M. Omar Faruque

Real-Time Simulation Technologies for Power Systems Design, Testing, and Analysis

This task force paper summarizes the state-of-the-art real-time digital simulation concepts and technologies that are used for the analysis, design, and testing of the electric power system and its apparatus. This paper highlights the main building blocks of the real-time simulator, i.e., hardware, software, input-output systems, modeling, and solution techniques, interfacing capabilities to external hardware and various applications. It covers the most commonly used real-time digital simulators in both industry and academia. A comprehensive list of the real-time simulators is provided in a tabular review. The objective of this paper is to summarize salient features of various real-time simulators, so that the reader can benefit from understanding the relevant technologies and their applications, which will be presented in a separate paper.

Characteristics and Design of Power Hardware-in-the-Loop Simulations for Electrical Power Systems

This paper presents a compendious summary of power hardware-in-the-loop (PHIL) simulations that are used for designing, analyzing, and testing of electrical power system components. PHIL simulations are an advanced application of real-time simulations that represent novel methods, which conjoin software and hardware testing. This contribution outlines necessary requirements for the implementation of PHIL simulations, which are defined by the nature of the digital real-time simulator, the power amplifier, and the power interface (PI). Fundamental characteristics, such as the input/output systems, PI, interface algorithm, and system stability considerations, are discussed for PHIL setups, in order to illustrate both flexibility and complexity of this compound simulation method. The objective of this work is to elaborate an understandable overview of PHIL simulation for electrical power systems and to constitute a contemporary state-of-the-art status of this research area.

Applications of Real-Time Simulation Technologies in Power and Energy Systems

Real-time (RT) simulation is a highly reliable simulation method that is mostly based on electromagnetic transient simulation of complex systems comprising many domains. It is increasingly used in power and energy systems for both academic research and industrial applications. Due to the evolution of the computing power of RT simulators in recent years, new classes of applications and expanded fields of practice could now be addressed with RT simulation. This increase in computation power implies that models can be built more accurately and the whole simulation system gets closer to reality. This Task Force paper summarizes various applications of digital RT simulation technologies in the design, analysis, and testing of power and energy systems.

Interfacing Power System and ICT Simulators: Challenges, State-of-the-Art, and Case Studies

With the transition toward a smart grid, the power system has become strongly intertwined with the information and communication technology (ICT) infrastructure. The interdependency of both domains requires a combined analysis of physical and ICT processes, but simulating these together is a major challenge due to the fundamentally different modeling and simulation concepts. After outlining these challenges, such as time synchronization and event handling, this paper presents an overview of state-of-the-art solutions to interface power system and ICT simulators. Due to their prominence in recent research, a special focus is set on co-simulation approaches and their challenges and potentials. Further, two case studies analyzing the impact of ICT on applications in power system operation illustrate the necessity of a holistic approach and show the capabilities of state-of-the-art co-simulation platforms.

Dynamic interactions between distribution network voltage regulators for large and distributed PV plants

This paper summarizes the initial investigation of dynamic interactions of voltage regulating equipment when allowed to act together with one or more large voltage-controlled solar photovoltaic (PV) generation plants. The study results are based on an existing large PV plant and distribution circuit in the service area of a major electric utility. The existing feeder does not have any voltage regulating equipment and the PV plant is not allowed to control voltage, hence injects real power only. However, in light of the growing interest in allowing PV plants to control voltage, several scenarios are considered by allowing PV plants to control the voltage at the Point of Common Coupling (PCC) along with the traditional voltage regulators. Further case studies are performed by distributing the large PV plant into six PV plants of equal power rating connected at different feeder locations. This configuration has been investigated to determine possible differences in interactions of voltage regulators between a large plant and distributed plants. The voltage regulating equipment considered are On-Load Tap-Changing Transformers (OLTC), Switched Capacitor Banks (SCB) and also PV plant inverters capable of controlling the voltage at the PCC. The 12.6 MW (peak a.c.) PV plant and its controls, the regulating equipment, and the distribution network are modeled using a Real Time Digital Simulator (RTDS). Initial study suggests that allowing PV plants to actively participate in the voltage control process requires a coordinated control to minimize the number of operations of traditional voltage regulators.

