Penetration Of Distributed Energy Resources Research Articles

Distributed optimal storage strategy in the ADMM-based peer-to-peer energy trading considering degradation cost

The increasing installed capacity of distributed energy resources (DERs) allows prosumers to have a more flexible and proactive role in power system operation. At the same time, it may affect the stability of the power grid. To reduce the DERs penetration in the main grid and maximize the profit of the end-users, a new energy trading paradigm called peer-to-peer (P2P) energy trading emerges in the area of the local community microgrid. However, few of the previous works combine types of energy generation and storage equipment to the microgrid framework and propose a throughout distributed optimization solution to this scalable framework considering the impact of battery degradation cost. In this paper, a novel parallel market clearing mechanism is proposed for P2P energy trading with end-users in a highly scalable residential community microgrid. The proposed mechanism takes into account a variety of realistic factors such as household privacy, user preferences, peak shaving services, community power grid-related usage fees, point-to-point bilateral transaction weights, and battery degradation costs. To make the microgrid more scalable, each household in the community is designed with different household energy generation and storage appliances including photovoltaic panels, wind turbines, plug-in electrical vehicles, and various household batteries with different capacities. A distributed approach based on the alternating direction method of multiplier (ADMM) algorithm is presented to solve the energy pricing problem while guaranteeing the privacy of all participants. The designed comparative case studies take into consideration the types of users, grid transaction methods, the influence of peak shaving fee, the impact of energy storage equipment, and the effect of battery degradation costs. The results show a significant reduction of both the cost of each user and the total cost in the P2P energy market while considering the degradation cost of home energy management systems and plug-in electric vehicles. The case studies also present that prosumers have greater advantages than consumers in P2P energy transactions. Peak shaving service and home energy storage devices can distribute and utilize energy more efficiently.

Influence of Distributed Energy Resources on the performance of phase topology identification in distribution networks

The increase of Distributed Energy Resources (DERs) in low-voltage distribution networks (LVDN) requires accurate phase topology information of single-phase users. However, this information is not always available or, when it is, is often unreliable. Although there are methods in the literature for the automatic phase topology identification in LVDN, the influence of DERs on their performance has not been widely studied. In this paper, an evaluation of the influence of DERs in phase topology identification is presented. Five DER penetration scenarios (0%, 5%, 10%, 20% and 40%) over a LVDN with 459 users were used. A total of three state-of-the-art methods from the literature were tested. All of them showed an accuracy decrease when DER penetration increases. However, the one proposed by the authors showed the smallest decrease (from 100% without DER to 95.87% with 40% DER penetration) compared to the others, which showed a greater influence (from 99.76% to 89.81% and from 97.77% to 52.67% respectively).

Challenges and Limitations of Artificial Intelligence Implementation in Modern Power Grid

Ongoing global decarbonization and energy transition have led to significant changes in the traditional power grid, resulting in new challenges for grid operators. These challenges, which are exacerbated by the increased penetration of distributed energy resources (DER), include power system stability, protection and control system malfunction, and supply and demand balance. To better understand the implications of high DER penetration, we proposed a classification of modern grids based on the DER integration level and identified the specific challenges faced by each category. We defined eight key challenges posed by DER on the grid and examined recent academic research on the application of AI techniques to modern power systems. Despite the potential benefits of AI in terms of power system stability and protection, there are currently no commercial applications of this research. Our study analyzed the limitations and barriers to practical AI implementation in power system protection and stability, including the use of synthetic data, insufficient real measurement data, protection selectivity, and the black-box nature of the models. We emphasize the importance of further research and development in the fields of Explainability AI and physics-informed ML to overcome these challenges and enable the successful implementation of AI in modern power grid stability and protection.

