M. Heydaripour, A. Akbari Foroud,
Volume 8, Issue 4 (12-2012)
Abstract
Congestion in the transmission lines is one of the technical problems that appear particularly in the deregulated environment. The voltage stability issue gets more important because of heavy loading in this environment. The main factor causing instability is the inability of the power system to meet the demand for reactive power. This paper presents a new approach for alleviation congestion relieving cost by feeding required reactive power of system in addition to re-dispatching active power of generators and load shedding. Furthermore with considering different static load models in congestion management problem with both thermal and voltage instability criteria, tries to the evaluated congestion management cost become more real, accurate and acceptable. The voltage stability is a dynamic phenomenon but often static tools are used for investigating the stability conditions, so this work offers new method that considers two snapshots after contingency to consider voltage stability phenomena more accurate. This algorithm uses different preventive and corrective actions to improve unsuitable voltage stability margin after contingency. The proposed method is tested on IEEE 24-bus Reliability test system, the simulation results shows the effectiveness of the method.
H. Sh. Solari, B. Majidi, M. Moazzami,
Volume 15, Issue 4 (12-2019)
Abstract
In this paper, a new method for modelling and estimation of reliability parameters of power transformer components in distribution and transmission voltage levels for preventive-corrective maintenance schedule of transformers is proposed. In this method, with optimal estimation of Weibull distribution parameters using least squares method and input data uncertainty reduction, failure rate and probable distributions of power transformers’ components as the key parameters of equipment reliability is estimated. Then by using the results of this modelling, a maintenance schedule for evaluation the effect of maintenance on reliability of this equipment is presented. Simulation results using real failure data of 196 power transformers on 33 to 230kV voltage levels show that applying the proposed method in addition to uncertainty reduction of raw input data and better estimation of equipment reliability, improve decision making regarding maintenance schedule of power transformers.
