CN105305491A - Virtual synchronous generator-based photovoltaic power control strategy - Google Patents

Abstract

The invention discloses a photovoltaic power supply control strategy based on a virtual synchronous generator, which includes: a photovoltaic power generation system, an energy storage device and an inverter device; the power output end of the photovoltaic power generation system is respectively connected to the energy storage device energy storage end and the inverter device The inverter end, the output end of the inverter device is connected to the power grid, the inverter device performs power control through the virtual synchronous generator method, and the output power of the inverter device is adjusted to reach a stable state through the virtual synchronous generator method. According to the fluctuation of the load, adjusting its own output power can maintain the frequency and voltage stability of the photovoltaic system, and effectively improve the grid-connected power generation performance of the photovoltaic power station.

Description

A Photovoltaic Power Control Strategy Based on Virtual Synchronous Generator

technical field

The invention relates to solar photovoltaic grid-connected power generation technology, in particular to a photovoltaic power supply control strategy based on a virtual synchronous generator.

Background technique

Solar photovoltaic grid-connected power generation technology is one of the hot spots in new energy research and development at present. However, there are great differences between photovoltaic power generation systems and traditional power generation methods. Solar photovoltaic power generation has the characteristics of intermittent, random, and low dispatchability. Power output is often subject to external environmental factors. Changes in light intensity and ambient temperature will cause fluctuations in the power output of photovoltaic power generation systems. Especially in cloudy weather, power fluctuations in photovoltaic power generation will affect the power supply of users in the microgrid. Quality has a serious negative impact. In addition, photovoltaic power generation is connected to the microgrid based on the power electronic interface. It does not have the moment of inertia of the traditional rotating generator, and its ability to overcome load fluctuations is relatively poor. Microgrid load fluctuations will cause voltage and frequency fluctuations in the power system. Compared with the traditional large power grid, the capacity of the microgrid is not high, the system inertia is relatively small, and photovoltaic power generation is random and uncontrollable. The safe and stable operation of the power grid has a negative impact.

Photovoltaic power generation is connected to the microgrid through inverters. When the microgrid is in the network operation mode, the large grid provides rigid voltage and frequency support, and the photovoltaic power generation works in the state of voltage source or current source. The traditional photovoltaic power generation control strategy is adopted to adjust the power output, and the system can run stably. When the large power grid fails, the micro-grid will enter the island operation mode, and the voltage (referring to the voltage amplitude) and frequency at this time must be adjusted by the internal micro-power controller. According to the micro-source control requirements of different operation modes of the micro-grid, it can be seen that the traditional photovoltaic power generation control method is difficult to meet the requirements of flexible and stable operation of the micro-grid. How to effectively control the photovoltaic power supply in the microgrid, realize the stable operation of different operating modes of the microgrid and the smooth switching between modes is the key to the reliable operation of the microgrid. This just needs those skilled in the art to solve corresponding technical problem badly.

Contents of the invention

The present invention aims at at least solving the technical problems existing in the prior art, and particularly innovatively proposes a photovoltaic power supply control strategy based on a virtual synchronous generator.

In order to achieve the above object of the present invention, the present invention provides a photovoltaic power supply control strategy based on a virtual synchronous generator, which includes: a photovoltaic power generation system, an energy storage device and an inverter device;

The output terminals of the power supply of the photovoltaic power generation system are respectively connected to the energy storage terminal of the energy storage device and the inverter terminal of the inverter device, and the output terminal of the inverter device is connected to the power grid. The generator method adjusts the output power of the inverter device to reach a steady state.

The photovoltaic power supply control strategy based on virtual synchronous power generation, preferably, also includes:

The second-order model of the synchronous generator mainly includes the rotor motion equation and the stator equation, as shown in formula (1), when the influence of the salient pole effect is ignored and the number of pole pairs p=1, the electrical angle is equal to the mechanical angle;

$\begin{array}{c}\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; =</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; wxya</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}\\ \mathrm{<span\; class="notranslate">\; J</span>}\frac{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, J is the moment of inertia, kg.m ² , D is the damping coefficient, reflecting the function of the damping winding;

P _m is the mechanical power, P _e is the electromagnetic power,

ω is the angular frequency of the rotor, θ is the electrical angle,

E is the electromotive force in the stator, V is the terminal voltage,

R _t is resistance, X _t is synchronous reactance,

I is the stator current;

The algorithm obtains multiple signals, including: three-phase stator internal electromotive force e _a , e _b , e _c , three-phase stator current i _a , i _b , i _c , output active power P _VSG , output reactive power Q _VSG and rotor Angular velocity ω.

