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As renewable power sources are increasing worldwide, those of South Korea are also expanding. South Korea is conducting a variety of research on renewable energy policies and technologies in order to install the renewable energy of about 58GW until 2031. In particular, South Korea is establishing a new grid code criteria based on the expansion of renewable energy. Currently, its grid code criteria consists of the frequency range, voltage range, and LVRT(Low Voltage Ride Through), etc. This paper explains the new grid code for active power, reactive power, and FRT(Fault Ride Through) that are conducted in South Korea. First, we create databases that include renewable power sources to simulate the grid code criteria. Second, we introduce the frequency range about the active power control for upper and lower frequency. Third, we present the reactive power control method, which is the reactive power requirement and operating range according to the voltage range. Fourth, we cover the FRT requirements: LVRT. When the renewable power source is expanded and the existing LVRT standard is applied, if any disturbance occurs, the renewable power source is dropped due to the violation of the LVRT standard. Therefore, we have applied a new LVRT characteristic curve. In this paper, we performed various grid analysis procedures on the newly developed grid code for the power system that includes renewable power sources. The active power, reactive power, and FRT criteria were examined based on PSS/E Python. [ABSTRACT FROM AUTHOR]

As renewable power sources are increasing worldwide, those of South Korea are also expanding. South Korea is conducting a variety of research on renewable energy policies and technologies in order to install the renewable energy of about 58GW until 2031. In particular, South Korea is establishing a new grid code criteria based on the expansion of renewable energy. Currently, its grid code criteria consists of the frequency range, voltage range, and LVRT(Low Voltage Ride Through), etc. This paper explains the new grid code for active power, reactive power, and FRT(Fault Ride Through) that are conducted in South Korea. First, we create databases that include renewable power sources to simulate the grid code criteria. Second, we introduce the frequency range about the active power control for upper and lower frequency. Third, we present the reactive power control method, which is the reactive power requirement and operating range according to the voltage range. Fourth, we cover the FRT requirements: LVRT. When the renewable power source is expanded and the existing LVRT standard is applied, if any disturbance occurs, the renewable power source is dropped due to the violation of the LVRT standard. Therefore, we have applied a new LVRT characteristic curve. In this paper, we performed various grid analysis procedures on the newly developed grid code for the power system that includes renewable power sources. The active power, reactive power, and FRT criteria were examined based on PSS/E Python. [ABSTRACT FROM AUTHOR]

The amount of kinetic energy in the Nordic power system decreases due to structural changes in the power system. In this paper, the Nordic Transmission System Operators (TSOs) provide a summary of a survey, which was sent out to some small- and medium-sized synchronous areas, in order to learn from their experiences with low kinetic energy situations. The paper summarizes the responses received, thereby providing a view on: the current and future assessment of inertia in the system (including key drivers behind the change), and mitigation methods for low inertia situations. [ABSTRACT FROM AUTHOR]

The intermittent output of photovoltaic (PV) generation depending on the weather condition makes the network demand more uncertain. Therefore, increasing of the introduction of PV may violate the criterion of frequency deviation. As a countermeasure to this problem, there is a method to suppress PV fluctuation by increasing the capacity of load frequency control (LFC). In this paper, the authors have proposed LFC using the hybrid air conditioners which can use electricity and/or gas. To prove the effectiveness of proposed hybrid air conditioner control, simulation studies have been performed using the AGC30 model [2] developed by the institute of electrical engineers of Japan (IEEJ). [ABSTRACT FROM AUTHOR]

The amount of kinetic energy in the Nordic power system decreases due to structural changes in the power system. In this paper, the Nordic Transmission System Operators (TSOs) provide a summary of a survey, which was sent out to some small- and medium-sized synchronous areas, in order to learn from their experiences with low kinetic energy situations. The paper summarizes the responses received, thereby providing a view on: the current and future assessment of inertia in the system (including key drivers behind the change), and mitigation methods for low inertia situations. [ABSTRACT FROM AUTHOR]

With the establishment of the Paris Climate Treaty in 2015, South Korea has set its ambitious goal of 'Reduce emissions by 37% compared to 2030 Greenhouse Gas Emissions Outlook (BAU)' as of June 2015. As a measure to reduce carbon, countries are increasing the ratio of renewable energy sources in each country. South Korea also aims to increase the proportion of renewable energy sources to 53GW by 2030. In this paper, we will study the methodology for the power system development plan of the future power system which consists of various scenarios such as the amount of renewable energy and the installation of new transmission line. First, we describe the construction process of database w.r.t the ratio of renewable energy and load level. In order to increase the stability of future power system in South Korea, we have come up with various scenarios for a combination of transmission line, VSC-HVDC and FACTS. Then, the comprehensive tests based on static and dynamic analysis are processed using the proposed simulator based on PSS/E Python. Through the above process, the optimum future system reinforcement plan is calculated. The automatic simulator with various function of DB creation, simulation and decision based on PSS/E Python have been developed to validate the proposed methodology and tested using the large-scale future power system. [ABSTRACT FROM AUTHOR]