Analysis of voltage control using V2G technology to support low voltage distribution networks

AbstractThe decarbonization of the power generation and transport sector encourage the analysis of connection of distributed energy resources (DER), such as electric vehicles (EVs), to the electrical system, as well as the evaluation of their impact on smart cities. A better understanding of the negative impacts on the power systems will lead to propose mitigation measures and eventually revolutionize the way distributed generation works. This paper aims at modelling and evaluating the impact of EVs on a real distribution network. The energy system chosen operates at 60 Hz, 34.5 kV (medium voltage) and 0.208 kV (low voltage) and it is simulated using PSCAD/EMTDC. To reproduce realistic user consumption profiles, dynamic load profiles based on EV owners behaviour have been simulated. The vehicle‐to‐grid (V2G) technology is modelled to mitigate the impacts of high penetration of EVs by supporting the network from undervoltage. The results show the importance of active management in modern power systems, especially considering the increase in DER penetration expected for the coming years. This work shows the benefits of implementing V2G technology while highlighting the challenges involved in a real case.

Are Australian regulatory and policy frameworks ready for a distributed‐energy‐resources‐led energy transition?

AbstractElectricity markets are facing innovation disruptions at levels never seen before. One of the major drivers is the introduction of distributed energy resources (DERs) technologies, especially those that apply to rooftop solar power. This has called into question established regulatory practices and brought new challenges to system operations. In this context, this article seeks to provide a comprehensive investigation of potential policy options for Australia's energy markets from two perspectives. We first examine recent and proposed reforms in this area, and then proceed to review the challenges for Australian regulators that will have major implications for the future, affecting policymaking, regulation, and market design.Points for practitioners The Australian energy framework is complicated, reflecting its regulatory history, geographical complexity, and federal governance structure. As a force for creative distraction, the penetration of DERs has created challenges for the electricity system and requires careful regulatory treatment. Topical themes in the regulation of DERs include, amongst others, technical standards, metering access, reserve capacity, new business models, network stability, the role of regulated utilities, and support for low‐income households. The necessary regulatory transition is accepted as being evolutionary rather than revolutionary in nature so as to enable the existing major stakeholders to adapt to the new environment.

Study on Malfunction of OCR Due to Penetration of DER into Power Distribution System with SFCL

Due to the demand for eco-friendly energy, distributed energy resources (DERs) using renewable energy have increased. The increase in DER has caused the power system to become more complex and caused problems in the protection system. Typical problems include an increase in fault current and a problem that causes malfunction of the overcurrent relay (OCR). If the fault current increases and exceeds the capacity of the existing protection devices, it may lead to a large blackout. The most effective way to limit the fault current is to install a superconducting current limiter (SFCL). The installation of SFCL and system penetration of DER both affect OCR operating characteristics. In this paper, a simulated power distribution system is constructed and OCR malfunctions caused by DER penetration and SFCL installation are analyzed.

Electrical substation grid testbed for DLT applications of electrical fault detection, power quality monitoring, DERs use cases and cyber-events

Electrical utilities continue to deploy more intelligent electronic devices (IEDs) inside and outside electrical substation, and are associated with customer-owned distributed energy resources (DERs). The integrity and confidentiality of data from these IEDs, like power meters and protective relays, is crucial. Blockchain technology could improve the resilience of microgrids by improving the security of data sharing. The penetration of customer-owned DERs (renewable energy sources) and the increasing deployment of IEDs can lead to integrate power system applications with Distributed Ledger Technology (DLT). In this study, we implemented the electrical faulted phase detection and power quality monitoring algorithms with a Cyber Grid Guard (CGG) system using DLT. In addition, the DERs (wind turbine farms) use case and protective relay cyber-event tests were assessed, by using the CGG system with DLT. In the experimental model, the testbed was created by using a real-time simulator and CGG system with power meters/ protective relays in-the-loop. The data collected from the CGG system and IEDs were compared with the same time stamp source. These results had shown the successful assessment of protection, control and monitoring applications using a CGG system with DLT. In the future, the ESGT with DERs and the CGG system will be used in other power system applications, based on implementing smart contracts between electrical utilities with customer-owned DERs.

