Warlley S. Sales

Long-Term Probabilistic Evaluation of Operating Reserve Requirements With Renewable Sources

This paper proposes a new methodology based on Monte Carlo chronological simulation to evaluate the operating reserve requirements of generating systems with large amounts of renewable energy sources. The main idea is to build a new probabilistic approach to assess several performance indices bearing in mind the long-term planning. Besides the conventional indices used in generating capacity reliability assessment and also those obtained from the well-being framework, a new set of indices are proposed to measure the availability of different types of operating reserve. The relationship between the proposed approach and the traditional PJM method is also discussed. Renewable in this study mainly comprises wind power sources and for that the IEEE RTS-96 is adapted to illustrate the proposed methodology. Finally, different planning criteria are discussed to deal with the design of generation system capacity, static and operational, in the long-term planning.

Chronological Power Flow for Planning Transmission Systems Considering Intermittent Sources

In light of the additional needs imposed by high penetration level of renewable sources on the planning of electric networks, this paper introduces new models and procedures for obtaining more robust and flexible networks. A new methodology, computational algorithm, and a new set of performance indices are presented based on the concept of chronological power flow (CPF). In view of the presence of intermittent energy resources, aspects related to the operation of the system during moments of high energy availability will be duly evaluated, since that is when there might be a waste of renewable energy, and also during low renewable production conditions, when the system may be more fragile. The results obtained for the IEEE Reliability Test System-1996 will also be presented and discussed.

Reliability assessment of time-dependent systems via quasi-sequential Monte Carlo simulation

This paper proposes a new methodology to assess system reliability considering time-dependent power sources and loads. Based on a non-sequential Monte Carlo simulation (MCS), the proposed method uses a multilevel non-aggregate Markov model to represent different chronological load patterns per area or bus. As a result, the fluctuation of generating capacities, a characteristic of renewable energy sources, can be duly captured by the proposed methodology. Comparisons with the chronological MCS are carried out using the IEEE-RTS-96 (Reliability Test System) and modifications of this system that include renewable sources. The results are deeply discussed.

Evolution Strategies to Transmission Expansion Planning Considering Unreliability Costs

This paper presents a new methodology to solve transmission expansion planning (TEP) problems based on evolution strategies (ES), but other heuristics are also used to assist the search process. The TEP problem includes the search for the least cost solution, bearing in mind investments and interruption costs. Unreliability costs are considered through the index LOLC-loss of load cost. Moreover, the dynamic nature of the TEP is accounted for by the proposed methodology. Case studies on a small test and on a real sub-transmission network (CEMIG Company, Brazil) are presented and discussed

Long term evaluation of operating reserve with high penetration of renewable energy sources

Due to the high penetration of renewable energy into the energy matrix of todays power networks, the design of generating systems based only on static reserve assessment does not seem to be enough to guarantee the security of power system operation. From the wind power integration perspective, this energy source imposes additional requirements, mainly due to the inherent unpredictable characteristic of the wind. Besides the uncertainties in load and generating unit availabilities, the operating reserve needs also to deal with the fluctuation characteristic of the wind power. Therefore, more flexibility of the conventional generators (hydro and thermal) is required to provide system support services. This paper discusses a new methodology based on chronological Monte Carlo simulation to evaluate the operating reserve requirements of generating systems with large amounts of renewable energy sources, in particular, wind power.

Analysis of the cumulative probability distribution of the stroke angle in lightning incidence to three-phase overhead transmission lines

Lightning leaders follow a random behavior when approaching ground surface, so the usual assumption of a vertical stroke is not realistic. This paper is aimed at analysing the sensitivity of the shielding failure flashover rate (SFFOR) of three-phase overhead transmission lines to a probability distribution of the stroke angle, i.e. both vertical and non-vertical strokes. A modified Electrogeometric Model (mod-EGM), derived from a probabilistic computation of the exposure area of phase conductors is described. A computational code is developed in MATLAB, along with IEEE Flash algorithm implementation. Sensitivity analyses are carried out for a waist-type transmission tower. Results show that considering particularly vertical leaders may lead to underestimated values for flashover rates.

Operational Reserve Assessment Considering Wind Power Fluctuations in Power Systems

Discussions on innovative criteria, operation strategies, and assessment tools are important insights when monitoring the security of supply considering renewable power sources for the years to come. In order to deal with the power fluctuations that come from wind uncertainties, this chapter explores a probabilistic methodology based on the chronological Monte Carlo simulation (MCS) to evaluate the long-term reserve requirements of generating systems considering wind energy sources. A new alternative to assess the power amount needs to adequately meet all assumed deviations is presented. Case studies with the IEEE-RTS 96 generating systems and some planning configurations of the Portuguese and Spanish generating systems are presented and discussed.