Band 11, Heft 2

This paper deals with a shunt active power filter (APF) realized using three-phase p-q (3-φ p-q) theory and single-phase p-q (1-φ p-q) theory approaches. A comparative evaluation between two p-q theories, applied to three-phase three-wire system, is presented. An in-depth simulation study is carried out for better understanding of the concepts and to explore the factors that affect the performance of both the theories. A shunt APF system is developed and tested using a DSP DS1104 of dSPACE. An extensive experimental investigation is carried out under balanced and/or unbalanced supply voltages, and balanced and/or unbalanced load conditions. It is found that both the p-q theories perform well under balanced supply voltages and balanced non-linear load condition, but, their performance degrades when supply voltages are highly distorted. The 3-φ p-q theory has advantage over 1-φ p-q theory when the load is unbalanced in nature. However, under unbalanced voltages, 3-φ p-q theory fails to demonstrate its ability to compensate the load current harmonics and reactive power, whereas, 1-φ p-q theory gives better performance.

Currently, there are several published reports on wind farms (WFs) for controlling output power by using pitch angle control. In addition, to reduce the adverse effects of frequency deviations, battery energy storage systems (BESSs) are introduced to small power systems. In this context, this paper presents a frequency control method by the WF and the BESS using load estimation. The load is estimated by a disturbance observer. The frequency deviations in low and high frequency domain are reduced by the WF using pitch angle control and battery charge/discharge, respectively. By using the proposed method, the reduction of the rated capacity of the BESS is possible. Furthermore, for the pitch angle control system of each WTG in the WF, generalized predictive control (GPC) is applied to achieve robust control performance. The effectiveness of the proposed method is verified by numerical simulation.

In the framework of the competitive electricity markets, electricity price forecasting is important for market participants in a deregulated electricity market. Rather than forecasting the value, market participants are sometimes more interested interval of the peak electricity price forecasting. Forecasting the peak price is essential for estimating the uncertainty involved in the price and thus is highly useful for making generation bidding strategies and investment decisions. The choice of the forecasting model becomes the important influence factor how to improve price forecasting accuracy. This paper proposes new approach to reduce the prediction error at occurrence time of the peak electricity price, and aims to enhance the accuracy of the next day electricity price forecasting. In the proposed method, the weekly variation data is used for input factors of the ANN at occurrence time of the peak electricity price in order to catch the price variation. Moreover, learning data for the ANN is selected by rough sets theory at occurrence time of the peak electricity price. This method is examined by using the data of the PJM electricity market. From the simulation results, it is observed that the proposed method provides a more accurate and effective forecasting, which helpful for suitable bidding strategy and risk management tool for market participants in a deregulated electricity market.

The TCSC is the electronically-controlled counterpart of the conventional series bank of capacitors. A mature member of the FACTS technology, the TCSC has the ability to regulate power flows along the compensated line and to rapidly modulate its effective impedance. In this paper its performance is evaluated using Individual Channel Analysis and Design. Fundamental analysis is carried out to explain the generator dynamic behavior as affected by the TCSC. Moreover, a control system design for the system is presented, with particular emphasis in the closed-loop performance and stability and structural robustness assessment. It is formally shown that the incorporation of a TCSC operating in its capacitive range improves the dynamical performance of the synchronous machine by decreasing the electrical distance and therefore considerably reducing the awkward switchback characteristic exhibited by synchronous generators. It is also formally proven in the paper that the inductive operation should be avoided as it impairs system operation. In general, the TCSC inclusion brings on fragility into the global system, making it non-minimum phase and introducing adverse dynamics in the speed channel of the synchronous machine. Moreover, it is shown that the minimum-phase condition may also be present in cases featuring high capacitive compensation levels.

This paper details the main requirements that must be taken into account to assemble a phasor unit measurement (PMU) for research and educational purposes. The device's main elements are described showing their interrelationship. Likewise, details about the most important functions are exposed. Results exhibit the suitability of the proposition according to the standard.

This paper introduces a developed simplified version for the recursive Gauss-Newton algorithm for extraction and mitigation of the stationary current quality problems such as current harmonics and current fluctuation. Adaptive notch filters are newly utilized for supplying the Gauss-Newton algorithm with the required values of frequencies for current disturbances such as non-characteristic harmonics, inter-harmonics and sub-harmonics. Also, this paper exhibits the mitigation results for current harmonics and fluctuation problems by using a shunt power conditioner. Moreover, in this paper the ramp-comparison current controller, linear current controller, is employed to operate the mitigation device. The effectiveness of the developed extraction technique associated with the employed current controller for the shunt power conditioner is verified by simulation results using MATLAB/SIMULINK.

Increasing debates over a gasoline independent future and the reduction of greenhouse gas (GHG) emissions has led to a surge in plug-in hybrid electric vehicles (PHEVs) being developed around the world. The majority of PHEV related research has been directed at improving engine and battery operations, studying future PHEV impacts on the grid, and projecting future PHEV charging infrastructure requirements. Due to the limited all-electric range of PHEVs, a daytime PHEV charging infrastructure will be required for most PHEV daily usage. In this paper, for the first time, we present a mixed integer mathematical programming model to solve the PHEV charging infrastructure planning (PCIP) problem for organizations with thousands of people working within a defined geographic location and parking lots well suited to charging station installations. Our case study, based on the Oak Ridge National Laboratory (ORNL) campus, produced encouraging results, indicates the viability of the modeling approach and substantiates the importance of considering both employee convenience and appropriate grid connections in the PCIP problem.

The relationship between the electric and magnetic fields along with soil resistivity is very important for direct lightning stroke. In this paper, the electric and magnetic fields produced by a parallel quadruple high voltage power lines (PQHVPL) have been measured. The measured fields are substantially high compared to the fields coming from conventional 132 kV and 275 kV power lines. The correlation between electric and magnetic fields emitted from PQHVPL and soil resistivity in the ground below the lines has also been investigated. The electric and magnetic field digital exposure system (EMDEX) hardware and software are used to measure and analyze the results. It is found that the electric field is higher at high soil resistivity and is lower at low soil resistivity.