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This paper presents an assessment of corona loss performance for two overhead transmission lines of different ages using synchronized phasor measurements. In general, it is believed that the aged overhead transmission lines have constrained performance compared to the newer ones as they have been exposed to different environmental conditions for longer period of time. Therefore, in view of availability of synchronized measurements it is possible and of relevance to assess how the corona losses are influenced by line age and what are the main influencing factors. The results of the analysis indicate that there are higher corona losses associated with older overhead transmission lines and respective information is directly applicable for transmission system operators in their system operational planning in order to optimize the purchase of losses from the market.

The increasing integration of renewable energy sources into the electricity sector for decarbonization purposes necessitates effective energy storage facilities, which can separate energy supply and demand. Battery Energy Storage Systems (BESS) provide a practical solution to enhance the security, flexibility, and reliability of electricity supply, and thus, will be key players in future energy markets. Directive 2019/944, which focuses on common rules for the internal market of electricity, provides a regulatory framework for the deployment of energy storage facilities. However, several gaps and challenges remain regarding the implementation of the directive, particularly in insular energy systems with immature storage infrastructures such as Cyprus, an EU Member State. This study examines these challenges and gaps by investigating the case study of Cyprus while also presenting the handling of energy storage in other European countries such as Germany and Poland. The primary aim of this study is to identify gaps in the legislation regarding energy storage and potential bottlenecks or monopolistic approaches that could hinder the widespread deployment of BESS under the liberalization of the energy market. In light of several BESS technologies available in the market, the study focuses on lithium-based technologies, which account for the largest share of the BESS market and are projected to grow at the highest compound annual growth rate by 2030. Therefore, the authors concentrate on Lithium BESS. The study highlights the crucial role of storage facilities in transforming the power generation sector by shifting toward renewable sources of energy. As such, the study emphasizes the importance of effective regulatory frameworks in enabling the deployment of BESS, particularly in insular energy systems. Overall, this study sheds light on the gaps and challenges facing the deployment of BESS, providing valuable insights for policymakers and stakeholders to design effective regulatory frameworks to facilitate the widespread adoption of BESS. [ABSTRACT FROM AUTHOR]

An optimization-based platform is presented to request ancillary services and perform demand response. The work has seen a joint effort of the Italian TSO and DSO (Transmission and Distribution System Operators) and active local prosumers within the LIVING GRID innovation and demonstration project. The platform, a pure software architecture based on existing control and supervision equipment in the prosumer's plant, embeds optimization models, can communicate reference values for active and reactive power and perform intentional islanding and demand response in portions of the distribution grid and microgrids. Two possible configurations have been tested: Single PoC (Point of Connection) and Multi-PoC. The results of the optimization model and in-field experiments are presented and discussed for the considered pilot site: the Savona Campus Smart Polygeneration Microgrid (University of Genova, Italy).

Planning public electric vehicle (EV) charging infrastructure has gradually become a key factor in the electrification of mobility and decarbonization of the transport sector. In order to achieve a high level of electrification in mobility, in recent years, different studies have been presented, proposing novel practices and methodologies for the planning and operation of electric vehicles charging infrastructure. In this paper, the authors present an up-to-date analysis of the existing literature in this research field, organized by considering the perspectives and objectives of the principal actors/operators of the EV public charging infrastructure value chain. Among these actors, the electric vehicle, the charging operators and service providers, and the power system infrastructure (transmission and distribution system) are analyzed in depth. By classifying the reviewed literature based on this manifold viewpoints approach, this paper aims to facilitate researchers and technology developers in exploring the state-of-the-art methodologies for each actor's perspective, and identify conflicting interests and synergies in charging infrastructure operation and planning. [ABSTRACT FROM AUTHOR]

Electrical power system operators (SOs) are free to realize grid operations according to their own strategies. However, because resulting power flows also depend on the actions of neighboring SOs, appropriate coordination is needed to improve the resulting system states from an overall perspective and from an individual SO perspective. In this paper, a new method is presented that preserves the data integrity of the SOs and their independent operation of their grids. This method is compared with a non-coordinated local control and another sequential method that has been identified as the most promising distributed optimization method in previous research. The time series simulations use transformer tap positioning as well as generation unit voltage setpoints and reactive power injections as flexibilities. The methods are tested on a multi-voltage, multi-SO, realistic benchmark grid with different objective combinations of the SOs. In conclusion, the results of the new method are much closer to the theoretical optimum represented by central optimization than those of the other two methods. Furthermore, the introduced method integrates a sophisticated procedure to provide fairness between SOs that is missing in other methods. [ABSTRACT FROM AUTHOR]