The photovoltaic power supply control strategy based on virtual synchronous power generation preferably also includes:

Obtain reference power from the inverter device through the virtual synchronous generator method, calculate the reference power through the inverter control method, send it to the virtual synchronous generator method and compare it with the energy management control method of the energy storage device, and adjust the energy storage in real time The output power of the device.

The photovoltaic power supply control strategy based on virtual synchronous power generation, preferably, also includes:

The current and voltage in the LC filter are detected by the current transformer and the voltage transformer respectively, and these signals are fed back to the power frequency controller and the excitation controller respectively to realize the input mechanical power and excitation electromotive force of the virtual synchronous generator. The command value is adjusted in real time, and then the output of the inverter device is adjusted through the algorithm of the virtual synchronous generator, so as to realize the balance of the system power output and maintain the stability of the system voltage and frequency.

The photovoltaic power supply control strategy based on virtual synchronous power generation preferably includes:

Applying the power-frequency characteristic adjustment method to the photovoltaic inverter control process based on the virtual synchronous generator,

Where f _ref is the frequency command value, f is the frequency feedback value, P _N is the rated value of active power, K _i is the integral coefficient, P _m is the output power of the power frequency controller, P _ref is the power given value; P _m is equivalent to The output mechanical power of the prime mover of the synchronous machine, the P _N value is given by the central controller of the microgrid; the frequency fluctuation variation Δf caused by the load fluctuation acts on the power frequency controller, and the active power output command value of the prime mover P _ref is obtained, At this time, P _ref = P _m , and then the balance of active power is realized, which is equivalent to a frequency regulation of the power system. Since the primary frequency regulation is only for load fluctuations with a short fluctuation period and a small change range, in order to adapt to a load with a long period and a large range fluctuations, it is necessary to further adjust the output active power of the virtual synchronous generator; therefore, the frequency deviation Δf can be adjusted to the frequency without difference through the integral regulator, and the frequency can be maintained at the command value f _ref to realize the virtual synchronous generator. Secondary FM.

The photovoltaic power supply control strategy based on virtual synchronous power generation preferably includes:

Form the excitation controller of the synchronous generator, when Q _N =Q, when the virtual synchronous generator runs in the state of rated reactive power, the output voltage of U′ _ref =U _ref system is the rated voltage; when the reactive load changes suddenly, ΔQ ≠0, the excitation control system adjusts the excitation current according to the voltage deviation △U, and changes the value of the excitation voltage; through the excitation controller, the excitation voltage of the virtual synchronous generator body is controlled, so that the machine terminal voltage increases with the reactive power The increase of the output increases, so that it has a drooping characteristic; since the proportional integral adjustment is used in the excitation controller, it can realize the non-difference control of the excitation voltage;

Photovoltaic grid-connected inverters have two control methods: grid-connected current control and output voltage control. The VSG algorithm outputs a voltage reference signal as a given reference signal for the inverter voltage control loop.

In summary, owing to adopting above-mentioned technical scheme, the beneficial effect of the present invention is:

Synchronous generators have good networking characteristics. If the photovoltaic power generation system can simulate the characteristics of synchronous generators, it will effectively avoid the hidden dangers of large-scale application of photovoltaic power generation, which is of great significance to the development of photovoltaic power generation technology. Therefore, the present invention designs a photovoltaic grid-connected power generation system structure and control strategy based on the idea of a virtual synchronous generator (Virtual Synchronous Generator, VSG), so that the power delivered by the photovoltaic power generation system to the grid is smooth, and the power of the synchronous generator is reflected in the large power grid. According to the fluctuation of the load, it can adjust its own output power, which can maintain the frequency and voltage stability of the photovoltaic system, and effectively improve the grid-connected power generation performance of the photovoltaic power station.

Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and comprehensible from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 is a schematic diagram of photovoltaic grid connection based on a virtual synchronous generator in the present invention;

Fig. 2 is the control block diagram of the voltage control mode grid-connected inverter based on the VSG algorithm of the present invention;

Fig. 3 is a schematic diagram of the VSG ontology algorithm of the present invention;

Fig. 4 is a schematic diagram of the virtual synchronous generator power frequency controller of the present invention;

Fig. 5 is a schematic diagram of a virtual synchronous generator excitation controller of the present invention;

Fig. 6 is a power control method based on a virtual synchronous generator algorithm of the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention.

