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IEA WIND R&D Task 25 on "Design and Operation of Power Systems with Large Amounts of Wind Power" collects and shares information on wind generation impacts on power systems, with analyses and guidelines on methodologies. The summary report published June 2016 contains summary of experience of wind integration as well as the most relevant wind power grid integration studies in the 16 participating countries. The studies address concerns about long-term planning issues and short-term operational impacts. There is already significant experience in integrating wind power in power systems. Electricity markets, with crossborder trade of intra-day and balancing resources, and emerging ancillary services markets are considered as a positive development for future large shares of wind power. Energy system integration between electricity, gas and heat sectors is studied for future high share renewable systems. Enhancing use of hydro power storage to balance larger systems is another promising option. Integration studies for >40 % shares of wind and solar power in the power system are pushing the limits of how much variable generation can be integrated. The results so far are promising and the work is ongoing with more detailed modelling possibilities in the future. Electricity storage is still not as cost effective in larger power systems as other means of flexibility, but different forms of storage have a large role in the emerging studies for 100 % renewable systems. [ABSTRACT FROM AUTHOR]

Large-scale integration of Inverter-based Resources (IBRs) such as wind parks brings new challenges in modelling, analysis and simulation of power systems for protection engineers and system operators. IBRs have complex controller and electronic circuit structures but the use of faster solvers in protection studies will save valuable engineering time and alleviate transfer of black box models between different parties including Original Equipment Manufacturers (OEMs) and system operators. This paper aims to evaluate solver relaxation in an objective manner for the first time in the analysis of impact of IBRs on power swing protections. The foundation of this work is a detailed Electromagnetic Transients-type (EMT-type) model of a wind park built in PowerFactory® software. Then, an equivalent of this model compatible with RMS solvers is developed in the same software by mapping circuit and controller components to ensure objective comparisons. The two models are equivalent in terms of power, short circuit ratings and fault behavior within the typical range of simulation resolution of RMS solvers. By using these two equivalent models, the impact of wind generation on power swing protection elements based on a conventional approach are studied in EMT and RMS solvers. The results suggest consistency in the response of the two solvers for the PSRC WG-D6 test case under investigation. [ABSTRACT FROM AUTHOR]

Large-scale integration of Inverter-based Resources (IBRs) such as wind parks brings new challenges in modelling, analysis and simulation of power systems for protection engineers and system operators. IBRs have complex controller and electronic circuit structures but the use of faster solvers in protection studies will save valuable engineering time and alleviate transfer of black box models between different parties including Original Equipment Manufacturers (OEMs) and system operators. This paper aims to evaluate solver relaxation in an objective manner for the first time in the analysis of impact of IBRs on power swing protections. The foundation of this work is a detailed Electromagnetic Transients-type (EMT-type) model of a wind park built in PowerFactory® software. Then, an equivalent of this model compatible with RMS solvers is developed in the same software by mapping circuit and controller components to ensure objective comparisons. The two models are equivalent in terms of power, short circuit ratings and fault behavior within the typical range of simulation resolution of RMS solvers. By using these two equivalent models, the impact of wind generation on power swing protection elements based on a conventional approach are studied in EMT and RMS solvers. The results suggest consistency in the response of the two solvers for the PSRC WG-D6 test case under investigation. [ABSTRACT FROM AUTHOR]

Future extension of renewable capacity can lead to surplus situation leading to more than 4,000 GWh not remunerated energy due to current market regulation and wind power support schemes. This can lead to inefficient dispatch decisions of wind power plants because no market premiums are payed during longer time periods of negative market prices. The result can be reduced wind power generation and increased conventional generation. Furthermore incentives for flexibility in the power market are reduced and costs for integration of wind energy are increased. [ABSTRACT FROM AUTHOR]

