The future European energy supply system will have a high share of renewable energy sources (RES) to meet the greenhouse gas emission policy of the European Commission. Such a system is characterized by the need for a strongly interconnected energy transport grid as well as a high demand of energy storage capacities to compensate the time fluctuating characteristic of most RE generation technologies. With the RE generators at the location of high harvest potential, the appropriate dimension of storage and transmission system between different regions, a cost efficient system can be achieved. To find the preferred target system, the optimization tool GENESYS (Genetic Optimization of a European Energy System) was developed. The example calculations under the assumption of 100% self-supply, show a need of about 2,500 GW RES in total, a storage capacity of about 240,000 GWh, corresponding to 6% of the annual energy demand, and a HVDC transmission grid of 375,000 GWkm. The combined cost for generation, storage and transmission excluding distribution, was estimated to be 6.87 ct/kWh

The transition from power systems dominated by synchronous machines to systems based on converter-based generation technologies (CGTs), is weakening currently robust power systems by reducing system inertia with the replacement of synchronous generators with low-inertia CGTs. From a frequency stability viewpoint, this is resulting in faster frequency dynamics and more frequent and larger frequency excursions after system contingencies, thus significantly affecting the stability of power systems dominated by CGTs, requiring detailed stability assessments to ensure the secure integration of CGTs. In this paper, a practical framework is presented for frequency stability studies based on time domain simulations of power systems with CGTs. A fundamental part of the proposed approach is the use of a filter to first identify worst-case scenarios among various possible system operating conditions. Once these worst-case scenarios are identified, a clustering technique is used to select representative worst-case operating conditions to evaluate the frequency stability of the system using time-domain simulations. The effectiveness of the proposed framework is demonstrated on the Chilean Northern Interconnected System (NIS), where it is shown that the proposed filter is able to quickly identify worst-case scenarios for further study. Moreover, we show that the selected representative operating conditions cover a wide-range of worst-case frequency responses, demonstrating the effectiveness of the proposed tool for frequency stability analyses.

Renewable generation technologies are rapidly penetrating electrical power systems, which challenge frequency stability, especially in power systems with low inertia. To prevent future instabilities, this issue should already be addressed in the planning stage of the power systems. With this purpose, this paper presents a generation expansion planning tool that incorporates a set of frequency stability constraints along with the capability of renewable technologies and batteries to support system frequency stability during major power imbalances. We study how the investment decisions change depending on (i) which technology—batteries, renewable or conventional generation—support system frequency stability, (ii) the available levels of system inertia, and (iii) the modeling detail of reserve allocation (system-wide versus zone-specific). Our results for a case study of Chile’s system in the year 2050 show that including fast frequency response from converter-based technologies will be mandatory to achieve a secure operation in power systems dominated by renewable generation. When batteries offer the service, the total investment sizes are only slightly impacted. More precise spatial modeling of the reserves primarily affects the location of the investments as well as the reserve provider. These findings are relevant to energy policy makers, energy planners, and energy companies.

Driven1 by decreasing prices for photovoltaic (PV) systems and incentive programs of different governments almost 100 GW of PV and over 100 GW of wind turbines (WT) have been integrated in the European power system today (2014). In some areas, the electricity generation already exceeds the demand, pushing the existing transport infrastructure to its limits in certain hours. In order to reach the European Commission's targets for 2050, the system integration will at some point require flexibility sources independent of conventional generation in order to keep today's standard in security of supply. There are several sources of flexibility. Together these flexibility sources will ensure the match of demand and supply at any given time. Energy storage systems can provide this flexibility by shifting of load in time while transmission grids provide the shift of load in space. Up to a certain extent, transmission capacity and storage capacity can replace each other, i.e. storage can reduce the load on transmission infrastructure by mitigating local peaks in load and/or generation. For the transition to a fully renewable energy system in 2050, major changes have to be achieved in the structure of the power supply system. The simulation tool GENESYS is a holistic approach to optimize the allocation and size of different generation technologies, storage systems and transnational grids of a European power system. The source code for the simulation tool is available free of charge under a public license. It can be freely parameterized by the user which allows the study of different electricity systems under the users’ assumptions with regard to load, generation potential and cost structure of the different system components. This publication will give an introduction to the simulation framework, the system model and the optimization strategy. Optimization results obtained with GENESYS for a fully renewable electricity system and a cost structure expected for 2050 will be presented together with sensitivity analyses investigating the main assumptions. The focus is the optimal allocation of PV and WT in a European electricity system, the resulting demand for storage capacities of different technologies and the capacity of the overlay grid.

Countries around the world are transitioning from conventional power systems dominated by synchronous generators towards low-carbon resources, characterized by high levels of converter-interfaced generators (CIGs). With this transformation, hundreds or even thousands of fast power electronic devices will be added to the grid as CIG penetration increases, thus making the system dynamic response progressively faster and more complex. This future scenario poses significant challenges in power system stability and control. To sustain power system stability in future power systems and achieve a seamless transition, we need to depart from current control practices based on decentralized and stand-alone local control actions and begin to explore new methods. A promising technology to overcome control complexities and underlying stability issues in future low-inertia power systems are wide area control (WAC). Within this technology, the control is no longer based on a purely localized tasks but rather a set of coordinated actions across wide areas in which interplant communication plays a key role. This paper presents the state of the art of existing research efforts in the field of WAC strategies for maintaining stability in large-scale low-inertia power systems of the future. We present different WAC solutions that have been put forward hitherto, we put these control strategies into context, classify them, and finally relate them to each other. We also raise open questions and challenges that need to be addressed in order to ensure a secure transition towards power systems dominated by CIGs.