With the establishment of the Paris Climate Treaty in 2015, South Korea has set its ambitious goal of 'Reduce emissions by 37% compared to 2030 Greenhouse Gas Emissions Outlook (BAU)' as of June 2015. As a measure to reduce carbon, countries are increasing the ratio of renewable energy sources in each country. South Korea also aims to increase the proportion of renewable energy sources to 53GW by 2030. In this paper, we will study the methodology for the power system development plan of the future power system which consists of various scenarios such as the amount of renewable energy and the installation of new transmission line. First, we describe the construction process of database w.r.t the ratio of renewable energy and load level. In order to increase the stability of future power system in South Korea, we have come up with various scenarios for a combination of transmission line, VSC-HVDC and FACTS. Then, the comprehensive tests based on static and dynamic analysis are processed using the proposed simulator based on PSS/E Python. Through the above process, the optimum future system reinforcement plan is calculated. The automatic simulator with various function of DB creation, simulation and decision based on PSS/E Python have been developed to validate the proposed methodology and tested using the large-scale future power system. [ABSTRACT FROM AUTHOR]

Recently the Venezuelan government has begun a more aggressive policies and incentives on renewable energy resources. In this paper a preliminary evaluation of wind energy resource on Margarita Island was developed. Results of this evaluation, La Vecindad area was diagnostic with sufficient potential from several points of view for utility wind farm developing. Considering maximizing of land use of La Vecindad, technical economic evaluation exhibit feasibility of built a wind farm with eleven Enercon E-20 wind turbines to provide 22 MW to Margarita Island electric utility on Los Mijanes substation at 115 kV. A final evaluation of wind energy resource is recommended for this location, and take account the no-sale fuel produced for wind farm, to make more attractive the final project. [ABSTRACT FROM AUTHOR]

Renewable energy has been an important component of India's energy planning process for quite some time, especially since India seeks to make significant contributions toward climate change mitigation and emerge as a responsible global powerhouse. Solar energy has rapidly emerged as a reliable, affordable and clean solution for meeting India's fast-growing energy demand and supply power to all. This, it is crucial for India to promote large-scale mega solar projects like solar parks in order to promote ecologically sustainable growth and to meet the challenges of climate change, with technology and investment flow from around the globe, is one of the National goals. Based on above object National Solar Mission was launched with the goal of 20 GW grid connected solar power by the year 2021-22. Further, Government of India has revised the target of Grid Connected Solar Power Projects from 20 GW by the year 2021-22 to 100 GW by the year 2021-22 under the Mission. This can be achieved through an integrated bid process including Make in India. The critical success factors including development of Solar Park in India and tariff trends are described in this article. India, with its large population and rapidly growing economy, needs access to clean, cheap and reliable sources of energy. India lies in the high solar insolation region, endowed with huge solar energy potential with most of the country having about 300 days of the sunshine per year with annual mean daily global solar radiation in the range of 4-6 kWh/m2/day. The solar park is a concentrated zone of the development of solar power generation projects and provides developers an area that is well characterized, with proper infrastructure and access to amenities and where the risk of the projects can be minimized. Solar Park also facilitates developers by reducing the number of required approvals. The most important benefit from the solar park for the private developer is a significant time saved. Solar power projects can be set up anywhere in the country, however, the scattering of solar power projects leads to higher project cost per MW and higher transmission losses. Individual projects of smaller capacity incur significant expenses in site development, drawing separate transmission lines to the nearest substation, procuring water and in the creation of other necessary infrastructure. It also takes a long time for project developers to acquire land, get a change of land use and various permissions, etc. which delays the project. The paper describes the concept of solar parks has indeed emerged as a powerful tool for the rapid development of solar power projects in India. Further, Assured availability of land and transmission infrastructure are the major benefits of the Solar Parks. The recent downward trends in solar tariff may be attributed to the factors like economies of scale, assured the availability of land and power evacuation systems under the Solar Parks also included. [ABSTRACT FROM AUTHOR]

This paper describes the local market for trade in energy, flexibility and energy related services developed in the ongoing H2020 project, EMPOWER. It is based on a network market approach. The establishment of a local community of prosumers and consumers, inspired by Internet communities, energy cooperatives and online shopping clubs, is central to the idea. At the heart of the community the Smart Energy Service Provider (SESP) can be found. The principal entities and operations associated with the local market concept developed are explained. Some early field results as well as regulatory challenges for a broader roll-out are described. [ABSTRACT FROM AUTHOR]

Japan has been experiencing rapid PV deployment since it introduced its first feed-in-tariff program in July of 2012, one year after the Great East Japan Earthquake and Tsunami, and the massive and rapid penetration of renewable generation, especially PV, has been affecting in each of the balancing area in Japan according to the level of the penetration. The Kyushu area, in a southern island among four main islands of Japan, is the most severely affected area by PV penetration. Last May, the area experienced 6 GW PV generation under 8 MW load and over 2GW base load operation of nuclear, hydro and geothermal plants. Under the situation, system operators ensured security of supply by a sophisticated operation of thermal and pumped storage plants and an interconnection. This paper presents the background and objective of the study, the situation of PV deployment in Japan, challenges of power system operation in Kyushu-area, demand and supply analysis of Kyushu-area, issues and possible solutions for secured system operation. [ABSTRACT FROM AUTHOR]

