This study presents a new hybrid eletromechanical–eletromagnetic simulation implementation in which a variable time step with simultaneous solution of differential and algebraic equations are the methods used for network solution and numerical integration of the electromechanical dynamics. The variable time step imposes changes in the parallel communication protocol between the positive-sequence phasor and three-phase waveform simulation algorithms. Results demonstrate the methodology accuracy applied to a modified version of the IEEE 39-bus test system.

The optimum design of power system components is becoming a relevant topic in power system studies. Genetic algorithms (GAs) are considered as a proper approach for optimisation problems in which non-linear elements are involved. Several trends are presently leading GAs to a new level; for instance, its combination with parallel computing can facilitate the solution of problems where individual evaluations of the fitness function require an important computational effort. This study presents a procedure based on a MATLAB-EMTP application and the usage of a multicore environment for the optimum selection of hybrid high-voltage DC (HVDC) circuit breaker parameters; the goal is to obtain a transient response of the hybrid design with voltages, currents and fault clearance times within specified limits.

This study presents a different approach to co-simulation based on an electromagnetic transient and transient stability (TS) hybrid line model for real-time (RT) hardware-in-the-loop applications. In the presented co-simulation scheme, instead of resorting to equivalent systems, the detailed and external systems are linked through a simple hybrid line model that accounts for wave propagation in both electromagnetic and TS simulation paradigms. After presenting and discussing the hybrid line model, the Hypersim RT co-simulation platform is detailed and the impacts of the RT constraint on various aspects of co-simulation software are explained. Two application cases are then presented: the first one to illustrate the validity of the presented approach and the second one to illustrate the performance of the RT co-simulation platform. This study concludes by describing the remaining challenges for future work.

This study presents a method to interface an electromagnetic transient (EMT) simulator with a dynamic phasor (DP) simulation program. The hybrid DP–EMT simulator offers flexibility in deciding the harmonic contents to be preserved in the DP domain; additionally, it offers significant reduction in computing time of large networks compared with EMT simulation. The proposed interfacing method is based on a generic transmission line, which uses specialised numerical techniques to transfer discretised waveform samples between the two simulators. These numerical methods produce the required mapping between EMT simulation samples and their counterpart DPs. This study describes the mathematical foundations of the DP–EMT interface and demonstrates them using an illustrative example. Several large networks are then studied to assess the interface's accuracy and performance in reducing computing time.

This study proposes a hybrid electromechanical and electro-magnetic transient (EMT) simulation algorithm, which interfaces the EMT-type modular multilevel converter (MMC) high-voltage direction current (HVDC) model into transient stability simulation. The proposed hybrid simulation algorithm offers high fidelity simulation results for the fast transient phenomenon of the MMC HVDC using the EMT program (EMTP). At the same time, the hybrid simulation algorithm utilises the transient stability program (TSP) to represent a large external AC network connected to the MMC HVDC. Thus, the proposed hybrid simulator combines the advantages of the TSP and EMTP simulations and offers accurate and efficient solutions for the integrated AC and HVDC systems. A case study of MMC HVDC system connected to 10-generator 39-bus New England AC System is simulated using hybrid and full-EMTP simulations in PSCAD/EMTDC. The simulation results demonstrate the proposed hybrid simulator produces accurate simulation results compared to the full-EMTP solutions.

Distribution networks are becoming increasingly ‘smarter’, as well as more complex, with the addition of power electronic devices, information and communication technologies, smart meters, and more. As a result, advanced control strategies to manage such networks are becoming necessary. These strategies need to be thoroughly tested and validated, before they can be implemented in a real network. For this reason, a smart grid control algorithm testing chain is proposed, that aims to gradually test control algorithms, in all their development stages, using increasingly advanced laboratory setups. In addition, the interfacing options and challenges of each stage of the chain are highlighted. The proposed testing chain is substantiated in an optimal centralised coordinated voltage control (CVC) algorithm and the final stage of the chain, namely the combination of control and power hardware-in-the-loop simulation, is presented in this study. As a specific example, the management technique for a storage system is implemented as part of the CVC algorithm. The laboratory results demonstrate that the proposed setup, despite its high complexity, enables the algorithm to be effectively and realistically tested as part of the overall system.

Phasor measurement units (PMUs) are increasingly being deployed in electric power systems in an attempt to improve grid reliability and make the grid smarter through real-time wide area situational awareness, monitoring, protection and control applications. PMU-based applications require communication networks in the transmission of synchrophasor measurements from the substations to the control centres. However, the quality-of-service of these synchrophasor measurements are not guaranteed when transmitted over a global wide area network especially in the presence of non-deterministic communication network conditions. This study presents the design, development, and integration of an IEEE Std. C37.118-based co-simulation platform comprising of power system hardware-in-the-loop simulations using the real-time digital simulator interfaced to a communication network. The impact of adverse communication network conditions such as latency, packet losses, and corruption on the exchange of data using the co-simulation platform and their impact on a centralised wide area monitoring, protection, and control (WAMPAC) system was investigated with software-in-the-loop simulations. Moreover, the maximum allowable adverse communication conditions are quantified with respect to the WAMPAC applications during emergency conditions.

