Integration Of Distributed Energy Resources Research Articles

Stochastic optimization and scenario generation for peak load shaving in Smart District microgrid: sizing and operation

Microgrids play an essential role in the integration of multiple distributed energy resources in buildings. They can meet critical loads in buildings while reducing peak loads and congestion and providing other types of ancillary services to the main electrical grid. Sizing the components of microgrids and scheduling their optimal operation while jointly integrating uncertain renewable energy generation and loads can significantly affect its ability to meet these objectives. In fact, microgrids face great challenges due to renewable energies and load uncertainties. In this paper, a two-stage stochastic programming model for optimal sizing and operation of various distributed energy resources for peak load shaving in district buildings is proposed. The first stage is related to the planning of photovoltaic panels and batteries, while the second stage aims to find the optimal operation of the system in grid-connected mode. The uncertainties are related to photovoltaic power generation and loads. The Generative Adversarial Network (GAN) is implemented to generate the scenarios of uncertain parameters, and the k-medoids classical method for scenario reduction is applied to decrease the number of scenarios. The proposed two-stage stochastic optimization is tested for a real case study of a university campus in Canada.

Hourly characterization of the integration of DER in a network from deterministic and probabilistic approaches using Co-simulation PowerFactory-Python

Distributed energy resources (DER) can have significant effects on distribution networks. Their growing integration makes it necessary to conduct characterisation studies on the effects of several operating scenarios. Such studies apply deterministic or probabilistic techniques to the modelling and simulation of networks and DER. Nevertheless, the lack of studies that integrate three DER within the same research to quantify the potential effects that each one singly and all jointly could have on the networks is perceptible. In addition, the analysis of the most significant number of parameters studied for correctly interpreting the results and using inferential statistics can be helpful. Moreover, we examined various modelling and simulation approaches to evaluate the differences and similarities among multiple scenarios. Accordingly, this paper presents and details deterministic and probabilistic analysis approaches to characterise the hourly impact of photovoltaic systems, storage units, and electric vehicle charging stations in a 13-node IEEE test feeder. This elucidates DER integration in networks and could guide future studies. Estimating the individual or collective effects of a DER consists of quantification and hourly comparison of RMS values of voltages and currents, voltage unbalance, chargeability of transformers, and power losses. We collected the data for analysis using a co-simulation PowerFactory-Python for eight operating scenarios. The hourly stochastic comparison between scenarios consisted of calculating the difference in sampling means and applying hypothesis testing of inferential statistics. This comparative analysis verifies that the applied approach (deterministic or probabilistic), specific hour of analysis and simultaneous number of DER in a simulated scenario influence the results.

Dynamic PQ Operating Envelopes for prosumers in distribution networks

The increasing integration of distributed energy resources (DERs) has provided the opportunity to deliver clean, and low-cost power for energy consumers. However, without appropriate coordination, injected power by DERs can violate the operational limits of the electricity distribution networks and cause issues such as over-voltage and lines congestion. Recently, the promising concept of Operating Envelopes (OEs) has been introduced to support the efficient integration of DERs without directly controlling their output. Within this context, this paper presents a novel framework in which prosumers are routinely provided with dynamic active and reactive OEs and can manage their assets accordingly. The network operator in each time step, collects customers’ expected export, and considering nodes voltage and lines current limits, calculates the dynamic OEs for each prosumer. Then, an energy management algorithm for prosumers is presented, which enables them to control their PV and battery energy storage system according to their defined PQ region. The performance of the proposed framework is evaluated using various simulation studies to demonstrate its significant effectiveness in solving the over-voltage and over-current problems associated with DERs. Furthermore, the comparison of the proposed framework with the state of the art exhibits its superiority in decreasing DERs power curtailment.

A Comparative Study of the Influence of BESS and STATCOM on Post-Fault Voltage Recovery in Microgrid

Reliable and efficient power flow in the electrical grid is crucial given network expansion and the incorporation of numerous renewable sources. Microgrids are becoming more and more important in the global energy sector due to its numerous benefits. The variable nature of distributed energy resources (DER) in microgrid makes large-scale DER integration potentially unstable for system voltage. Grid regulations place restrictions on the voltage control of DER unit, which raises the need for reactive power support. Proper placement of flexible AC transmission system (FACTS) under post-fault conditions may enable faster voltage recovery. In this work, battery energy storage system (BESS) and static synchronous compensator (STATCOM) have been considered for improving the post-fault voltage in DER integrated weakly grid-connected microgrid system. Two operation scenarios have been considered for analyzing the behavior of BESS and STATCOM individually at post-fault situation. According to the results of the simulation, BESS requires lesser rating than STATCOM for faster recovery of post-fault voltage of the system.

Distributed energy resource interconnection: An overview of challenges and opportunities in the United States

Decarbonizing the energy sector and electrifying buildings and transportation requires the rapid and cost-efficient build-out of solar, energy storage, demand management, and other distributed energy resources (DERs). Many jurisdictions have recognized the critical importance of DERs to the clean energy transition and are developing solutions to enable the more rapid and cost-efficient integration of DERs onto the electric grid. At the same time, as the scale and speed of DER deployment grows, more challenges are emerging, including lengthy interconnection timelines, costly grid upgrades, and regulatory and technical barriers to enabling the variety of benefits DERs can provide to the grid. Interconnection, in particular, can pose a significant challenge to growing DER penetration. Interconnection rules and regulations spell out the procedural and technical requirements for connecting DERs to the grid. When these rules are well-designed, they can support faster and more cost-effective DER integration, but when they are outdated or poorly designed, they can slow or even halt DER growth. This article describes some of the key challenges that U.S. states are facing with DER interconnection to the distribution system, and highlights leading solutions to address those challenges. While the article focuses on DER interconnection rules and regulations in the United States, many of the lessons learned and solutions are likely applicable to other jurisdictions that are experiencing rapid DER market growth.

