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Power system simulation models are a class of computer simulation programs that focus on the operation of electrical power systems. These computer programs are used in a wide range of planning and operational situations including: #Long-term generation and transmission expansion planning #Short-term operational simulations #Market analysis (e.g. price forecasting) These programs typically make use of mathematical optimization techniques such linear programming, quadratic programming, and mixed integer programming. Key elements of power systems that are modeled include: #Load flow (power flow study) #Short circuit #Transient stability #Optimal dispatch of generating units (unit commitment) #Transmission (optimal power flow) Layered on top if this physical framework are models of competition such as Cournot, Bertrand competition, and Supply Function Equilibrium. Before the advent of large scale digital computers, power system simulation was carried out on network analyzers, which were essentially miniature scale models of power systems with scaled generators, loads, and line simulators. ==Load flow calculation== The load-flow calculation is the most common network analysis tool for examining the undisturbed and disturbed network within the scope of operational and strategical planning. On the basis of the network topology with the impedances of all devices as well as with the infeeds and the consumers, the load-flow calculation can provide voltage profiles for all nodes and loading of network components, such as cables and transformers. With this information, compliance to operating limitations such as those stipulated by voltage ranges and maximum loads, can be examined. This is, for example, important for determining the transmission capacity of underground cables, where the influence of cable bundling on the load capability of each cable has to be taken also into account. Due to the ability to determine losses and reactive-power allocation, load-flow calculation also supports the planning engineer in the investigation of the most economical operation mode of the network. When changing over from single and/or multi-phase infeed low-voltage meshed networks to isolated networks, load-flow calculation is essential for operational and economical reasons. Load-flow calculation is also the basis of all further network studies, such as motor start-up or investigation of scheduled or unscheduled outages of equipment within the outage simulation. Especially when investigating motor start-up, the load-flow calculation results give helpful hints, for example, of whether the motor can be started in spite of the voltage drop caused by the start-up current. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Power system simulation」の詳細全文を読む スポンサード リンク
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