The wind energy conversion system is a complex dynamic system which contains multi-coupling and multi-time-scales. The commonly used simplified models are unable to uncover all the detailed dynamics. The real-time co-simulation platform based on real-time digital simulator and GH Bladed is built with a controller hardware-in-loop, in which the kinematics equation of generator rotor is used as the interface to decouple the different time scales, and a specific programmable logic controller is used to build the two-way communication. The effect of signal delay between the two simulation platforms is discussed and the stability of the system is analysed. The proposed co-simulation platform is able to show detailed dynamics of the whole turbine as well as the comprehensive effects of the controllers. The correctness and superiorities are verified by number of simulations.

This study presents a novel interfacing setup for testing and validating wide-area monitoring and control (WAMC) techniques used in smart grids. The main purpose of this study is to provide a realistic approach for conducting WAMC studies. In here, a wide-area controller (WAC) for a flexible AC transmission system (FACTS) device is implemented. The measurements for the WAC are collected using phasor measurements units (PMUs). Three main segments are being interfaced in this study. First, the real-power grid, the local area controller of the actual FACTS device, and the PMUs are simulated using real-time digital simulator. This simulation represents the central simulation and is interfaced with the WAC, which is realised using a MATLAB-based program. This interface represents a novel software-in-the-loop (SIL) scheme. On the other hand, an actual FACTS device is designed and interfaced to the central simulation via hardware-in-the-loop (HIL) scheme. This SIL and HIL combination makes the experimental testbed more realistic and closer to the industrial standard. Various tests are conducted to examine the performance of the developed testbed.

The increasing penetration level of renewable energy brings new challenges to the field of islanding detection. In this study, a decision-tree (DT)-learning method with hardware-in-the-loop (HIL) simulations is proposed to address the non-detection zone (NDZ) issue of islanding detection in hybrid distributed generation systems including both inverter- and synchronous-machine-based distributed energy resources. This method can effectively reduce the NDZ through advanced relay training strategy and utilise the advantage of real-time simulators on simulation efficiency. In addition, the generated DT can be programmed into a real relay and then get validated through HIL simulations. The HIL implementation adds a practical dimension to the proposed method. With the proposed method, the laboratory testing results indicate promising islanding detection performance in terms of dependability, security, reduced NDZ area and detection time.

This study introduces a laboratory test set up developed to evaluate the functionality of a novel decentralised distribution automation architecture. The demonstration system consists of a simulated distribution network in real-time simulation environment including simulated monitoring and control devices as well as physical devices interfaced with the simulator as hardware-in-the-loop test devices. System involves also substation automation units for real-time monitoring and control that are interfaced with the simulator and physical devices. The operating principle of the system is demonstrated with an example simulation case. The main goal for this system was to test the functionality of the decentralised distribution automation architecture and track out any potential interfacing issues of automation system before implementing the concept to actual field demonstrations. Based on the tests executed with the system described in this study, the proper functionality of all the features of the automation architecture was verified and successfully deployed at the field test sites.

Direct current (DC) microgrid is characterised by attractive features such as high efficiency, reduced cost and needless for synchronisation. The control and operation of the DC mirogrid become significantly important with the high penetration of distributed energy resources. Therefore, development of an advanced platform for testing control and operation of the DC microgrid has attracted more and more attention nowadays. This study proposes a hardware-in-the-loop (HIL) simulation system as a new method to develop and test control algorithms and operation strategies for the DC microgrid. The proposed HIL simulation system is composed of a RT-LAB for real-time simulation, an actual controller under test, a cRIO for coordination control and the DC microgrid management system for optimal operation. Both the actual controller of key research objects and coordination control with different time scales can be tested in the proposed HIL simulation system. Hence, the platform is designed for flexibility and universality. Moreover, configuration and communication of the HIL simulation system are illustrated in this study. Finally, simulation tests are carried out to show the validation of the proposed HIL simulation platform.

This study establishes a new basis for understanding the stability of power hardware-in-the-loop (PHIL) systems considering their hybrid (analogue/digital) nature. Such systems are known to have closed-loop stability issues due to delays between the simulator and the power amplifier (PA). This work demonstrates that the conventional method for determining the stability criterion, which considers the system as a continuous model, is not appropriate. A new method of assessing the stability of a PHIL system based on discrete-time impedance frequency responses is thus presented. Hydro-Québec's Research Institute will use this innovative approach for the development of its own PHIL system, which will involve connecting the institute's real-life experimental distribution test line to its large-scale real-time digital simulator through a 25-kV, 10-MVA PA. The validity of the new method is demonstrated for simulation models of a well-known inductive system and of a distribution feeder connected to a large-scale power system.