Stochastic power generation is the new reality in power system management. Voltage Control mechanisms based on physical assets of the power system are deemed inadequate and are not guaranteed to lead the energy transformation in a way that ensures system security as well as cost-effective operation. Many countries that recently attained deregulated Balancing Market environments are in need of regulatory provisions and rigorous extension of electricity market mechanisms. On 1 November 2020, the Greek Electricity Market commenced operations conforming to the European Target Model. Apart from the innate difficulties a transformation such as this contains, more challenges occur as Greece is bound by European law to design market-based incentive mechanisms to remunerate Ancillary Services provided to the power system. This paper aims to examine some of the technical and regulatory aspects linked with—future—Transmission System Operator (TSO) and Distribution System Operator (DSO) cooperation in overcoming local transmission system problems concerning Voltage regulation. The interaction between localized Voltage Control Market (VCM) and the Balancing Market, the incorporation and competition of Distributed Energy Resources (DER) and Transmission Energy Resources (TER) within the VCM along with the TSO - DSO procedures and products standardization are the focus points of the present research paper. [ABSTRACT FROM AUTHOR]

The power grid consists of the production, transmission, and distribution system. Each of them, and particularly the transmission system plays a specific and significant role in the reliability and safety of the power grid. Compliably with the technological requirements and economic development trends, the power systems are upgraded and modernized in terms of their structuring, management and operation. Because of the interconnection between these systems and their role in a safe and reliable operation, their management and coordination are very specific and complex task. The primary task of the power Dispatch Center of the power transmission system is assuring the energy balance between the power production, and consumption, import and export of the active power and synchronous frequency. The dispatch center controls the active power flow and other electrical parameters and coordinate power generation and integration of renewable resources, and safety and reliability of power components (lines, transformers, substations). It coordinates the interconnected operation of power transmission systems in the synchronous area (tie lines), electricity market, and contingencies according to the set levels. It manages faults in power transmission system components, coordinates the power distribution system, and ensures an optimal, and economic power dispatch. [ABSTRACT FROM AUTHOR]

Transmission system operators (TSOs) in recent years have faced challenges in order to ensure maximum transmission capacity of the system to satisfy market needs, while maintaining operational safety and permissible impact on the environment. A great help in the decision-making process was introduced with the Dynamic Thermal Rating (DTR) – an instrument to monitor and predict the maximal allowed ampacity of the power grid based on weather measurements and forecast. However, the introduction of DTR raises a number of questions related to the accuracy and uncertainty of the results of thermal assessment and the level of acceptable risk and its management. In this paper, we present a solution for estimating DTR uncertainty, appropriate for operational use at TSOs. With the help of conductor surface temperature measurements, weather measurements and predicted weather data, we also estimate the error of the weather forecast and the DTR itself. Following the results of the data analyses, we build an operative solution for estimating the ampacity uncertainty based on Monte Carlo random simulations and integrate it into the operational environment of ELES – the operator of the Slovenian electric power transmission network. [ABSTRACT FROM AUTHOR]

Electrical power system operators (SOs) are free to realize grid operations according to their own strategies. However, because resulting power flows also depend on the actions of neighboring SOs, appropriate coordination is needed to improve the resulting system states from an overall perspective and from an individual SO perspective. In this paper, a new method is presented that preserves the data integrity of the SOs and their independent operation of their grids. This method is compared with a non-coordinated local control and another sequential method that has been identified as the most promising distributed optimization method in previous research. The time series simulations use transformer tap positioning as well as generation unit voltage setpoints and reactive power injections as flexibilities. The methods are tested on a multi-voltage, multi-SO, realistic benchmark grid with different objective combinations of the SOs. In conclusion, the results of the new method are much closer to the theoretical optimum represented by central optimization than those of the other two methods. Furthermore, the introduced method integrates a sophisticated procedure to provide fairness between SOs that is missing in other methods.

