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Variable renewable generation and load fluctuations induce significant balancing cost in power system operation. To overcome this issue, this paper proposes a control architecture that leverages inherent regulation capabilities of wind turbines to minimize the system‐wide balancing costs. Instead of handling wind power fluctuations via power filtering algorithms that are agnostic to system‐wide power imbalance, this paper aims to optimize the wind power generation profile from system perspective. In the proposed method, wind turbines are modelled as semi‐dispatchable units, where the dispatch command is dynamically generated at every automatic generation control cycle by considering mileage payments as an indicator of system‐wide imbalance. As a result, local resources of wind turbines are optimally leveraged in real‐time to mitigate system‐wide power imbalances. The proposed strategy and state‐of‐the‐art techniques are compared in comprehensive high‐fidelity case studies. Our simulation results demonstrate that the proposed system‐aware regulation scheme can alleviate system balancing costs without investments into energy storage systems. [ABSTRACT FROM AUTHOR]

The pan‐European power grid is experiencing an increasing penetration of Variable Renewable Energy (VRE). The fluctuating and non‐dispatchable nature of VRE hinders them in providing the Ancillary Service (AS) needed for the reliability and stability of the grid. Therefore, Energy Storage Systems (ESS) are needed along the VRE. Among the different ESS, a particularly viable and reliable option is Pumped Hydro Storage (PHS), given its cost‐effective implementation and considerable lifespan, in comparison to other technologies. Traditional PHS plants with Francis turbines operate at a high head difference. However, not all regions have the necessary topology to make these plants cost‐effective and efficient. Therefore, the ALPHEUS project will introduce low‐head PHS for regions with a relatively flat topography. In this paper, a grid‐forming controlled converter coupled with low‐head PHS that can contribute to the grid stability is introduced, emphasising its ability to provide different AS, especially frequency control, through the provision of fast Frequency Containment Reserve (fFCR) as well as synthetic system inertia. This paper is an extended version of the paper "The Contribution of Low‐head Pumped Hydro Storage to a successful Energy Transition", which was presented at the 19th Wind Integration Workshop 2020. [ABSTRACT FROM AUTHOR]

The pan‐European power grid is experiencing an increasing penetration of Variable Renewable Energy (VRE). The fluctuating and non‐dispatchable nature of VRE hinders them in providing the Ancillary Service (AS) needed for the reliability and stability of the grid. Therefore, Energy Storage Systems (ESS) are needed along the VRE. Among the different ESS, a particularly viable and reliable option is Pumped Hydro Storage (PHS), given its cost‐effective implementation and considerable lifespan, in comparison to other technologies. Traditional PHS plants with Francis turbines operate at a high head difference. However, not all regions have the necessary topology to make these plants cost‐effective and efficient. Therefore, the ALPHEUS project will introduce low‐head PHS for regions with a relatively flat topography. In this paper, a grid‐forming controlled converter coupled with low‐head PHS that can contribute to the grid stability is introduced, emphasising its ability to provide different AS, especially frequency control, through the provision of fast Frequency Containment Reserve (fFCR) as well as synthetic system inertia. This paper is an extended version of the paper "The Contribution of Low‐head Pumped Hydro Storage to a successful Energy Transition", which was presented at the 19th Wind Integration Workshop 2020. [ABSTRACT FROM AUTHOR]

Renewable energy sources play an important role in providing clean energy for future electricity networks. As the penetration level of these resources grows, their integration with the grid will be more challenging. Each renewable energy source has different inherent characteristics that, if appropriately used in the generation mix, could complement each other and create many technical and economic benefits for the power system. Usually, renewable energy resource complementarity studies are carried out with the objectives of smooth effect, reducing the need for storage and load tracking. In this study, the economic complementarity approach is introduced with the help of a Mixed integer nonlinear programming (MINLP) model. This approach can integrate renewable and storage energy sources with the grid and determine the optimal capacity of these resources in complementary used mode. The results show that the proposed method always imposes the system's lowest annual operation and investment costs. [ABSTRACT FROM AUTHOR]

Aiming at the problem of multi‐point power source layout planning for power systems, the output characteristics of a power system composed of wind power, photovoltaic power, hydropower, traditional thermal power, concentrated solar power and electrochemical energy storage are comprehensively analyzed. A power source multi‐point layout planning model for a power system based on complex adaptive system theory is proposed with a focus on the complementarity among these different energies and the combination of power optimization planning and complex adaptive system theory. With the minimum construction unit of various types of power sources as the 'agent', considering the interactions among agents and the accumulation of experiences, the behaviour rules of the model are constantly changed, the grid‐connected positions of various types of power sources are adjusted, and the optimal layout schemes for all kinds of power capacities for each node are obtained. In addition, an agent modelling method based on complex phenomena emergence with simple rules is proposed, which reveals the core idea of the complex adaptive system theory: adaptability creates complexity. Taking the new energy construction base in Northwest China as an example, the proposed method is verified to have a significant effect on improving energy consumption in the new system. Based on the current power capacity layout and the future grid structure in this area, the future power optimization scheme is determined, and it provides guiding significance for actual engineering construction. [ABSTRACT FROM AUTHOR]