The need for advanced monitoring and control applications (MCAs) in future distribution networks calls for highly accurate and fully integrated simulation solutions for the purpose of performance assessment of these MCAs. Offline simulation using models of the power system, measurement equipment, local controllers and the information and communication infrastructure do not always resemble reality accurate enough. Therefore, power hardware-in-the-loop (PHIL) simulations are considered a cost-effective approach to overcome these challenges. This study presents the design of a PHIL-interface that allows to integrate a physical low-voltage feeder within a larger real-time simulated distribution network. Using the combination of the physical network and the larger simulated network, MCAs can be tested for scalability as well as accuracy. A data acquisition and processing system is presented that acquires all the true system states of both the physical feeder and the real-time simulated network, such that the MCAs can be verified in real-time. The functioning of the PHIL-interface is validated using practical results and illustrated using a test case for the performance assessment of a branch current state estimation algorithm.

Real-time simulation of a microgrid involving massive high-frequency power electronic converters, various distributed generators and energy storage systems is computationally demanding. Due to the prominent computing resources and high speed communication, field programmable gate arrays (FPGAs) can be used together to realise the real-time simulation of a microgrid. For a complete multi-FPGA-based real-time simulator, interfaces are essential to communicate with each other and with different types of apparatus. The internal interfaces between FPGAs make it possible to operate in parallel, sharing the computational burden. External interfaces between an FPGA and physical devices contribute to the implementation of hardware-in-the-loop simulation. In this study, interfacing techniques including multi-FPGA system topology determination, time-step synchronisation mechanism and precise communication are proposed in detail. An analogue-to-digital and digital-to-analogue interface is designed to facilitate physical connections to external devices. A modified microgrid benchmark with photovoltaics and a battery is simulated with a time-step of 3 μs on a 4-FPGA-based real-time simulator. Simulation results are compared with PSCAD/EMTDC to validate the interface design.

The distributed system and multi-agent system (MAS) enable the effective and efficient management of complex distribution network. How to realise the co-simulation with a large number of controllers for these systems is being a hot issue. In this study, the characteristics of the simulation environment, which is suitable for the distributed control system, are discussed, and a new co-simulation method based on Java agent development framework (JADE) is proposed. It fits for the simulation of distributed system and MAS, and can simulate the physical and the communication models concurrently. After the introduction of co-simulation environment, the modelling methods of distributed controllers are described in detail. Finally, a comprehensive evaluation on the distributed protection algorithm is carried out by means of the co-simulation, and the effectiveness of the proposed co-simulation environment is validated.

The penetration of low carbon technologies (LCTs) is expected to increase in the near future given the attractive incentives from governments, the cost effectiveness of the technologies and the appearance of smart grid schemes. To understand the corresponding benefits and challenges associated with them, power utilities are expected to run more sophisticated studies supported by more accurate and detailed models of distribution network (DN) elements and the network itself. This study presents the development of two software plugins that allow the integration of a geographical information system platform with a distribution system simulator. These plugins are intended to provide power utilities free and open source tools to explore the benefits and impacts of newly adopted LCTs and to analyse smart grid opportunities in large-scale DNs. The effectiveness of the plugins is illustrated considering a real DN with 13,323 customers in Costa Rica. Results demonstrate that the plugins can successfully support in the creation of detailed network models and studies.

A ‘Run Time Scheduler’ (RunTS) is presented, a minimalist Discrete Event Simulator able to sequence the operation of multiple simulators, coordinating a simulation of several elements so to form a whole system. Dynamic cause-effect chains may emerge. In operation the net simulation possesses a known steady-state other than when changed. RunTS controls the application of state-changes, passing these to specific simulators to determine new steady-states. Messages can pass between simulations concerning configuration data, commands and results. Simulators must meet connectability criteria. The method allows variable periods between simulation stages rather than a fixed tempo, and can undertake specific simulation sequences unique to each event, through use of a novel per-event state-machine. RunTS is part of INSim, a Smart Grid simulator working with a mix of components including Electric Vehicles, Smart Agents and OpenDSS, a power network analysis tool.