For transportation electrification, fossil fuel-based vehicles are replaced by electric vehicles (EVs) or fuel cell vehicles (FCVs). To charge EVs and FCVs, electric vehicle charging stations (EVCSs) and hydrogen fuelling stations (HFSs) are respectively needed. The review of the literature indicates that the operational planning of EVCSs integrated in distribution systems has not received enough attention; on the other hand, it is crucial to push EVCSs, HFSs and distribution systems towards 100 % renewable systems; so, in this research, the aim is to build a framework for the integration of emission-free EVCSs and HFSs in emission-free distribution systems considering their impact on transmission system operator. The Case study is the IEEE 57-bus transmission system connected to three 33-bus distribution systems, integrated with EVCSs and HFSs. Mixed-integer linear programming (MILP) models are used for EVs, FCVs, HFSs, EVCSs and transmission system, while Mixed-integer quadratic programming (MIQCP) model is used for distribution system. According to the results, the expected profits of distribution systems 1–3 are respectively $3509.41, $3550.27 and $3685.13. The expected cost of transmission system is as high as $1,818,020. The results show that due to PV modules and storage systems, the operation of all EVCSs and HFSs is profitable. The results show that the operation of all DSs is profitable; indeed, due to the existence of PV and wind generators which have no operation cost, the revenue of DSs is higher than their cost. The results also show that batteries increase the expected profit of EVCSs by 475 %. • A model for integration of EV charging stations (EVCS) and hydrogen stations in DS. • 100 % renewable DSs as well as 100 % renewable EVCSs are used. • A comprehensive model is employed for transmission system. • The effect of storage systems on economics of EVCSs has been evaluated. [ABSTRACT FROM AUTHOR]

Due to decarbonisation and decentralisation of energy sectors, the rise of distributed generation (DG) will modify generation and demand patterns at grid supply points (GSPs), where the interface between distribution and transmission systems takes place. With the increasing penetration of such devices, methodologies able to evaluate its contribution to both local distribution network and transmission system become crucial. This article proposes an analytical method to evaluate the DG locational incremental contribution (LIC) to the interface with the transmission grid. Accordingly, the original model of the U.K. engineering recommendation P2 is enhanced by studying the impacts from high-voltage distribution networks (i.e., ≤ 132 kV) under normal and contingent conditions. This approach enables a more accurate network security assessment, especially when considering contingencies such as distribution system faults. To illustrate the proposed method, the original P2 model is compared against different enhanced approaches on three basic distribution networks, followed by a case study and a sensitivity analysis on a revised IEEE 14-bus GSP system. The proposed LIC method produces results that assess a wider range of conditions including DG penetration, concentration, and system reliability. Furthermore, it provides an increased DG visibility for transmission planning and operation. [ABSTRACT FROM AUTHOR]

Stochastic power generation is the new reality in power system management. Voltage Control mechanisms based on physical assets of the power system are deemed inadequate and are not guaranteed to lead the energy transformation in a way that ensures system security as well as cost-effective operation. Many countries that recently attained deregulated Balancing Market environments are in need of regulatory provisions and rigorous extension of electricity market mechanisms. On 1 November 2020, the Greek Electricity Market commenced operations conforming to the European Target Model. Apart from the innate difficulties a transformation such as this contains, more challenges occur as Greece is bound by European law to design market-based incentive mechanisms to remunerate Ancillary Services provided to the power system. This paper aims to examine some of the technical and regulatory aspects linked with—future—Transmission System Operator (TSO) and Distribution System Operator (DSO) cooperation in overcoming local transmission system problems concerning Voltage regulation. The interaction between localized Voltage Control Market (VCM) and the Balancing Market, the incorporation and competition of Distributed Energy Resources (DER) and Transmission Energy Resources (TER) within the VCM along with the TSO - DSO procedures and products standardization are the focus points of the present research paper.