Hydropower plants have ideal properties to provide production flexibility for the achievement of renewable targets for variable generation like wind and solar. However, given the typical constraints in the operation of hydro, it is often unclear how much flexibility is left in the dispatch of hydro to assist the system. This is especially true when assessing future system operation with increasing amounts of variable generation (VG). Numerous studies have simulated the operation of electric systems under different levels of VG penetration and found that the integration of renewables is facilitated with a fleet of flexible generators. Yet, due to the complex mix of nontechnical constraints, hydropower representation in these electric sector models is often simplified. This impact leads to underconstrained or over-constrained estimates of the flexibility available in reservoirs. In both cases, the results of the studies are influenced by these assumptions. Higher level of details regarding hydro dispatch constraints (detailed cascading hydro systems, detailed watercourses and inflow patterns) might have to be considered in future power system studies and for the calculation of water values. Including more details in a hydrothermal scheduling model leads to more realistic simulation results. However, a high model detail significantly affects computation time, which limits the model complexity in practice when studying larger regions. [ABSTRACT FROM AUTHOR]

Wind and Solar integration within the NEM Grid (eastern seaboard of Australia) has developed significantly in the past 10 years, with the South Australian region having a very high penetration of wind and decreasing synchronous generation. Given this context and 5-minute Energy and Frequency Control Ancillary Service (FCAS) market designs, these developments have necessitated a maturing of wind and solar power plant dispatch operation that requires the provision of optimised market-based energy and ancillary services provisions. An overview of recent dispatch-time line improvements required and some of the likely steps forward required of wind power plant vendors as wind power plant operators move towards provision of more market based frequency control services in these markets is presented. [ABSTRACT FROM AUTHOR]

Renewable energy especially from wind and PV will in future replace fossil energy. The grid integration of these sources with high generating power at low time of usage forms a challenge to the existing grid. New design of wind generators for low wind application will help to reduce the installed wind power and the grid investments. [ABSTRACT FROM AUTHOR]

This paper describes the current status of Active Network Management (ANM); a smart network control solution that enables economically efficient and faster connections of generation to distribution networks. ANM functions by utilising real-time measurements of network behaviour to inform and implement autonomous control actions on network devices such as generators, maintaining network parameters within secure limits. In recent years ANM has developed from prototype to a mature, "Business as Usual" solution now being deployed by several UK Distribution Network Operators (DNOs) to enhance access to their networks in support of generation customer developments and the wider national targets for renewable generation. This paper presents learning from deployment projects and discusses the challenges to be addressed towards wide-scale ANM deployment. [ABSTRACT FROM AUTHOR]

This paper analyzes selected interconnectors in Europe using several evaluation factors; capacity factor, congested time, and congestion ratio. In a quantitative and objective evaluation, the authors propose to use publically available data on maximum net transmission capacity (NTC) levels during a single year to study congestion rates, realizing that the capacity factor depends upon the chosen capacity of the selected interconnector. This value will be referred to as "the annual maximum transmission capacity (AMTC)", which gives a transparent and objective evaluation of interconnector usage based on the published grid data. While the method is general, its initial application is motivated by transfer of renewable energy. [ABSTRACT FROM AUTHOR]

Dynamic Line Rating (DLR) systems are effective solutions for managing grid congestion. Grid congestions may be caused by increasing power flows due to growth in peak demand or distributed generation, or power flows that are rerouted due to maintenance outage. Wind speed has the strongest impact on conductor cooling and therefore the DLR. An increase in wind speed from 0.5 m/s to 2 m/s results in a 50% gain above the static line rating. This is why, the business case for wind integration appears to be the most attractive use case of DLR systems. In Belgium, DLR systems are installed on numerous 70 kV, 150 kV and 380 kV lines. Cases from each voltage level are reported in this paper. The DLR systems collect wind speed, load current, ambient temperature, and seasonal static ratings, and calculate the dynamic rating every 5 minutes. Where the line loading increased with higher wind infeed, the correlation of this data with DLR was analyzed. The results are noteworthy because they are based on actual measurements rather than theoretical modeling. The results show that, at all voltage levels around 10-15% latent capacity above the seasonal static ratings are available 90% of the time. The extra line capacity, made accessible by the DLR system, reduces the instances of high line loading by 5-10%. Furthermore, this congestion management effect applied to a radial connection of a wind farm could be used to reduce the need for curtailment by up to 10%, increase infeed by up to 50%, and increase hosting capacity by up to 40% without the need for any curtailment. [ABSTRACT FROM AUTHOR]

The article presents the schedule of the 15th Wind Integration Workshop to be held in Austria from November 15-17, 2016.