With the advantages of fast response and bidirectional charge/discharge, an energy storage system (ESS) plays a promising role in wind power ramp control. In this study, an optimisation model based on refined ramp event characterisation is proposed to achieve continuous wind power ramp control using ESS. Firstly, four kinds of ramp scenarios are characterised considering both the wind power ramp event prediction and the charge/discharge state of ESS. State of charge of ESS is managed within its limits during ramp control, based on the classified ramp scenarios. Secondly, for the classified ramp scenarios, an active adjustment strategy is proposed to decide the expected charging/discharging energy of ESS according to the conditions of wind power and ESS. Thus, an appropriate energy storage reserve can be determined for anticipated ramp events. Refined ramp event characterisation is able to achieve better control performance with higher satisfaction of ramp requirement, less wind energy curtailment as well as promising adaptability to different ramp event predictions, wind conditions and changes of ESS parameters. The effectiveness of the proposed method is verified through case studies with real‐world data from a 100 MW wind farm in China. [ABSTRACT FROM AUTHOR]

In recent two decades, the power systems have confronted with considerable changes such as the power system restructuring, growth of distributed energy sources and renewable energy sources (RESs), and emergence of smart grid concept. One of the common challenges caused by these changes is flexibility necessity of energy resources. One of the best solutions to mitigate this challenge is energy storage systems (ESSs) utilisation. The main question is how to determine size, site, and type of ESSs to maximise their benefits. This study reviews the answers to this question according to the research studies. This study first classifies the studies related to ESS expansion planning into two main categories from the viewpoint of the power system operators and the investors. Next, the first main category is divided into three subcategories: ESS expansion planning in microgrids, distribution networks, and transmission networks. The second main category is classified into two subcategories: ESS expansion planning aim to smooth RESs output power and to maximise profit. In each subcategory the modelling approaches, solving methods, and the results are evaluated. Finally, based on the existing challenges, the future research directions of ESS expansion planning are outlined. [ABSTRACT FROM AUTHOR]

The fast‐growing awareness of depleting fossil fuel and the adverse impact of conventional energy generation methods on the environment has brought passionate attention to renewable energy sources (RE source). Owing to stochastic nature of energy production from renewable energy system (RES), two or more sources are combined to form hybrid RE system (HRES). Optimisation of size, cost and reliability of power production of HRES are important factors in the planning of HRES. This study presents a review of optimisation tools and constraints on which HRES system is optimised. The types of storage/backup system available for HRES are also presented in this study. [ABSTRACT FROM AUTHOR]

In off-grid wind power plants, the uncertainty of net load becomes the main factor that controls the operation and planning of these plants. The term net load refers to system demand minus the generation from variable renewable resources. Energy storage system is a key solution for system operators to provide the required flexibility needed to balance the net load uncertainty. This study proposes a probabilistic approach for sizing a battery storage system (BSS) with the aim of mitigating the net load uncertainty associated with the off-grid wind power plant. A novel battery-sizing index that takes into account the probabilistic nature of the wind resources and the electric load is developed. The proposed sizing approach aims to quantify the required BSS capacity for operating the wind plant without incurring excessive battery installation cost as well as for reducing the mismatch between the wind generation and the electric load. An 8.5 MW utility-scale wind farm is used as a test system to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The optimal control of state‐of‐charge (SOC) for superconducting magnetic energy storage (SMES), which is used to smooth power fluctuations from wind turbine, is essential to improve its technical and economical performance. Without an efficient control strategy, the SMES may go to the state of over‐charge or deep‐discharge, which will pose a significant effect on its service life and its technical performance. In this study, combined with wind forecasting technology and real‐time monitoring of SOC for the SMES, a double fuzzy logic control strategy is proposed that is applied to regulate SOC of SMES with the purpose of not only effectively smoothing the power fluctuations of wind turbine, but also preventing the SMES from occurring of the state of over‐charge/deep‐discharge and adjusting it to the appropriate SOC. The effectiveness of the proposed control strategy is verified by the simulation results. [ABSTRACT FROM AUTHOR]