To cope with wind power uncertainty, balancing authorities are required to procure adequate ancillary services (ASs) with the aim of maintaining the security of the power system operation. The transmission system operator (TSO) is responsible for maintaining the balance between supply and demand in delivery hours. Besides the generating units, demand response (DR) has the potential capabilities to be considered as a source of AS. The demand-side AS can be used both locally (by the local entities in distribution networks) and system-wide (by the TSO). However, the optimal coordination between the local and global beneficiaries is a challenging task. This study proposes a distributed DR market model, in which the DR is traded as a public good among the providers and beneficiaries through the local DR markets. The local DR markets can be run in each load bus to trade the DR provided by retail customers connected to that bus with the buyers. To include the interactions between the energy/reserve market and the local DR markets, a bi-level programming model is proposed. The bi-level problem is translated into a single-level mixed-integer linear programming problem using the duality theorem. The proposed model is verified by simple and realistic case studies.

Budget constraints may cause delays in the development of transmission expansion projects. These delays increase the probability of congestion in power systems. The congestions preclude a non‐discriminatory access of Generation Companies (GenCos) to transmission network, thus leading to financial losses to certain GenCos. On the other hand, a higher degree of risk is involved in transmission investment, and a long time period is required to return the capital cost. It would, therefore, be effective to offer structures to promote merchant investments in order to lighten the financial burden on the transmission service provider to avoid lengthy delays. This paper proposes a structure to involve the GenCos in merchant transmission investment. The rationale for engaging in such projects is that, as well as the profit from the merchant investment, the GenCos could make further profit from energy production by gaining improved access to load areas. The merchant investment cost of the transmission project is returned through long‐term firm contracts together with revenues from financial transmission right. The most profitable plan of the GenCo is identified by conducting a cost‐benefit analysis among expansion plans specified by the transmission system operator. [ABSTRACT FROM AUTHOR]

The increased penetration of distributed energy resources (DERs) installed in distribution networks via power electronic converters reduces the overall rotating inertia of the power system, causing faster frequency dynamics after a large disturbance. However, these DERs coupled with energy storage systems (ESSs) can be managed to provide valuable grid support functions such as fast frequency response (FFR) and assist the transmission system operator (TSO) in frequency control. In this study, single‐ and three‐phase clusters of electric vehicles (EVs), acting as mobile‐ESSs, are grouped together as virtual power plants (VPPs) to centralise the provision of FFR for the distribution system operator (DSO) whilst considering network unbalance. Furthermore, the parameters of the EV clusters within each VPP are optimised to minimise the inertia‐weighed maximum frequency deviation following a disturbance whilst adhering to network security and power quality constraints. To this aim, a variant of the metaheuristic optimisation algorithm called improved harmony search is used for the optimisation process. Finally, the merits of the proposed methodology are shown with an illustrative example of an unbalanced three‐phase transmission and distribution network modelled in DIgSILENT PowerFactory. The results show that clusters of EVs grouped as VPPs effectively improve frequency support via the TSO–DSO interaction. [ABSTRACT FROM AUTHOR]

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Copyright of Collected Papers of the Law Faculty of the University of Rijeka / Zbornik Pravnog Fakulteta Sveučilišta u Rijeci is the property of Pravni fakultet Sveucilista u Rijeci and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An asynchronous heterogeneous decomposition (async‐HGD) algorithm for integrated transmission and distribution networks coordinated optimisation considering communication conditions is proposed. Compared with traditional synchronous HGD (sync‐HGD), a partial synchronisation mechanism is introduced instead of the full synchronisation to alleviate the influence of communication delays. Under this mechanism, the transmission system operator does not need to wait for the slowest distribution system operator to complete its subproblem and update boundary parameters before the next iteration can proceed. Also, a bounded delay is introduced under this mechanism to ensure sufficient freshness of all the updates. Further, the previous value strategy (PVS) and linear regression strategy (LVS) are applied to handle non‐instantaneous interruptions in the communication networks as an improvement of the async‐HGD. Numerical experiments show that considering communication delays in the actual operation; the async‐HGD takes less time to converge compared with the sync‐HGD under appropriate settings. In addition, PVS and LVS can both enhance the robustness of the overall algorithm by achieving approximate solutions, and the LVS can achieve more accurate results compared with the PVS. [ABSTRACT FROM AUTHOR]

