Future Perspectives of Co-Simulation in the Smart Grid Domain

The recent attention towards research and development in cyber-physical energy systems has introduced the necessity of emerging multi-domain co-simulation tools. Different educational, research and industrial efforts have been set to tackle the co-simulation topic from several perspectives. The majority of previous works has addressed the standardization of models and interfaces for data exchange, automation of simulation, as well as improving performance and accuracy of co-simulation setups. Furthermore, the domains of interest so far have involved communication, control, markets and the environment in addition to physical energy systems. However, the current characteristics and state of co-simulation testbeds need to be re-evaluated for future research demands. These demands vary from new domains of interest, such as human and social behavior models, to new applications of co-simulation, such as holistic prognosis and system planning. This paper aims to formulate these research demands that can then be used as a road map and guideline for future development of co-simulation in cyber-physical energy systems

Accelerated Real-Time Simulations for Testing a Reactive Power Flow Controller in Long-Term Case Studies

This paper presents the development of an accelerated real-time cosimulation and testing platform, especially for long-term simulations of power systems. The platform is planned to be utilized in the development and testing of active network management functions for microgrids and smart grids. Long-term simulations are needed in order to study, for example, the potential weekly, monthly, or yearly usage of distribution-network-connected distributed energy resources for different technical flexibility services. In order to test new algorithms in long-term study cases, real-time simulations or hardware-in-the-loop tests should be accelerated. This paper analyzes the possibilities and challenges of accelerated long-term simulations in studying the potential use of a large-scale wind turbine for reactive power flow control between distribution system operator (DSO) and transmission system operator (TSO) networks. To this end, the reactive power flow control is studied for different voltage levels (HV and MV) in the Sundom Smart Grid in Vaasa, Finland. The control of reactive power flow between HV and MV networks is realized with a reactive power window control algorithm for a 3.6 MW MV-network-connected wind turbine with a full-scale power converter. The behaviour of the reactive power controller during long-term simulations is studied by offline and real-time simulations. Moreover, the real-time simulations are performed with both software-in-the-loop and controller-hardware-in-the-loop.Copyright © 2020 Katja H. Sirviö et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.fi=vertaisarvioitu|en=peerReviewed

Controller development for reactive power flow management between DSO and TSO networks

In the future, new solutions for active and reactive power control related to the flexibility services offered by distributed energy resources (DER) will be needed even more. One ancillary service which DER could provide is the reactive power flow management between DSO and TSO networks. This research aims to develop a reactive power controller from a preliminary algorithm to a light-weight IED for a wind turbine converter. The purpose of the controller is to maintain the reactive power flow of a medium voltage network within the limit set by a transmission system operator. In his paper, the controller development stages are presented - starting from the preliminary algorithm development by Simscape Power Systems to real hardware and testing it by Controller-Hardware-In-the-Loop simulations. The operation of the controller is investigated in the different development stages of the power network. The outcome is the development suggestions of the real-time simulation platform, as well as the discussion of further improvement possibilities for the controller.fi=vertaisarvioitu|en=peerReviewed

Integrated Planning of Multi-energy Grids: Concepts and Challenges

In order to meet ever-stricter climate targets and achieve the eventual decarbonization of the energy supply of German industrial metropolises, the focus is on gradually phasing out nuclear power, then coal and gas combined with the increased use of renewable energy sources and employing hydrogen as a clean energy carrier. While complete electrification of the energy supply of households and the transportation sector may be the ultimate goal, a transitional phase is necessary as such massive as well as rapid expansion of the electrical distribution grid is infeasible. Additionally, German industries have expressed their plans to use hydrogen as their primary strategy in meeting carbon targets. This poses challenges to the existing electrical, gas, and heating distribution grids. It becomes necessary to integrate the planning and developing procedures for these grids to maximize efficiencies and guarantee security of supply during the transition. The aim of this paper is thus to highlight those challenges and present novel concepts for the integrated planning of the three grids as one multi-energy grid.Comment: NEIS 2022; Conference on Sustainable Energy Supply and Energy Storage System

ERIGrid Holistic Test Description for Validating Cyber-Physical Energy Systems

Smart energy solutions aim to modify and optimise the operation of existing energy infrastructure. Such cyber-physical technology must be mature before deployment to the actual infrastructure, and competitive solutions will have to be compliant to standards still under development. Achieving this technology readiness and harmonisation requires reproducible experiments and appropriately realistic testing environments. Such testbeds for multi-domain cyber-physical experiments are complex in and of themselves. This work addresses a method for the scoping and design of experiments where both testbed and solution each require detailed expertise. This empirical work first revisited present test description approaches, developed a newdescription method for cyber-physical energy systems testing, and matured it by means of user involvement. The new Holistic Test Description (HTD) method facilitates the conception, deconstruction and reproduction of complex experimental designs in the domains of cyber-physical energy systems. This work develops the background and motivation, offers a guideline and examples to the proposed approach, and summarises experience from three years of its application.This work received funding in the European Community’s Horizon 2020 Program (H2020/2014–2020) under project “ERIGrid” (Grant Agreement No. 654113)