This paper examines the possibility of subsynchronous resonance (SSR) between voltage-source converters (VSC) and the power grid under different configurations and in different applications. SSR between Type-III wind turbines and a weak grid with series compensation has been discussed in the literature. The purpose of this work is to understand whether a VSC operating as an inverter for Type-IV wind turbine and PV application could form SSR with the grid, especially a weak grid with or without series compensation. The analysis is based on analytical impedance models of the VSC and is performed in two steps. In the first step, dynamics of the dc bus voltage are ignored, allowing the use of relatively simple models of the VSC to be used. In the second step, the effects of dc bus dynamics on the inverter output impedance are considered. In each case, both an inductive grid and a capacitive grid (when series compensation is used) are considered, and design guidelines to avoid SSR and possible mitigation methods when SSR occurs are also presented. It is found that, with an ideal dc bus, SSR could happen but is unlikely if there is no series compensation in the grid. A soft dc bus, on the other hand, may form resonance with the grid through the inverter and, when such a resonance occurs, the inverter output current typically exhibits a supersynchronous as well as a subsynchronous resonance at frequencies that are symmetrical about the fundamental frequency. The impedance-based small-signal analysis is verified by detailed circuit simulation. [ABSTRACT FROM AUTHOR]

An international forum for exchange of knowledge of power system impacts of wind power has been formed under the IEA Implementing Agreement on Wind Energy. The task "Design and Operation of Power Systems with Large Amounts of Wind Power" will analyse existing case studies from different power systems. There are a multitude of studies made and ongoing related to cost of wind integration. However, the results are not easy to compare. This paper summarises results from 10 countries and outlines studies made at European Wind Energy Association and the European system operators UCTE and ETSO. A state-of-the art review process of the new IEA collaboration will seek reasons behind the wide range of results for costs of wind integration. [ABSTRACT FROM AUTHOR]

For effective climate change mitigation, the share of renewable energy should be increased. Also, for low-emission carbon neutral aviation, synthetic fuels from renewable energy sources are assumed to be increasingly used in the future. The fluctuating nature of the renewable energies results in periods with production exceeding the demand. Consequently, some kind of energy storage is needed to balance power supply and demand. The X-to-Liquid routes proved to offer promising solutions in the chemical energy storage area, and this work considers the Power-Biomass-to-Liquid (PBtL) process as an energy storage solution. Yet, publications [1, 2] concerning the PBtL process discuss only the steady-state mode operation mode. However, since renewable energy is of a fluctuating nature, the dynamic process operation is of a particular interest. This thesis compares the steady-state and dynamic operation mode for a PBtL process. The plant size is scaled to an 24.8 MW electrolyzer power input. These process operation modes simulated on Aspen Plus and Aspen Dynamics. Moreover, they are economically assessed with the DLR in-house program TEPET. The dynamic mode results in a NPC of 5.06 while the steady-state results in 3.84 The FCI of the dynamic mode amounted to 2.45 times that of the steady-state. The FT products per annum in the dynamic mode is 92% of that of the steady-state mode. [ABSTRACT FROM AUTHOR]

The article offers information on "13th International Workshop on Large-Scale Integration of Wind Power into Power Systems as well as on Transmission Networks for Offshore Wind Power Plants" that is to be held in in Berlin, Germany, from 11-13 November 2014.

A significant number of wind and solar integration studies have been conducted in recent years, and methodologies have evolved steadily. Since power system characteristics and data availability vary significantly, the results and methodologies used in these studies have varied accordingly. This article presents findings from an international collaboration under two IEA Technology Collaboration Programmes (WIND and PVPS) working towards updating Recommended Practices for Wind Integration studies to also include those for solar photovoltaics (PV). An overview of a complete wind and solar integration study is presented as a flow chart. The set-up of a study and the main assumptions can have a large impact on the results, and therefore significant attention must be paid to ensure that these choices conform to international best practices. The main steps in the simulations are presented with recommendations on methodologies for assessing impacts on reserve requirements, on other generation and balancing, capacity value, and increases in transmission capacity. [ABSTRACT FROM AUTHOR]

The article lists the participants from various countries for the International Wind Integration Workshop to be held in Vienna, Austria from November 15-17, 2016 including Florian Ackermann of Germany, John Bech of Denmark, and Nadine Chapalain of France.