Stability analysis framework for isolated microgrids with energy resources integrated using voltage source converters

Integrating distributed energy resources (DERs) enables the development of microgrids, which opens up a broad field of study. However, the dynamic behaviour of these energy resources presents challenges in these new electric systems. The stability of systems with high penetration of DERs is a developing research topic, where enhancement strategies are typically focused on specific issues, while general approaches often present several challenges without testing scenarios. In this document, an analysis of several stability issues is presented and tested in an islanded system based on the CIGRE low voltage benchmark. The conclusions obtained are noteworthy and propose further discussion and research, to enhance the understanding and future study of islanded microgrid stability with only converter-integrated energy resources.

P2P flexibility markets models to support the coordination between the transmission system operators and distribution system operators

The increasing integration of Distributed Energy Resources (DER) in the distribution network has brought more importance to Peer-to-Peer (P2P) markets. However, energy traded in P2P markets can lead to voltage and congestion constraints in distribution networks operated by Distribution System Operators (DSOs). At the same time, Transmission System Operators (TSOs) may need to solve system problems, requesting the participation of DERs in frequency regulation services. To ensure competitive participation in P2P markets, as well as to ensure a correct operation of distribution networks and to contribute to mitigate problems at the system level, coordination mechanisms between the P2P market and the System Operators (SOs) are required. This paper introduces a set of mathematical models considering P2P flexibility trading at the distribution system, while assisting the DSO and TSO in solving the congestion, voltage and frequency problems, respectively. The models are assessed on an IEEE 37-bus distribution network with high DER penetration. The first and second models are based on product differentiation to avoid violating the lines’ thermal limits and the nodes’ voltage limits, respectively. The second model also considers reactive power control in order to impact voltage constraints. The third model uses a virtual load, connected to the TSO network (before the power transformer), to model frequency regulation services. The last model proposes the integration of all methods. Results showed that each model was effective in solving its constraint. However, they do not dismiss the use of the peers’ flexibility assets to assure an overall feasible techno-economic solution. The use of the methodology proposed in the present paper can significantly facilitate the adoption of full P2P markets as well as the confidence of the system operators in the integration of these markets.

Local integrated energy system operational optimization considering multi‐type uncertainties: A reinforcement learning approach based on improved TD3 algorithm

AbstractLocal integrated energy system (IES), usually a multi‐building heating and cooling system incorporating cogeneration systems and distributed energy resources (DERs), is becoming an efficient energy infrastructure for energy system decarbonization. However, for small and medium‐scale local IESs, the fluctuation of user loads seriously influences energy system operation, and the increasing DER penetration also enlarges the influence. Given the necessity of exploring an efficient way to handle the uncertainties in local IES, this paper proposes a reinforcement learning (RL) approach based on the improved TD3 algorithm. The mathematical model of local IES is first established considering supply‐ and load‐side flexible resources. The local IES dispatch problem is formulated as a Markov decision process (MDP), in which multi‐type uncertainties of renewable generation, electric load and heat load are considered. For solving the MDP, an improved twin delayed deep deterministic policy gradient (TD3) algorithm is proposed with a dynamic balance mechanism of exploration noise. Based on a local IES testbed in the Nantong Central Innovation District, China, a comparison analysis is conducted to verify the promoting effect of flexible resources on the operation economy and renewable energy consumption. The system operating cost reduces by 18.46%, and surplus renewable energy can all be accommodated considering flexible resources. The dispatch policies obtained by the deep deterministic policy gradient (DDPG), the improved TD3, the original TD3 and traditional optimization algorithms are also compared. The results reveal that the convergence stability and solving accuracy of the improved TD3 outperform the other two RL algorithms. Specifically, the system operating cost of the improved TD3 reduces by 2.76% compared with the DDPG, and the energy supply imbalance decreases by around 88%. Meanwhile, the improved TD3 exhibits better operation economy and adaptability to the uncertain environment than the deterministic optimization and intraday rolling algorithms.