This article describes a novel power system architecture and operational concept which is founded on the idea of organising sets of distributed generators, loads, storages and multimodal interfaces at distribution level in supervised and controlled grid subsections called smart power cells, which are controllable entities intended to enforce the stability of the transmission network and participate in its operation. Further, the article addresses a control scheme which can be implemented within a smart power cell to control its active and reactive power exchange with the transmission network following set points provided by a superimposed control system, and thus participate in the operation of the transmission grid (e.g. participation in congestion management, system optimisation, balancing of generation and load). The dynamic behaviour of a future power system under consideration of the proposed system architecture including several smart power cells controlled with the developed control scheme is demonstrated through time‐domain simulation using a combined transmission–distribution power system model. [ABSTRACT FROM AUTHOR]

As the coupling between transmission systems and distribution systems is significantly enhanced, transmission–distribution coordinated optimisation becomes more and more necessary. Considering that the objectives of the transmission system operator (TSO) and the distribution system operator (DSO) are usually significantly different in the type and dimension, a synthesised‐objective collaborative model is proposed in this study, by normalising different objectives, introducing a weight factor to reflect the importance degree difference of multiple objectives and constructing a common objective. Then, a modified heterogeneous decomposition (M‐HGD) algorithm is proposed to solve the model. In the M‐HGD, two modifications on the update of iterative variables and the stop criteria are proposed, which effectively relieves the fluctuation of the iterative variables and restrains the tail effect of the convergence curve. The proposed model and algorithm can avoid privacy issues between the TSO and the DSO, achieve Pareto optimality solutions, and have powerful flexibility. Numerical experiments validate the effectiveness of the proposed model and demonstrate that the M‐HGD has high accuracy and has better convergence and efficiency than traditional distributed optimisation methods. [ABSTRACT FROM AUTHOR]

• Explores the changing roles of TSOs and DSOs in the active energy sector, highlighting the complexity of their changing responsibilities and the challenges faced by each operator. • Underlines the critical need to improve coordination between TSOs and DSOs, focusing on the integration of DERs into this complex framework, and examines the associated challenges and strategies developed to overcome them. • Outlines various TSO-DSO coordination models, discusses key stakeholders, highlights successful real-life projects implementing coordination strategies, and ultimately aims to provide the energy industry with a comprehensive roadmap for future developments. The digitalization transforms grids into a much more complex grid structure than it is today. Based on this transformation, commitments to renewable energy sources (RESs), energy integration at large and small scales, bidirectional energy flows, and storage resources are increasing. Because many of today's electrical grids are obsolete, these developments require radical changes to our existing power systems. The flexibility of the market is essential for the increasing number of small and large-scale producers, consumers, and prosumers. Transmission System Operators (TSOs) and Distribution System Operators (DSOs) will be key buyers from this market, but their effectiveness depends on efficient collaboration and use distributed flexibility resources at scale. In particular, Distributed Energy Resources (DERs) play an essential role in ensuring market flexibility and balancing flexible networks. The use of DERs at both the transmission and distribution level enables collaboration between TSOs and DSOs. This article discusses the individual roles of TSOs and DSOs and the challenges they face in the power system. Coordination schemes and key stakeholders are presented. It comprehensively examines optimization-based solution and blockchain-based applications developed for TSO and DSO coordination challenges and provides a roadmap for developing a more efficient, reliable, and sustainable power system in the future. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of how corona losses on transmission lines depend on weather conditions in their vicinity. Two years of synchronized phasor measurement data has been collected to monitor corona losses over a longer period of time. From the same time period, both hourly and 10 min weather monitoring data has been obtained for comparison. The dependence between various weather parameters and corona losses is presented with graphical data analysis. In addition, feature importance methods have been applied to rank the weather parameters and determine which of them have the largest influence on the occurrence of significant corona losses. The results presented in this paper are directly applicable for transmission systems operators for adequate planning of system operation. • Transmission network corona loss monitoring using Phasor Measurement Units. • Analysis of corona loss dependency on various weather parameters. • Ranking of weather parameters based on importance. • Dependency of data availability on corona loss estimation results. [ABSTRACT FROM AUTHOR]

