Real-Time Power System Simulation Hardware-In-The-Loop Testbed for Coordinated Voltage Control System

Superconducting Generator (SCG) has many advantages such as small size, high generation efficiency, low impedance, and so on. An improved power system with many potential good properties may be obtained by introduction of SCG. In order to study the behaviors of SCG in power systems, a digital type SCG model for an existing analog type real-time power system simulator is developed in this work, which is suitable for real-time simulations when the generator constants and control systems are changed frequently. By use of the above-mentioned equipments, real-time simulation in cases of SCG with different generator constants and in case of SCG in multi-machine power system has been conducted. The real-time simulation results verify the effects of SCG on power system stability enhancement and show the influence of generator constants on its stability-improving effects.

KEPCO proposes enhanced voltage management system that is a coordinate voltage control system between the hierarchical voltage control system and the slow voltage control system. It has been installing in Jeju island. VMS consists of a master controller, CVC (Continuous Voltage Controller) and DVC (Discrete Voltage Controller). CVC consists of main controller, FDMU (Field Data Measurement Unit) and several RPDs (Reactive Power Dispatcher). CVC has a control scheme with AVRs of generator to maintain the voltage of a pilot bus in a power system, DVC has a control scheme with static reactive power sources, like a shunt capacitor, a shunt reactor, ULTC and so on, to maintain the reactive power reserve of a power system and a master controller is executed to recover reactive power margin of a power system through coordinated control between CVC and DVC.

Disturbances, including uncertinities are a common phenomenon in power grids, and they can occur in source or load side at different time or simultaneously in both sides. Among the most frequent disturbances, source and load uncertainties are considered as the most catastrophic features. These disturbances can deteriorate the performances of the associate controller and contribute to oscillation and resonance. Conventional Proportional Integral (PI) controllers fail to provide supply quality assurance and system security against moderate to strong disturbances. If a disturbance occurs, it usually deteriorates both controller performance and supply voltage quality at DC bus in microgrids. This issue, however, has not been fully understood and addressed in the existing literature. Hence, this paper presents the effect of the conventional PI controller in a DC microgrid under disturbances. Consequently, a few case studies has been conducted with traditional single-variable controllers in a real time simulation environment and found that disturbances can causes overshoot or undershoot, along with power oscillation at DC bus. Thus, to overcome this oscillation and to enhance the stability and resilience of the DC microgrid, a Linear Quadratic Regulator (LQR) controller is proposed. Results demonstrate that the LQR controller can handle small to moderate disturbances and stabilise the voltages at the DC bus when compared to a conventional PI controllers. It can also minimize overshoot and undershoot along with damping power oscillation at common DC bus and removing the possibilities of resonance.

This paper presents the implementation of an advanced real-time simulation platform as an effective approach for testing and validation of PMU-based applications. At present, many PMU-based applications, such as linear state estimator (LSE), is still in active development and have not been widely implemented in large-scale power systems as it requires the installation of a large number of PMUs to achieve a state estimator exclusively based on PMU measurements. To ensure the successful deployment of such a large-scale and complex system, it requires thorough testing and validation to evaluate its performance and reliability in different scenarios. However, the complexity of performing comprehensive system-level testing through large-scale integration of PMU devices with the interoperability of various smart grid applications remains a unique challenge making the functionality and performance of LSE in an operational power system environment difficult to fully evaluate and demonstrate. Therefore, the digital real-time power system simulator has enabled comprehensive real-time testing and validation of LSE to be implemented and analysis can be performed efficiently in different scenarios and grid conditions within a safe environment. The results indicate that the implementation of this advanced real-time simulation platform significantly reduces the time required to discover practical problems that arise and enables any rectification work to be determined and applied immediately, thus reducing the risk of system failure and enhancing the integrity of the PMU-based linear state estimator for actual system deployment.

In all-electric navy ships, severe damage or faults may occur during battle conditions. This might even affect the generators, and as a result, critical loads might suffer from power deficiencies for a long time, ultimately leading to a complete system collapse. A fast reconfiguration of the power path is therefore necessary in order to serve the critical loads and to maintain a proper power balance in the ship's power system. A fast intelligent reconfiguration algorithm based on small-population-based particle swarm optimization (PSO) (SPPSO) is presented in this paper. The reconfiguration of the electric ship's power system is formulated as a single objective as well as a multiobjective optimization problem. In the case of multiobjective optimization, the Pareto optimal solutions are obtained by SPPSO from two conflicting objective functions. From the Pareto set, the final solution is chosen depending on users' preferences regarding the mission of the navy ship. SPPSO is a variant of PSO having fewer numbers of particles and regenerating new solutions within the search space every few iterations. This concept of regeneration in SPPSO makes the algorithm fast and greatly enhances its capability. The strength of the proposed reconfiguration strategy is demonstrated on a real-time digital simulator environment.

This paper presents the features of the implementation of automatic exciting regulators (AER) models in the Hybrid Real-Time Power System Simulator (HRTSim). This simulator has unique abilities: simulation without decomposition, no restrictions on the dimension of the simulated power system, realtime simulation, exclusion of methodological error of simulation, usage of full and adequate models of primary and auxiliary power system equipment. These features allow using HRTSim for a variety of tasks in the energy sector. The article presents fragments of AER research and setting in Tomsk power system with using of HRTSim.

