A Study On The Methods Of Operation Of The Connected Parallel Inverters Network

A study on the methods of operation of the connected parallel inverters network is significant in control not only for our country but also for China and other countries in the world. Three phase inverters have become the main power supply systems, such as office automation, hospital, bank, play an important role in the field of communications, defense. Parallel inverter technology is a potential market and has great potential, can be studied extensively and has many specialized applications. Some recent years, one phase parallel inverter became mature, and 3-phase connected parallel inverter is gradually becoming a new research focus of the scientific research.Three phase inverters in parallel can provide electricity with high capacity as well as backup power, which is an important research direction, is increasingly being recognized in the inverter control technology. Using parallel inverter enhance the flexibility of the system, reduce the volume, the size of the system, increasing the quality of the switching process, improve reliability, increase power density and reduce the cost of production systems system.Moreover, using inverters connected in parallel may perform redundant power supply, improve the reliability of the system work. Parallel inverter technology allows pairing parallel N+1 modules, so during operation if one module fails, the remaining N modules will generate sufficient load capacity of 100%, so the cost will be much cheaper than the equipped with redundant power supply separately, but the reliability of the system is improved.Parallel inverter control Technology is now the first choice for control systems require high performance and high reliability. Therefore, parallel inverter technology is now widely applied in many fields such as core:aviation, power supply for computer, communication systems, power supply systems for banks, the system resources required to provide quality and high reliability. Parallel inverter technology is a hot spot for the supply of energy in recent years, this study is a significant high practical application.Parallel inverter control system traditionally use PID controller (proportional, integral, derivative) to control the voltage, the traditional PID controller has reached maturity, the resulting control good, but the design parameter is not really optimal, very sensitive to the variation of other parameters in the system, performance and features of the system is difficult to achieve an optimal level, so that the amount of highly customizable.This thesis introduce method using fractional PIλDμ controller to replace the traditional PID controller design parameters for the controller fractional PIλDμ. The controller segment brought dramatic changes in the past controls, achieve better control that traditional PID controller is not reached.Study on the methods of operation of the connected parallel inverters network has been done in following steps:1) The first, thesis analyzes the meaning and context of the study subjects, a general introduction to the current state of development and application of inverter technology, the current state of technological development driver pairing in parallel inverter China and other countries around the world.2) Analysis of the pattern and texture of the 3-phase inverter, inverter control method of three-phase inverter models in parallel, working principle analysis of parallel inverter, introduces the control method common parallel inverter.3) Analysis and method research to directly control current (DCC) PWM inverter, control principle two close loop analysis method of space vector PWM inverter, analytical methods feedback current control and analysis methods to directly current control to the parallel inverter. Using matlab/simulink to setup and simulate system, simulation results analysis.4) Analysis of balanced current system paired parallel inverter, current limiting method when paired parallel inverter, affecting the output voltage of the inverter parallel coupling. Engineering controls stratospheric parallel inverter, then analyzes some of the stratospheric control method used in parallel inverter system analysis and control methods are applied in this thesis is the method automatically current maximum average. Performance is simulated by Matlab/Simulink and analyze simulation results5) Referring to the issues in the fractional control, the definition fractional, the nature of the area fraction, analysis changing methods in fractional control, analyze the characteristics of the stages typical volume fraction.6) Research fractional PIλDμ controller, introduce some approximate analytical methods of fractional controller, then design the fractional controller for 3-phase inverter system, designed adapters FO-PID controller and its features, analysis and setting the parameters of the system, through the FO-PID control voltage is stable at a certain value, the voltage is kept constant even even when the load changes, the grid fluctuations or other parameters of the system change. Ensuring the performance of three-phase inverter and the majority of the damage reduction. Simulation results and experiments have demonstrated that the use of FO-PID control method with direct current control to achieve the results desired control, the grid current is very close to sinusoidal, power factor is high, moreover FO-PID controller is not sensitive to changes in the parameters of the system, the DC voltage stability quickly at a certain value, and the sharp correction and more accurate.7) Finally, thesis designs main power circuit and locked loop system design experiments paired parallel inverter (including hardware and software applications), through the table experiments, analysis of experimental results and draw conclusions:experimental results have proved the thesis system design reasonable structure, precise control, efficient, results-driven requirements, meet the requirements of the grid, the efficiency of the system is improved, and has the effect of inhibiting the appearance of harmonics, grid quality is not affected, reducing heating systems, safety is enhanced, reduced maintenance workload, valuable practical application high structure was renovated parallel system, creating favorable conditions for real life production, reduce waste and conserve natural resources.