Using energy storage systems to extend the life of hydropower plants

Despite their advantages, distributed energy resources (DERs) bring inherent uncertainty and variability into the landscape of modern power systems. As DER penetration grows, conventional generators like hydropower plants have to respond more often to arrest the imbalance in the net load. Hydropower turbines provide their best operational performance with minimal wear and tear when operating at regions of maximum efficiency. However, the current needs for hydropower plants require them to operate under varying load conditions and thus sub-optimal operating points leading to additional stress. To relieve the hydropower plants, this paper proposes a hybridization strategy where a hydropower unit is paired with an energy storage system (ESS) to increase operational flexibility and mitigate damage to the hydro plant. Models are developed to represent the operation of the hybrid system, quantify degradation, and assess economic benefits. Moreover, an innovative controller disaggregates the market dispatch signal into separate control setpoints for the ESS and hydropower unit. In case studies performed on a real-world hydropower facility, it was found that the ESS-based hybridization can extend the life of the hydropower plant by 5% on average. The economic benefits from reduced maintenance and deferred investment are estimated to be around $3.6 million.

Adoption of Local Peer-to-Peer Energy Markets: Technical and Economical Perspectives for Utilities

Peer-to-peer (P2P) energy markets constitute a promising approach for locally coordinating the increasing amount of distributed energy resources (DERs) in the distribution system. Although the benefits of P2P markets for the prosumers are already well understood, their impact on utilities is not well discussed nor well understood. This hinders the development of regulatory frameworks, which are still needed to allow for the widespread adoption of decentralized energy markets in any interested country. So far, research has been conducted in specific isolated aspects, making it difficult to understand the overall implications for utilities. The present study aims to tackle this research gap by comprehensively evaluating P2P markets’ effects, considering utilities as primary stakeholders. A qualitative roadmap with the overall benefits and challenges of adopting P2P by utilities is outlined to reach this purpose. Technical and economic criteria are assigned for comparing a P2P market to the current regulatory framework. Each criterion is evaluated in a co-simulation platform connecting a market model to a power flow model. Market performance is assessed by revenue analysis, and grid operation indicators evaluate grid performance. Furthermore, network fees are introduced as compensation mechanisms for the net revenue loss. Comparison scenarios encompass network fees and the number of agents, PV, and storage penetration. Results demonstrate that there is no possible benefit for both utilities and prosumers simultaneously if looking exclusively at the financial balance of the market. An equilibrium in benefits for all stakeholders is achievable if non-financial metrics are considered in an integrated market and fee structure analysis. Moreover, results demonstrate that the design of market structures must be sensitive to network configurations and DER penetration changes. This study contributes toward comprehending how the utilities could embrace P2P markets as a feasible solution for grid coordination challenges, opening a new set of questions for further research.

Effective Frequency Regulation via Electricity Rate: Comparison to Other Frequency Control Strategies

Considering the significant share of the residential and commercial buildings in the overall electricity consumption and the peak electricity demand, increasing penetration of distributed energy resources (DERs) in buildings and having innovative building energy management strategies can solve some of the utility problems as well as contribute to overall carbon-free energy goals. Electricity tariff is considered as a powerful tool to provide economic incentives for buildings to modify their load profile and enable grid flexibility to improve grid reliability. However, a sudden deviation of the load profile due to unstudied electricity tariffs in a power system with multiple DER-equipped buddings can cause high-frequency deviations. This article studies the effect of the increased DER penetration in buildings on the power system frequency under existing and proposed modified tariffs. The frequency deviation results under the proposed modified tariff are compared to the existing frequency control approaches and utility-size battery integration into the system. Results show that the tariff modification and its effective integration into energy management systems can be considered as a promising frequency control method.

