High Order Taylor Series Based ATC Calculation

In power market, available transfer capability is an important index, indicating that how much extra capacity is available for the transmission equipment in energy transaction. Fast and exact calculation of available transfer capability is helpful for the security and stable operation of electricity system and power market. In this article a fast and available method is proposed and its reliability and feasibility were testified by programming. The four main aspects in this arcticle are as follows.Firstly, power market in the past several years was reviewed and transfer capability calculated methods were presented. Deterministic solutions and probabilistic resolutions were outlined simply. The methods include repeat power flow, linear power flow, continuation power flow and optimal power flow.Secondly, power system power flow is presented, mathematical model for power flow is analyzed in detailed, and Newton-Raphson method is stressed. Based on the physics characteristic about practical operation in electrical power system, math model of Newton-Raphson method was simplified reasonably , fast decoupled load flow algorithm was obtained.Thirdly , with the electrical power system expansion and the increase of electricity transaction, security adjustment in the electric power system attracts more and more attention. In this article the higher order Taylor series is used to estimate node voltage and branch power flow after one line outage. In the proposed method, it is not necessary to re-factorize the admittance matrix after one branch is outage. Various higher order derivatives can be obtained only using fast forward and fast backward iteration based on triangle decomposing. By using higher order Taylor series method, the computation burden of one update for the voltage is similar to the computation burden of one forward and backward calculation. Compared with the compensation method, higher order Taylor series shows the superior rapidity and the reliability. For the large-scale electrical power system, it has the obvious superiority in the computation benefit. In this article, IEEE118 system is used to test the validity and rapidity of the proposed method.Finally, calculation methods are introduced on three distribution factors, including Generation Shifting Factor, Load Open Distribution and Power Transfer Distribution. After the voltage variety is known above, available transfer capability can be calculated. Meanwhile, with three values of power and three values of voltage , the relation curve between power and voltage can be fitted.