Vahid Salehi

Laboratory-Based Smart Power System, Part I: Design and System Development

This paper presents the design and development of a hardware-based laboratory smart grid test-bed. This system is developed at the Energy Systems Research Laboratory, Florida International University. The hardware/software based system includes implementation of control strategies for generating stations, and power transfer to programmable loads in a laboratory scale of up to 35 kilowatts in ac power and 36 kW in renewable sources and energy storages. Appropriate software was developed to monitor all system parameters as well as operate and control the various interconnected components in varying connectivity architectures. The interconnection of alternate energy such as wind emulators, PV arrays, and fuel cell emulators are implemented, studied and integrated into this system. Educational experiences were drawn during the design and system development of this laboratory-based smart grid. The real-time operation and analysis capability provides a platform for investigation of many challenging aspects of a real smart power system. The design, development, and hardware setup of this laboratory is presented here in Part I of this paper. This includes component development, hardware implementation, and control and communication capabilities. Part II of the paper presents the implementation of the monitoring, control, and protection system of the whole setup with detailed experimental and simulation results.

Real-Time Energy Management Algorithm for Mitigation of Pulse Loads in Hybrid Microgrids

This paper presents a real-time energy management algorithm for hybrid ac/dc microgrids involving sustainable energy and hybrid energy storage. This hybrid storage system consists of super capacitors (SC) for ultra-fast load matching beside lithium-ion batteries for relatively long term load buffering. The energy management algorithm aims mainly at managing the energy within the system such that the effect of pulsed (short duration) loads on the power system stability is minimized. Moreover, an average annual saving of around 7% is achieved by shifting loads to off-peak hours. The expected energy needed during a future peak, the time of its occurrence and the current state of charge of both elements of the hybrid storage system are all examples of the inputs to the algorithm. A nonlinear regression technique is used to obtain mathematical models for the uncertain quantities including load and sustainable energy curves. The results show a significant improvement for the system in terms of voltage and power stability by applying the proposed algorithm.

Laboratory-Based Smart Power System, Part II: Control, Monitoring, and Protection

Wide area monitoring (WAM), wide area protection (WAP), and wide area control (WAC) systems will enhance the future of smart grid operation in terms of reliability and security. In part I of this paper, a proposed architecture for a hybrid ac/dc smart grid hardware test-bed system was presented. Design details of the various components and their connectivity in the overall system architecture were identified. In part II of the paper, the focus is on the design of monitoring, control, and protection systems and their integrated real-time operation. Various control scenarios for system startup and continuous operation are examined. We have developed a control system based on wide area measurements. The advanced measurement system based on synchrophasors was also implemented using DAQs real-time synchronous data. The developed system features a wide variety of capabilities such as online system parameters calculation and online voltage stability monitoring. These are implemented as an experimental case to enhance wide area monitoring systems. Moreover, the protection system was designed inside of the real-time software environment to monitor the real-time wide area data, and make a comprehensive and reliable coordination for the whole system. Ideas related to the interaction of a dc microgrid involving sustainable energy sources with the main ac grid have been also implemented and presented. The implemented system is explicit and achievable in any research laboratory and for real-time real-world smart grid applications.

Development and implementation of a phasor measurement unit for real-time monitoring, control and protection of power systems

Measurement and calculations of actual power system parameters in real-time have been carried out by Synchronized Phasor Measurement Units (PMUs). The applications of PMUs in power system are extended to protection, control and monitoring of wide area of power system. This research will present the real-time calculation of power system parameters using PMUs and their application in power system studies. The developed system has the capability of utilizing the designed PMU for analyzing the power system in real-time. A laboratory test setup was utilized to test real-time application of the developed PMU. This system uses different DAQs to gather voltage and current data, and measure power system parameters such as the voltage and current phasors, positive, negative and zero sequences, powers and frequency of each component. The results of PMUs were verified by measurement devices. The potential of the developed PMU system in calculating the power system stability index in real-time as well as the line parameters by the available phasors data was discussed.

