Photovoltaic grid-connected inverter dynamic performance optimization method based on MPDPC
A technology of dynamic performance and optimization method, which is applied in the direction of photovoltaic power generation, AC network circuit, single-network parallel feeding arrangement, etc., can solve the problems affecting the popularization and application, the deterioration of the dynamic performance of the inverter system, and the impact, so as to achieve accurate design and simple , improve dynamic response performance, and suppress the effect of coupling
Active Publication Date: 2018-08-14
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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However, the index function of this method is composed of the error sum of the squares of the two control objectives of active power and reactive power, so these two control objectives cannot be separated from the other independent control, and any change in one of them will have an impact on the other
With the increase of active power and reactive power variation, the coupling phenomenon of the two in the control process becomes more and more serious, and the dynamic performance of the inverter system deteriorates.
In this regard, "DynamicPerformance Improvement of AC / DC Converter Using Model Predictive DirectPower Control Finite Control Set" published by Dae KeunChoi et al. on IEEE Transactions on Industrial Electronics reduced the dynamic performance of the system by adding two weight coefficients to the indicator function. However, it is very difficult to accurately design the weight coefficients of this method, which requires repeated trials and debugging, which affects its popularization and application
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[0046] The topology of the main circuit of the three-phase voltage photovoltaic grid-connected inverter is as follows: figure 1 shown. Its mathematical model in the stationary αβ coordinate system is:
[0047]
[0048] In the formula: R and L are the AC side resistance and inductance respectively; u s and i s Respectively, grid voltage and current; u c is the inverter output voltage vector, its value is determined by the switch state and DC side voltage, the expression is as follows:
[0049]
[0050] Among them, U dc is the DC side voltage of the inverter, S con is the inverter switch state vector; where, s j =1(j=a,b,c) means the upper bridge arm is on and the lower bridge arm is off, s j = 0 means the lower bridge arm is turned on and the upper bridge arm is turned off.
[0051] According to the instantaneous power theory, the grid-side complex power S can be expressed as:
[0052]
[0053] Among them, "*" is the conjugate factor, and p and q represent act...
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The invention relates to a photovoltaic grid-connected inverter dynamic performance optimization method based on MPDPC, and the method comprises the following steps: S1, detecting three-phase grid voltage, three-phase grid current and direct current bus voltage of a three-phase voltage type photovoltaic grid-connected inverter system of the current moment k, and performing calculation to predict active power and reactive power of a moment k+1; S2, according to the active power and the reactive power of the moment k+1, predicting backwards one beat and acquiring the active power and the reactive power of a moment k+2; S3, substituting the active power and the reactive power of the moment k+2 into an improved index function, performing amplitude limiting for a power difference value, therebyselecting an optimal nonzero vector; S4, acquiring duty ratio of the time when the optimal nonzero vector and a zero vector act in combination, and through modulating the duty ratio, obtaining a switching signal for controlling power devices. Compared with the existing technology, the method provided by the invention can restrain coupling between active and reactive of a grid-connected system, moreover, system dynamic response performance is improved remarkably while power control steady-state performance of the conventional MPDPC method is kept.
Description
technical field [0001] The invention relates to the technical field of power electronics, in particular to a method for optimizing the dynamic performance of a photovoltaic grid-connected inverter based on MPDPC. Background technique [0002] With the rapid development of the economy, the reduction of non-renewable energy sources and the increasingly serious problems of environmental pollution, distributed generation technology has attracted widespread attention. As the interface between the photovoltaic power generation system and the grid, the grid-connected inverter is the core of the distributed power generation system, and its control performance directly affects the power quality output by the power generation system, so it has been extensively studied. [0003] At present, grid-connected inverter control technology has become a research hotspot in the field of power electronics. The most commonly used inverter control methods are voltage oriented control (voltage ori...
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IPC IPC(8): H02J3/38H02J3/48H02J3/50
CPCH02J3/383H02J3/48H02J3/50H02J2203/20Y02E10/56
Inventor 杨兴武牛梦娇王孟结符杨李豪李芬米阳
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER