Solar photovoltaic‑based microgrid hosting capacity evaluation in electrical energy distribution network with voltage quality analysis

Part of a collection: Engineering: Integrated Sustainable Electrical Energy Systems, SN Applied Sciences volume 3, Article number: 567 (2021). Abstract: In this paper, solar photovoltaic hosting capacity within the electrical distribution network is estimated for different buses, and the impacts of high PV penetration are evaluated using power hardware-in-loop testing methods. It is observed that the considered operational constraints (i.e. voltage and loadings) and their operational limits have a significant impact on the hosting capacity results. However, with increasing photovoltaic penetration, some of the network buses reach maximum hosting capacity, which affects the network operation (e.g. bus voltages, line loading). The results show that even distributing the maximum hosting capacity among different buses can increase the bus voltage rise to 9%. To maintain the network bus voltages within acceptable limits, reactive power voltage-based droop control is implemented in the photovoltaic conditioning devices to test the dynamics of the network operation. The results show that implementation of the droop control technique can reduce the maximum voltage rise from 9% to 4% in the considered case. This paper also presents the impact of forming a mesh type network (i.e. from radial network) on the voltage profile during PV penetration, and a comparative analysis of the operational performance of a mesh type and radial type electrical network is performed. It is observed that the cumulative effect of forming a mesh type network along with a droop control strategy can further improve the voltage profile and contribute to increase photovoltaic penetration. The results are verified using an experimental setup of digital real-time simulator and power hardware-in-loop test methods. The results from this work will be useful for estimating the appropriate photovoltaic hosting capacity within a distribution network and implementation of a droop control strategy in power conditioning devices to maintain the network operational parameters within the specified limits.publishedVersio

Educational programme management methodology for research projects

Smart grids and intelligent energy systems play a pivotal role in fostering the sustainable advancement of our civilization. Over the past few decades, power systems, like many other sectors, have undergone a rapid digital transformation. This rapid development necessitates a proactive response from universities, research institutes, industry stakeholders in relation to educational programmes. Educators must rapidly adapt their curricula and teaching methodologies to effectively train the next generation of engineering professionals. While curriculum crafting for new educational programs is inherently challenging, another layer of complexity arises when research collaborations in large consortia are tasked with delivering high-quality education within a given project scope and time frame. This paper outlines a methodology for establishing an educational strategy for such research projects. This approach takes into account the available resources and expertise of the project participants, while embracing modern, learner-centric educational methodologies. It also ensures alignment with broader objectives or frameworks. Furthermore, the strategy incorporates a dynamic evaluation process that runs concurrently with the educational activities. Finally, the ERIGrid 2.0 H2020 project upon which the proposed methodology was developed, is presented as a case study

Virtual shifting impedance method for extended range high-fidelity PHIL testing

A novel power hardware-in-the-loop interface algorithm, the Virtual Shifting Impedance, is developed, validated and demonstrated in this paper. Building on existing interface algorithms, this method involves shifting a part of the software impedance to the hardware side to improve the stability and accuracy of power hardware-in-the-loop setups. However, compared to existing approaches, this impedance shifting is realized by modifying the command signals of the power amplifier controller, thus avoiding the requirement for hardware passive components. The mathematical derivation of the Virtual Shifting Impedance interface algorithm is realized step-by-step, while its stability and accuracy properties are thoroughly examined. Finally, the applicability of the proposed method is verified through power hardware-in-the-loop simulation results

Operational Issues on Adaptive Protection of Microgrids Due to Cyber Attacks

This brief shows how false data injection attacks (FDIAs) affect adaptive projection in microgrids. Specifically, we implemented a directional over-current relay in the CIGRE low voltage benchmark system to carry out experiments to manipulate protection decisions via cyber-attacks. The aim of the newly proposed cyber-attack is to cause false relay tripping and unbalanced conditions in microgrid that can result in power outages and blackouts. The proposed study has been validated on commercial relays using a real-time digital simulator equipped with the IEC 61850 standard communication protocol. These results allow the power systems engineers to understand the cyber-physical interactions more closely and adapt their protection schemes accordingly.</p

Solar photovoltaic‑based microgrid hosting capacity evaluation in electrical energy distribution network with voltage quality analysis