In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be mechanical connection or electrical connection, or two The internal communication of each element may be directly connected or indirectly connected through an intermediary. Those skilled in the art can understand the specific meanings of the above terms according to specific situations.

The present invention learns from many advantages of synchronous generators operating in the power system and the method of frequency regulation and voltage regulation, adopts the second-order classic model of synchronous generators, adds the algorithm of synchronous generators to the inverter control link, and invents virtual synchronous generators and Its power frequency controller and excitation controller enable distributed photovoltaic power generation to have the characteristics of synchronous generators. The schematic diagram of the realization process of synchronous generators is shown in Figure 1:

The invention provides a photovoltaic power supply control strategy based on a virtual synchronous generator, which includes: a photovoltaic power generation system, an energy storage device and an inverter device;

The output terminal of the power supply of the photovoltaic power generation system is connected to the energy storage terminal of the energy storage device and the inverter terminal of the inverter device respectively, and the output terminal of the inverter device is connected to the power grid. The generator method adjusts the output power of the inverter device to reach a steady state.

The distributed power supply, energy storage device and inverter device included in the dotted line box in Figure 1 are the hardware part of the virtual synchronous generator. By debugging the parameters of these devices, the control algorithm of the virtual synchronous generator is implemented through the inverter device. accomplish.

At present, the photovoltaic power generation system using the commonly used grid-connected inverter control strategy has no inertia. In order to make the photovoltaic power generation system simulate the virtual inertia of the synchronous generator, the most direct way to implement the virtual synchronous generator (VSG) algorithm in the photovoltaic power generation system is to combine it with the inverter control strategy. Photovoltaic grid-connected inverters have two control methods: grid-connected current control and output voltage control. The VSG algorithm can obtain both the corresponding voltage reference signal and the current reference signal.

The present invention learns from many advantages of synchronous generators operating in the power system and the method of frequency regulation and voltage regulation, adopts the second-order classic model of synchronous generators, adds the algorithm of synchronous generators into the inverter control link, and invents virtual synchronous generators and Its power frequency controller and excitation controller can more realistically simulate the operating characteristics of synchronous generators, so that distributed photovoltaic power generation has the characteristics of synchronous generators.

The second-order model of the synchronous generator mainly includes the rotor motion equation and the stator equation, as shown in formula (1), when the saliency effect is ignored and the number of pole pairs p=1, the electrical angle is equal to the mechanical angle.

$\begin{array}{c}\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; =</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; u</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; wxya</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; )</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; I</span>}}\\ \mathrm{<span\; class="notranslate">\; J</span>}\frac{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; \&omega;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; \&omega;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}\mathrm{<span\; class="notranslate">\; t</span>}}\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, J is the moment of inertia, kg.m ² , D is the damping coefficient, reflecting the function of the damping winding;

P _m is the mechanical power, P _e is the electromagnetic power,

ω is the angular frequency of the rotor, θ is the electrical angle,

E is the electromotive force in the stator, V is the terminal voltage,

R _t is resistance, X _t is synchronous reactance,

I is the stator current;

According to the equation shown in formula (1), the virtual synchronous generator control block diagram shown in Figure 3 can be obtained. This figure shows the VSG algorithm model for the three-phase system. Since the prime mover and excitation system are not considered, it is called the VSG body algorithm. This algorithm can obtain multiple signals, including: three-phase stator internal electromotive force e _a , e _b , e _c , three-phase stator current i _a , i _b , i _c , output active power P _VSG , output reactive power Q _VSG and Rotor angular velocity ω.

The present invention learns from the traditional synchronous generator control structure, establishes a photovoltaic inverter power supply based on a virtual synchronous generator, and replaces the governor and the excitation system with a power frequency controller and an excitation controller, as shown in Figure 2. The current and voltage in the LC filter are detected by the current transformer and the voltage transformer respectively, and these signals are fed back to the power frequency controller and the excitation controller respectively to realize the input mechanical power and excitation electromotive force of the virtual synchronous generator. The command value is adjusted in real time, and then the output of the inverter device is adjusted through the algorithm of the virtual synchronous generator, so as to realize the balance of the system power output and maintain the stability of the system voltage and frequency.

