Control method for photovoltaic grid connection inverter with wide input range
A control method and inverter technology, applied in the direction of photovoltaic power generation, control/regulation systems, instruments, etc., can solve the problems of difficult selection of system component parameters, difficulty in controller optimization design, etc., and achieve simplified optimization design and convenient selection Effect
Inactive Publication Date: 2009-07-15
SHANGHAI AERO SHARP ELECTRIC TECH
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Problems solved by technology
[0006] In view of the above-mentioned technical limitations and the technical problems to be solved, the purpose of the present invention is to solve the problem that the single-stage grid-connected inverter is difficult to select the parameters of the system components and the optimal design of the controller due to the large input voltage range, and proposes a The improved control method keeps the transfer function of the control system constant when the DC voltage changes relative to the rated voltage, so as to overcome the influence of the DC voltage change on the system
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[0023] In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the present invention will be further described below in conjunction with specific illustrations.
[0024] The following is the specific implementation process according to the technical solution of the present invention:
[0025] (1) Control method and design;
[0026] figure 2 Shown is the DC voltage control block diagram. Voltage controller transfer function G v (s) are:
[0027] G v (s)=k pv +k iv / s (1)
[0028] where k pv is the proportional coefficient, k iv is the integral coefficient. G v output i of (s) m is the given peak value of the current, the effective value I of the inverter output current s By the current sampling coefficient k if and current peak signal i m decide, there are:
[0029] I s i m = ...
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The present invention discloses a control method for wide inputting range single-stage grid-connected inverter, and the single-stage solar energy grid-connected inverter is required to have wide direct-current input scope and big deviation rated input voltage, hence system control characteristics have big variation problem; adjust control parameter at real time according to variation of direct current voltage relative to the rated voltage, thereby system transfer function keeps the same under condition of rated direct voltage. Particularly two methods are adopted to realize steadfastness of system closed loop transfer function: one is to make proportionality and integration coefficient of PI controller change correspondingly along with variation of direct current voltage in a same proportion; two is to change amplitude of radio-frequency carrier signal. The method provided in the invention allows control characteristics of single-stage grid-connected inverter keep the same relative to variation of direct-current input voltage, hence control system of the inverter can design according to rated condition, and that provides great conveniency for selection of circuit components and parts parameter and optimum design of controller.
Description
Technical field: [0001] The invention relates to a control method for a grid-connected inverter, in particular to a current control method for a single-stage photovoltaic grid-connected inverter with a wide voltage input range. Background technique: [0002] In the solar grid-connected power generation system, the output characteristics of the solar cell array change with the external environmental conditions, and the ratio of the highest working voltage to the lowest working voltage can reach 2.5-3 or even higher, so the inverter must be able to operate in a wide range Normal operation within the DC input voltage range. The single-stage photovoltaic grid-connected inverter has only one stage of power conversion, which has the advantage of high conversion efficiency. The system control characteristics change with the change of the photovoltaic array operating voltage. The control system design should consider the extreme input voltage and cannot be carried out according to t...
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Login to View More IPC IPC(8): H02J3/38H02N6/00G05F1/10
CPCY02E10/563Y02E10/56
Inventor 相海涛蒋海江
Owner SHANGHAI AERO SHARP ELECTRIC TECH