| Energy is the material basis of human activity and the core driving force of economic development.With the steady and rapid economic development,a large number of non-renewable resources have been mined and exhausted.In order to achieve sustainable socio-economic development,vigorously developing renewable distributed energy is an important solution.However,a large number of distributed power grid has not only changed the tide flows and voltage distribution grid,and increased consumption of reactive power,so that the stability of the grid become more prominent,be more prone to instability and chaotic phenomenon.Currently,there is a few study about distributed power connected into grid instability and chaos phenomenon.Therefore,this study will focus on the following aspects in-depth.1.The nature and the basic characteristics of chaotic phenomenon are analyzed,a variety of commonly used analysis method of chaotic behavior are studied.The composition of power system model is overviewed macroscopically a variety of classical nonlinear power system model is studied.The relationship between the complexity and accuracy of the description of the original system with different models is cleared.And all kinds of chaos analysis method actual power system model are effectively.The chaotic phenomena produce electric power system conditions and instability process and commonly used control methods in power systems are studied.2.For grid-connected photovoltaic systems,two mathematical models are established,and their simulation results are analyzed.In the first model,based on the simulation results and time-domain diagram of the phase space trajectories indicate that due to the lack of self-built model state variable nonlinear terms,leading real Jacobian eigenvalues is not greater than zero,the chaos has not been produced.In the second model,since the stand-alone PV system is equivalent to an infinite power system load portion,resulting in a chaotic phenomenon.Finally,according to the Takens theory,C-C combined method for grid-connected photovoltaic system phase space reconstruction,simulation results detected that the system is into chaos.3.A network of asynchronous turbine model and dynamic model of the power system is established.Through the wind power established model simulation analysis,the wind power injection power at a certain range is obtained,and it will lead the grid into a chaotic state.To suppress this phenomenon,for the fans and asynchronous network model nonlinear,strong coupling,this paper put forward the innovative use of generalized fuzzy hyperbolic model with Universal Approximation to approximate the original system model to simplify the design of control system.The generalized fuzzy hyperbolic model is obtained based on system identification results.By solving a LMI,a new type of controller is designed to suppress chaos asynchronous with fan grid caused.The grid stability power injected into the grid fan-range practical value is guaranteed.Through numerical simulations,the effectiveness of the controller design has been verified.4.A variety of distributed power and network interface control method is analyzed.The droop control strategy has been used to characterize the new energy grid inverter P-Q regulation characteristics.The equivalent generator model and dynamic load model are used to establish a modern power system dynamic model with analyzing the instability of the electricity system and Chaos.Under different initial values,the simulation of the model indicated that the presence of distributed power grid system has asymptotically stable operation period,the quasi-periodic operation,chaos,and voltage collapse.During the study,it has been found that bifurcation,chaos,super middle of chaos and collapse are process of the grid voltage instability.In order to prevent instability of the accident,it must be timely control effectively before the critical buckling point,which provides a theoretical basis for the study of grid stability and prevention of instability. |
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