The application of artificial intelligent tools to the transmission expansion problem

Wide-Area system monitoring has the ability to provide many new avenues for grid analysis. Some of the most interesting areas include an ability to monitor frequency dynamics and visualize how frequency disturbances propagate across an interconnection. This paper provides a brief history of FNET and how the data it collects is being used in efforts to enhance the understanding of the electric grid. The visualization strategy presented here is a way of displaying low-frequency oscillations or “modes” on the electric grid. This visualization strategy could be used determine the trends and behavior of oscillations during various grid conditions.

Wide-Area mode visualization strategy based on FNET measurements

The author presents the application of fuzzy concepts to the analysis of power system dynamic stability. The analogy and relations between system eigenstructure and fuzzy sets are discussed and employed in the analysis of electromechanical oscillation modes. From the eigenstructure of the electromechanical oscillation modes, one can construct fuzzy sets to associate each system generator with the relative effect which the respective modes impose on it. The proposed fuzzy-based analysis approach is illustrated through an application to a four-machine study system. It is found that the approach is more systematic and informative than the traditional empirical analysis of system eigenstructure. >

Analysis of power system dynamic stability via fuzzy concepts

Effect of non-utility generator siting on oscillatory stability of Taiwan power system

In this work and in order to solve the long-term transmission expansion planning problems, a novel mathematical model which is based on a change in the concept of expanding a transmission system is presented. In traditional transmission system expansion planning, only the additions of candidate lines are considered. In this work, a new concept of transmission system expansion planning is to find a new solution for the base topology where all the lines are temporarily disconnected and the implementation of these lines are reconsidered when they may return to their previous position. Therefore, the lines of the base topology will not be reconnected if they prevent the system performance. Afterwards a new problem is solved to find the future plan of the electrical system network with the addition of new candidate lines in the modified base topology. In order to find a more efficient plan for the future network, the proposed methodology is implemented using a Modeling Language for Mathematical Programming (AMPL) and solved using the commercial solver of CPLEX. In order to validate the proposed approach and make some comparison with the method in the literature, three test systems are conducted such as: the 24-Bus IEEE test system with 41 candidate lines, a practical case studies of 46-Bus South Brazilian system with 79 candidate lines, and the 93-Bus Colombian system with 155 candidates. For large-scale systems, in order to facilitate the implementation of the mathematical model, a strategy to reduce the search space of the buses in which the generation or demand has been presented. In the transmission expansion planning problems, usually we face with a mixed integer non-linear programming problem (MINLP) using the DC model, which make it impossible to use the linear solver of CPLEX. The strategy to overcome this problem is using the disjunctive linear model, which is a DC linear equivalent model. The relevant modifications of the disjunctive linear model make it possible to model the new problem in the form of a mixed integer linear programming problem (MILP) which is solved by linear-based solvers.

Modelagem generalizada do problema de planejamento da expansão de sistemas de transmissão

Due to fast economic growth on the island of Taiwan, load demand in Taiwan Power Company (TPC) has been rapidly increasing in the past ten years and is expected to continue throughout the next decade. By 1995, the peak load demand in Taiwan is forecasted to reach 16,000 MW, an increase of 60% from the present level of 10,000 MW. Several new generating units have been under construction to meet the future demand. As a result, additional transmission lines are needed to avoid overloads on present lines. The objective of this paper is to report the results from a recent study which was aimed at reaching an optimal transmission expansion plan by comparing the relative merits of three feasible alternatives: EHV lines (345 KV), UHV lines (765 KV), and HVDC lines (± 250 KV). At present, the main factors considered in transmission expansion planning in TPC are the maximum power transfer limits, fault currents, transient stability, system losses, and cost [1]. In addition to these factors used in current practice, oscillatory stability of the power system under each expansion plan will be extensively studied. In particular, the low frequency electromechanical oscillations which tend to appear in a longitudinal power system such as the one in Taiwan will be investigated. The dampings of these oscillation modes are essential in system operation and planning, especially in the case when the transmission line is heavily loaded.

Huang Pei-Hwa

Papers

Oscillatory stability considerations in transmission expansion planning