Harmonic-by-harmonic time delay compensation Method for PHIL simulation of low impedance power systems

In PHIL simulations different time delays are introduced. Although it can be reduced, there is always some time delay. As a consequence, when the device under test is part of a low impedance power system such as: microgrids, marine or aero power systems, the simulation process becomes challenging due to the poor accuracy of the results achieved by the introduction of the time delay. Therefore, in order to accurately compensate for the inherent time delay introduced in Power Hardware in the Loop (PHIL) simulations, a method based on phase-shifting the reference voltage signal harmonic-by-harmonic and phase-by-phase is proposed. In this manner the time delay compensation will not affect to the system topology and therefore the dynamic behaviour of the original system will stay as it originally was in terms of power angles and V-I phase relationships for all the harmonics processed. In this paper, an experiment where the reference voltage is altered with 5th and 7th harmonics shows that the accuracy of PHIL simulations after the application of this compensation method is greatly improved compared with traditional methods. As a result, low impedance power systems are now able to experience an accurate PHIL simulation

Controller HIL testing of real-time distributed frequency control for future power systems

With the evolution of power system components and structures driven mainly by renewable energy technologies, reliability of the network could be compromised with traditional control methodologies. Therefore, it is crucial to thoroughly validate and test future power system control concepts before deployment. In this paper, a Controller Hardware in the Loop (CHIL) simulation for a real-time distributed control algorithm concept developed within the ELECTRA IRP project is performed. CHIL allows exploration of many real-world issues such as noise, randomness of event timings, and hardware design issues that are often not present on a simulation-only system. Octave has been used as the programming language of the controller in order to facilitate the transition between software simulation and real-time control testing. The distributed controller achieved frequency restoration with a collaborative response between different controllers very fast after the unbalanced area is located

Characterization of time delay in power hardware in the loop setups

The testing of complex power components by means of power hardware in the loop (PHIL) requires accurate and stable PHIL platforms. The total time delay typically present within these platforms is commonly acknowledged to be an important factor to be considered due to its impact on accuracy and stability. However, a thorough assessment of the total loop delay in PHIL platforms has not been performed in the literature. Therefore, time delay is typically accounted for as a constant parameter. However, with the detailed analysis of the total loop delay performed in this article, variability in time delay has been detected as a result of the interaction between discrete components. Furthermore, a time delay characterization methodology (which includes variability in time delay) has been proposed. This will allow for performing stability analysis with higher precision as well as to perform accurate compensation of these delays. The implications on stability and accuracy that the time delay variability can introduce in PHIL simulations has also been studied. Finally, with an experimental validation procedure, the presence of the variability and the effectiveness of the proposed characterization approach have been demonstrated

Distributed negotiation in future power networks : rapid prototyping using multi-agent system

Technologies like multi-agent system (MAS) have the capability to deal with future power grid requirements such as frequency management and voltage control under a flexible, intelligent and active feature. Based on web of cells (WoC) architecture proposed by European Liaison on Electricity Committed Towards longer-term Research Activity Integrated Research Programme (ELECTRA IRP), a distributed MAS with distributed negotiation ability for future distributed control (including frequency management and voltage control) is proposed. Each cell is designed as an intelligent agent and is investigated in case studies with constraints, where each agent can only communicate with its neighbouring agents. The interaction logic among agents is according to the distributed negotiation algorithm under consideration by the authors. Simulation results indicate that the WoC architecture could negotiate resources in a distributed manner and achieve successful exchange of resources by coordinating distributed agents. Moreover, the prototype reported in this paper can be extended further for future grids' distributed control regimes. The option of MAS to be exploited for the support of the development and integration of novel power system concepts is explored

Analysis of responsibilization within primary frequency control

The emerging need to prioritize remedial frequency control measures closer to the source of an imbalance event, referred to as responsibilization, is being acknowledged. As responsibilization is inherent within secondary frequency control, novel primary frequency control (PFC) approaches to incorporate responsibilization are being proposed in literature. This contribution is aimed to enhance the understanding of responsibilization to enable further improvement and development of the concept. To this end, this paper extends the knowledge-base by presenting an analysis of responsibilization within conventional PFC and a responsibilizing PFC reported in literature. The analysis is undertaken by means of real-time simulation conducted on a six-area reduced model of the Great Britain power system

A novel decentralized responsibilizing primary frequency control

There is an emerging need to prioritize remedial frequency control measures closer to the source of an imbalance event. This approach, referred to herein as responsibilization, is challenging to achieve within the conventional operating times of Primary Frequency Control (PFC) and therefore novel methods are sought. In this letter, a novel decentralized PFC is proposed which relies on transient phase offset to achieve fast responsibilization autonomously. The effectiveness of the proposed control is demonstrated by real-time simulations and its stability assessed by small-signal analysis. This development will lead to increased system resilience during imbalance events

Review of approaches for using synchrophasor data for real-time wide-area control

Due to the changing nature of power systems—with reduced electrical inertia and the prevalence of smaller controllable power resources rather than large generators—new control approaches are required to mitigate disturbances. Ubiquitous measurements and communications networks can beleveraged to accelerate and provide a targeted, real-time response in such future systems. However, autonomous control of power systems requires dependable measurements. This paper provides a review of state of the art approaches to real-time power system control using synchrophasor measurements. In particular, examples are given involving recent developments in frequency regulation. Through a case study, it is shown how laboratories can be linked using Software-Defined Networking technologies to conveniently share resources in order to realistically and comprehensively validate synchrophasor-based control systems

The role of experimental test beds for the systems testing of future marine electrical power systems

Marine electrical power systems (MEPS) are experiencing a progressive change with increased electrification - incorporation of distributed power generation, high power density requirement, increased storage integration, availability of alternative technologies and incorporation of novel loads to name a few. In recent years, smart grid (advanced land based power systems) concepts have increasingly been incorporated within MEPS to leverage on their proven advantages. Due to the distinct nature of the two power systems, upon incorporation, the solutions need to be further proven by simulations and experimentation. This paper presents two smart grid enabled MEPS test beds at the University of Strathclyde developed to allow for proof of concept validations, prototyping, component characterization, test driven development/enhancement of emerging MEPS solutions, technologies and architectures. The capabilities of the test beds for rapid proof of concept validations and component characterization are discussed by means of two case studies. Drawing on from the two case studies, this paper further presents a discussion on the requirements of systems testing of future more electric MEPS

Education and training needs, methods, and tools

The importance of education and training in the domain of power and energy systems targeting the topics of cyber-physical energy systems/smart grids is discussed in this chapter. State-of-the art laboratory-based and simulation-based tools are presented, aiming to address the new educational needs