The main objective of this work was to integrate short-circuit analyzes with reliability adequacy assessment, providing a chronological perspective to the evaluation methodology. For this purpose, a SMCS approach was applied.

 

The growth of the use of sensitive equipment increases the power quality concerns and the need for indices which represent them. Sequential Monte Carlo Simulation is crucial for estimating these indices, since it allows not only to obtain the average values for reliability indices, but also to get the probability distributions of these indices. Furthermore, the simulation model is based upon building time-sequential synthetic operating cycles and, consequently, the impact of operational/control solutions in the power distribution system operation can be verified through the uprising/downsitting of the performance indices over the synthetic years of operation.

 

The following research contributions were provided in this thesis.

 

 

1. Combining short-circuit analyzes with reliability adequacy assessment.

During the thesis discussions, we emphasize that the traditional adequacy evaluation of distribution systems does not consider the effect of momentary interruptions or voltage sags, assessing only sustained interruptions lasting longer than few minutes. This can lead to an overestimation of the reliability distribution system, by neglecting failures related with power quality disturbance, such as voltage sags and momentary interruptions. So, it is necessary to combine short-circuit analyzes with reliability adequacy assessment in order to evaluate the impacts of the voltage sags and momentary interruptions in the distribution system adequacy.

 

 

2. Development of novel indices and test-functions for momentary and voltage sag events.

In this work, novel indices were created in order to provide quantitative information regarding the service delivered, in what concerns momentary and voltage sags events. These indices are SARDI, which measures how many voltage sags hours an average customer will experience over the course of a year; CARDI, that measures how long an average voltage sag lasts; MAIDIE, that measures how many momentary interruptions hours an average customer will experience over the course of a year and, nally, CMAIDIE, which measures how long an average momentary interruption lasts. The development of these indices aroused from the necessity to know (and measure) these durations while constructing the proposed computational algorithm and obtain quantitative information regarding the service delivered.

 

3. Design of a computational model that integrates short-circuit analyzes with reliability adequacy assessment.

The proposed computational model was developed to capture phenomena associated with short-circuit events and uses various software simulation packages with the purpose of incorporating short-circuit analyzes in power distribution system adequacy. The algorithm is based on sequential Monte Carlo simulation and samples resident time of components in temporary and permanent failures, as well as, fault impedance, fault section location, fault type, and phases involved. The sampled events are then evaluated to compose test functions and performance indices.

 

4. Development of a model to capture information to support the setting of protective devices.

As contribution, this research promoted the concept of gathering information regarding surveyed stochastic sampled data to aid the setting of protective devices. For instance, the pick-up current and maximum time can be estimated in other to perform the protective devices setting based on the knowledge provided by a large number of simulation sampled years.