The transmission of natural gas is a key element of the Polish energy system. The published data of the Polish distribution system operators and the transmission system operator on the volume of gaseous fuel transmitted indicate a growing trend in the consumption of energy produced from natural gas. In connection with the energy transformation, switching energy generation sources from hard coal to natural gas in Poland, it is important for transmission operators to know the future demand for gaseous fuel. The aim of the article is to attempt to develop an econometric model related to the consumption of gaseous fuel by Polish entrepreneurs. The knowledge therein may be useful for making business decisions related to the possible expansion of the transmission system, and thus investing financial resources for this purpose. This knowledge will also provide quantitative information related to the interest in gaseous fuel among industrial consumers and the analysis of the trend of natural gas consumption in Poland in the aspect of energy transition. The intention of the publication was to determine the macroeconomic indicators that strongly affect natural gas consumption by the Polish industry and the quantitative growth of consumption depending on changes in these indicators. The results showed that the highest correlation of the growth of natural gas consumption is related to the production of chemistry, the chemical industry, and the power industry.

The article examines the most important aspects of the problem of the reverse of gas to Ukraine, its significance and consequences for the further development of contemporary international relations in the energy sector between the Russian Federation (gas exporter), Ukraine (transit country) and the European Union (importer). Considering all the elements that are important for the analyzed problem, the answer to the question “how the reverse gas flow influenced the energy security of Russia, Ukraine and the European Union, and the relationship between them” is given, using the explicative method of content analysis and the analysis of several press conferences. To understand all the nuances of relationships in this triangle, a detailed description of the term “reverse gas flow” is offered, as well as an explanation of the differences between “physical” (or real) and “virtual” reverse, which play a key role in the study of this problem. The essence of the conflict lies in the fact that the parties have different points of view on the legitimacy of the so-called “virtual” backhaul. In contrast to the physical reverse, i.e. to the real gas flow through the pipeline, in case of a virtual or a paper reverse, a one-way gas flow takes place, part of the total volume of which the transit state buys and leaves on its territory. The EU and Ukraine believe that a virtual backhaul between them is possible according to the provisions of the Third Energy Package and its relevant norms, based on the fact that the EU countries and Ukraine are part of the so-called. Energy Community. Another point of view regarding virtual backhaul is Russian, which initially opposed virtual reverse on the grounds that the raw material is the property of the state-owned company OAO Gazprom until it crosses the western border of Ukraine. The article details the legal documents on which the above-mentioned countries rely, as well as the official statements of the parties. Based on the analysis conducted, it is concluded that reverse gas supplies to Ukraine represent a temporary and far from perfect scheme, which does not fundamentally solve the problem of disagreements between the EU, Ukraine and Russia in the energy sector, namely, the gas transit. Nevertheless, the observed increase in the volume of Russian natural gas supplies to the EU in 2016 and early 2017 and the forecast for a further demand increase for gas from Russia in the EU in the future indicates that the provision of gas transit through the territory of the Visegrad Group countries, Members of the EU from Southeastern Europe and the search for new ways of supply, as well as the preservation of some of the current ones, occupy the leading positions on the political agenda of the EU countries, Russia and Ukraine, as they relate to their energy security

The power sector is experiencing a considerable transformation, shifting primary sources of energy production towards more sustainable alternatives. Despite the benefits, the increasing penetration of renewable raised concerns in terms of intermittency and unpredictability of electricity production, challenging the balance between demand and supply. To this end, the GRIDSOL project proposes Smart Renewable Hubs designed to provide a single and steady output of electricity combining different renewable and storage technologies such as concentrated solar power, photovoltaic, electrical and thermal batteries. This study investigates the technical application and economic feasibility of GRIDSOL for the case of Fuerteventura. Based on different technology configurations, the outcomes show a relevant role of the concentrated solar power plant, replacing diesel plants for electricity generation. In one configuration, GRIDSOL can provide up to 68% of the energy consumption, with a capacity factor of 67% for the concentrated solar power plant and a 24% CO2 emission reduction compared to 2016 levels. The economic assessment, performed over different scenarios, shows that the applicability of GRIDSOL in the Canary system requires support in terms of investments grants on the capital expenditure (58% of the costs) or as feed-in premiums on energy production (54–67 €/MWh) to break-even.