A Hierarchical Local Electricity Market for a DER-Rich Grid Edge

With increasing penetration of distributed energy resources (DER) in the distribution system, it is critical to design market structures that enable smooth integration of DERs. A hierarchical local electricity market (LEM) structure is proposed in this paper with a secondary market (SM) at the lower level representing secondary feeders and a primary market (PM) at the upper level, representing primary feeders, in order to effectively use DERs to increase grid efficiency and resilience. The lower level SM enforces budget, power balance, and flexibility constraints and accounts for costs related to consumers, such as their disutility, flexibility limits, and commitment reliability, while the upper level PM enforces grid physics constraints such as power balance and capacity limits, and also minimizes line losses. The hierarchical LEM is extensively evaluated using a modified IEEE-123 bus with high DER penetration, with each primary feeder consisting of at least three secondary feeders. Data from a GridLAB-D model is used to emulate realistic power injections and load profiles over the course of 24 hours. The performance of the LEM is illustrated by delineating the family of power-injection profiles across the primary and secondary feeders as well as corresponding local electricity tariffs that vary across the distribution grid. Through numerical simulations, the hierarchical LEM is shown to improve the efficiency of the market in terms of lowering overall costs, including both the distribution-level locational marginal prices (d-LMP) as well as retail tariffs paid by customers. Together, it represents an overall framework for a Distribution System Operator (DSO) who can provide the oversight for the entire LEM.

Challenges in Smartizing Operational Management of Functionally-Smart Inverters for Distributed Energy Resources: A Review on Machine Learning Aspects

The widespread introduction of functionally-smart inverters will be an indispensable factor for the large-scale penetration of distributed energy resources (DERs) via the power system. On the other hand, further smartization based on the data-centric operation of smart inverters (S-INVs) is required to cost-effectively achieve the same level of power system operational performance as before under circumstances where the spatio-temporal behavior of power flow is becoming significantly complex due to the penetration of DERs. This review provides an overview of current ambitious efforts toward smartization of operational management of DER inverters, clarifies the expected contribution of machine learning technology to the smart operation of DER inverters, and attempts to identify the issues currently open and areas where research is expected to be promoted in the future.

Integrated T&D Voltage Stability Assessment Considering Impact of DERs and Distribution Network Topology

Electric distribution systems are going through a major upgrade with increasing penetration of distributed energy resources (DERs) and impacting transmission system operational analysis. Traditionally, the transmission system’s voltage stability margin is computed by performing a continuation power flow (CPF) analysis. In transmission-CPF, loads in distribution systems are aggregated at the transmission-distribution (T&D) interface buses, and the distribution system’s electrical characteristics, like feeder length, increasing penetration of DERs, and associated control, are not considered. The traditional CPF thus considers the distribution network as a purely passive network without active network management and distributed energy resources. In this paper, two integrated T&D CPF methods are implemented using a co-simulation framework that uses individual transmission and distribution solvers. The first method is iteratively-coupled T&D CPF (IC-TDCPF), where the iterative coupling concept forces convergence of boundary variables at T&D PCC (Point of common coupling) at every CPF step. The second method, Loosely Coupled T&D CPF (LC-TDCPF), relaxes the boundary convergence constraints at PCC to achieve faster calculation speed. Moreover, a reduced distribution network equivalent is also developed to enable faster computation of VSM by reducing the number of integrated T&D buses. The developed T&D CPF co-simulation framework uses an open-source platform <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MATPOWER</i> for solving transmission system and open-source software <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OPENDSS</i> for solving distribution system. Three large integrated T&D systems with 4196, 10587, and 12295 buses are developed to demonstrate the impact of DERs, voltage-dependent load models, and distribution network topology on integrated voltage stability margin using the proposed T&D CPF and co-simulation.

Decentralized Distributed Convex Optimal Power Flow Model for Power Distribution System Based on Alternating Direction Method of Multipliers

This paper proposes a fully decentralized distributed convex optimal power flow model for inverter-based distributed energy resources (DERs) integrated electric distribution networks based on Semi-Definite Programming (SDP) and alternating direction method of multipliers (ADMM) namely (SDP D-ADMM). The proposed approach is based on the SDP relaxed branch flow model of distribution networks within an auto-tuned accelerated decentralized ADMM architecture. The approach is based on dividing the power grid network into subproblems representing individual areas by interchanging minimum network information. In the proposed model the requirement of a central processor is also waived thus making the proposed approach more robust toward cyber-attacks. The effectiveness and scalability of the proposed method are validated by implementing modified IEEE 123 and IEEE 8500 bus systems with different levels of DER penetration. It has been observed that the proposed architecture outperforms other distributed optimization variants in terms of accuracy, global optimality, scalability, and computational time.

