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August 2013

Volume: 15, Issue: 2, August 2013

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Up to 30 Years Peak Load Forecasting of Jordanian Power Grid using Radial Basis Function Neural Networks

Author: Almaita, E., Aulimat, B.

Abstract:

In this paper, the Radial Basis Function Neural Networks (RBFNN) algorithm is used to forecast the electrical peak load in Jordan. The total load consumption is divided into different sectors. These sectors are; households, commercial, services, industrial, water pumping and public lighting sector.  The total load forecasting is calculated by the algebraic sum of the forecasted value of the different sectors. The forecasted total energy consumption, the average temperature, and the peak temperature are used to forecast the electrical peak load. The model used to forecast the peak load utilize a small, but important, number of factors that drive the peak load demand. In order to validate the effectiveness of the model the output of the model is compared with the output of another linear regression model. The  forecasted growth rate of  both models and the peak load historical growth rate show that the output of the RBFNN model is more realistic.

(pp. 787-791)                    Download PDF

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Circulating Current Produced in a System of Two Inverters Connected in Parallel

Authors: Carlos Alonso Sanz, José Miguel Ruiz González, José Antonio Domínguez Vázquez

Abstract:

This paper analyzes the imbalances that produce circulating current in a system of two three-phase Voltage Source Inverters (VSI) with Space Vector Pulse Width Modulation (SVPWM) that, sharing the same DC link, is connected to a balanced three-phase load without galvanic isolation. This analysis has identified two principal imbalances: the difference between the dead times of the two inverters, and the difference between the zero-vector parameters of the two inverters. The first imbalance studied in this paper is generic and can occur in any system of parallel connected inverters. The second imbalance studied in this paper is specific to the space-vector modulation. The study proposes the correction of the imbalances by measurement algorithms and Proportional Integral Control (using the Ziegler Nichols method to tune the controller), in order to reduce or eliminate the circulation current and increase system performance, when the imbalances act independently. It provides a method that does not use an equivalent circuit or a model, determining the value of the imbalance directly and through a system output signal.

(pp. 792-798)                    Download PDF

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An Adaptive Kalman Filter for Voltage Sag Diagnosis in power system

Author: Hisham Alrawashdeh, Johnson Asumadu

Abstract:

This paper proposed an adaptive kalman filter for amplitude tracking to help in diagnosing the voltage sag problem in power system, the proposed algorithm uses two kalman filter; one of them for figuring the dynamic change in the system parameters and the other for signal tracking, the kalman filter is adaptive by updating the state covariance matrix when the dynamic change occurs, exact knowledge of yhe noise covariance matrices are not needed in the proposed algorithm, where the noise covariance matrices are set to be incorrect in the kalman filter model, then the proposed algorithm is used to detect the amplitude of the fundamental component of a signal contains harmonics and noise. 

(pp. 799-806)                    Download PDF

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The Study of Fuzzy-Logic Controller for SSSC

Author: Abdesselam Abderrahmani, Abdelkader Chaker, Abdellah Laoufi

Abstract:

Power transfer capability of long transmission lines is limited by stability considerations. Reducing the effective reactance of lines by series compensation is a direct approach to increase transmission capability; often, it is the most economical solution. The Static Synchronous Series Compensator (SSSC) is a series connected FACTS controller, which is capable of providing reactive power compensation to a power system. The reactive power flow/transmission line side voltage is controlled by adjusting the phase angle of the series injected voltage. In this paper, an improved fuzzy logic-based controller for SSSC is developed for the stability of the power system. These models are first validated by means of MATLAB simulations on a test system.

(pp. 807-811)                    Download PDF