Controller to enable the enhanced frequency response services from a multi-electrical energy storage system
01 Jan 2019-Iet Generation Transmission & Distribution (The Institution of Engineering and Technology)-Vol. 13, Iss: 2, pp 258-265
TL;DR: Simulation results highlight the benefits of managing the SOC of the energy storage assets with the proposed controller, which include a reduced rate of change of frequency and frequency nadir following a loss of generation as well as an increase in the service performance measure which renders into increased economic benefits for the service provider.
Abstract: The increased adoption of renewable energy generation is reducing the inertial response of the Great Britain (GB) power system, which translates into larger frequency variations in both transient and pseudo-steady-state operation. To help mitigate this, National Grid, the transmission system operator in GB, has designed a control scheme called enhanced frequency response (EFR) specifically aimed at energy storage systems (ESSs). This study proposes a control system that enables the provision of EFR services from a multi-electrical ESS and at the same time allows the management of the state of charge (SOC) of each ESS. The proposed control system uses a Fuzzy Logic Controller to maintain the SOC as near as possible to the desired SOC of each ESS while providing EFR. The performance of the proposed controller is validated in transient and steady-state domains. Simulation results highlight the benefits of managing the SOC of the energy storage assets with the proposed controller. These benefits include a reduced rate of change of frequency and frequency nadir following a loss of generation as well as an increase in the service performance measure which renders into increased economic benefits for the service provider.
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TL;DR: This paper makes a review on the above mentioned aspects, including the emerging frequency regulation services, updated grid codes and grid-scale ESS projects, and some key technical issues are discussed and prospects are outlined.
Abstract: Electric power systems foresee challenges in stability due to the high penetration of power electronics interfaced renewable energy sources. The value of energy storage systems (ESS) to provide fast frequency response has been more and more recognized. Although the development of energy storage technologies has made ESSs technically feasible to be integrated in larger scale with required performance, the policies, grid codes and economic issues are still presenting barriers for wider application and investment. Recent years, a few regions and countries have designed new services to meet the upcoming grid challenges. A number of grid-scale ESS projects are also implemented aiming to trial performance, demonstrate values, and gain experience. This paper makes a review on the above mentioned aspects, including the emerging frequency regulation services, updated grid codes and grid-scale ESS projects. Some key technical issues are also discussed and prospects are outlined.
134 citations
Cites background from "Controller to enable the enhanced f..."
...Recent research also throw emphasis on the design and control issues of ESS with multi-sources [32], [48], [66],...
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TL;DR: A deep reinforcement learning (DRL) based controller to manage the state of charge (SOC) of a Multi-EESS, providing frequency response services to the power grid, is proposed and results show the effectiveness of the proposed approach.
Abstract: The ongoing reduction of the total rotational inertia in modern power systems brings about faster frequency dynamics that must be limited to maintain a secure and economical operation. Electrical energy storage systems (EESSs) have become increasingly attractive to provide fast frequency response services due to their response times. However, proper management of their finite energy reserves is required to ensure timely and secure operation. This paper proposes a deep reinforcement learning (DRL) based controller to manage the state of charge (SOC) of a Multi-EESS (M-EESS), providing frequency response services to the power grid. The proposed DRL agent is trained using an actor-critic method called Deep Deterministic Policy Gradients (DDPG) that allows for continuous action and smoother SOC control of the M-EESS. Deep neural networks (DNNs) are used to represent the actor and critic policies. The proposed strategy comprises granting the agent a constant reward for each time step that the SOC is within a specific band of its target value combined with a substantial penalty if the SOC reaches its minimum or maximum allowable values. The proposed controller is compared to benchmark DRL methods and other control techniques, i.e., Fuzzy Logic and a traditional PID control. Simulation results show the effectiveness of the proposed approach.
48 citations
Cites background or methods from "Controller to enable the enhanced f..."
...For further details on the dynamic models used for each EESS in this paper, the reader is referred to [8]....
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...The FLC is based on the proposed by [8]....
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...trol (MPC) [7] and fuzzy logic (FL) [8]....
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TL;DR: In this paper, the authors proposed a method to calculate and apply a frequency droop, which is basically required according to the power system condition based on swing equation and effective inertia assessment.
Abstract: As the penetration rate of renewable enery resources (RES) in the power system increases, uncertainty and variability in system operation increase. The application of energy storage systems (ESS) in the power system has been increased to compensate for the characteristics of renewable energy resources. Since ESS is a controllable and highly responsive power resource, primary frequency response and inertia response are possible in case of system contingency, so it can be utilized for frequency regulation (FR) purposes. In frequency regulation, reduction of the Rate of Change of Frequency (RoCoF) and increase the frequency nadir by improving the response characteristics are important factors to secure frequency stability. Therefore, it is important to control ESS with proper parameters according to changing system situation. In this paper, we propose a method to calculate and apply a frequency droop, which is basically required according to the power system condition based on swing equation and effective inertia assessment. In addition, a method to estimate RoCoF droop according to the correlation with frequency by estimating the systematic inertia in the current situation is proposed. The case study for verification of the proposed method was performed through dynamic simulation using actual Korean power system data. The results show that the proposed method is more effective than the governor-free of the conventional thermal generator and conventional droop control-based FR-ESS.
22 citations
14 Oct 2020
TL;DR: In this paper, a decomposable time series model is used to forecast the total kinetic energy (KE) of a power system for short-term forecast of the total rotating inertia.
Abstract: Modern power systems are experiencing a gradual substitution of the classical synchronous generators by power electronic-based technologies; as a consequence, there is an increased interested in estimating the total rotating inertia. This paper proposes the use of the decomposable time series model to short term forecast of the total kinetic energy (KE) of a power system. The structure of the forecasting model includes three main components: trend, a seasonal and an irregular component. As the Nordic Power System (NPS) is expected a reduction of the total kinetic energy, this paper uses a time series of KE to test the proposed approach. A cross-validation process is used in this paper, numerical results of the mean absolute percentage error indicate forecast the error in the forecasting is below 5% for predictions one hour into the future.
