Research On Synchronization And Control Technology Of LCL Grid-connected Inverter Under Non-ideal Conditions

The non-ideal condition of power grid is an important factor affecting the stability of power grid.In this paper,the non-ideal characteristics of solar power generation system under the operation mode of power grid are analyzed.Specifically,more and more solar systems are connected to the grid by connecting to it.How to connect the network safely under the non-ideal conditions is a problem that many experts and scholars are exploring.In this paper,the non-ideal power grid conditions are three-phase voltage imbalance and high-order harmonic pollution.The method based on state space average is used to model the system,and the three-phase LCL gridconnected inverter is studied and discussed.On this basis,the synchronization technology of LCL grid-connected inverter and predictive control strategy of grid-connected model are studied.To continue to,as order to get higher the machine’s energy output,to avoid design issues.We examine the Shippers grid-connected inverter’s based on the theory of operation and the circuit design,construct a mathematical model in three-phase static coordinate system(ABC coordinate system),then perform coordinate transformations and state space modeling on that model.Trajectory tracking regulation and transitional period loop generator transformers can be investigated experimentally using the process outlined above.The inverter system’s stability and output power quality can both be improved and the transmitter service’s power transfer can be reduced thanks to this topology.Secondly,the power quality of the plug-in inverter is improved by analyzing the phaselocking loop technology of the LCL plug-in inverter.Synchronous rotational reference coordinate system(SRF-PLL)is often used in LCL-linked inverters.As time progresses a DSOGI-PLL,dual second order generalized integrator(DSOGI-PLL)improved by SRF-PLL,Experts and academics alike are adopting this approach.The findings of replicating two main methods are addressed in this section.that while the classic phase locking methodology is effective in ideal power grid conditions,it is no longer acceptable when the power grid collapses.so a new phase locking method is needed.When the grid fails,The SRF-PLL removes any phase detector feature,while an DSOGI-PLL can indeed reliably lock the phasing,but still the system’s system response continues high.Aiming at the disadvantage of DSOGI-PLL,a second order generalized integral phase-locking loop(ZPMAF-SOGI)with zero-phase sliding mean filter is studied.In very little conditions,the sequence loop should not only hold the amplitude and phase of the grid fast and efficiently,but it can also lock every frequency and phase of the grid continuously,However,harmonics can also be filtered out of the inverter’s output current by using a filter.The program’s performance is displayed by the low imbalances for both measured data.Thirdly,the cost function of model predictive control is conceived in attempt to remedy the decision problems of LCL generator inverter.and the voltage quality is improved by optimizing the system parameters.By optimizing the controller parameters in the model prediction control,the system has better robustness.According to the mechanism of model prediction.A testable prediction of the inverter is discretized,and a role in the form of cubic difference is devised.In the simulation,the software’s switching frequency and cost were both significantly increased.At last,a prototype of LCL internet-inverter was built and a controller based on STM32F103 was designed.The hardware part mainly designs control circuit,main circuit and sampled circuit.The controller can meet the problem of power quality when the power grid fails.The design of LCL internet-inverter controller consists of hardware and software.Finally,it is proved that this improved SOGI algorithm can track phase and frequency more quickly and accurately,and avoid miscalculation.