This paper analyses the behaviour of a HVDC Diode Rectifier (HVDC-DR) connected wind power piant during HVDC cabie fauits. The study has been carried out by means of a detailed PSCAD simuiation of a 400 MW off-shore wind power piant (WPP), considering an on-shore VSC Moduiar-MuitHevei power converter station, transformer saturation and detailed cabie modeis. The main goai is to evaiuate under which conditions it is possible for the wind power piant to control the diode rectifier currents during cabie fauits and hence reduce the HVDC-DR transformer breaker short-circuit breaking capacity or, eventuaiiy, avoid its use altogether. It wiii be shown that WPP current referenced control strategies can be used to reduce the HVDC-DR currents to zero in approx. 35 ms for midpoint cabie fauits and in approx. 110 ms for DR converter terminal fauits. [ABSTRACT FROM AUTHOR]

This paper presents a summary of the recent work by the authors on the modeling and mitigation of subsynchronous resonance (SSR) between Type-III wind turbines and the grids that uses series compensation. The basis for the work is analytical impedance models describing small-signal behaviors of the turbine from subsynchronous to supersynchronous frequencies. The method and general procedure to develop such impedance models are outlined, followed by a complete set of models for Type-III turbines employing standard control architectures. Use of the models to predict SSR when the grid is equipped with series compensation is then illustrated and validated. The analytical impedance models also provide a basis for the development of SSR mitigation solutions. As an example, damping of SSR through control of either the rotor-side or stator-side converter to reshape the overall turbine output impedance in the subsynchronous frequency range will be discussed and a case study utilizing active damping on rotor-side converter is presented. [ABSTRACT FROM AUTHOR]

As HVDC-Diode Rectifier (HVDC-DR) stations cannot control the off-shore ac-grid, several strategies have been proposed for the off-shore ac-grid voltage and frequency control using wind turbines with fully rated converters (type 4). However, there is little existing literature on the connection of DFIG-based (type 3) wind farms to HVDC-DR stations. Therefore, the main aim of this paper is to present a procedure to develop new control strategies for type 3 wind turbines and adapt those already developed for type 4 wind turbines. The proposed methodology is based on the ability of stand-alone DFIG wind turbines to control independently their stator voltage magnitude and angle. Therefore, it will be shown that any control strategy that could be translated into a voltage and angle reference can be used, with little modification, for the control of DFIG-based wind farms. This paper includes the verification of the aforementioned approach by means of PSCAD simulations and a thorough discussion on the characteristics and limitations of the proposed methodology. [ABSTRACT FROM AUTHOR]

Wind power forecasts have been operationally used for over 25 years. Despite this fact, there are still many possibilities to improve and enhance forecasts, both from the weather prediction side and in the use of the forecasts. Until now, most applications have focused on deterministic forecast methods. This is likely to change in the future as penetration levels increase and weather conditions become more unstable due to climate change. Probabilistic methods are therefore receiving more attention from users. The International Energy Agency (IEA) Wind Task 36 on Wind Power Forecasting organises international collaboration, among national weather centres with an interest and/or large projects on wind forecast improvements (NOAA, DWD, UK MetOffice,...), forecast vendors and forecast users to facilitate scientific exchange to be prepared for future challenges. Collaboration is open to IEA Wind member states; 12 countries are already actively collaborating. The Task is divided in three work packages: Work Package (WP) 1 is a collaboration on the improvement of the scientific basis for the wind predictions themselves. This includes numerical weather prediction (NWP) model physics, but also widely distributed information on accessible datasets. This WP will also organise benchmarks for NWP models. The efforts of WP2 resulted in the publication of an international pre-standard (an IEA Recommended Practice) on how to select an optimal wind power forecast solution for a specific application. The focus of WP3 is on the engagement of end users to disseminate the best practice in the use of wind power predictions, especially probabilistic forecasts. The paper presents an overview of the recently completed first phase and the ongoing second phase of IEA Task 36 on Wind Power Forecasting, which provides a forum for international collaboration in this important field for meteorologists, wind power forecasters and end users. For collaboration, please contact the author (grgi@dtu.dk) and see the website at www.ieawindforecasting.dk. [ABSTRACT FROM AUTHOR]