16 citations
Cites background from "Controller to enable the enhanced f..."
...One key aspect that is negatively affected by the integration of power electronic-based technologies is the reduction of physical inertia [9]....
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...Transmission system operators (TSO) has been interested in knowing the total system rotational inertia in order to take action regarding the system stability [9], [19]....
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TL;DR: In this paper, the effects of high penetration level of wind turbine-generators (WTG) on the power system operational planning from the frequency point of view are investigated to compute the maximum acceptable generation outage as a function of penetration level.
Abstract: With the proliferation of intermittent renewable energy sources, power systems need to withstand an increasing number of disturbances that may affect system frequency. In this paper, we focus on the effects of high penetration level of wind turbine-generators (WTG) on the power system operational planning from the frequency point of view. Specifically, an exact formulation for the minimum frequency calculation is presented to increase accuracy and speed of analyses. Then, the effect of WTG's frequency response on the power system frequency stability is investigated to compute the maximum acceptable generation outage as a function of penetration level. Finally, as an application to power system operational planning, the obtained frequency dynamics of the power system and the wind turbine frequency response are integrated into the unit commitment problem. Simulations are performed on the IEEE 39-bus test system to study the effects of the WTGs on the frequency stability of the system. Results illustrate a more secure and reliable operation of the power system when the wind turbines participate in the frequency regulation task. Moreover, including the frequency response of the wind turbines in the unit commitment problem can reduce the ancillary cost, meanwhile increase the frequency stability of the system.
15 citations
References
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TL;DR: A comprehensive and clear picture of the state-of-the-art technologies available, and where they would be suited for integration into a power generation and distribution system is provided in this article.
2,790 citations
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03 Mar 2009
TL;DR: In this article, the authors provide a comprehensive coverage of robust power system frequency control understanding, simulation and design, and develop an appropriate intuition relative to the robust load frequency regulation problem in real-world power systems, rather than to describe sophisticated mathematical analytical methods.
Abstract: Frequency control as a major function of automatic generation control is one of the important control problems in electric power system design and operation, and is becoming more significant today due to the increasing size, changing structure, emerging new uncertainties, environmental constraints, and the complexity of power systems. Robust Power System Frequency Control uses the recent development of linear robust control theory to provide practical, systematic, fast, and flexible algorithms for the tuning of power system load-frequency controllers. The physical constraints and important challenges related to the frequency regulation issue in a deregulated environment are emphasized, and most results are supplemented by real-time simulations. The developed control strategies attempt to bridge the existing gap between the advantages of robust/optimal control and traditional power system frequency control design. The material summarizes the long term research outcomes and contributions of the author’s experience with power system frequency regulation. It provides a thorough understanding of the basic principles of power system frequency behavior over a wide range of operating conditions. It uses simple frequency response models, control structures and mathematical algorithms to adapt modern robust control theorems with frequency control issues as well as conceptual explanations. The engineering aspects of frequency regulation have been considered, and practical methods for computer analysis and design are also discussed. Robust Power System Frequency Control provides a comprehensive coverage of frequency control understanding, simulation and design. The material develops an appropriate intuition relative to the robust load frequency regulation problem in real-world power systems, rather than to describe sophisticated mathematical analytical methods.
1,018 citations
TL;DR: In this paper, Kornyshev et al. applied the principles that Gouy, Chapman and Stern adopted in their classic treatments of the double layer at a (metal)/(electrolyte solution) interface.
486 citations
TL;DR: In this article, a comparative analysis of these high-power storage technologies in terms of power, energy, cost, life, and performance is carried out and the applications, advantages, and limitations of these technologies in a power grid and transportation system as well as critical and pulse loads are presented.
Abstract: Energy storage systems provide viable solutions for improving efficiency and power quality as well as reliability issues in dc/ac power systems including power grid with considerable penetrations of renewable energy. The storage systems are also essential for aircraft powertrains, shipboard power systems, electric vehicles, and hybrid electric vehicles to meet the peak load economically and improve the system’s reliability and efficiency. Significant development and research efforts have recently been made in high-power storage technologies such as supercapacitors, superconducting magnetic energy storage (SMES), and flywheels. These devices have a very high-power density and fast response time and are suitable for applications with rapid charge and discharge requirements. In this paper, the latest technological developments of these devices as well as advancements in the lithium-ion battery, the most power dense commercially available battery, are presented. Also, a comparative analysis of these high-power storage technologies in terms of power, energy, cost, life, and performance is carried out. This paper also presents the applications, advantages, and limitations of these technologies in a power grid and transportation system as well as critical and pulse loads.
278 citations
TL;DR: In this paper, an energy storage system (ESS) might be a viable solution for providing inertial response and primary frequency regulation in the power system with a high penetration of wind power.
Abstract: Large-scale integration of renewable energy sources in power system leads to the replacement of conventional power plants (CPPs) and consequently challenges in power system reliability and security are introduced. This study is focused on improving the grid frequency response after a contingency event in the power system with a high penetration of wind power. An energy storage system (ESS) might be a viable solution for providing inertial response and primary frequency regulation. A methodology has been presented here for the sizing of the ESS in terms of required power and energy. It describes the contribution of the ESS to the grid, in terms of inertial constant and droop. The methodology is applied to a 12-bus grid model with high wind power penetration. The estimated ESS size for inertial response and primary frequency regulation services are validated through real-time simulations. Moreover, it is demonstrated that the ESS can provide the response similar to that provided by the CPPs.
271 citations