William H. Kersting

Bio: William H. Kersting is an academic researcher from New Mexico State University. The author has contributed to research in topics: Overhead (computing) & Distribution transformer. The author has an hindex of 5, co-authored 9 publications receiving 1510 citations.

Distribution system modeling and analysis

Abstract: Introduction to Distribution Systems The Distribution System Distribution Substations Radial Feeders Distribution Feeder Map Distribution Feeder Electrical Characteristics Summary The Nature of Loads Definitions Individual Customer Load Distribution Transformer Loading Feeder Load Summary Approximate Method of Analysis Voltage Drop Line Impedance K Factors Uniformly Distributed Loads Lumping Loads in Geometric Configurations Summary References Series Impedance of Overhead and Underground Lines Series Impedance of Overhead Lines Series Impedance of Underground Lines Series Impedances of Parallel Lines Summary References Shunt Admittance of Overhead and Underground Lines General Voltage Drop Equation Overhead Lines Concentric Neutral Cable Underground Lines Tape-Shielded Cable Underground Lines Sequence Admittance The Shunt Admittance of Parallel Underground Lines Summary References Distribution System Line Models Exact Line Segment Model The Modified Line Model The Approximate Line Segment Model The General Matrices for Parallel Lines Summary References Voltage Regulation Standard Voltage Ratings Two-Winding Transformer Theory Two-Winding Autotransformer Step-Voltage Regulators Summary References Three-Phase Transformer Models Introduction Generalized Matrices The Delta-Grounded Wye Step-Down Connection The Ungrounded Wye-Delta Step-Down Connection The Grounded Wye--Grounded Wye Connection The Delta-Delta Connection Open Wye--Open Delta Thevenin Equivalent Circuit Summary Load Models Wye Connected Loads Delta Connected Loads Two-Phase and Single-Phase Loads Shunt Capacitors The Three-Phase Induction Machine Summary References Distribution Feeder Analysis Power-Flow Analysis Short-Circuit Studies Summary References Center-Tapped Transformers and Secondaries Center-Tapped Single-Phase Transformer Model Ungrounded Wye-Delta Transformer Bank Leading Open Wye--Open Delta Transformer Connection Lagging Open Wye--Open Delta Connection Four-Wire Secondary Putting It All Together Summary Reference Appendix A Appendix B Index

Roadmap for the IEEE PES test feeders

Abstract: The Distribution System Analysis Subcommittee (DSAS) of the IEEE PES Power System Analysis, Computing, and Economics Committee has been developing benchmarks for distribution system analysis tools. A number of test cases have already been developed may be easily downloaded on the Internet. Other test cases have been requested. This paper describes the purpose and planned direction for these test cases in the near future. Participation from the power industry is solicited.

The Impact of Charging Plug-In Hybrid Electric Vehicles on a Residential Distribution Grid

Abstract: Alternative vehicles, such as plug-in hybrid electric vehicles, are becoming more popular The batteries of these plug-in hybrid electric vehicles are to be charged at home from a standard outlet or on a corporate car park These extra electrical loads have an impact on the distribution grid which is analyzed in terms of power losses and voltage deviations Without coordination of the charging, the vehicles are charged instantaneously when they are plugged in or after a fixed start delay This uncoordinated power consumption on a local scale can lead to grid problems Therefore, coordinated charging is proposed to minimize the power losses and to maximize the main grid load factor The optimal charging profile of the plug-in hybrid electric vehicles is computed by minimizing the power losses As the exact forecasting of household loads is not possible, stochastic programming is introduced Two main techniques are analyzed: quadratic and dynamic programming

A Centralized Energy Management System for Isolated Microgrids

Abstract: This paper presents the mathematical formulation of the microgrid's energy management problem and its implementation in a centralized Energy Management System (EMS) for isolated microgrids Using the model predictive control technique, the optimal operation of the microgrid is determined using an extended horizon of evaluation and recourse, which allows a proper dispatch of the energy storage units The energy management problem is decomposed into Unit Commitment (UC) and Optimal Power Flow (OPF) problems in order to avoid a mixed-integer non-linear formulation The microgrid is modeled as a three-phase unbalanced system with presence of both dispatchable and non-dispatchable distributed generation The proposed EMS is tested in an isolated microgrid based on a CIGRE medium-voltage benchmark system Results justify the need for detailed three-phase models of the microgrid in order to properly account for voltage limits and procure reactive power support

Optimal Charging of Electric Vehicles in Low-Voltage Distribution Systems

Abstract: Advances in the development of electric vehicles, along with policy incentives, will see a wider uptake of this technology in the transport sector in future years. However, the widespread adoption of electric vehicles could lead to adverse effects on the power system, especially for existing distribution networks. These effects would include excessive voltage drops and overloading of network components, which occur mainly during periods of simultaneous charging of large numbers of electric vehicles. This paper demonstrates how controlling the rate at which electric vehicles charge can lead to better utilization of existing networks. A technique based on linear programming is employed, which determines the optimal charging rate for each electric vehicle in order to maximize the total power that can be delivered to the vehicles while operating within network limits. The technique is tested on a section of residential distribution network. Results show that, by controlling the charging rate of individual vehicles, high penetrations can be accommodated on existing residential networks with little or no need for upgrading network infrastructure.

Voltage fluctuations on distribution level introduced by photovoltaic systems

Abstract: In moderate climates, short fluctuations in solar irradiance and their impact on the distribution grid will become an important issue with regard to the future large-scale application of embedded photovoltaic systems. Several related studies from the past are recalled. The approach that is presented here applies a localized spectral analysis to the solar irradiance and derived quantities in order to determine the power content of fluctuations, depending on their characteristic persistence. Pseudorandom time series of solar irradiance, based on measured values of the instantaneous clearness index, are applied as input data. Power-flow calculations are carried out in order to assess the impact of fluctuating solar irradiance on the grid voltage. The "fluctuation power index" is defined as a measure for the mean-square value of fluctuations of a specific persistence. A typical scenario is simulated, and the results are interpreted.