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In this paper, minute-to-minute wind power variations are decomposed into slow, fast, and ramp components to assess the influence of each component on power system operation. Using detailed, long-term simulation models, this paper confirms that most power systems can absorb the impacts of wind power variations with little difficulty. Yet, since ramps in wind power and system demand could coincide, systems with limited ramping capabilities are at risk. It is shown that extending simulation models to include load dynamics and automatic generation control (AGC) time delays do not alter these conclusions. This paper also discusses wind penetration approaches and control area performance measures, linking the latter to the placement of the wind farms within the interconnection. Index Terms--AGC model, automatic generation control (AGC), long-term dynamic model, penetration limit, system dynamic response, wind events, wind farm model, wind power.

This paper first investigates a local voltage and reactive power control (local control) in a distribution system based on local control of on-load tap-changer (OLTC), substation capacitors, and feeder capacitors, and how the presence of induction machine based distributed generation (DG) affects it. A proper coordination among those available voltage and reactive power control equipment to minimize losses in the distribution system, with and without DG, is formulated. Secondly, a combined local and remote voltage and reactive power control (local-remote control), which is based on automated remote adjustment to the local control in order to minimize the losses even more, is proposed. The automated remote adjustment in the local-remote control is also intended to keep the operating constraints fulfilled all the time, which cannot be achieved by using the local control when DG is present in the system. The OLTC and substation capacitors are assumed to be remotely controllable, while the feeder capacitors are not. DG with both constant power and varying power are investigated. Index Terms--Capacitor, distributed generation, distribution system, induction machine, losses, on-load tap-changer, reactive power control, voltage control.

Key issues for distributed generation (DG) inclusion in a distribution system include operation, control, protection, harmonics, and transients. This paper analyzes two of the main issues: operation and control for DG installation. Inclusion of DG in distribution networks has the potential to adversely affect the control of voltage. Both DG and tap changers aim to improve voltage profile of the network, and hence they can interact causing unstable operation or increased losses. Simulations show that a fast responding DG with appropriate voltage references is capable of reduction of such problems in the network. A DG control model is developed based on voltage sensitivity of lines and evaluated on a single wire earth return (SWER) system. An investigation of voltage interaction between DG controllers is conducted and interaction-index is developed to predict the degree of interaction. From the simulation it is found that the best power factor for DG injection to achieve voltage correction becomes higher for high resistance lines. A drastic reduction in power losses can be achieved in SWER systems if DG is installed. Multiple DG can aid voltage profile of feeder and should provide higher reliability. Setting the voltage references of separate DGs can provide a graduated response to voltage correction. Index Terms--Dynamics, eigenvalues and eigenfunction, power distribution, power generation control, sensitivity, voltage control.

Wind turbines with double output induction generators can operate at variable speed permitting conversion efficiency maximization over a wide range of wind velocities. However, random wind fluctuations, wind shear and tower shadow, may excite the oscillation mode of the mechanical system, producing large torque ripple. Consequently, damage to drive train components and power quality problems may occur. In this paper, a sliding mode control is developed which provides a suitable compromise between conversion efficiency and torque oscillation smoothing. The resultant sliding dynamics is completely robust to uncertainties in the electrical variables and parameters. In addition, to prevent windup problems due to saturation, a combined sliding surface that incorporates such limitations is proposed. Index Terms--Wind Energy, Power Generation Control, Variable Structure Systems.

Presented in this paper are the design and simulation results of a new AGC logic. The new logic is specifically designed to work under NERC's new Control Performance Standard and Disturbance Control Standard with improved effectiveness and efficiency. The old Control Performance Criteria and the new Control Performance Standard are briefly described and compared. The considerations in constructing a simulation environment are included. Texas Utilities Electric Company (TU), in a joint effort with the University of Texas at Arlington, has begun implementation of this new AGC logic. Index Terms--AGC, CPS, DCS, CPC.