Studies On Boundary Characteristics Of Security Region In Multi-dimensional Space

The serious imbalance of regional distribution between the primary energy andeconomic development of china and load center far away from power sources, as wellas the rapid growth of electricity load, make much more power need to be transmittedfor long distance through transmission system. As a result, a transmission section maybe operated close to its transmission limit and perhaps experience instability after asevere contingency. Therefore, studies on the thermal limits of transmission sectionsduring different operational scenarios are of great importance in order to ensuresecurity of electric power system.This paper proposes a method for forming section thermal security region, basedon the security region theory. Also the feature of the boundary of security is analyzed,and another method for fast forming security region is proposed in this paper.The main work is as follows:1) A method for forming section thermal security region in multi-dimensionalspace is proposed. With output of sensitive generators, whose output changes havesignificant impact on the section thermal limits, the security region can be formedunder the condition of the security “N-1” criterion.2) The boundary hyperplane characteristic of security region is analyzed with themethod of linear regression analysis, and two important test indicators are given.3) As there is a relation between a generator’s power transfer distribution factor(PTDF) on section lines and the influence of the generator on section thermal limit, Amethod for fast forming section thermal security region is proposed, after a series ofmathematical derivation and approximation. Not only the method can fast calculatethe security region, but also the boundary of security region exist smaller error.Finally, results on a practical power grid in the south of China demonstrate thefeasibility and effectiveness of the proposed method.