High-voltage power equipment like offshore wind farms is exposed to grid faults within its supplying high-voltage power network. It is desirable to perform standardized grid code testing directly on site including all turbine components. The herein presented test equipment is capable to emulate the required undervoltage and overvoltage grid faults on the 66 kV high-voltage level without the need for additional transformers. Its mobile design allows the use at various test sites. Fully installed high-voltage wind turbine systems can be tested without further adjustments and under real environmental conditions. [ABSTRACT FROM AUTHOR]

The ability of generators to ride through overvoltages has become increasingly important in recent years. The research project OVRTuere (FKZ 0350041) investigates whether existing HVRT (high-voltage ride-through) requirements represent the most cost-effective solution. It also deals with the verification of the HVRT-capability of generators by means of testing. This includes the comparison of the capabilities of different test facilities, such as temporary over-voltage magnitudes, voltage phase shifts and transients at the beginning and end of disturbances. This paper gives an overview of six types of HVRT test facilities. It provides an initial comparison of the facilities in terms of sub-cycle transients after beginning and end of disturbances. [ABSTRACT FROM AUTHOR]

A common conclusion from wind integration studies is the benefit of spatial diversification of Wind Power Plants for power systems. However, few of these studies quantify the benefit that may be apparent from different wind power portfolios. To quantify that benefit, temporally and spatially accurate models of wind power are required. A wind power model is constructed starting with wind speed time-series extracted from the ECMWF-interim reanalysis model. The wind speed time-series are interpolated, scaled, and imputed such that they are representative of the wind incident on the Wind Power Plants. Imputation is performed using a Wavelet Multi-Resolution Analysis approach that ensures temporally consistent correlations while accommodating heteroskedasticity. The wind speed time-series are transformed to power by applying wind power plant power curves, low pass filters, and a Markov Chain model for operational efficiency. Simulated wind power time-series are validated using a set of measurements made at Wind Power Plants in New Zealand. The wind power model is used to simulate power time-series for 2GW portfolios of wind power plants representing compact, disperse, diverse, and Business As Usual portfolios. Metrics for dependability, variability, and predictability are used to quantify the benefits of spatial diversification. [ABSTRACT FROM AUTHOR]

Wind energy has been one on the major sources of electrical energy in the Spanish peninsular system for almost a decade. In 2013, it was even the technology with the highest energy produced and it has consistently provided since then around 20% of the electrical energy in this system. The first steps to achieve this level of wind integration in the Spanish peninsular system were developed into observability and controllability areas. Currently, almost 99% of wind installations can be observed and controlled. These high standards allow to move forward to new objectives related to align the European new requirements with the Spanish electrical system necessities. As a result, regulatory changes introduced in 2014 have adapted also the regulatory framework in order to delete as much as possible the distinctions between renewable energy resources and conventional generation. The two main changes have been the possibility of participation of variable RES in the balancing markets such as the tertiary reserve market and the introduction of market-based downward redispatching for solving congestions on either the TSO or the DSO's network. This paper describes the different ancillary services currently considered in the Spanish electrical system and the participation of RES, focusing particularly on its provision with wind energy. The paper describes the functioning and RES participation on the following topics: * Replacement Reserves or generation-load imbalance market. * Tertiary reserve. * Secondary reserve and AGC connected units. * Voltage control. Additionally, this paper introduces the prequalification processes for those ancillary services, which are a prerequisite for all technologies, including conventional generation, and the state of actual participation in the different services of wind generation in Spain. An important issue on the provision of ancillary services with RES generation which has raised recently some debate in Europe is the crucial coordination between the participation on balancing markets of units that may be affected by congestion management. This issue, while not new at all, since conventional generators may as well be subject to congestion management limits in the transmission network, requires further development when applying to a larger number of renewable generators or these generators are connected to distribution grids. The issue of congestion management for TSO connected and distributed flexibilities has been coordinated by the Control Centre for Renewables (CECRE) in Spain since its commissioning in 2007, but a new degree of coordination needs to be introduced when these resources participate also in the ancillary services markets. The paper describes how this interaction between balancing markets and congestion management is performed in the CECRE on a real-time basis regardless of where congestions arise, whether in the transmission network or in the distribution network. [ABSTRACT FROM AUTHOR]

