Hybrid energy storage system (HESS) based on Li-ion and supercapacitor (SC) can play a potential role to stabilize the grid by providing the fast frequency ancillary services. The SC helps to reduce ...the battery charge/discharge stress and, hence, assists to extend the battery lifespan. The power sharing method (PSM) is the heart in control part to improve the HESS performance and reduce the battery stress. This paper proposes a hybrid PSM and investigates its impact on battery life extension along with its relation to the system design and regulation signal. The performance of hybrid PSM is compared with three other PSMs (low-pass filter, first and second rule based) in a 10 MW/10 MWh full-active parallel HESS for frequency regulation service in two networks: U.K. (national grid) and USA (PJM). Considering maximum possible battery lifetime upto 25 years, result shows that the hybrid PSM approach allows a degree of the better performance for both grid while the sharing of SC is kept maximum 2.0% and 2.5% (for U.S. and U.K. grid, respectively) of the HESS capacity. This study also analyses the impact of PSM on shared capacity and design of HESS for different grid regulation signals.
This paper presents a bottom-up approach for techno-economic analysis of a Li-ion battery based Energy Storage System (BESS) to provide grid ancillary services under the “Delivering a Secure, ...Sustainable Electricity System” (DS3) programme in the Irish market. There are two types of service procurement mechanisms that exist in the DS3 programme: volume capped and volume uncapped. A design methodology of the storage system is investigated to optimise the installed capacity and minimize the initial cost for volume capped DS3 services. Based on the real-life project assessment, three different cost models are considered to evaluate different investment indices. The goal is to assess the economic performance of BESS for different contracted capacity systems under the different operating and financial conditions. Extensive simulation and sensitivity analysis based on the Monte Carlo method have been carried out to compare the cost model outputs. The findings are expected to give a clear idea to the investors and decision-makers about the Irish DS3 ancillary service market and clarify specific concerns on the economic feasibility of BESS for DS3 services. Moreover, it discusses the risks and opportunities related to the high volatility of the system component costs.
•A bottom-up approach for Techno-economic analysis of ESS to provide DS3 grid services.•A simplified optimal sizing method for a Volume Capped ESS-based DS3 providing unit.•Clarify specific concerns on the economic feasibility of ESS for DS3 Services.•Analyse the solution economic sensitivity towards equipment cost variations.•Provide a comprehensive perception to stakeholders into the Irish DS3 service market.
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.
The concept of a community grid is presented here. It involves the distribution grid and an increased use of renewable energy coming from distributed resources along with consumer/prosumer engagement ...in the energy trading mechanism. The possible operation and management with energy trading flexibility are briefly outlined. Under such scenario, the classical operation of the distribution grid is challenged by the issues brought about by the large penetration level of the new energy resources. This paper presents a status review of the technical issues that may appear under the community grid scenario. Building up on these surveyed issues, this paper also reviews and discusses approaches to solutions, which are required in order to make the community grid highly renewable and sustainable.
In recent years, power systems have undergone changes in technology and definition of the associated stakeholders. With the increase in distributed renewable generation and small- to medium-sized ...consumers starting to actively participate on the supply side, a suitable incorporation of decentralized agents into the power system is required. A promising scheme to support this shift is given by local electricity markets. These provide an opportunity to extend the liberal wholesale markets for electrical power found in Europe and the United States to the communal level. Compared to these more established markets, local electricity markets, however, neither have few practical implementations nor standardized frameworks. In order to fill this research gap and classify the types of local electricity markets, the presented paper therefore starts with the challenges that these markets attempt to solve. This is then extended to an analysis of the theoretical and practical background with a focus on these derived challenges. The theoretical background is provided in the form of an introduction to state-of-the-art models and the associated literature, whereas the practical background is provided in form of a summary of ongoing and recent projects on local electricity markets. As a result, this paper presents a foundation for future research and projects attempting to approach the here presented challenges in distribution of generation, integration of demand response, decentralization of markets and legal and social issues via local electricity markets.
