Pisitpol Chirapongsananurak

Voltage regulation in distribution circuits with wind power

This paper presents an analysis of the voltage regulation for four wind turbine technologies and compares the reactive power control methods (constant power factor control, active power factor control, and active voltage control). The test system used in this study is a radial distribution circuit with a wind turbine connected at the end of the feeder. The distribution circuit model and the wind turbine model are developed in Open Distribution System Simulator™ (OpenDSS). Simulation results show that the constant power factor control and the active power factor control regulate the power factor of the wind turbine to the desired value. In addition, the active voltage control regulates the voltage at the point of interconnection to the desired value.

Analytical Approach to Estimate Feeder Accommodation Limits Based on Protection Criteria

Widespread deployment of large-scale photovoltaics (PVs) and energy storage systems (ESSs) in distribution networks necessitates the development of methods to assess their possible system impacts. One of the primary concerns related to the integration of these systems is short-circuit overcurrent protection problems. Present techniques use simulations of full and detailed distribution circuit models with a large number of scenarios to estimate the PV and ESS sizes a distribution feeder can accommodate without causing adverse impacts. As this process requires considerable time and effort, this paper develops a practical and simplified analytical approach to conservatively estimate a utility distribution feeders accommodation limits without causing protection problems. Sympathetic tripping and relay insensitivity problems are considered in this paper under both symmetrical and unsymmetrical fault conditions. Using the analysis presented, the factors influencing these protection problems are determined to provide insights into relay settings. The feeder accommodation limits obtained using the proposed analytical approach are compared with those obtained using simulations of an actual detailed distribution circuit model. The findings show that the proposed approach is accurate in estimating the feeders accommodation limits for integrating large-scale PV and ESS.

Harmonic analysis for fixed-speed wind turbines

This paper presents harmonic analysis of a fixed-speed wind turbine in a utility distribution system. It shows a condition of how the wind turbine may be involved in harmonic resonance through its power factor correction capacitors. In addition the effect of wind speed on the resonant frequency is also considered. The test system used in this study is a distribution feeder with an equivalent nonlinear load and a wind turbine connected at the feeder end. The results show that severe harmonic distortion can occur due to the interaction of the power factor correction capacitors and the system impedances. Although, wind speed does not have a direct effect on the resonant frequency, the number of power factor correction capacitors affects the resonance condition. A single-tuned notch filter is shown to be efficient in reducing the harmonic distortion.

Distribution system multi-domain simulation tool for wind power analysis

This paper develops an integrated multi-domain simulation tool for distribution systems designed specifically for applications in wind power analysis. The proposed tool consists of steady-state, electromechanical transient, and electromagnetic transient models of voltage sources, transmission lines, transformers, capacitor banks, fixed-speed wind turbines (FSWTs), and wide-slip wind turbines (WSWTs). The test circuit used to demonstrate the multi-domain simulation approach is the IEEE four-node test feeder with a wind turbine connected at the feeder end. The simulation is performed for a one-day period. During this period, wind speed changes every ten minutes, a capacitor is switched on and off, and a temporary single-line-to-ground fault occurs. The results show that the proposed multi-domain simulation tool is able to simulate and analyze long-term power system phenomena.

Operating fixed-speed and wide-slip wind turbines in isolated microgrids

This paper demonstrates the feasibility of operating wind farms consisting of fixed-speed wind turbines (FSWTs) and wide-slip wind turbines (WSWTs) in an isolated microgrid. Operating requirements of the microgrid and additional equipment needed to operate the wind farms in a standalone microgrid are described. The microgrid and wind farm models are developed in a time-domain simulation platform. The microgrid test system is a distribution feeder consisting of wind farms. This microgrid is initially connected to the grid, but operates as an isolated microgrid during a fault restoration period. Energy storage systems, fixed capacitor banks, and STATCOMs are proposed to be installed to manage real and reactive power of the wind farms. This paper also describes the size of energy storage systems required and the amount of reactive power compensation needed.

Controller design for DFIG-based wind power generation using Zakian's framework

In this paper, a real power controller design for wind power generation has been conducted. The wind power station is assumed to be a type of doubly-fed induction generator (DFIG). Zakians framework has been employed to maximize power output and to limit the system frequency negative impact, concurrently. Under fluctuation of wind speed in two-machine test system, the performances of the design controller are examined. Simulated test results show that the proposed method is effective.