Using batteries as energy storage is a fundamental practice to promote renewable energy generation and reduce fossil energy consumptions to mitigate greenhouse gas emissions. By integrating grid-connected photovoltaics (PV) and Battery Energy Storage System (BESS) into a local energy system, the renewable energy shares and self-consumption rate of the system can be significantly increased. Especially for high power energy users, e.g., industrial plants, energy storage even provides the possibility of peak shaving to reduce the cost of electricity and network utilization. This paper proposes a general workflow to simulate and optimize the PV-BESS system used for peak shaving in an industrial energy system, which consists of a fabrication plant for electronic devices, together with an attached office building, a battery storage system, and a PV system. The paper presents an innovative method to model the electric load of the system, considering both electric and thermal demand. The electric demand is a time-series model from the actual measurement of productionconsumption of various production machines and electric devices in the office. The thermal demand contains the electricity required from the heat pump for cooling and heating. The state-space model describing the thermal behavior of the office building is applied to the calculation. Based on the first simulation results, an energy management strategy is developed to control the proposed system. The management strategy is implemented in a lifetime simulation. Based on the simulation, the optimization problem considering the economic and environmental impact has been solved to find the optimal configurations, which minimize the annual cost of the system. The Levelized Cost Of Storage (LCOS) is integrated into the objective function. Local feed-in tariffs and environmental policies are also considered in the optimization. The simulation results are assessed in both technical and economic prospects. The optimization result provides an optimal capacity configuration of the PV and BESS system. By applying a suitable size of the PV/BESS system in the proposed industrial plant, it is possible to improve both the economic profitability and the ecological welfare by reducing CO2 emissions. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of the 3DMicroGrid project, which Energynautics worked on with a total of 10 partners between September 2016 and February 2020. The 3DMicroGrid project has developed a hybrid control architecture for AC microgrids, incorporating both centralized and decentralized principles in a multi-agent scheme. Software components have been developed and tested using simulation models, which were based on real-world pilot sites of different topologies, locations and sizes. To assess the results from both the simulation models and the control paradigms created, various key performance indicators (KPIs) have been defined, encompassing economic and technical terms such as assets costs, environmental aspects, quality of supply, voltage and frequency control performance in island operation. [ABSTRACT FROM AUTHOR]

Using batteries as energy storage is a fundamental practice to promote renewable energy generation and reduce fossil energy consumptions to mitigate greenhouse gas emissions. By integrating grid-connected photovoltaics (PV) and Battery Energy Storage System (BESS) into a local energy system, the renewable energy shares and self-consumption rate of the system can be significantly increased. Especially for high power energy users, e.g., industrial plants, energy storage even provides the possibility of peak shaving to reduce the cost of electricity and network utilization. This paper proposes a general workflow to simulate and optimize the PV-BESS system used for peak shaving in an industrial energy system, which consists of a fabrication plant for electronic devices, together with an attached office building, a battery storage system, and a PV system. The paper presents an innovative method to model the electric load of the system, considering both electric and thermal demand. The electric demand is a time-series model from the actual measurement of production-consumption of various production machines and electric devices in the office. The thermal demand contains the electricity required from the heat pump for cooling and heating. The state-space model describing the thermal behavior of the office building is applied to the calculation. Based on the first simulation results, an energy management strategy is developed to control the proposed system. The management strategy is implemented in a lifetime simulation. Based on the simulation, the optimization problem considering the economic and environmental impact has been solved to find the optimal configurations, which minimize the annual cost of the system. The Levelized Cost Of Storage (LCOS) is integrated into the objective function. Local feed-in tariffs and environmental policies are also considered in the optimization. The simulation results are assessed in both technical and economic prospects. The optimization result provides an optimal capacity configuration of the PV and BESS system. By applying a suitable size of the PV/BESS system in the proposed industrial plant, it is possible to improve both the economic profitability and the ecological welfare by reducing CO2 emissions. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of the 3DMicroGrid project, which Energynautics worked on with a total of 10 partners between September 2016 and February 2020. The 3DMicroGrid project has developed a hybrid control architecture for AC microgrids, incorporating both centralized and decentralized principles in a multi-agent scheme. Software components have been developed and tested using simulation models, which were based on real-world pilot sites of different topologies, locations and sizes. To assess the results from both the simulation models and the control paradigms created, various key performance indicators (KPIs) have been defined, encompassing economic and technical terms such as assets costs, environmental aspects, quality of supply, voltage and frequency control performance in island operation. [ABSTRACT FROM AUTHOR]

Nowadays, from the viewpoint of environmental issues, wind turbines and photovoltaic generators are gaining a lot of attention. Thus, a large number of wind turbines have been introduced into power systems. Besides, small wind turbines have been introduced into a household. However, Japan is visited by many typhoons every year. Therefore in this paper, operation method for small vertical axis wind turbine under strong wind condition is proposed. The conventional control system of wind turbine stops generation when the wind speed exceeds 25 m/s. However, the proposed wind turbine is rotated at a low speed, and it continues generation when the wind speed is more than 25 m/s. The house is also equipped with battery. Hence, it can be isolated operation or connected to the power systems. The advantage of the proposed method is that it can reduce adverse effects for household electrical equipment and a power system due to sudden reduction of supply power. In addition, it is possible to improve the recovery rate of wind energy. [ABSTRACT FROM AUTHOR]

In this paper an RMS simulation model of a low voltage photovoltaic system for dynamic studies in the range of seconds up to minutes is developed. The model is based on a low voltage photovoltaic system model developed by the Western Electricity Coordinating Council (WECC) Renewable Energy Modeling Task Force. The model is validated with an experimental setup consisting of a photovoltaic emulator, an inverter, a cable and a grid emulator. The laboratory tests show an unexpected dead time of the Q(V ) and P(V ) responses which the authors could not find in published literature. The novelty, compared to state-of-the-art models, is the introduction of a dead time in order to model the measured behavior correctly. The new model is capable of explaining the grid coupled behavior of the investigated photovoltaic system in retrospective. Therefore, this work suggests more laboratory investigations on the dynamic behavior of photovoltaic systems. [ABSTRACT FROM AUTHOR]

Japan has been experiencing rapid PV deployment since it introduced its first feed-in-tariff program in July of 2012, one year after the Great East Japan Earthquake and Tsunami. This massive and rapid penetration of PV systems has been affecting the 10 power balancing areas in Japan. Among those areas, Kyushu area, the southern the most island of the four main islands of Japan, is the most severely affected. On October 21st, 2018, the Kyushu's transmission operator executed the first renewable energy generation curtailment in Japan. In this paper we present the situation of PV deployment in Japan, the challenges of the power system operation in Kyushu area, power demand and supply analysis with a novel flexibility model. Furthermore, we discuss implications for a future power system. [ABSTRACT FROM AUTHOR]

Japan has been experiencing rapid PV deployment since it introduced its first feed-in-tariff program in July of 2012, one year after the Great East Japan Earthquake and Tsunami. This massive and rapid penetration of PV systems has been affecting the 10 power balancing areas in Japan. Among those areas, Kyushu area, the southern the most island of the four main islands of Japan, is the most severely affected. On October 21st, 2018, the Kyushu's transmission operator executed the first renewable energy generation curtailment in Japan. In this paper we present the situation of PV deployment in Japan, the challenges of the power system operation in Kyushu area, power demand and supply analysis with a novel flexibility model. Furthermore, we discuss implications for a future power system. [ABSTRACT FROM AUTHOR]

Japan has been experiencing rapid PV deployment since it introduced its first feed-in-tariff program in July of 2012, one year after the Great East Japan Earthquake and Tsunami. This massive and rapid penetration of PV systems has been affecting the 10 power balancing areas in Japan. Among those areas, Kyushu area, the southern the most island of the four main islands of Japan, is the most severely affected. On October 21st, 2018, the Kyushu's transmission operator executed the first renewable energy generation curtailment in Japan. In this paper we present the situation of PV deployment in Japan, the challenges of the power system operation in Kyushu area, power demand and supply analysis with a novel flexibility model. Furthermore, we discuss implications for a future power system. [ABSTRACT FROM AUTHOR]

The research project Kombikraftwerk 2 examined whether and how a reliable and stable electricity supply for Germany with 100% renewable energy sources can be realised in the future. To this end, an assessment of the demand and the provision of ancillary services in such a system with a high share of wind energy was undertaken. Besides presenting an overview of the results of the project, this paper discusses the role of wind energy in the system in particular. [ABSTRACT FROM AUTHOR]

The introduction of renewable energy source (RES), into modern power systems for generation is steadily increasing, resulting in a reduction in conventional hydrocarbon-based generation. This paper studies the utilization of energy storage to support grid frequency and energy in future high percentage penetration renewable energy networks. One potential energy storage system (ESS) technology suitable for this application is the Battery Energy Storage System (BESS) utilizing Lithium-ion or Sodium- Nickel-Chloride batteries. The paper analyses frequency profiles for the years 2014-2016 to study preliminary requirements for BESS power-train equipment. [ABSTRACT FROM AUTHOR]

Renewable energies have been increasingly deployed under the global trend of reduction of CO2 emission. It is necessary to use more enhanced forecast and control technologies to integrate them in power systems operation planning and real-time operation in order to increase the share of renewable energy. This is the objective of the R&D project "Grid Integration of Variable Renewable Energy: Mitigation Technologies on Output Fluctuations of Renewable Energy Generations in Power Grid", which has been going on since 2014. We aim to break through the critical issue regarding the forecast error of wind power output: that it is too large to properly estimate up/down ramps within short time. The R&D project focuses on wind power ramp forecasting which has not tackled yet even though it is critical issue to forecast wind power ramp phenomena. This paper overviews the project of Wind Ramp Forecast. [ABSTRACT FROM AUTHOR]

The focus of the paper lies on the feasibility evaluation of solar power generation technologies for the power system to achieve the balance of energy generation and support costs in a more efficient way. The case study is based on a time series of examples with an hourly resolution for several years of electricity prices from the Nord Pool power market, power demand and solar generation of Latvian prosumers. Electric energy generation and consumption data from more than 200 clients were collected and used. The article analyses the influence of net metering supporting scheme variants on the profitability of a projected investment of PV batteries. A recommendation to change the current net metering system to a more perfect one, taking into account the market cost of energy, concludes the paper. [ABSTRACT FROM AUTHOR]

In recent years the amount of congestion management actions increased by the factor of 10. To adress this problem, various regulatory adjustments, like a market split or a specific re-dispatch for renewable energy, are under discussion. However, beyond the general aspects of congestions the actual relationship between single system operation measurements, like re-dispatch and curtailment of wind energy, and the current network utilisation is becoming more complex. In this paper, Ecofys and AIT presents a first analysis, which aims to describe and compare the actual characteristic of the power systems during congestion management actions to provide a better understanding of the relationship between various system parameters and actual measurements. The analysis is based on an empirical research for the German power system. [ABSTRACT FROM AUTHOR]

In this paper, impact of current priority dispatch rule on the demand and supply operation, the unlimited and uncompensated curtailment and the wholesale power market trading were analyzed. As a matter of the current priority dispatch rule, first is that the Japan's priority dispatch rule focus to maintain supply and demand mainly within the region. Second, Japan's electricity system can't afford to connect large amount of variable renewable energy because it focuses on individual supply-demand balance in each area and gives high priority of long-term fixed power sources. Furthermore, it is expected that the economic rational cross-regional operation will be expanded through wholesale electricity market, but curtailment of variable renewable energy starts at zero yen. On the other hand, It is possible for long-term fixed power sources to supply electricity at a constant output without negative price risk. Furthermore, evaluation of curtailment prospects in FY2017 turned out that there is possibility that future restart of nuclear power plant is trigger of start of curtailment of variable renewable energy during low demand period in Kyushu area. There is possibility that current priority dispatch rule gives a disincentive to transit more flexible system in the market. It is necessary to discuss for improvement that enables economic curtailment through cross-regional real-time market, negative price etc. [ABSTRACT FROM AUTHOR]

In this paper, impact of current priority dispatch rule on the demand and supply operation, the unlimited and uncompensated curtailment and the wholesale power market trading were analyzed. As a matter of the current priority dispatch rule, first is that the Japan's priority dispatch rule focus to maintain supply and demand mainly within the region. Second, Japan's electricity system can't afford to connect large amount of variable renewable energy because it focuses on individual supply-demand balance in each area and gives high priority of long-term fixed power sources. Furthermore, it is expected that the economic rational crossregional operation will be expanded through wholesale electricity market, but curtailment of variable renewable energy starts at zero yen. On the other hand, It is possible for long-term fixed power sources to supply electricity at a constant output without negative price risk. Furthermore, evaluation of curtailment prospects in FY2017 turned out that there is possibility that future restart of nuclear power plant is trigger of start of curtailment of variable renewable energy during low demand period in Kyushu area. There is possibility that current priority dispatch rule gives a disincentive to transit more flexible system in the market. It is necessary to discuss for improvement that enables economic curtailment through cross-regional real-time market, negative price etc. [ABSTRACT FROM AUTHOR]

Electricity industries worldwide are undertaking the challenging transition towards more sustainable energy demand and supply, including further electrification, optimum generation mix changes and the development of innovative system structure and tecnologies. In order to accommodate new demand and the variable renewable sources such as PV and wind, there are emerging needs to enhance the system architecture and system operation. The authors, who are in Activity 3.4 and 3.5 of Task 14 "High-Penetration of PV Systems in Electricity Grids" of International Energy Agency Photovoltaic Power System Program, are surveying practices and case studies of innovative transmission system operation of large scale PV penetration with generation forecast and innovative flexibility resources. This paper fist presents the background and objective of the study (Section I). The authors then describe, as interim survey results of Activity 3.4 and 3.5, 1) existing and possible issues of PV and variable renewable penetration (Section II), 2) structure of PV integration studies to date and emerging trends for analysis, (Section III), 3) case studies (Section IV), and finally some key conclusions from the work to date (Section V). [ABSTRACT FROM AUTHOR]

The paper presents issues concerning power system modelling and model validation, with particular emphasis on renewable energy sources and their integration in large electrical networks. These issues were raised at a workshop organized by UVIG and IREQ held earlier this year. From the presentations and discussions, we synthesize a general framework to summarize the model validation process. Presented in the form of tables, this framework can serve as a checklist of considerations to help model designers validate their models. [ABSTRACT FROM AUTHOR]

Electricity industries worldwide are undertaking the challenging transition towards more sustainable energy demand and supply, including further electrification, optimum generation mix changes and the development of innovative system structure and tecnologies. In order to accommodate new demand and the variable renewable sources such as PV and wind, there are emerging needs to enhance the system architecture and system operation. The authors, who are in Activity 3.4 and 3.5 of Task 14 "High-Penetration of PV Systems in Electricity Grids" of International Energy Agency Photovoltaic Power System Program, are surveying practices and case studies of innovative transmission system operation of large scale PV penetration with generation forecast and innovative flexibility resources. This paper fist presents the background and objective of the study (Section I). The authors then describe, as interim survey results of Activity 3.4 and 3.5, 1) existing and possible issues of PV and variable renewable penetration (Section II), 2) structure of PV integration studies to date and emerging trends for analysis, (Section III), 3) case studies (Section IV), and finally some key conclusions from the work to date (Section V). [ABSTRACT FROM AUTHOR]

Renewable generation is mainly connected through converters. It can provide more and more services to the grid such as voltage support or frequency control. However, these services may not be sufficient for extremely high penetrations. As the share of such generating units is growing rapidly, some synchronous areas could in the future occasionally be operated without synchronous machines. In such conditions, system stability will have to be ensured with the same level of reliability as today. Presently, operation of power systems is based on the presence of synchronous machines. Frequency is linked to the balance between load and generation via the rotating masses equation. This will not be inherently valid for grids without synchronous machines. The matter of operating a network with 100 % power electronics is quite well resolved for small isolated systems. The same doesn't apply for large transmission systems where grid topology and power injections are highly variable and are not known at every moment by all system components or even by a centralized entity. This paper describes the research that needs to be achieved to remove barriers for high penetrations of converters. [ABSTRACT FROM AUTHOR]

This paper addresses the question of how variable renewable energy production can be included in the planning of the electricity system as a substitute for conventional electricity generation, and with what weight. In order to answer this question, the study investigates the contribution of variable renewable energies to security of supply and system adequacy in Denmark. The study is based on hourly 2013 data from offshore wind, onshore wind, wave and solar PV power production. The analysis is done over a year based on hourly values and based on a historical year. Provided that the capacity credit is the amount of power variable renewables can reliably be expected to produce at the times when demand for electricity is highest, the study focuses on the capacity credit of future Danish scenarios including high penetrations of offshore wind, onshore wind, wave and solar PV. The results of this project can ultimately lead towards the improvement of existing rules and methods in system planning and the development of integrated energy systems where the electricity, heating and transport sectors are merged. [ABSTRACT FROM AUTHOR]

Over a decade has passed since the European Union's First Electricity Directive that set in motion the establishment of wholesale electricity markets across the continent. The "golden" period of the late nineties was characterised by the development of wholesale markets that facilitated the trading of electricity between generators and suppliers based on short-run marginal costs. This was an age where there was abundant electricity generation capacity, namely from fossil-fuel sources, that was sufficient to meet the demands of industry and the population. However, more than one decade later, the structural and bidding patterns of European power plant portfolios are changing, driven by a significant increasing share of variable renewable electricity generation (RES-E). The European power industry is responding to these changes. The European-wide Target Model for electricity market integration across regions was decided in November 2008 by the European Electricity Regulatory Forum, based on the concept of interlinking energy-only national markets to become one integrated European market. The idea of having a single integrated market is to take advantage of the complementary generation assets across Europe with the only limitation to cross-border trade being congestion constraints. This pan-European electricity market is expected to be fully implemented by 2015. It will include day-ahead price coupling, cross-border intraday continuous trading and long-term cross-border capacity allocation with harmonised rules. Given these changes, the European Commission funded Market4RES project was established to assess the design of the current and future target electricity market model to support more efficient integration of RES-E into the pan-European electricity system. This was analysed in accordance with the EU's 2020 renewables objectives and forthcoming 2030 target. This paper draws on the main conclusions of the report entitled "Opportunities, Challenges and Risks for RES-E Deployment in a Fully Integrated European Electricity Market" for the Market4RES project. The report assesses the current status of the European integrated electricity market with respect to renewable penetration trends and other major events that are or have taken place on the market. The challenges and issues for the short-term, medium and long-term markets are analysed through a selection of case studies that cover three different market regions in the European electricity market: the Nordel system, Central-Western European system and the Iberian system. The full report is available on http://market4res.eu/ [ABSTRACT FROM AUTHOR]