Wind energy has been one on the major sources of electrical energy in the Spanish peninsular system for almost a decade. In 2013, it was even the technology with the highest energy produced and it has consistently provided since then around 20% of the electrical energy in this system. The first steps to achieve this level of wind integration in the Spanish peninsular system were developed into observability and controllability areas. Currently, almost 99% of wind installations can be observed and controlled. These high standards allow to move forward to new objectives related to align the European new requirements with the Spanish electrical system necessities. As a result, regulatory changes introduced in 2014 have adapted also the regulatory framework in order to delete as much as possible the distinctions between renewable energy resources and conventional generation. The two main changes have been the possibility of participation of variable RES in the balancing markets such as the tertiary reserve market and the introduction of market-based downward redispatching for solving congestions on either the TSO or the DSO's network. This paper describes the different ancillary services currently considered in the Spanish electrical system and the participation of RES, focusing particularly on its provision with wind energy. The paper describes the functioning and RES participation on the following topics: • Replacement Reserves or generation-load imbalance market. • Tertiary reserve. • Secondary reserve and AGC connected units. • Voltage control. Additionally, this paper introduces the prequalification processes for those ancillary services, which are a prerequisite for all technologies, including conventional generation, and the state of actual participation in the different services of wind generation in Spain. An important issue on the provision of ancillary services with RES generation which has raised recently some debate in Europe is the crucial coordination between the participation on balancing markets of units that may be affected by congestion management. This issue, while not new at all, since conventional generators may as well be subject to congestion management limits in the transmission network, requires further development when applying to a larger number of renewable generators or these generators are connected to distribution grids. The issue of congestion management for TSO connected and distributed flexibilities has been coordinated by the Control Centre for Renewables (CECRE) in Spain since its commissioning in 2007, but a new degree of coordination needs to be introduced when these resources participate also in the ancillary services markets. The paper describes how this interaction between balancing markets and congestion management is performed in the CECRE on a real-time basis regardless of where congestions arise, whether in the transmission network or in the distribution network. [ABSTRACT FROM AUTHOR]

This paper introduces a control strategy which can be used for the connection of both type-3 and type-4 wind turbines to HVDC-Diode Rectifier (HVDC-DR) stations. In this way, wind turbines from different technologies could effectively connected to the same HVDC Diode Rectifier station. The proposed strategy is verified by means of PSCAD simulations including start-up operation, optimal power tracking with changing wind conditions and off-shore ac-grid frequency reference changes. Moreover, reactive power sharing amongst the wind turbines is proven for the aforementioned scenarios. [ABSTRACT FROM AUTHOR]

This paper presents a detailed dynamic simulation study to demonstrate the potential capability of a 400 MW offshore wind farm to black start an onshore grid, using grid forming converter controls in the wind turbines (WTs) with P/f and Q/V droop control. The wind farm modelled comprises 50 WTs of 8 MW rating, and is connected via a 120 km long AC export cable to the onshore grid. Simulations indicate that it is theoretically possible to black start an onshore grid by adding block loads of up to 50 MW, provided the grid forming controllers and electrical system are properly designed for black start, and there is adequate wind. Energization of the large offshore transformer, export cable and onshore transformer, result in significant transient voltage distortions, aggravated by transformer saturation, but do not cause a trip of the modelled WT protection. Practical challenges to allow an offshore wind farm to black start a grid are also discussed. This project received financial and technical support from The Carbon Trust's Offshore Wind Accelerator (OWA), a collaborative R&D program funded by nine leading offshore wind developers (E.ON, EnBW, Equinor, Innogy, Ørsted, SPR, Shell, SSE, Vattenfall) and the Scottish Government. [ABSTRACT FROM AUTHOR]

In practically all end-user wind and solar power prediction applications, the majority of tasks besides the predictions itself can be tackled on a generic level. A mature and proven solution with a high level of quality management and resilience may be an alternative to a proprietary development for benchmark and in-house prediction handling, using a number of prediction data feeds. Since many years, the Anemos prediction platform has been developed in several research and commercial contexts, originally for wind power forecasts and today also for advanced solar power predictions. Many of the Anemos developments are generic, and may be used for the implementation of individual wind and solar power prediction systems with respect to data interfaces, data storage, aggregations and uncertainties, GUIs, monitoring, QM and O&M support and benchmark reporting. In particular, it contains an advanced combination module, which combines the data feeds from different FSPs and generates an optimized overall forecast. [ABSTRACT FROM AUTHOR]

