Research On Control Devices With Multiple Inverters Parallel For Power Quality Compensation

In recent years,the inverter technology is widely used.In this paper,the three phase island inverter and multilevel converter system and the hierarchical control strategy under an island mode for the linear/nonlinear,unbalanced,intermittent and seasonal load is studied;the related work is as follows:(1)The modular inverter parallel system main circuit design and mathematical modeling research.In view of the island micro grid system with LCL filter output device of single and parallel inverter,design the main circuit topology and operation.Accurate analysis of the resonance mechanism and inhibition measures of the system LCL output filter,and the pulse width modulation PWM method is studied.Under ideal conditions,the matrix state,small signal and linear model of the system are establishment and analyzed.(2)The modular inverter system reactive power compensation control method research.In view of the island micro grid system,puts forward a kind of more closed loop hierarchical control strategy based on inverter voltage current and droop secondary control.Considering the actual situation,the voltage current inner loop control and the drop,predict complex outer loop control are built,which ensure the voltage and power transmission and satisfy the energy transfer function under the condition of intermittent and seasonal load.Under the unbalanced load conditions,the reactive power compensation control for modular inverter system is researched,which ensure the stability of voltage and power of the system.(3)The modular inverter system harmonic compensation control method research.Aiming at the island multiple inverter micro grid system,the more proportional resonant PR controllers are used to the voltage harmonic compensation function.At the system internal voltage control loop,the 5th,7th,11 th harmonics are suppressed.The droop,secondary and compound control strategy is adopted to realize the closed-loop regulation control of output voltage amplitude and frequency.(4)The parallel modular multilevel converter(MMC)topology model and control method research.On the basis of parallel inverter topology,the research focusing on parallel modular multilevel converter(MMC)topology modeling and control method is worked,and the mathematical modeling of multilevel converter island operation system based on the mode of drop-secondary control is established,also the run stability performance and the mechanism of reactive power compensation of the multilevel converter island system is analyzed,put forward a kind of voltage and power high quality and stable-reliable transmission control method under different load conditions for complex power grid which applicable to the multilevel parallel inverter.Through the system simulation and independent designed experiment,the effectiveness of the control strategy is verified.