Karl Schoder

PAT: a power analysis toolbox for MATLAB/Simulink

A power system simulation environment in MATLAB/Simulink is presented in this paper. The developed Power Analysis Toolbox (PAT) is a very flexible and modular tool for load flow, transient and small signal analysis of electric power systems. Standard power system component models and a wide range of FACTS devices are included. Its data structure and block library have been tested to confirm its applicability to small-to medium-sized power systems. Its advantages over an existing commercial package are given.

Selection and design of a TCSC control signal in damping power system inter-area oscillations for multiple operating conditions

Abstract A method is proposed to identify an effective local signal that can be used by a thyristor controlled series compensation (TCSC) device as a supplementary controller to dampen inter-area oscillations for multiple power system operating conditions. Two residue-based indices are developed for this purpose. The first index is to identify the most effective signal to feedback for different operating conditions, and the second index is to assess the interaction of the controller with other oscillation modes than the critical mode, i.e. the mode that is to be controlled. Two designs are presented to illustrate the proposed methodologies, a conventional lead–lag controller, and a controller using a multi-step control design approach. The proposed techniques are applied to a four-generator two-area power system. Nonlinear simulation is used to demonstrate the effectiveness of the designed controller.

Control of grid-connected split-shaft microturbine distributed generator

In this paper, a split-shaft microturbine model using induction generators is used to assist transient stability of microturbines when connected to the grid as distributed generator. Microturbines can be controlled via two paths, control of the turbines mechanical power and control of terminal voltage from induction generator using connected SVC at the generators terminal. PI controllers, for SVC and output turbine mechanical power, are designed based on a linearized model using genetic algorithms as optimization technique. Model development and simulation are presented within the MATLAB/Simulink (Power System Analysis Toolbox (PAT)) environment using various toolboxes.

Power system stability enhancement using backstepping controller tuned by particle swarm optimization technique

A method for designing controls through the excitation system and particle swarm optimization technique to search for the optimal setting of the controller gains to improve transient stability and damping is presented. Simulation of multi-machine power systems are performed to show the effectiveness of the proposed controller. Comparisons with two other control schemes namely (i) a voltage regulator combined with a power system stabilizer and (ii) excitation controls designed by using the direct feedback linearization (DFL) technique are given to further benchmark the control scheme.

Power system damping using fuzzy controlled unified power flow controller

The paper presents a design of a UPFC damping controller using two fuzzy logic schemes one based on Mamdani inference engine using the center of gravity method to find the controller output, and the second based on Takagi-Sugeno engine computing the controller output as linear combination of the inputs. Fuzzy control design is attractive for nonlinear systems application because it does not require a mathematical model, and it can cover a wide range of operating conditions. The advantages of the proposed controllers are their feasibility guaranteed by the use of a local measurement, which in this case is the tie line power flow, and their simplicity. The effectiveness of the controllers under dynamic conditions is illustrated through nonlinear simulations of a two area-four-machine power system. Simulations are carried out using the Power System Toolbox (PST).

Load-flow and dynamic model of the unified power flow controller (UPFC) within the Power System Toolbox (PST)

To assess the UPFCs capabilities through simulation, a software tool is needed. The Power System Toolbox (PST) has several power device models but not the UPFC. This paper develops a UPFC module that is integrated within the PST. It consists of three components: a steady-state model or load-flow model, a dynamic model, and an interface algorithm. All of these three components are described in this paper following the section on the UPFCs basic operation. A two-area-four-generator power system with a UPFC is used to demonstrate the proposed tools.

Gas Turbine Control and Load Sharing for Shipboard Power Systems

The objective of this research is to design an energy management strategy for an Electric Shipboard Power System. The prime mover is a gas turbine for which a Proportional Integral Derivative speed controller is designed using Particle Swarm Optimization technique. The load on the system has three components: a propulsion load, a power supply load comprising the dc zonal loads and a pulse load to simulate a high energy weapons system. Based on the priorities of the loads and the available power, a strategy is presented to share the power among the load components. As the electric shipboard power system has fixed or limited generating units, load shedding is inevitable when demand exceeds the generation capacity. To illustrate this, a generic load allocation algorithm is developed. The potential of this algorithm is demonstrated by two case studies performed using the three loads of the ESPS supplied by a 59 kW gas turbine and generator. The results of this research are promising and can be extended to real time applications.

An Integrated Electric Shipboard Power System Testbed

The authors have developed a multi-agent system for autonomous energy management aboard an all electric naval ship. Simulation results were used to demonstrate the effectiveness of the proposed methodologies. To prove the concept and gain insight into this important problem, a hardware prototype is being built. The objective of this paper is to describe the prototype, its hardware components, and the communication scheme that has been adopted. We also discuss the integrated system setup with its multi-agent components to perform tests.

Circuit of the future: Interoperability and SCE’s DER program

This paper describes the concept of improving operation of a distribution circuit of the future through installment of interoperable devices, including distributed energy resources (DER) that are controlled using a multi-agent system approach. This concept for improving distribution service is being considered by SCEs DER Program, with additional assistance from West Virginia University in the development of a conceptual implementation methodology that includes multi-agent control.

Object-Oriented Modeling and Simulation of AC/DC Systems

This paper summarizes the experience gained while using the object-oriented language Modelica for modeling an AC/DC electric distribution system: the Naval electric shipboard power generation and DC distribution testbed. Modelicas hybrid system modeling capabilities allow efficient formulation of continuous and discrete information processing systems and these have been used to map the power systems components to objects in Modelica. The language clearly shows its advantages in the design phase, as domain knowledge can be directly incorporated into the basic and well-defined components. The limiting factor of using this approach could be the large set of algebraic-differential equations handled at event detection that would slow down the simulation.