We are in the middle of an important transition of electrical power systems. Conventional power plants are being replaced by renewable energy sources, which are mainly connected to the grid via power electronic converters. Whenever a conventional, synchronous generator (SG) based, power plant is decommissioned some inertia, frequency and voltage control mechanism are lost. Conventional plant is being replaced by converter-based generation, creating critical challenges in power systems. A main interest is how these systems will operate with the known level of effectiveness and reliability. Nowadays, the converter-based generation that is connected to the grid is grid-feeding. They can operate sufficiently under the presumption that they are connected to a strong AC network. New control techniques for converters, for example grid-forming strategies, are being developed to address these challenges and to offer ancillary services that until now have been provided by SGs. In this paper, a gridforming system and control strategy is explained and developed. Its impact on the wider electrical power system will be discussed and a grid forming grid forming control strategy will be presented. The grid forming system is tested on a IEEE sample 9 bus network that is 80% and 100% converter based. The system behavior will be presented subject to load increase/decrease and post fault behavior. [ABSTRACT FROM AUTHOR]

Three medium voltage transformer-based test units for Fault Ride Through (FRT) tests are already in operation. Others are in planning or in process of building. The new users are impressed of the wide range of possibilities for testing with a smarter test device. The increasing requirements of accuracy in model validation of the devices under test (DUT) caused the requirements that as well the test unit itself needs a better description. This paper will serve mathematic approaches how to handle this kind of network fault generator in the computer simulation area. FRT test devices in general were taken to demonstrate that real wind turbines or other DUT are able to handle grid faults. In this context a grid fault is a 2 or 3 phase instantaneous voltage drop or rise over some 100 ms up to not more than 3 s usually. The way how a DUT has to handle this grid faults is postulated in the grid codes of each system operator or in general country grid codes. In Europe the network code requirements for generators and in Germany the VDE AR N 4105, -4110 and -4120 in conjunction with the measurement procedures of FGW technical guideline TR 3 and DIN VDE 0124-100 are setting the standards. Compared to previous years, not only voltage drops need to be simulated but also overvoltage events up to 150%voltage. Long term measurements with voltages of 115% or 85% have a test duration of up to 60 s. The new IEC 61400-21-1 proposes to measure not only the requirements according to the grid codes. The suggestion of the new IEC 61400-21-1 is, to simulate the maximum capabilities of the wind turbines. These capabilities can be far beyond the mentioned test. To meet these new requirements a new generation of FRT test equipment was developed. [ABSTRACT FROM AUTHOR]

Nowadays many markets require power plant characteristics, ancillary services and fault behavior from renewable and conventional generation units equivalently. As a result advanced control strategies for WPPs and WTs are required which more and more influence and determine the systems behavior and not just only the behavior of the point of common coupling (PCC). For developing and verifying the functionality of future products which meet the system's needs testing is required. Yet due to the high cost of prototype test-stands and of field testing, testing in special designed test facilities can be utilized alternatively and additionally during the development process. Worldwide different experimental platforms with different orientation, e.g. component testing, system testing, etc. exist nowadays. Taking into consideration such experimental platforms, a wide variation of test possibilities depending on the targeted power level can be considered. In this paper the utilized demonstrator test power system will be introduced and three examples of the usage of the demonstrator test power system with respect to wind integration in power systems will be shown and discussed. [ABSTRACT FROM AUTHOR]

In practically all end-user wind and solar power prediction applications, the majority of tasks besides the predictions itself can be tackled on a generic level. A mature and proven solution with a high level of quality management and resilience may be an alternative to a proprietary development for benchmark and in-house prediction handling, using a number of prediction data feeds. Since many years, the Anemos prediction platform has been developed in several research and commercial contexts, originally for wind power forecasts and today also for advanced solar power predictions. Many of the Anemos developments are generic, and may be used for the implementation of individual wind and solar power prediction systems with respect to data interfaces, data storage, aggregations and uncertainties, GUIs, monitoring, QM and O&M support and benchmark reporting. In particular, it contains an advanced combination module, which combines the data feeds from different FSPs and generates an optimized overall forecast. [ABSTRACT FROM AUTHOR]