A Novel Proposed Algorithm to Enhance the Overcurrent Relays’ Performance in Active Distribution Networks

This research addresses two topics: the first is the optimal coordination of overcurrent relays (OCRs), which has recently become a major challenge to ensure reliability and speed of relays’ operation, and the second is a modified circuit added to the OCR to vanquish the barriers caused by the ever-increasing participation of distributed energy resources (DERs), at a lower cost. For robust and reliable OCRs coordination, various types of optimization techniques are frequently used to find optimal OCRs settings in distribution networks (DNs). In this study, the improved wild horse optimization (IWHO) algorithm is used as a novel metaheuristic method for solving optimization issues in coordination of OCRs in a distribution network, for the first time. This technique is used to determine the optimal time multiplier setting (TMS) and optimal pickup setting (PS) of OCRs in order to minimize the overall operating time. The results of the proposed algorithm are compared with those obtained from other recent metaheuristic techniques. The obtained TMS and PS settings of each relay show the effectiveness of the proposed IWHO technique in terms of accuracy and speed in a medium scale radial network configuration. To replace the costly mitigation methods employed in the DN comprising DER, a simple circuit was proposed to be added to the OCR. Using the angle’s sign of positive sequence current component (PSCC) of fault current solely, this proposed circuit can detect the fault direction and assist the OCR in making the correct decision in fault detection and clearing with high penetration of DERs. IEEE-33 bus electrical power system has been used to validate the newly proposed protective solutions.

Prospects and Challenges of Malaysia's Distributed Energy Resources in Business Models Towards Zero – Carbon Emission and Energy Security

For a decade, distributed energy resources in Malaysia have growth as one of the paths in battling with sustainable energy crisis and environmental pollution. Several intriguing initiatives and incentives have been established to encourage the use and sales-side of renewable energy at the distribution consumers. However, Malaysia's distributed energy resources penetration is still at its slow pace, with only 7.6% (excluding large hydropower) shared in energy mix generation. Therefore, innovation in power systems is required to drive the uptake of distributed energy resources. This paper reviews the business model innovation that allows distributed energy resources to participate in national grid services and the wholesale electricity market. Different technical and non-technical challenges with high shares of variable renewable energy in power systems are highlighted, and the current update on compensation scheme, Net-Energy-Metering 3.0 is also discussed. Along with these challenges, stance the prospect of adopting distributed energy resources innovation projects such as peer-to-peer energy trading and virtual power plant in the electricity market. It could further furnish the benefits to a better environmental and power system in terms of carbon dioxide avoidance, grid flexibility and increase revenue for distributed energy resources owners respectively. Through the review, it led to observation that policy and regulatory in Malaysia are the main factors in accelerating the distributed energy resources deployment. Therefore, the abilities and roles of Malaysia Energy Commission and Sustainable Energy Development Authority as a regulator and implementing agencies are crucial in determining the present and future distributed energy resources business model.

Improving the Power System Dynamic Response Through a Combined Voltage-Frequency Control of Distributed Energy Resources

The paper proposes a control scheme to improve the dynamic response of power systems through the automatic regulators of converter-based Distributed Energy Resources (DERs). In this scheme, both active and reactive power control of DERs are varied to regulate both frequency and voltage, as opposed to current practice where frequency and voltage controllers are decoupled. To assess the proposed control against the current state-of-art, the paper also defines a metric that captures the combined effect of frequency/voltage response at any given bus of the network. Results indicate that the proposed control strategy leads to a significant improvement in the stability and performance of the overall power system. These results are based on a comprehensive case study carried out by employing a modified version of the IEEE 39-bus benchmark system, where a portion of the synchronous machines is substituted by converter-interfaced DERs. The impact on the proposed control of load models, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$R/X$</tex-math></inline-formula> ratio of network lines, as well as the level of DER penetration to the grid, are properly evaluated and conclusions are duly drawn.