This paper investigates reactive power control in transmission system and how the advent of multiple photovoltaic plants affects the control strategy in term of loading margin (LM) enhancement with regard to voltage stability. Substantially a proper coordination and provision among the photovoltaic (PV) generators in order to acquire optimum voltage control and reactive power distribution is proposed. It is assumed that three locations have been chosen at most in the network system to accommodate decently for current and forthcoming operation. Compared to the conventional reactive power compensation, the PV reactive power has higher reliability by virtue of the facts that solar resources are stable and not fluctuated. In a way to minimize network loss and voltage deviation whilst increasing loading margin, particle swarm optimization (PSO) is implemented in reactive power optimization problem. Further, it is also shown that the proposed method could embrace for fault occurrences. Explicitly, the simulation results are obtained using MATLAB software to yields optimal setting of reactive power injection illustrated in Malaysia Electric Power System (MEPS) network and successfully uphold for voltage collapse vicinity. [ABSTRACT FROM AUTHOR]

High voltage grids play a central role in the current energy concept of the german government. In this grid onshore wind farms with power above 10 MW and also offshore wind farms are integrated. For an optimized grid integration of wind energy converters (WEC) the grid impedance at the point of common coupling (PCC) has to be known. Thereby the grid impedance measurement allows to identify the grid impedance more precisely than by simulation. Up to now there are no measurement devices that are planned for a mobile measurement at high voltage level. Currently at the Helmut-Schmidt-University such a measurement device is under development. In this paper this government-funded measurement device developing project is introduced. [ABSTRACT FROM AUTHOR]

Basic characteristics of the wind farms with synchronous-compensator-commutated inverter (SCI)/HVDC system composed of series-connected wind generators, a current-source thyristor inverter, and a synchronous compensator with duplex reactor are discussed. The system operation is given on the basis of the equivalent circuits for the synchronous compensator with duplex reactor and phasor diagrams. As basic system characteristics, relationships between inverter dc-side voltage, the ratio of synchronous compensator current to inverter output current and inverter leading angle are shown. The experimental investigations revealed that system output current with almost no distortion was realized with the SCI/HVDC system having no additional power filters for the cases of reactive output power of leading and lagging power factors. [ABSTRACT FROM AUTHOR]

Expectations to the development of offshore wind are high, especially in Europe. Offshore wind is expected to contribute significantly to the reaching on renewable energy targets, in 2020 and beyond. However, offshore wind power plants are expensive. They currently still cost approximately twice as much as onshore wind. Moreover, upfront investment costs make up to 75% of the total lifetime cost, which makes financing extremely difficult. We investigate the development of offshore wind based on a unique collection of economic data comprising all major offshore wind power plants in Europe. We use our data set to investigate trends in investment cost, operation and maintenance cost, financing and profitability, and identify key economic drivers for offshore wind energy. More specifically, we analyse economic consequences in areas such as project sizes, turbine capacity, distance to shore and water depth, as well as the interrelations of the economic drivers in the areas. We then proceed to analysing industry expectations of cost reductions for offshore wind. This includes both previous cost reduction expectations and in how far they could be realised, as well as current cost reductions. We set them in perspective and identify the most important drivers for cost reductions in European offshore wind in the short and long term. [ABSTRACT FROM AUTHOR]

Wind energy is important for generating lowcarbon electricity and thus achieving national and international climate goals. From today's perspective, the spatial distribution of wind turbines is linked to a number of criteria. For example, the wind frequency at different locations and the availability of potential areas depending on the land use. Furthermore, the social acceptance, ecological aspects and the regulatory framework are taken into account as soft criteria. The mentioned criteria address different parameters in the wind energy model of the FfE Munich. The aim of the study is to find an approach for the spatial distribution of wind turbines in 2050 that combines numerous criteria and reflects a plausible pattern based on the current turbine stock. For this purpose, model sensitivities are shown, based on variations of a single parameter chosen to represent an extreme expression of a spatial and temporal distribution characteristic. The variation of each parameter is shown and discussed as sensitivities. The results of the spatial and temporal distribution of wind energy serve as input for further models such as the energy system analysis in the project eXtremOS (FKZ: 03ET4062A). [ABSTRACT FROM AUTHOR]

The Australian National Electricity Market (NEM) has experienced a dramatic transformation due to the rapid uptake of both small and large-scale renewable energy generation, along with the closure of multiple coal power plants. The Australian state, South Australia, epitomises this transformation as the share of renewable energy generation in the state grew from 14% in 2009 to 47% in 2018, dominated by wind power. Combined with limited interstate transmission capacity, the state's power system has experienced instantaneous penetration from wind generation in excess of 120% - the highest for any major power system in the world. This high presence of non-synchronous generation reduces the system strength that has traditionally been provided by synchronous generators. The ESCRI-SA 30MW Battery Energy Storage System (BESS) installed on the lower Yorke Peninsula in 2018, near the end of a long 132kV single-circuit radial feeder, is a Grid Forming BESS built on ABB's Virtual Synchronous Generator platform, which strengthens the grid by providing inertia, high fault current and fast power injection, as well as competitive market services on the NEM. It is also capable of seamlessly transitioning into islanded operation when faults occur on the upstream feeder, thus ensuring continuity of supply to local customers by operating an islanded power system with the nearby 91 MW Wattle Point Wind Farm and distributed solar PV. ESCRI-SA addresses an array of challenges, and reinforces how BESS with Virtual Synchronous Generator technology, can provide multiple value streams to utilities, consumers and the broader electricity market, as well as enabling large scale power systems to operate at 100% renewable energy. [ABSTRACT FROM AUTHOR]

