Research On Reliability Evaluation Of Power System Incorporating Large-scale Renewable Energy Resource

Wind power generation, solar photovoltaic power generation and other renewableenergy generation technologies remain rapid and sustained development worldwide due tothe deteriorating environment, depleting fossil resources and public concerns about thesafety of nuclear power. The intermittency and randomness are typical operational charac-teristics of these renewable energy generation technologies. Fluctuant power output anduncontrollable driving force bring negative effects to the safety and reliability of powersystem operation. It is therefore necessary to evaluate the reliability of system after inter-connecting large-scale renewable energy sources to the power system. This paper focus onassessing the impacts of integrating large-scale new energy into grid on reliability of dif-ferent hierarchical level of power system bases on sequential Monte Carlo approach afterdeeply studying the energy conversion characteristic of wind power and solar power.The first priority for reliability evaluation is to build chronological models of windpower and solar Photovoltaic (PV) which can keep inherent characteristic of natural re-source as much as possible. Models of solar energy and wind energy for reliability as-sessment are developed based on sequential Monte Carlo approach. For wind farm, windspeeds are simulated with auto-regressive and moving average model (ARMA) time seriesmodel, stochastic forced outage of wind turbine and power output feature determined bydesign parameters and control characteristic are taken into consideration. For solar PVpower station, extraterrestrial solar radiation calculated by solar-terrestrial relations istaken as the base. Hourly clearness index is introduced to represent the randomness of so-lar radiation variation. Time series model is used to mimic daily temperature. After this,hourly temperature can be generated with sub-sine method. Finally power output time se-quence can be obtained according to energy conversion characteristic of solar PV module.After modeling wind power and solar PV for reliability assessment, they are com-bined with load model to evaluate generation adequacy and capacity credit of system withsingle renewable resource based on sequential Monte Carlo approach. The results of ca-pacity credit calculated with different reliability index are compared. A method for ade-quacy assessment of generating system consists of wind, solar and energy storage consid- ering the coordinated operation is proposed and the effects of different operating strategyon system reliability are investigated. Finally power output state transition model of solarPV for operating reserve risk assessment is proposed on the basis of simulation results ofincident radiation and probability theory. The impacts of solar PV on unit commitmentrisk are studied with the established model.Composite generation and transmission system adequacy assessment can be used tomeasure the ability of bulk electric system to supply reliable electrical energy to the majorsystem load point. The reliability model of wind power and solar power are incorporatedinto bulk electric system reliability evaluation framework. The effects of connecting windenergy conversion system, solar PV as well as hybrid generation system using both ofthem to different locations on system reliability are investigated. Moreover, the capacitymodel of high voltage direct current (HVDC) transmission system is obtained with statetransition sampling technique. A procedure for adequacy assessment of composite genera-tion and transmission system with HVDC links containing large-scale renewable energygeneration is proposed. And how the different transmission schemes affect the system re-liability is discussed.Universal generating function (UGF) allows one to find the performance distributionof consecutive system consists of multistate elements in a straightforward and systematicway. It is particularly useful for solving optimization problem based on reliability due toits extraordinary computational performance. Reliability modeling for wind power andsolar PV using UGF are proposed. The foundation for building model is reliability blockdiagram method, which can be used to obtain the partition of the subsystem and depend-ency relationship between elements within a system in the sense of reliability. Theu-function which can represent the performance distribution of whole system can be ob-tained by recursively computing theu-function of the subsystem bases on the commuta-tive and associative property of UGF. The established model can merge into existing relia-bility analysis method by self-defined composition operator, which can provide differentpoint of view for power system reliability evaluation.