching _mpptwith photovoltaic DC-to-AC converter capacity S _invtry to achieve and maximumly send reactive power with P _mpptbe multiplied by meritorious inverse dip dot factor k _pdroopobtain islands active power reference instruction P ₀', with Q _maxbe multiplied by idle inverse dip dot factor k _qdroopobtain isolated island reactive power reference instruction Q ₀'; The active power instruction P dispatched by micro-capacitance sensor central controller _mggcwith reactive power instruction Q _mggtgrid-connected active power reference instruction P is obtained through saturation element ₀ ^*with grid-connected reactive power reference instruction Q ₀ ^*, meritorious saturation limiting scope is 0 ~ P _mppt, idle saturation limiting scope is-Q _max~ Q _max; If grid-connected signal IF _{grid_tied}be zero, then meritorious, reactive power reference instruction P ₀, Q ₀with islands active, reactive power reference instruction P ₀', Q ₀' equal; If grid-connected signal IF _{grid_tied}be 1, then meritorious, reactive power reference instruction P ₀, Q ₀with grid-connected meritorious, reactive power reference instruction P ₀ ^*, Q ₀ ^*equal; Wherein, meritorious inverse dip dot factor k _pdroopspan between 0 ~ 1, idle inverse dip dot factor k _qdroopspan is between-1 ~ 1.

5. method according to claim 2, is characterized in that:

(1) when micro-capacitance sensor be in and net state time, grid-connected signal IF _{grid_tied}be 1, micro-capacitance sensor central controller scheduling active power instruction P _mggcwith reactive power instruction Q _mggcgained merit through saturation element, reactive power reference instruction P ₀, Q ₀, to be gained merit by the superposition of inverse dip part, reactive power instruction P _ref, Q _ref; As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, if active power instruction P _refbe greater than P _mppt, then by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; If active power instruction P _refbe less than P _mppt, then photovoltaic power-the voltage curve obtained in matching searches out active power instruction P _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in inverse dip control model; In addition, and under net state, the frequency f of micro-capacitance sensor ac bus and rated frequency f ₀, the voltage V of micro-capacitance sensor ac bus and rated voltage V ₀difference be all 0, so as micro-capacitance sensor central controller scheduling active power instruction P _mggcand reactive power instruction Q _mggcbe not more than maximum power point power P _mpptreactive power Q is sent with maximum _maxtime, meritorious, reactive power instruction P _ref, Q _refrespectively with P _mggc, Q _mggcequal, namely photovoltaic generation unit operates in and determines power tracking pattern, and the power sent is dispatched by micro-capacitance sensor central controller;

(2) when micro-capacitance sensor is in island state, grid-connected signal IF _{grid_tied}be 0, meritorious, reactive power reference instruction P ₀, Q ₀with islands active, reactive power reference instruction P ₀', Q ₀' equal, to be gained merit by the superposition of inverse dip part, reactive power instruction P _ref, Q _ref; As MPPT maximum power point tracking enable signal EN _mpptwhen being 1, by maximum power point voltage value V _mpptas photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in MPPT maximum power point tracking pattern; As MPPT maximum power point tracking enable signal EN _mpptwhen being 0, photovoltaic power-voltage curve that matching obtains searches out active power instruction P _refcorresponding magnitude of voltage, owing to photovoltaic power-voltage curve there being the corresponding P of two magnitudes of voltage _ref, get larger magnitude of voltage as photovoltaic DC busbar voltage reference value V _dcref, through closed-loop control, photovoltaic generation unit will operate in inverse dip control model, and the frequency and voltage of photovoltaic power output and micro-capacitance sensor meets inverse dip relation.