Worldwide, economies are faced to the challenge of decarbonizing their power sectors in the next couple of decades. In most cases, this means integration of renewable energy sources (RES). Adapting successful experiences of other countries to the own situation may help to accelerate progress. Of course, the stage of the transformation process has to be similar for successful replication of best practice examples. However, also conditions between countries differ and many factors will not change by power system transformation. We propose a method to first categorise countries using a limited number of indicators. Consequently, for each category specific steps of RES integration can be defined. [ABSTRACT FROM AUTHOR]

Brazil has increased the installed capacity of wind power plants due to its great wind potential, especially in the Northeast and South regions, and due to the decrease in the final price of production, motivated by improvements in the technologies of wind turbine generators and plants, and the generation expansion model based on energy auctions. The country has the highest capacity factor of wind power generation in the world (42% in 2016) and the wind generation capacity in Brazil is expected to grow from 10.74 GW in 2016 to 17.30 GW in 2020, which represents 6.5% and 10.1%, respectively, of the total installed capacity of the Brazilian interconnected system. In order to adapt to this reality, the Brazilian Power System Operator (ONS) developed a wind generation forecast model based on wind and observed generation data and numerical weather prediction. The influence of the Intertropical Convergence Zone on wind generation in the state of Ceará shows that one of ONS's challenges is to improve the understanding of these meteorological system uncertainties, which are inherent to the predictions and model of their impacts in the wind power generation [ABSTRACT FROM AUTHOR]

Brazil has increased the installed capacity of wind power plants due to its great wind potential, especially in the Northeast and South regions, and due to the decrease in the final price of production, motivated by improvements in the technologies of wind turbine generators and plants, and the generation expansion model based on energy auctions. The country has the highest capacity factor of wind power generation in the world (42% in 2016) and the wind generation capacity in Brazil is expected to grow from 10.74 GW in 2016 to 17.30 GW in 2020, which represents 6.5% and 10.1%, respectively, of the total installed capacity of the Brazilian interconnected system. In order to adapt to this reality, the Brazilian Power System Operator (ONS) developed a wind generation forecast model based on wind and observed generation data and numerical weather prediction. The influence of the Intertropical Convergence Zone on wind generation in the state of Ceará shows that one of ONS's challenges is to improve the understanding of these meteorological system uncertainties, which are inherent to the predictions and model of their impacts in the wind power generation. [ABSTRACT FROM AUTHOR]

System performances of 100MW offshore wind power plant without substation composed of 20 sets of 5MW direct-drive wind turbine generators are simulated for the series-connected system using current-source type thyristor inverter with rated dc-link voltage of 100kV. The characteristics of dc-link voltage and current, and leading angle of commutation as well as margin angle of commutation for thyristor inverter are simulated for various wind velocities at the wind turbines in which Weibull distribution is used. Simulation results for different transmission distances are also given. [ABSTRACT FROM AUTHOR]

Topologies for enlarging the scale of wind power plants are discussed. The characteristics of a series-connected wind power plant with current-source thyristor inverter are first studied for different numbers of the wind turbine/synchronous generators connected in series in the rectifier outputs. A topology for two clusters of the series-connected wind power generators is then introduced, and the basic characteristics are shown. Finally, a novel topology for a wind power plant consisting of several clusters of series-connected systems is proposed, and it is shown that when the proposed topology is used, the plant output is increased without increasing system voltage. [ABSTRACT FROM AUTHOR]

Simulation models are an obligatory part of many hardware (HW) components in the field of renewable energies. The functionality of a HW component must correspond closely to the functionality of the related simulation model. The behavior of many HW components is dominated by their embedded software (SW), known as firmware. A SW development process that is related to the firmware for the HW component and to a firmware dynamic link library (dll) as part of the simulation model minimizes the parallel SW development for the HW component and for the simulation model. Possible discrepancies in the behavior of the simulation model and the corresponding HW component are kept to a minimum. The simulation model and the HW component can easily be upgraded to the same firmware release by flashing the HW with a new firmware and exchanging the firmware dll in the simulation model. A revalidation of the simulation model after a firmware upgrade, if needed at all, is minor. The customer can parameterize, monitor, control, and debug the simulation model with the tools already being used with the HW component. The simulation model also serves as an additional test instance for firmware tests, thus enabling tests that would be hard or even impossible to perform with the HW component. The SW platform of the simulation model delivered to the customer is decoupled from its local development platform. The simulation model can be delivered as a dll, as a model in SimPowerSystems (Mathworks) - including the model dll - as a model in PowerFactory (DIgSILENT) - including the modeldll - or as a model in any other SW that allows the inclusion of a dll. Here, the implementation of this approach is shown for a converter model. [ABSTRACT FROM AUTHOR]