(1), virtual synchronous generator power frequency controller

Referring to the frequency adjustment method of synchronous generators, the power-frequency characteristic adjustment method is applied to the photovoltaic inverter control process based on synchronous generators. The control algorithm is shown in Figure 4:

Where f _ref is the frequency command value, f is the frequency feedback value, P _N is the rated value of active power, K _i is the integral coefficient, P _m is the output power of the power frequency controller, and P _ref is the power given value. P _m is equivalent to the output mechanical power of the prime mover of the synchronous machine, and the value of P _N is given by the central controller of the microgrid. After the frequency fluctuation variation Δf caused by load fluctuation acts on the power-frequency controller, the active power output command value P _ref of the prime mover (at this time P _ref =P _m ) is obtained, and then the active power balance is realized, which is equivalent to the power system one FM. Since the primary frequency regulation is only aimed at load fluctuations with a short fluctuation period and a small change range, in order to adapt to the load fluctuations with a longer period and a larger range, it is necessary to further adjust the output active power of the virtual synchronous generator. Therefore, the frequency deviation Δf can be adjusted without difference through the integral regulator, that is, the frequency can be maintained at the command value f _ref , and the secondary frequency regulation of the virtual synchronous generator can be realized.

(2) Excitation controller of virtual synchronous generator

The synchronous generator excitation controller of the present invention is shown in Fig. 5, when Q _N =Q, when the virtual synchronous generator operates in the state of rated reactive power, the output voltage of the U' _ref =U _ref system is the rated voltage. When the reactive load changes suddenly, ΔQ≠0, the excitation control system adjusts the excitation current according to the voltage deviation ΔU, and changes the value of the excitation voltage. The excitation controller can control the excitation voltage of the virtual synchronous generator body, so that the machine terminal voltage increases with the increase of reactive power output, so that it has a drooping characteristic. Since the proportional integral regulation is adopted in the controller, it can realize the non-difference control of the excitation voltage.

The most direct way to realize the virtual synchronous generator (VSG) algorithm in photovoltaic power generation system is to combine it with the inverter control strategy. Photovoltaic grid-connected inverters have two control methods: grid-connected current control and output voltage control. The VSG algorithm can obtain both the corresponding voltage reference signal and the current reference signal. The present invention selects an output voltage control type photovoltaic inverter, adopts an LC type filter, and uses a VSG algorithm to output a voltage reference signal as a given reference signal of the voltage control loop of the inverter. The grid-connected inverter and the overall control block diagram of the voltage control method using the VSG algorithm are shown in Figure 3:

For photovoltaic power generation systems, the role of virtual inertia is mainly reflected in the impact on its power output characteristics during the transient process. Therefore, the role of virtual inertia can be realized by using special power control. The adjustment of active power needs to be combined with energy storage devices. The inverter itself has the function of adjusting reactive power, and the commonly used control strategies of grid-connected inverters can achieve a given output of reactive power, and the instantaneous reactive power can be precisely adjusted when calculating the given current reference signal Its output reactive power, based on the analysis of the characteristics of the VSG algorithm, the present invention invents a power control strategy based on the VSG algorithm, as shown in Figure 6:

When the inverter adopts the voltage and current double closed-loop control strategy, its output active power is dynamically adjusted with the power supplied to the DC bus by the previous stage, and it is only necessary to make the sum of the output power of the photovoltaic array and the energy storage device and the real-time active power of the VSG algorithm If P _VSG is equal, the photovoltaic system as a whole will have active power output characteristics under the action of virtual inertia.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.

Claims (6)

1. based on a photo-voltaic power supply control strategy for virtual synchronous generator, it is characterized in that, comprising: photovoltaic generating system, energy storage device and inverter;

Photovoltaic generating system power output end connects energy storage device energy storage end and inverter inversion end respectively, described inverter output connects electrical network, described inverter carries out power control by virtual synchronous generator method, regulates inverter power output to reach stable state by virtual synchronous generator method.

