Fast Calculation Of Probabilistic Total Transfer Capability Considering Voltage Stability Constraints

In the new competitive environment especially with interconnection of powersystems, Available Transfer Capability (ATC) is a very important parameter forindependent system operators (ISO) and all companies participating in powertransaction activities. The calculation of Total Transfer Capability (TTC) is thegroundwork of ATC research. Generally, TTC is on-line calculated based ondeterministic models. Without considering the probabilistic nature of power system,the results are often conservative and can not offer adequate information. Moreover,Traditional TTC calculation considers only thermal and voltage limits, ignoringstability constraints. However, in recent years voltage instability has aroused severalblackouts, and now voltage stability constraints have been important factors affectingATC. A new methodology to evaluate TTC with static voltage stability constraints isdeveloped in this thesis and the following work is completed:1. For the fast calculation of probabilistic TTC, a plane function is derived toestimate part of the boundary of the Static Voltage Stability Region (SVSR) in the fullpower injection space. The whole SVSR boundary can then be described by severalplanes. The number of the planes and the positions of the tangent points aredetermined by VQ clustering method.2. A fast TTC calculation method is proposed with the consideration of load andgenerator output uncertainties by Monte Carlo simulation. The SVSR boundarydescribed by several planes is employed to the fast calculation.3. A layered TTC calculation model is developed for line outage uncertaintiesbased on Monte Carlo simulation and the SVSR method. The Damped NewtonMethod is used to calculate the post-contingency point directly from thepre-contingency point.4. A new Monte Carlo method is applied to simulate the cascading contingencies,which is used in the calculation of probabilistic TTC.5. The IEEE RTS-118 system is illustrated as an example to validate theadvantages of the proposed methods. The speed and the accuracy both meetengineering requirements. The effects of load uncertainties, power increasing modesand cascading contingencies on the TTC calculation are also discussed.