This study introduces an open-source Python-OpenDSS simulation tool where the phasor simulation software OpenDSS is interfaced with an electromagnetic transient (EMT) program-type simulation tool implemented in Python environment. The tool is designed to perform impact study of photovoltaic (PV) integration in distribution systems. It is composed of an EMT model of a grid-tied PV system interfaced with a phasor model of the distribution network. The proposed tool provides an add-on that expands OpenDSS capabilities in order to perform various PV impact studies that cannot be performed inherently by OpenDSS since they require detailed modelling. This study describes the methodology and theory behind the interfacing of the EMT model with OpenDSS. The tool is tested with various case studies using the IEEE 37-bus system with multiple interconnected PV systems. The tool is validated by comparing its results with those of a full EMT model of the IEEE 37-bus system simulated using SimPowerSystems. The results indicate that the hybrid tool offers significant advantages over single-rate simulations that use either full phasor or full EMT simulation approach. It provides faster simulation time and less computational intensity, and the accuracy is remarkably close to the full blown, more complex and slower, EMT simulation.

The process of advancement and validation of smart grid technologies and systems calls for the availability of diverse expertise and resources. In response to this consideration, the virtual smart grid laboratory (VSGL) was developed as described in this study. At the core of the VSGL is a novel communication platform for seamlessly connecting geographically distributed laboratories with distinct competences. The platform has the dual purpose of opening access to resources of remote partner laboratory sites and offering the capability to emulate, analyse, and test smart grid communication networks involved in linking the distributed laboratory resources. The VSGL implementation is validated through a use case, in which the resources of R&D laboratories in three European countries are connected to form an aggregated system of distributed energy resources. The operation of the latter was coordinated through an energy management system based on model predictive control (MPC). The VSGL was found to be very suitable to meet the communication-specific requirements of such type of study. In addition, for this particular case the effectiveness of the MPC subject to diverse implementations of communication links was substantiated.

To establish a real closed-loop control centre testing environment for a cyber–physical power system, a cyber–physical testbed was established by integrating industry supervisory control and data acquisition with a source-grid co-simulation system in the laboratory at the North China Electric Power University. The testbed employs a multi-time scale interface and virtual remote terminal units to overcome the shortcomings of the real-time digital simulator. Physical simulation was performed with a source-grid co-simulation system based on a real-time digital simulator. Control system simulation was implemented using a commercial energy management system. The testbed was also integrated with a wide-area-network emulator to provide wide-area-network emulation and advanced attack simulation. An overview of the system and the key technologies used in the cyber–physical system testbed is provided in this study. In addition, two specific cyberattacks are simulated to demonstrate the capacity of the cyber–physical system testbed.

The promise of the smart grid entails more interactions between the transmission and distribution networks, and there is an immediate need for tools to provide the comprehensive modelling and simulation required to integrate operations at both transmission and distribution levels. Existing electromagnetic transient simulators can perform simulations with integration of transmission and distribution systems, but the computational burden is high for large-scale system analysis. For transient stability analysis, currently there are only separate tools for simulating transient dynamics of the transmission and distribution systems. In this study, the authors introduce an open-source co-simulation framework ‘framework for network co-simulation’ (FNCS), together with the decoupled simulation approach that links existing transmission and distribution dynamic simulators through FNCS. FNCS is a middleware interface and framework that manages the interaction and synchronisation of the transmission and distribution simulators. Preliminary testing results show the validity and capability of the proposed open-source co-simulation framework and the decoupled co-simulation methodology.

The authors present a graph-based computational framework that facilitates the construction, instantiation, and analysis of large-scale optimisation and simulation applications of coupled infrastructure networks. The framework integrates the optimisation modelling package PLASMO and the simulation package DMNetwork (built around PETSc). These tools use a common graph-based modelling abstraction that enables them to achieve compatibility between interfaces and data structures and facilitates the modular creation and exchange of component models. The authors also describe how to embed these tools within complex computational workflows using SWIFT, which is a tool that facilitates parallel execution of multiple simulation runs and management of input and output data. Finally, the authors discuss how to use these capabilities to target coupled natural gas and electricity systems.

This series of studies present the state-of-the-art for the solution of the transient stability constrained optimal power flow problem (TSC-OPF). Three different classes of solution techniques: dynamic optimisation-based, SIME method, and computational intelligence, are discussed in detail. Moreover, discussed are issues to consider while solving such problems, various application areas, and future directions in this research area. A comprehensive resource of the available literature, publicly available test systems, and relevant numerical libraries is also provided. This study presents the TSC-OPF formulation and discusses various dynamic optimisation-based approaches. Two optimisation techniques, full-space and reduced-space method, are presented for solving the resulting non-linear optimisation problem.

Transient stability-constrained optimal power flow is an important emerging problem with power systems pushed to the limits for economic benefits, dense and larger interconnected systems, and reduced inertia due to expected proliferation of renewable energy resources. In this study, two more approaches: single machine equivalent and computational intelligence are presented. Also discussed are various application areas, and future directions in this research area. A comprehensive resource for the available literature, publicly available test systems, and relevant numerical libraries is also provided.