Pulse-load effects on ship power system stability

In this investigation, the performance of a fully-integrated ship power system with a pulsed power load is analyzed. There are particular loads in shipboard power systems such as electromagnetic guns, electromagnetic launch systems, and free electron lasers, which draw very high short time current in an intermittent fashion. In this research, the power system is thoroughly simulated to capture its transient and dynamic behaviors during the occurrence of a pulse-load. This simulation provides better understanding of the system performance and its stability under such severe conditions, and the results demonstrate the effect of different pulse-load characteristics, i.e. the magnitude and duration of the load, and the system topology, controllers and major parameters affect the stability of the system.

Real-time analysis for developed laboratory-based smart micro grid

The modern power network incorporates communications and information technology infrastructures into the electrical power system to create a smart grid. The smart grid will utilize digital information technology to create a more efficient, reliable, flexible and responsive network. The objective of this paper is to apply the concept of real time analysis in a smart grid by developing a test-bed smart grid in power system laboratories. The laboratory experiment and analysis guarantee a high level of reliability when the smart grid is implemented in the actual field. Educational application of the laboratory-based smart grid and its real-time analysis capability, provide the platform for investigation of the most challenging aspects of real power system.

Reactive power compensation in hybrid AC/DC Networks for Smart Grid applications

In this paper, the utilization of hybrid AC/DC micro grids as a reactive power compensator is investigated. Wide Area Monitoring (WAM), Wide Area Protection (WAP), and Wide Area Control (WAC) systems will enhance the future of Smart Grid operation in terms of reliability and security. A proposed architecture for a hybrid AC/DC Smart Grid hardware test-bed system is presented. Design details of the various components and their connectivity in the overall system architecture are identified. The utilization of the DC side of the network as a reactive power source to the main grid is developed and presented. In order to allow this reactive power compensation process and voltage regulation on the AC side, a vector decoupling controlled pulse width modulation (PWM) voltage source inverter (VSI) was used as an interface between the DC micro grid and the main AC grid. This converter has the capability of controlling the active and reactive power independently. Hence, any extra power available from renewable energy sources connected to the DC micro grid will be used to regulate the voltage on the AC side. Experimental results were obtained from a hardware test-bed system totaling 72 kW (with 35 kW on the AC side and 37 kW on the DC side) to verify the ideas and concepts presented in the paper. Experimental and simulation results show excellent comparisons.

Real-time power system analysis and security monitoring by WAMPAC systems

The outline of this paper is to implement real-time analysis and security monitoring in the smart power system. Security is the ability of the power system to withstand contingencies. The principal role of Wide Area Monitoring, Protection and Control (WAMPAC) system is to maintain a secure system state, i.e. the system that can withstand each specified contingency. The advanced WAM system uses real-time measurements to monitor system status and hence determines whether or not it is secure. The WAMPAC system is used to deploy proper control actions on load, transmission and generation in a wide time frame from fast protection systems to slower control of generators. This paper also explores the challenges and opportunities to implement online system analysis capability in order to monitor system security and stability indices. Therefore, the implemented hardware/software setup for monitoring and analyzing system in real-time format will be presented by the online results available with real-time software. Online load flow and contingency results aim to proper security monitoring of power system in wide area which is useful for most application such as system remedial actions.

Developing virtual protection system for control and self-healing of power system

Using new technologies for communication in power system creates new opportunities for developing wide area system monitoring, protection and control system. Virtual Protection System (VPS) is a system that can be implemented in control center to detect any system abnormalities in a virtual environment by using PMUs data from whole system area. The control system can use the VPS fault analyses to detect system states and apply the proper remedies for self-healing of power system. Developed laboratory test setup is presented and several tests are accomplished in this regard. Applications of this system in power system control and self-healing will be discussed.

Implementation of real-time optimal power flow management system on hybrid AC/DC smart microgrid

The concept of microgrid involves coordination between distributed load and generation by enhancing the system controllability, flexibility, energy management and storage capability. The problem of optimal management of the resources in a microgrid is under investigation and recent studies propose new strategies to use centralize and distributed control schemes by utilizing real-time monitoring and control system. This paper presents the development of a real-time Optimal Power Flow (OPF) management system which is implemented in the Smart Grid Test-bed lab at Florida International University. The paper will discuss briefly the developed Hybrid AC/DC microgrid and its components. Implementation of real-time monitoring and control system creates the feasibility of performing online OPF and applying load-generation settings and strategies in real-time format.