Part of a collection: Engineering: Integrated Sustainable Electrical Energy Systems, SN Applied Sciences volume 3, Article number: 567 (2021). Abstract: In this paper, solar photovoltaic hosting capacity within the electrical distribution network is estimated for different buses, and the impacts of high PV penetration are evaluated using power hardware-in-loop testing methods. It is observed that the considered operational constraints (i.e. voltage and loadings) and their operational limits have a significant impact on the hosting capacity results. However, with increasing photovoltaic penetration, some of the network buses reach maximum hosting capacity, which affects the network operation (e.g. bus voltages, line loading). The results show that even distributing the maximum hosting capacity among different buses can increase the bus voltage rise to 9%. To maintain the network bus voltages within acceptable limits, reactive power voltage-based droop control is implemented in the photovoltaic conditioning devices to test the dynamics of the network operation. The results show that implementation of the droop control technique can reduce the maximum voltage rise from 9% to 4% in the considered case. This paper also presents the impact of forming a mesh type network (i.e. from radial network) on the voltage profile during PV penetration, and a comparative analysis of the operational performance of a mesh type and radial type electrical network is performed. It is observed that the cumulative effect of forming a mesh type network along with a droop control strategy can further improve the voltage profile and contribute to increase photovoltaic penetration. The results are verified using an experimental setup of digital real-time simulator and power hardware-in-loop test methods. The results from this work will be useful for estimating the appropriate photovoltaic hosting capacity within a distribution network and implementation of a droop control strategy in power conditioning devices to maintain the network operational parameters within the specified limits

A framework for sensitivity analysis of real-time power hardware-in-the-loop (PHIL) systems

Power hardware-in-the-loop (PHIL) simulation leverages the advanced real-time emulation based technique to carry out in-depth investigations on novel real-world power components. Power amplifiers, sensors, and signal conversion units based power interfaces (PI) incorporate physical hardware systems and real-time simulation platforms into PHIL setups. However, the employment of any interfacing technique inevitably introduces disturbances such as sensor noise, switching harmonics, or quantization noise to PHIL systems. To facilitate quantitatively analyzing and assessing the impact of external disturbances on PHIL simulation systems, a framework for sensitivity analysis of PHIL setups has been developed in this paper. Detailed modelling principles related to the sensitivity analysis of PHIL systems and the inherent relationship between sensitivity transfer functions and stability criteria are elaborated along with theoretical and experimental validation. Based on this concept, accuracy assessment methods are employed in this framework to quantify generic sensitivity criteria. Moreover, physical passive load and converter-based PHIL setups are applied and experimental results are presented to characterize and demonstrate the applicability of the proposed framework

Applicability of geographically distributed simulations

Geographically distributed simulations (GDS) overcome the inherent limitations in capabilities of single research infrastructure to accurately represent large-scale complex power and energy systems within representative operating environments in real-time. The feasibility of GDS has been proven, however, there is a lack of confidence in its adoption owing to limited evidence of its stability and accuracy that ascertain its practical applicability. This paper presents detailed small signal stability models for GDS setups with two interface signals transformations. The models have been validated by empirical analysis and used for determining the boundaries for stable operation of GDS setups. For the common region of stability of the two transformations considered, accuracy analysis presented offers insights for their selection. This advancement, thereby, enables realisation of experimental setups that can cater for the growing need to design and validate operational schemes that ensure robust and resilient operation of critical national infrastructure

