A kind of multifunctional photovoltaic parallel control method design
Requirement based on the energy, environment and economy sustainable development, designs the replacement to traditional electrical network, developing intellectual resource type, makes full use of the direction that renewable energy power generation is 21 century electric network reconstruction.Distributed photovoltaic power generation is owing to having adopted the clean solar energy of a large amount of greens and can become the important component part of power network development from now on for user provides reliable, high-quality electric energy.Up to now, being incorporated into the power networks in developing stage of distributed photovoltaic power generation, is very important so increase the research and design of the grid-connected control of distributed photovoltaic power generation.
The present invention---a kind of multifunctional photovoltaic parallel control method design, mainly for the end at distribution network, particularly, away from the outlying district of electrical network, the reactive power fluctuation of load will produce larger impact to mains supply voltage, and then has influence on other loads on this node.If can utilize photovoltaic generating system to regulate the alternating voltage of grid-connected node, will produce active influence to the application of photovoltaic generating system, tool is of great significance.
For the problems referred to above, the present invention is a kind of three-phase photovoltaic grid-connected control strategy combining with voltage control based on MPPT maximum power point tracking (MPPT), make photovoltaic system when realizing MPPT maximum power point tracking, can also control the alternating voltage of grid integration point place system side, maintain the voltage constant of system, with this, save the investment of relevant device, promote the application prospect of grid-connected photovoltaic system.The invention enables that distributed photovoltaic power generation is grid-connected provides frequency support to become possibility, for advancing the development of China's intelligent grid, played positive effect.
Distributed photovoltaic power generation is electric network reconstruction, developing intellectual resource type, make full use of a Typical Representative of the generating of regenerative resource, yet in the grid-connected function of distributed photovoltaic power generation, the example of the method that neither one is clear and definite, therefore by photovoltaic generation and storage battery, coordinate for electrical network provides the method design that frequency supports and be necessary, this,, when advancing development of new techniques, has reached again significant effect.
Summary of the invention
Technical problem to be solved by this invention is, proposes the method for designing of the grid-connected control of a kind of effective photovoltaic generating system, for electrical network provides more electric energy, promotes the development of photovoltaic industry.
The present invention includes: photovoltaic generation model, battery model, control structure model, DC/DC controller, DC/AC controller, coupling inductor, circuit breaker, industrial load model, power-measuring device.
Photovoltaic generation model is the photovoltaic generation power stage in different illumination conditions, varying environment temperature for realistic simulation.
Battery model is the charge status of the different state-of-charges of main imitated storage battery from DC/DC controller.
DC/AC controller is that simulation control distributed power source is grid-connected, and coupling inductor is that simulation guarantees that line impedance presents perception.
Power detection device is for detection of the real-time active power of electrical network and reactive power.
MPPT-voltage controller is for DC/AC controller being produced to the control of specific function.
Accompanying drawing explanation
Fig. 1 is the whole principle assumption diagram of photovoltaic storage battery electricity generation system networking operation;
Fig. 2 is MPPT-voltage control strategy figure;
Below in conjunction with example and accompanying drawing, the present invention-a kind of multifunctional photovoltaic parallel control method design is elaborated.
As shown in Figure 1, photovoltaic cells does not adopt DC/DC controller, photovoltaic generation unit is connected on same DC bus with the storage battery through DC/DC controller, DC bus connects two-way DC/AC controller, by circuit breaker S1, connect industrial load model, butt coupling inductor again, this coupling inductor can, by circuit breaker S3 bypass, be connected with main electrical network finally by crossing circuit breaker S2.In Fig. 1, control system is divided into 3 parts: phase-locked loop module, MPPT-voltage controller module and impulse wave modulation module (PWM ripple).Phase-locked loop module is used for guaranteeing that photovoltaic system grid-connected current (Iabc) synchronizes with system voltage (Us), and output Sin_cos signal is to MPPT-voltage controller.MPPT-voltage controller receives measured value (Urms) and the reference value (Uref) of direct voltage (Udc), direct current (Idc), grid-connected current, alternating voltage, after MPPT-voltage control strategy is controlled, produce modulating wave (uabc), deliver to impulse wave modulation module, control photovoltaic generation from DC converting to the process exchanging.
As shown in Figure 2, a kind of three-phase photovoltaic grid-connected control strategy combining with voltage control based on MPPT maximum power point tracking (MPPT), its design philosophy is as follows:
In actual grid-connected photovoltaic system, its DC terminal is parallel with electric capacity of voltage regulation C, therefore, can utilize this electric capacity, controls the idle component of its output grid-connected current, with this, maintains the constant of grid-connected system side alternating voltage.The real component of simultaneously controlling grid-connected current by MPPT completes the control to meritorious output.By the control strategy of MPPT-voltage, control respectively the meritorious and idle component of grid-connected current, realize grid-connected maximum power point output and maintain node voltage constant.
As shown in Figure 2, what this control strategy was taked is two closed loop controlling structures, and its outer shroud is Voltage loop, and interior ring is grid-connected current ring.By abc/dq0, converting, is real component and idle component 2 parts by grid-connected current decoupling zero.
For real component, using the output valve of MPPT maximum power point tracking module (MPPT) (Um) as reference value, the real work voltage (Udc) of this value and photovoltaic array is compared, its deviation after proportional integral (PI) regulates resulting value (Idref) as the active component of current reference value of grid-connected current ring.
For idle component, the alternating voltage reference value (Uref) of setting and the virtual voltage (Urms) of AC system are compared, its deviation after PI regulates resulting value (Iqref) as the reactive component of current reference value of grid-connected current ring.
The real component of grid-connected current (Id) and idle component (Iq) be the difference after relatively with reference quantity Idref, Iqref respectively, through proportional component PI, regulate, and after dq0/abc inverse transformation, output modulating wave (uabc), realizes grid-connected direct current to the inversion exchanging with this.
Therefore, this control strategy system not only can realize three-phase photovoltaic grid-connected MPPT maximum power point tracking, can also control the alternating voltage of photovoltaic generating system access point, has further promoted the effect of grid-connected photovoltaic system.