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A new method of measurement of harmonics of potentially time-varying frequency is presented. The proposed method is based on adaptive estimation of the fundamental and individual harmonic components of the power signal and tracking their variations over time. The structure and mathematical formulation of the proposed technique are presented and its performance is demonstrated in a variety of scenarios where the frequency of the power signal undergoes variations over time. Throughout the experiments, the proposed technique is compared to two of the most promising techniques recently reported in the literature. Index Terms--Harmonic measurement, nonstationary signal processing, power quality.

A planning methodology for distribution system harmonic filtering is proposed. The method is intended for use on radial distribution systems with no large harmonic sources. It is proposed that 60 hertz var planning be done first to allocate the var resources. Following this process, the harmonic filter planning can be readily accomplished. Characteristics of the distribution systems and the harmonic sources are exploited to provide a practical filter planning technique which is effective and efficient. Keywords: Harmonic filtering, electric power distribution systems.

This paper presents a new switching control scheme for braking resistors using a fuzzy logic to enhance overall stability of electric power systems. In addition, the coordination with an SVC is also considered to achieve a wider stable region. The braking resistor is set on one of the generator busbars, where the real power output from the generator is measured to determine the firing-angle of the thyristor switch. The switching control scheme is simple so as not to require heavy computation on the micro-computer based switching controller. An SVC is set on one of the busbars in the transmission system. The switching of the SVC is performed by using a similar fuzzy logic control scheme to the one for the BR. Simulation results show the effectiveness of the proposed fuzzy logic switching control scheme. Keywords: Fuzzy logic control scheme, Real time control, Braking Resistor, Static Var Compensator, FACTS

This paper presents a neural network based maximum power tracking controller for interconnected PV systems to commercial power sources. The neural network is utilized to identify the optimal operating voltage of the PV system. The controller generates the control signal in real time, and the control signal is fed back to the voltage control loop of the inverter to shift the terminal voltage of the PV system to the identified optimal one, which yields the maximum power generation. The controller is a PI type one. The proportional and the integral gains are set to their optimal values to achieve the fast response and also to prevent the overshoot and also the undershoot. The continuous measurement is required for the open circuit voltage on the monitoring cell, and also for the terminal voltage of the PV system. Because of the accurate identification of the optimal operating voltage of the PV system, more than 99% power is drawn from the actual maximum power. Keywords: PV module, Neural Network, Poly-crystalline Silicon, Maximum power tracking control, Real time control, Inverter control.

The fuzzy polar power system stabilizer (FPPSS) which has been recently developed is analyzed using frequency domain methods. The frequency domain approach allows the PSS designer to compare the new FPPSS with more conventional controllers. The significance of the three FPPSS design parameters are readily seen from the frequency response data, and their relationship to the conventional lead-lag design approach can be evaluated. Furthermore, the frequency response data for the FPPSS allows an alternate design approach for this stabilizer, and can be used to develop information concerning the small signal stability of the resulting system. Keywords: Power system stabilizer, fuzzy control.

For harmonic analysis it is not practically possible to model a large transmission network with its neighboring interconnected systems in detail due to computer time and memory limitations. Furthermore, a large number of outage contingencies has to be analyzed to compute harmonic impedance boundaries for filter designs. Current methods do not address modeling simplification errors and also accuracy of harmonic impedance boundaries, and depend mostly on trial and error or individual experience approaches. A methodology has been presented to model transmission network more accurately and efficiently by using adjoint network sensitivity analysis and bilinear theorem. A new method is also presented that reduces the number of outage contingencies to be analyzed by a large factor, that considerably reduces the engineering and computer time, and increases dependability.

This paper presents a new method for the continuous regulation of series compensation. The two proposed control circuits consist of capacitor banks inserted in a transmission line and are controlled by bi-directional GTO switches. The level of compensation is controlled by varying the on and off time of the GTO switch. To avoid current surge, the switch is turned on before the capacitor voltage is zero. The feasibility of this method was verified by transient analysis and through measurements on a small scale model. The advantage of the proposed circuit is the fast and continuous regulation of series compensation. The circuit can be built with available components and can be used, for example, for impedance control, and oscillation reduction.

Distortion levels on power systems have been continuously increasing due to the increasing presence of power converters. The distortion currents injected by some converters can include interharmonics as well as harmonics. The generation of interharmonics in ac-dc-ac power converters is discussed, and a method to predict levels of current interharmonics is developed. The results show that very low interharmonic levels can be expected for a well designed PWM inverter operating with linear modulation and balanced load. Interharmonics can be expected in cases when the inverter is in overmodulation or when the inverter load is unbalanced. The paper also discusses the relative effects of dc link inductance and source inductance on interharmonic propagation. Index Terms--Power converter harmonics, power quality, pulse width modulated inverter.