D-NA4.1 Functional Scenarios:WP5 Deliverable D5.1: D-NA4.1 Functional Scenarios

This deliverable describes the work conducted in ERIGrid 2.0 task NA4.1 ’Definition of Functional Scenarios’. The work has been conducted via a survey and a brainstorming workshop. The results are six Functional Scenarios: Ancillary services provided by Distributed Energy Resources (DERs) and active grid assets, Microgrids & energy communities, Sector coupling, Frequency and voltage stability in inverter dominated power systems, Aggregation and flexibility management, and Digitalisation, which describe the overarching topics within ERIGrid 2.0. The Functional Scenarios will be used as an input in further ERIGrid 2.0 work. Smart grid and smart energy systems solutions have become complex and multidisciplinary. With the further integration of Information and Communication Technology (ICT) and other energy systems new testing scenarios, profiles, and processes must be defined. In order to achieve this, big trends affecting research, testing, and validation processes have been reviewed, with a special focus on new aspects such as interoperability testing or digitalisation. The scenario descriptions define requirements, actors, etc. on a functional level. ERIGrid 2.0 work package NA4 ’Iterative Creation of Scenarios and Test Case Profiles’ addresses these needs. This work has been conducted with emphasis on the alignment with the European Green Deal, further support on the technology validation and roll-out phases, and further integration of the research infrastructures. A Functional Scenario has been defined as an umbrella term comprising of motivation and relevance for ERIGrid 2.0, system descriptions, use case and test case descriptions, and experimental setup descriptions. Each scenario has a single core idea and is formed on the basis of inclusiveness. Functional Scenarios consider several high-level scenarios in other projects and networks as a background forming the overall circumstances in which the Functional Scenario is considered. The high-level scenarios provide a holistic understanding of the current status and development while also highlighting future visions and requirements impacting the Functional Scenarios. The high-level scenarios also address the high-level drivers for the Functional Scenarios, such as needs for digitalisation of the smart energy systems. Furthermore, Functional Scenarios are related to the generic system configurations developed in ERIGrid and consider the work conducted in ERIGrid as a strong background for ERIGrid 2.0. The necessity for a mutual understanding of scenarios which are of interest to the ERIGrid 2.0 partners and their research infrastructures and in alignment of the project objectives, led to conducting a survey regarding the first actions of the NA4.1 work. The purpose of this survey was to gather inputs on a set of Functional Scenarios that were analysed in more detail to deduce the most relevant approaches for ERIGrid 2.0. Overall, 15 partners participated in the survey and submitted 35 scenarios. The survey results include scenarios on sector coupling, multi-energy systems, ICT and automation, energy communities, microgrids and low- inertia grids, and stability, control and grid code challenges. Detailed descriptions of Functional Scenarios submitted to the survey are presented in Appendix A: Functional Scenario Survey Data of this deliverable. The formation of the Functional Scenarios was organised in six working groups, each of which focused on a single Functional Scenario. The decision on the six Functional Scenario was taken during the NA4 regular meetings and the brainstorming workshop itself based on the results of the Functional Scenario survey. The focus of the first working group has been on a component focused scenario developed based on the survey results on DERs and inverters. The resulting Functional Scenario 1 integrates key components, such as DER inverters and controllers with ICT, control and automation architectures to enable new grid services with the development of interfaces between the active components. The second working group has been focused on topics related to microgrids and energy communities forming Functional Scenario 2 to support the local microgrid and energy community development by enabling flexibility services locally with ICT and control including exploitation of grid intelligence. While the third working group has been working on the survey results on sector coupling and multi-energy systems with Functional Scenario 3 anticipating a massive roll-out of power-to-X components in the near future by developing system level understanding of the impacts on the electrical domain. The fourth working group has been focused on grid management and overall the perspectives of Distribution System Operators (DSOs) and Transmission System Operators (TSOs) resulting in Functional Scenario 4 assuring frequency and voltage stability in low inertia systems through capabilities of Renewable Energy Sources (RES), Distributed Generation (DG), controllable loads and storage systems as well as ICT and control systems. The fifth working group has been based on the survey results comprising of aggregation, flexibility, market and reserve topics and defined Functional Scenario 5 to focus on communication functionality for aggregation, service matching, fail-over, configuration, and interoperability addressing scale-related properties of aggregation and control solutions. Lastly, the sixth working group has been focused on digitalisation including wide range of topics such as ICT infrastructure, communication, automation, control and monitoring. Functional Scenario 6 explores the impact of ICT solutions on the physical (electrical power) system covering new applications of data and data processing as well as new paths for exchanging data. The Functional Scenario templates used during the brainstorming workshop have been included in the Appendix B: Functional Scenario Templates. The work started in NA4.1 will continue in NA4.2 and NA4.4 with discussions on more detailed definitions of the test cases which will initially provide the inputs for other project activities. The discourse on the Functional Scenarios is also assumed to support ERIGrid 2.0 physical lab and virtual access work and decision-making beyond ERIGrid 2.0