Dionysios C. Aliprantis

Load Scheduling and Dispatch for Aggregators of Plug-In Electric Vehicles

This paper proposes an operating framework for aggregators of plug-in electric vehicles (PEVs). First, a minimum-cost load scheduling algorithm is designed, which determines the purchase of energy in the day-ahead market based on the forecast electricity price and PEV power demands. The same algorithm is applicable for negotiating bilateral contracts. Second, a dynamic dispatch algorithm is developed, used for distributing the purchased energy to PEVs on the operating day. Simulation results are used to evaluate the proposed algorithms, and to demonstrate the potential impact of an aggregated PEV fleet on the power system.

A brushless exciter model incorporating multiple rectifier modes and Preisach's hysteresis theory

A brushless excitation system model is set forth that includes an average-value rectifier representation that is valid for all three rectification modes. Furthermore, magnetic hysteresis is incorporated into the d-axis of the excitation using Preisachs theory. The resulting model is very accurate and is ideal for situations where the exciters response is of particular interest. The models predictions are compared to experimental results.

An induction machine model for predicting inverter-machine interaction

The conventional qd induction motor model typically used in drive simulations is very inaccurate in predicting machine performance, except perhaps for the fundamental component of the current and the average torque near rated operating conditions. Predictions of current and torque ripple are often in error by a factor of two to five. This work sets forth an induction machine model specifically designed for use with inverter models to study machine-inverter interaction. Key features include stator and rotor leakage saturation as a function of current and magnetizing flux, distributed effects in the rotor circuits, and a highly computationally efficient implementation. The model is considerably more accurate than the traditional qd model, particularly in its ability to predict switching frequency phenomena. The predictions of the proposed model are compared to those of the standard qd model and to experimental measurements on a 37 kW induction motor drive.

A synchronous machine model with saturation and arbitrary rotor network representation

This paper addresses equivalent circuit and magnetic saturation issues associated with synchronous machine modeling. In the proposed synchronous machine model, the rotor equivalent circuits are replaced by arbitrary linear networks. This allows for elimination of the equivalent circuit parameter identification procedure since the measured frequency response may be directly embedded into the model. Magnetic saturation is also represented in both the q- and d-axis. The model is computationally efficient and suitable for dynamic time-domain power system studies.

Experimental characterization procedure for use with an advanced induction machine model

An advanced induction motor model that includes stator leakage saturation, rotor leakage saturation, magnetizing saturation, and distributed system effects in the rotor circuits has been set forth. This model is considerably more accurate than traditional models, particularly in terms of predicting switching-frequency dynamics. The model proposed is very general in terms of the range of magnetic properties that can be incorporated. This paper provides suggestions for specific forms for the leakage and magnetizing characteristics and derives the resulting small-signal impedance and large-signal steady-state equivalent circuit. Based on these results, a test procedure for experimentally characterizing the machine is developed. The application of the procedure to a 50 hp test machine is included as an example.

Genetic algorithm-based parameter identification of a hysteretic brushless exciter model

In this paper, a parameter identification procedure for a recently proposed hysteretic brushless exciter model is discussed. The model features average-value representation of all rectification modes, and incorporation of magnetic hysteresis in the d-axis main flux path using Preisachs theory. Herein, a method for obtaining the models parameters from the waveforms of exciter field current and main alternator terminal voltage is set forth. In particular, a genetic algorithm is employed to solve the optimization problem of minimizing the models prediction error during a change in reference voltage level.

Intelligent Residential Air-Conditioning System With Smart-Grid Functionality

This paper sets forth a novel intelligent residential air-conditioning (A/C) system controller that has smart grid functionality. The qualifier “intelligent” means the A/C system has advanced computational capabilities and uses an array of environmental and occupancy parameters in order to provide optimal intertemporal comfort/cost trade-offs for the resident, conditional on anticipated retail energy prices. The term “smart-grid functionality” means that retail energy prices can depend on wholesale energy prices. Simulation studies are used to demonstrate the capabilities of the proposed A/C system controller.

Analysis of Squirrel-Cage Induction Generator With Vienna Rectifier for Wind Energy Conversion System

This paper analyzes a topology consisting of a squirrel-cage induction machine and a Vienna rectifier for a wind energy conversion system. Simulation results reveal that this configuration is advantageous with respect to energy efficiency compared to a traditional six-switch two-level converter. In addition, it can have higher reliability, due to reduced blocking voltage stress across the semiconductors. The theoretical analysis and feasibility of the proposed configuration are validated by experimental results obtained from a prototype system.

Experimental characterization procedure for a synchronous machine model with saturation and arbitrary rotor network representation

This paper sets forth the experimental procedure for obtaining the parameter set of a synchronous machine model with saturation and arbitrary linear network representation for the rotor. The method utilizes a combination of magnetization curves and standstill frequency-response tests. A novel test procedure is proposed for obtaining the turns ratio. The rotors transfer function and stator leakage inductance are extracted from the frequency response using genetic algorithms.

A Voltage-Behind-Reactance Synchronous Machine Model With Saturation and Arbitrary Rotor Network Representation

A voltage-behind-reactance formulation of a synchronous machine model is set forth, which incorporates saturation and cross-saturation, and is general enough to encapsulate a variety of rotor structures by use of arbitrary linear networks instead of equivalent circuits. Specifically, the models equations - originally expressed in the qd-axes framework - are rewritten in such a way as to allow the actual abc stator windings to be represented by inductive branches, which can then be naturally connected in the desired circuit topology, e.g., to a rectifier. The models predictions are validated against experimental results.