This paper studies two cutting edge technologies applied to the power system: FACTS devices and real time (RT) simulation tools. On the one hand, the complexity of the power system and its components, makes power system simulators very useful and even necessary. Amongst all the existing simulators, real time digital simulators permit the test of power system components in conditions that are quite close to reality. On the other hand power electronic devices such as FACTS, are becoming more and more frequent on the power system, and it is necessary to evaluate their impact on the performance of the system. For all these reasons it is very important to develop FACTS models which can be suitable for real time simulation in order to test their interaction with other power system components. This paper presents the generalized average model of two FACTS devices the static VAr compensator (SVC) and the static VAr generator, which have been then introduced in ARENE for the realization of real time simulations.

Sharing memory spaces between parallel processes is a common practice in a real-time simulation environment. In an environment where parallel processes can exist on the same machine or on different machines, it is a challenge to develop and maintain reusable software that interfaces with shared memory spaces. The two main problems involved in dealing with shared memory spaces are: 1) providing platform independent access to the memory space, and 2) providing to all processes a consistent view of the structure and content of the memory space. Object-oriented techniques were used to create a software architecture designed to manage shared memory spaces. Object-oriented design patterns were used to present client code with a conceptual model of shared memory spaces while concealing the underlying implementation details. The resulting architecture is largely computing platform independent, with platform specific code being isolated to a few selected classes. The design was implemented in C++ for the NASA Langley Standard Real-Time Simulation (LaSRS++) Application Framework. This paper provides an overview of the design and implementation of the LaSRS++ shared memory management software.

Though the deep penetration of cyber systems across the smart grid sub-domains enrich the operation of the wide-area protection, control, and smart grid applications, the stochastic nature of cyber-attacks by adversaries inflict their performance and the system operation. Various hardware-in-the-loop (HIL) cyber-physical system (CPS) testbeds have attempted to evaluate the cyberattack dynamics and power system perturbations for robust wide-area protection algorithms. However, physical resource constraints and modular integration designs have been significant barriers while modeling large-scale grid models (scalability) and have limited many of the CPS testbeds to either small-scale HIL environment or complete simulation environments. This paper proposes a meticulous design and efficient modeling of IEC-61850 logical nodes in physical relays to simulate large-scale grid models in a HIL real-time digital simulator environment integrated with industry-grade hardware and software systems for wide-area power system applications. The proposed meticulous design includes multi-breaker emulation in the physical relays, which extends the capacity of a physical relay to accommodate more number of CPS interfaces in the HIL CPS security testbed environment. We have used our existing HIL CPS security testbed to demonstrate scalability by the real-time performance of ten simultaneous IEEE-39 CPS grid models. The experiments demonstrated significant results by 100% real-time performance with zero overruns, and low latency while receiving and executing control signals from physical SEL relays via IEC-61850 and DNP-3 protocols to real-time digital simulator, substation remote terminal unit (RTU) software and supervisory control and data acquisition (SCADA) software at control center.

Real-Time Simulations (RTS) are increasingly being used to understand the complex device and system level interactions in power grids. RTS provides the capability to create detailed, highly accurate, and diverse set of power and control system components at low time steps (order of microseconds) that are based on “real-world clock-time.” RT simulator is a unique architecture with specialized processors and communication boards that allow time synchronization of simulations and the clocktime. Lean operating systems, specialized processors, faster communications, etc. are the typical attributes of RT simulators. RT simulators provide a unique capability of interfacing with power and control components via analog and digital interfaces. However, RT simulators have limited computational capability that constrains the size of power and control systems that can be simulated. Multiple simulators connected locally is typically used to increase the computation capability, however this is not always economical. Additionally, RT simulators are used at facilities with unique test infrastructure in the form of grid emulators, inverters, photovoltaic, wind turbine, microgrids, etc. Performing distributed RTS via Internet can augment simulation capacity and leverage unique infrastructure that is dispersed in academia and research laboratories. Research related to distributed RTS and its application in electric power engineering is discussed in this chapter.

The complexity of a smart grid with a high share of renewable energy resources introduces several issues in testing power equipment and controls. In this context, real-time simulation and Hardware in the Loop (HIL) techniques can tackle these problems that are typical for power system testing. However, implementing a convoluted HIL setup in a single infrastructure can be physically impossible or can increase the time required to test a smart grid application in detail. This paper introduces the Joint Test Facility for Smart Energy Networks with Distributed Energy Resources (JaNDER) that allows users to exchange data in real-time between two or more infrastructures. This tool enables the integration of infrastructures, exploiting the synergies between them, and creating a virtual infrastructure that can perform more experiments using a combination of the resources installed in each infrastructure. In particular, JaNDER can extend a HIL setup. In order to validate this new testing concept, a coordinated voltage controller has been tested in a Controller HIL setup where JaNDER was used to interact with an actual On Load Tap Changer (OLTC) controller located in a remote infrastructure. The results show that the latency introduced by JaNDER is not critical; hence, under certain circumstances, it can be used to expand the real-time testing without affecting the stability of the experiment.

Guest Editorial

Distributed Energy Resources (DER) are being used to support the energy requirement in the power system and to feed the local loads in remote area, where the utility grids are not available. DER, as a microgrids can also be used to regulate active and reactive power requirement as well as to fulfil the power quality requirement of the power system. In this paper, a grid interactive wind energy conversion system has been discussed and analyzed by connecting with IEEE-9 bus system in normal working condition as well as in faulty network condition. Mathematical modelling and simulation of the system has been done in MATLAB-RT-LAB and results have been validated in real time simulation environment.

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