APPLICATION OF SUPERCONDUCTING MAGNETIC ENERGY STORAGE UNIT IN POWER SYSTEMS

Abstract

Superconducting magnetic Energy Storage (SMES) is considered to be one of the effective measures to suppress system instabilities in electric power systems because of its fast response in exchanging electric power. By storing energy during the periods of power surplus and supplying power during the periods of power shortage, the SMES can serve the purpose of peak plants and can replace uneconomical spinning reserve units. A SMES not only has benefits in peak shaving and load leveling, but also in dynamic improvement, such as voltage and frequency regulation, long line stabilization. The application of SMES unit has received great attention since the successful commissioning test at Bonnevile Power administration (BPA) substation in Tacoma, Washington. However, the effective use of SMES unit is greatly depends on control strategy. An appropriate control using SMES unit being cost effective is more beneficial to the network under disturbance. In this research, different controllers for the SMES unit are briefly discussed. Then new types of intelligent controllers based on fuzzy logic theory and artificial neural network are presented in detail for the SMES unit, namely the Adaptive Fuzzy Logic Controller (AFC) and Artificial Neural Network (ANN) Controller. The structure of AFC and the algorithm for the Rule Adaptation are then discussed and suitable models are developed. Then the ANN is designed and its parameters are determined using a set of designed steps. The performance of these two controllers with other existing controllers are compared in terms of settling time reduction, improvement in damping, the amount of SMES energy requirement and inductor current variation. Detailed analysis and simulation results are presented. All simulations have been done using MATLAB software. A comparison is also made between fuzzy and neural network controllers.

To demonstrate the effectiveness of the proposed intelligent controllers, the SMES unit is used for various applications such as static V AR controller, improvement in damping in synchronous generator etc. Their control strategies are discussed and corresponding models are developed. Detailed analysis and simulation results for each application are provided. Lastly, the influence of unequal cx,-mode on active and reactive power modulation of SMES units for the controllers is briefly touched with inclusion of equations and figures. Besides the control strategy is also proposed.

The proposed intelligent controllers of the SMES unit based on the fuzzy logic theory and neural network are applied for various power system problems. It is evident from the results that the SMES performs far helter than the conventional controllers in harnessing the active and reactive power for power system stabilization. This means that a relatively smaller size SMES unit can effectively stabilize a large disturbance. This feasibility aspect of SMES unit can make it more attractive to the utility engineers and the industries alike to construct a cheaper and yet smaller and powerful version of it for the commercial purpose.