In this paper, an alternative control method is proposed to improve the harmonic suppression efficiency of the active power filter in a distorted and an unbalanced power system to compensate for the ...perturbations caused by the unbalanced non-linear loads. The proposed method uses a self-tuning filter (STF) to process the grid voltage in order to provide a uniform reference voltage to obtain the correct angular position of the phase locked loop. Moreover, the required compensation currents are obtained by implementing another STF in the transformed set of currents in order to separate the fundamental and the harmonic currents. This allows the calculation of a precise reference current for the unbalanced, the non-linear and the variable load conditions. The proposed control method gives an adequate compensating current reference even for a non-ideal voltage and unbalanced current conditions. The real-time control of the filter under the distorted and the unbalanced power system is developed in an RT-LAB real-time platform. The results obtained in the software-in-the-loop configuration are presented to verify the effectiveness of the proposed control technique.
A new proposal for the placement, integration, and control of unified power quality conditioner (UPQC) in distributed generation (DG)-based grid connected/autonomous microgrid/microgeneration (μG) ...system has been presented here. The DG converters (with storage) and the shunt part of the UPQC Active Power Filter (APF sh ) is placed at the Point of Common Coupling (PCC). The series part of the UPQC (APF se ) is connected before the PCC and in series with the grid. The dc link can also be integrated with the storage system. An intelligent islanding detection and reconnection technique (IR) are introduced in the UPQC as a secondary control. Hence, it is termed as UPQC μG-IR . The advantages of the proposed UPQC μG-IR over the normal UPQC are to compensate voltage interruption in addition to voltage sag/swell, harmonic, and reactive power compensation in the interconnected mode. During the interconnected and islanded mode, DG converter with storage will supply the active power only and the shunt part of the UPQC will compensate the reactive and harmonic power of the load. It also offers the DG converter to remain connected during the voltage disturbance including phase jump.
In this study, a control method is proposed to improve the harmonic suppression efficiency of the single-phase active power filter in a distorted power system to suppress current harmonics and ...reactive power. The proposed method uses the self-tuning filter (STF) algorithm to process single-phase grid voltage in order to provide a uniform reference grid current, which increases the efficiency of the system. The results of the simulation study are presented to verify the effectiveness of the proposed control technique in this study.
The dynamic voltage restorer (DVR) is mainly used in a utility grid to protect sensitive loads from power quality problems, such as voltage sags and swells. However, the effectiveness of the DVR can ...wane under unbalanced grid voltage conditions. Recently, DVR control algorithms have been developed that enable the elimination of voltage harmonics in weak and distorted utility networks. This paper presents a modified control method for the DVR, which can (1) compensate the voltage swell and (2) eliminate the voltage harmonics in a combined utility condition consisting of voltage unbalance and harmonic distortion. A self-tuning filter (STF) is used along with the pq control method to increase the control performance of the DVR. One of the advantages of STF is that it eliminates the need to have multiple filters as part of the control method, and thus reduces the controller complexity. Analysis of the fault ride-through capability of the new DVR revealed an improvement in the voltage stability offered to distributed generation-integrated weak utility networks. The proposed DVR control method is modeled in MATLAB/Simulink and tested in both off-line and real-time environments using the OPAL RT real-time platform. Results are then presented as a verification of the proposed system.
This study proposes a statistical analytic method for collocating a PV power plant and utility-scale energy storage system (UESS) to minimise clipping losses. The novelty of this approach is to ...assist the PVPP operator in estimating the clipped energy in case of scaling up/down the PVPP generation and/or inverter conversion capacity. Moreover, a detailed economic model is presented to analyse the viability of the UESS and identify the most appropriate technology, storage capacity, and power budgets among the available ones in the market. As a real-life example, the 5-MW Kelmoney PVPP in Ireland has been considered for this analysis. Different case studies have been presented considering different inverter loading ratio (ILR) indices and design scenarios. Results show that the financial viability of UESS deployment for PV clipping losses minimisation as a unique service is a conservative option. The increase in the ILR value of the installation and the development of energy storage technologies greatly impact the UESS sizing and will play a potential role in improving the economic sustainability for clipping losses minimisation application for UESS. Meanwhile, it is suggested combining this service within a multi-service provision framework to achieve a profitable operation.
•A statistical PVPP modelling method with an estimating capability of the clipped energy.•An analytical ESS sizing method for PVPP clipping losses minimisation.•Investigate the sustainability of the UESS in clipping losses minimisation application.•Propose a detailed analysis for various ESS technologies for clipping losses minimisation.•Assist the investor for defining future investment conditions.
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