2. the photo-voltaic power supply control strategy based on virtual synchronous generating according to claim 1, is characterized in that, also comprise:

Synchronous generator second-order model mainly comprises equation of rotor motion and stator equation, and shown in (1), when ignoring saliency impact, and make number of pole-pairs p=1, then electrical degree equals mechanical angle;

$\begin{array}{c}\stackrel{\&CenterDot;}{E}=\stackrel{\&CenterDot;}{U}+\left(R_t+{\mathrm{jX}}_t\right)\stackrel{\&CenterDot;}{I}\\ J\frac{d\mathrm{\&Delta;}\mathrm{\&omega;}}{dt}=\frac{P_m-P_e}{\mathrm{\&omega;}}-D\left(\mathrm{\&omega;}-{\mathrm{\&omega;}}_N\right)\end{array}---\left(1\right)$

$\mathrm{\&omega;}=\frac{d\mathrm{\&theta;}}{dt}$

In formula, J is moment of inertia, kg.m ², D is damping coefficient, embodies the effect of damping winding;

P _mfor mechanical output, P _efor electromagnetic power,

ω is rotor angle frequency, and θ is electrical degree,

E is stator internal e.m.f., and V is terminal voltage,

R _tfor resistance, X _tfor synchronous reactance,

I is stator current;

This algorithm obtains multiple signal, comprising: threephase stator internal e.m.f. e _a, e _b, e _c, threephase stator current i _a, i _b, i _c, active power of output P _vSG, output reactive power Q _vSGand rotor velocity ω.

3. the photo-voltaic power supply control strategy based on virtual synchronous generating according to claim 2, is characterized in that, also comprise:

Reference power is obtained from inverter by described virtual synchronous generator method, reference power calculating is carried out by inversion controlling method, the energy management control method being sent to virtual synchronous generator method and energy storage device is compared, in real time the power output of adjustment energy storage device.

4. the photo-voltaic power supply control strategy based on virtual synchronous generating according to claim 1, is characterized in that, also comprise:

Respectively electric current, voltage in LC filter are detected by current transformer and voltage transformer, and these signals are fed back to power and frequency control device and excitation controller respectively, realize adjusting in real time the input mechanical output of virtual synchronous generator and the command value of excitation electric gesture, export through virtual synchronous generator algorithm adjustment inverter again, and then realize the balance of system power output, maintain system voltage and frequency stabilization.

5. the photo-voltaic power supply control strategy based on virtual synchronous generating according to claim 1, is characterized in that, comprising:

Merit frequency method of regulating characteristics is applied in the photovoltaic inversion control procedure based on virtual synchronous generator,

Wherein f _reffor frequency instruction value, f is frequency feedback value, P _nfor active power rated value, K _ifor integral coefficient, P _mfor power and frequency control device power output, P _reffor power given value; P _mbe equivalent to synchronous motor prime mover output mechanical power, P _nbe worth given by microgrid central controller; After the frequency fluctuation variation delta f caused by load fluctuation acts on power and frequency control device, the active power obtaining prime mover is exerted oneself command value P _ref, now P _ref=P _mand then realize active power balance, this is equivalent to the primary frequency modulation of electric power system, due to primary frequency modulation only, load fluctuation that amplitude of variation little short for period of waves, longer in order to adapt to the cycle, the load fluctuation that scope is larger, needs the active power of output regulating virtual synchronous generator further; Therefore, frequency deviation f can be made to realize the non differential regulation to frequency through integral controller, frequency can be maintained command value f _ref, realize the frequency modulation frequency modulation of virtual synchronous generator.

6. the photo-voltaic power supply control strategy based on virtual synchronous generating according to claim 1, is characterized in that, comprising:

Form synchronous generator exciting controller, work as Q _nduring=Q, virtual synchronous generator operation when the state of nominal reactive, U ' _ref=U _refthe output voltage of system is rated voltage; When reactive load suddenlys change, Δ Q ≠ 0, exciter control system regulates exciting current according to voltage deviation △ U, changes the size of exciting voltage value; Controlled by the exciting voltage of this excitation controller to virtual synchronous engine block, the increase that set end voltage is exported along with reactive power and increasing, make it that there is droop characteristic; Due to adoption rate integral adjustment in this excitation controller, so the indifference that can realize exciting voltage controls;

Photovoltaic combining inverter has grid-connected current to control and output voltage control two kinds of control modes respectively, and VSG algorithm obtains corresponding voltage reference signal and current reference signal; Select output voltage control type photovoltaic DC-to-AC converter, adopt LC mode filter, VSG algorithm output voltage reference signal is as the given reference signal of contravarianter voltage control ring.