Thermo-electric co-simulation on geographically distributed real-time simulators

In this paper, we report a combined electrical and thermal simulation carried out using two real-time digital simulators located approximately 3500 km from each other. The electrical model was developed on the RTDS simulator at the Center for Advanced Power Systems, Florida State University, Tallahassee, Florida, while the thermal model was developed on an OPAL-RT simulator located in the RTX-Lab at the University of Alberta, Edmonton, Alberta. The two simulators exchange data in an asynchronous mode on the Internet utilizing the TCP/IP and UDP protocols. Before running the actual thermo-electric co-simulation, a loop-back test was designed and run to investigate the accuracy, latency, and stability of the communication link. The loop-back test revealed a maximum latency of 0.1s for transmitting a signal from one simulator to the other including all the communication and processing delays. Simulation results corroborate the fact that despite this latency, the thermo-electric co-simulation on geographically distributed real-time simulators can be performed with sufficient accuracy and stability.

Impact of PV on distribution protection system

This paper investigates the impacts of PV interconnection on the protection systems of a distribution network, especially when power flow is reversed in high penetration scenarios. A Florida based substation and its six-feeders were selected for the study. The system was slightly modified to make it a notional system that still closely represents the actual system behavior from the point of view of system protection. The main modification is in the representations of loads, where all the loads were represented by fewer aggregated loads on each feeder. One of the feeders is 9 miles long and has a 12.6 MW (AC) PV plant connected to the primary side of the feeder at a distance of 4.8 miles from the substation. The feeder has an average load of approximately 11 MVA that makes it a contender for a high penetration (more than 100%) feeder when PV reaches its peak generation. The model of the entire substation, its feeders and protection system has been built using a high fidelity transient simulation tool RSCAD. Initial simulation results indicate that if protection devices are coordinated properly, a reverse power flow does not create any nuisance trip or malfunction of the protection system. However, based on the location of the PV plant with respect to the fault, slight change in the trip time of the time-overcurrent relays was observed.

Size and Weight Computation of MVDC Power Equipment in Architectures Developed Using the Smart Ship Systems Design Environment

The smart ship systems design (S3D) environment under development is intended to enable users to estimate the size and weight requirements for various devices and subsystems of a naval vessel. This paper continues work done related to the modular multilevel converter (MMC) scaling approach and applies it to other devices of the medium voltage dc (MVdc) portion of the power network. The analysis shown uses a 10 kV baseline ship design within S3D and uses the developed scaling values to calculate the total weight and volume of particular equipment. Comparisons between power densities of the overall MMC system at different MVdc bus voltages and using power electronic building blocks of different ratings are also shown. This provides vital insight that enables S3D users to assess and evaluate different power architectures using metrics such as functionality, mass, and volume among other factors.

Geographically distributed thermo-electric co-simulation of all-electric ship

In this paper, a thermo-electric co-simulation of an all-electric ship type notional system using two geographically distributed heterogeneous real-time simulators is presented. The two real-time simulators, from RTDS and OPAL-RT, are used for modeling the electrical system and the thermal system of an all-electric ship, respectively. RTDS is located at the Center for Advanced Power Systems, Florida State University, Tallahassee, Florida, USA whereas the OPAL-RT simulator is located in the RTX-Lab at the University of Alberta, Edmonton, Canada. The two simulators separated by approximately 3500 km, exchange data through an asynchronous link over the Internet utilizing the TCP/IP and UDP protocols. The electrical model was developed using RSCAD and simulated on RTDS while the thermal model was developed using SIMULINK and simulated in the RT-LAB environment. RTDS sends the electrical power losses to the OPAL-RT simulator, which computes the temperatures of the thermal systems and sends the data back to the RTDS simulator. Simulation results indicate that despite the large physical distance between the two simulators, the co-simulation is accurate and stable. A low latency of 0.208 s was observed which is within acceptable limits for a slow system response expected from the thermal system, which has time constants in the range of seconds. Results indicate that co-simulation of different types of systems is a viable and may be a cost-effective option to perform remote hardware-in-the-loop simulation of complex multi-engineering models.

Impacts of distributed generation on power quality

This paper studies the impacts on power quality due to the interconnection of multiple distributed generators on a distribution utility feeder. For this purpose, a Florida-based distribution feeder was modeled and studied by integrating different types of distributed generation (DG) sources. Different scenarios were implemented in which solar and wind plants were modeled with high variability of load and generation to observe their impacts on systems power quality. All the modeling and simulations were carried out using a high fidelity electromagnetic real-time transient simulation tool.