To provide continuity of balancing demand and generation, renewable sources will be more active than today in near future due to the tendency of massive investment on renewable energy sources (RESs) by countries. However, due to the uncertain and intermittent nature of RESs, RESs would create problems on power system operations such as power quality, efficiency, stability and reliability. Owing to having problems with RESs integration, virtual power plant (VPP) has introduced to make this integration smooth without compromising the grid stability and reliability along with offering many other techno‐economic benefits. This study reviews structures, types, architecture and operations of VPP along with the status of present implementations worldwide. The types of VPP are introduced in details with the optimisation algorithm used with each type. In addition, VPP is linked with the most of the components in power systems such as distributed generation, active prosumers, transmission system operator and distribution system operator, grid services such as fault ride through, reactive power control as well as with the help of technology such as communications, control and optimisations. This study gives a comprehensive outline of transforming microgrid to VPP that is useful for researchers, consumers, prosumers and utility operators. [ABSTRACT FROM AUTHOR]

Demand flexibility will be an inevitable part of the future power system operation to compensate stochastic variations of ever-increasing renewable generation. One way to achieve demand flexibility is to provide time-varying prices to customers at the edge of the grid. However, appropriate models are needed to estimate the potential flexibility of different types of consumers for day ahead and real-time ancillary services (AS) provision. The proposed method should account for rebound effect and variability of the customers’ reaction to the price signals. In this study, an efficient algorithm is developed for consumers’ flexibility estimation by the transmission system operator (TSO) based on offline data. No aggregator or real-time communication is involved in the process of flexibility estimation, although real-time communication channels are needed to broadcast price signals to the end-users. Also, the consumers’ elasticity and technical differences between various types of loads are taken into account in the formulation. The problem is formulated as a mixed-integer linear programming (MILP) problem, which is then converted to a chance-constrained programming to account for the stochastic behavior of the consumers. Simulation results show the applicability of the proposed method for the provision of AS from consumers at the TSO level. [ABSTRACT FROM AUTHOR]

The solar power installed capacity all over the world is growing and this renewable energy technology is playing an important role to build a clean energy future. The solar forecast is a necessary tool for the transmission system operator in order to maintain the electricity network safety and reliability. This study aims to report the experience of R&D Nester in the solar forecast at national level in Portugal, forecasting for all solar plants connected to the very high voltage (400, 220 and 150 kV) and high voltage (60 kV) networks, providing this information to the Portuguese transmission system operator, REN. A novel approach to calculate cloud index from images from a sky camera is presented. [ABSTRACT FROM AUTHOR]

The increased adoption of renewable energy generation is reducing the inertial response of the Great Britain (GB) power system, which translates into larger frequency variations in both transient and pseudo‐steady‐state operation. To help mitigate this, National Grid, the transmission system operator in GB, has designed a control scheme called enhanced frequency response (EFR) specifically aimed at energy storage systems (ESSs). This study proposes a control system that enables the provision of EFR services from a multi‐electrical ESS and at the same time allows the management of the state of charge (SOC) of each ESS. The proposed control system uses a Fuzzy Logic Controller to maintain the SOC as near as possible to the desired SOC of each ESS while providing EFR. The performance of the proposed controller is validated in transient and steady‐state domains. Simulation results highlight the benefits of managing the SOC of the energy storage assets with the proposed controller. These benefits include a reduced rate of change of frequency and frequency nadir following a loss of generation as well as an increase in the service performance measure which renders into increased economic benefits for the service provider. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of how best to coordinate, or “stack,” energy storage services in systems that lack centralized markets. Specifically, its focus is on how to coordinate transmission-level congestion relief with local, distribution-level objectives. We describe and demonstrate a unified communication and optimization framework for performing this coordination. The congestion relief problem formulation employs a weighted ${\ell _{1}\text{-norm}}$ objective. This approach determines a set of corrective actions, i.e., energy storage injections and conventional generation adjustments, that minimize the required deviations from a planned schedule. To exercise this coordination framework, we present two case studies. The first is based on a 3-bus test system, and the second on a realistic representation of the Pacific Northwest region of the United States. The results indicate that the scheduling methodology provides congestion relief, cost savings, and improved renewable energy integration. The large-scale case study informed the design of a live demonstration carried out in partnership with the University of Washington, Doosan GridTech, Snohomish County PUD, and the Bonneville Power Administration. The goal of the demonstration was to test the feasibility of the scheduling framework in a production environment with real-world energy storage assets. The demonstration results were consistent with computational simulations. [ABSTRACT FROM AUTHOR]