Distributed Control of HVDC Transmission Grids

Recent issues such as priority access of renewable resources recommended by European energy directives and increase the electricity trading among countries lead to new requirements on the operation and expansion of transmission grids. Since AC grid expansions are limited by legislative issues and long distance transmission capacity, there is a considerable attention drawn to application of HVDC transmission grids on top of, or in complement to, existing AC power systems. The secure operation of HVDC grids requires a hierarchical control system. In HVDC grids, the primary control action to deal with power or DC voltage deviations is communication-free and local. In addition to primary control, the higher supervisory control actions are needed to guarantee the optimal operation of HVDC grids. However, the implementation of supervisory control functions is linked to the arrangement of system operators; i.e. an individual HVDC operator (central structure) or sharing tasks among AC system operators (distributed structure). This thesis presents distributed control of an HVDC grid. To this end, three possible supervisory functions are investigated; coordination of power injection set-points, DC slack bus selection and network topology identification. In this thesis, all three functions are first studied for the central structure. For the distributed solution, two algorithms based on Alternating Direction Method of Multipliers (ADMM) and Auxiliary Problem Principle (APP) are adopted to solve the coordination of power injection. For distributed selection of DC slack bus, the choice of parameters for quantitative ranking of converters is important. These parameters should be calculated based on local measurements if distributed decision is desired. To this end, the short circuit capacity of connected AC grid and power margin of converters are considered. To estimate the short circuit capacity as one of the required selection parameters, the result shows that the recursive least square algorithm can be very efficiently used. Besides, it is possible to intelligently use a naturally occurring droop response in HVDC grids as a local measurement for this estimation algorithm. Regarding the network topology, a two-stage distributed algorithm is introduced to use the abstract information about the neighbouring substation topology to determine the grid connectivity.QC 20170306</p

Flexible and reconfigurable data sharing for smart grid functions

Abstract Electrical power systems are undergoing major transformations as the share of decentralized energy resources increases. One important aspect is that the system is required to cope and adapt to the fluctuating behavior of these elements in order to maintain a stable and reliable operation. Consequently, this new challenges call for novel approaches for control and protection devices, both new and already deployed in the field. One alternative is the possibility to have a reconfigurable architecture, which ensures a modular and flexible operation of the system depending on the situation at hand. With this in mind, the main challenge addressed here is the configuration of the intelligent devices and the distribution of the data to ensure a resilient operation of the electrical grid

Systematic dynamic assessment for resilient operation of distribution networks

Abstract The integration of decentralized energy resources is changing the ways distribution grids are being operated. Moreover, a major change is the implementation of active control strategies to adapt to the energy transition, such as voltage and reactive power in-feed control. Correspondingly, the dynamic nature of these controllers, the potential conflict of control objectives and uncertainty of these sources require frequent assessment of the system’s dynamic behaviour. For this reason, this paper defines high level guidelines that allow simplifying Dynamic Security Assessment (DSA) in distribution networks, through the implementation of a methodology to determine the interactions of the network with its controllers. With this in mind, the focus of these guidelines is kept in reducing the computational effort, by reducing the number of dynamic simulations, as well as the amount of active controllers necessary for DSA. These guidelines are verified in an artificial 242-busbar distribution network, resulting in a reduction of 21,4% in number of dynamic simulations required for DSA

Trust in control: a trust model for power system network assessment

The question of whether a process variable transmitted from a device in the field to a power system control center is trustworthy is of high importance nowadays. Traditional bad data detection schemes have their limits in cases of elaborated cyberattacks and cascading failures in a system of systems such as a digitalized power system. This paper proposes a trust model designed for power system network assessment (PSNA). Different to other domains, where trust models already exist (e.g., OC-Trust for organic computing systems), the environment for PSNA is more centralized, and the focus lies on other facets than in organic computing due to the nature of the environment. Therefore, OC-Trust is tailored by categorizing its facets regarding their relevance for PSNA on the one hand. On the other hand, the trust model is extended to realize context-sensitive intersections of trust values. Furthermore, an example of an instantiation of the resulting PSNA-Trust model is given. Two security metrics and one credibility metric based on literature are presented as well as an equation for a context-sensitive intersection

Trust in control: a trust model for power system network assessment

The question of whether a process variable transmitted from a device in the field to a power system control center is trustworthy is of high importance nowadays. Traditional bad data detection schemes have their limits in cases of elaborated cyberattacks and cascading failures in a system of systems such as a digitalized power system. This paper proposes a trust model designed for power system network assessment (PSNA). Different to other domains, where trust models already exist (e.g., OC-Trust for organic computing systems), the environment for PSNA is more centralized, and the focus lies on other facets than in organic computing due to the nature of the environment. Therefore, OC-Trust is tailored by categorizing its facets regarding their relevance for PSNA on the one hand. On the other hand, the trust model is extended to realize context-sensitive intersections of trust values. Furthermore, an example of an instantiation of the resulting PSNA-Trust model is given. Two security metrics and one credibility metric based on literature are presented as well as an equation for a context-sensitive intersection