A Resilience-Oriented Methodology for Transformation of the Distribution Networks into MicroGrid

Transformation of the distribution network, integrated with Distributed Energy Resources (DER), into a MicroGrid (MG) is an attractive approach in improving the reliability and resilience of the network. In this paper, by introducing the important and necessary aspects of the MG formation problem, an effective methodology for transformation of a distribution network into the MG is proposed. In the presented methodology, optimal allocation of DERs within MG is obtained by optimization of power losses and voltage stabilization along feeders. Moreover, the short-circuit constraints are also taken into account simultaneously while allocating DERs. The reason for the latter is that the integration of DERs alters the amplitude and direction of the short circuit current, which can cause the overall fault current to exceed the designed fault-level capability of the circuit breakers. This issue may put CBs at risk of failure and degrading MG resilience. In this regard, resilience-oriented evaluation of the MG formation, from the perspective of considering short circuit level and coordination of OCRs, is also performed. Another advantage of short circuit studies is devising complete and economic overcurrent-based protection plan for MG in both operating modes (grid-connected and islanded). It should be pointed out that adopting an appropriate control routine is a key element in the MG formation. Hence, a control strategy, based on Energy Storage System (ESS) utilization, is suggested in this paper. This feature, which is another contribution of the paper, will guarantee seamless transition to island mode and stable operation of the MG. The proposed formulation of the MG formation is solved using a modified multi-objective PSO and the Pareto-optimal set is obtained. However, since the optimal solutions are nondominated to each other, a Fuzzy Satisfaction Method (FSM) is utilized to find the optimal solution among the Pareto-set. Utilization of the proposed methodology leads to the successful transformation of the distribution network into a MG, which not only considers the load flow constraints but also preserves the optimal coordination of the protective relays and resilience of the MG. In addition, seamless transition and stable operation of the MG in island mode is achieved.

Transactive energy revolution: Innovative leverage for reliable operation of modern energy networks—A critical review

The electric industry is developing towards a more efficient, reliable, and resilient electric power network. In this way, utilizing distributed energy resources (DERs), especially renewable DERs (RDERs) are a paradigm change. DERs offer many advantages in power systems, including transmission loss reduction, environmental benefits of RDERs, and enhancement of security, reliability, and resiliency of the network. However, high penetration of DERs increases uncertainty and challenges the efficient and reliable operation of the power system. This paper provides a thorough review of the transactive distribution platform which is essential to address the aforementioned challenges. This distribution platform includes a transactive distribution system operator providing a seamless and coordinated control to dynamically balance supply and demand and follow uncertain generations of RDERs. Indeed, this review paper highlights the capability of transactive energy (TE) by considering its key aspect in providing energy sharing opportunities for the integration of DERs into smart grids (SGs). TE is acombination of economic and control methods that enable optimum, reliable, sustainable, and efficient operation of SGs. Furthermore, a fully transactive framework offers more choices for DERs to control and manage the energy transactions in the retail market, as well as improves the inter operability among various market players.

Non-Bias Allocation of Export Capacity for Distribution Network Planning With High Distributed Energy Resource Integration

A novel distributed energy resources (DER) allocation method focused on grid constraints that avoids topological bias is proposed for distribution networks. A technology-agnostic approach is used, where a non-bias allocation of export capacity (NAEC) not specific to generation type is calculated. Moreover, the proposed NAEC is extended from an export capacity into a hosting capacity (HC) using a statistical approach. The methods are tested using the IEEE 33-bus distribution system, and two typical Irish distribution feeders -one urban, one rural- as case studies. Using a high-resolution year-long quasi-static time series simulation (QSTS) and three different generation profiles, the proposed NAEC method is validated against current practices and state of the art allocation methods in terms of active balancing, security of supply, interactions between users, operational concerns, and fairness. Results show that an equivalent or higher level of DER penetration is achieved using the proposed methodology. There are no additional constraint violations using the NAEC methodology, moreover, time slots with violations are reduced, improving security of supply. Furthermore, results suggest that avoiding topological bias makes the network accessible for more users, and prioritises self-consumption.

Network-secure bidding strategy for aggregators under uncertainty

The widespread adoption of distributed energy resources (DER) is creating an opportunity for aggregators to transform DER flexibility into electricity market services. In a scenario of high DER integration, aggregators will need to coordinate the optimisation of DER with the distribution system operator (DSO) in order to avoid congestion and voltage incursions in the distribution networks. This coordination task is notably complex since both network and DER operation are impacted by multiple sources of uncertainty. To address these challenges, this paper proposes a new bidding strategy for aggregators of prosumers to make robust network-secure bidding decisions in day-ahead energy and reserve markets. The bidding strategy computes robust network-secure bids without jeopardising the data privacy of aggregators and the DSO. The data privacy is preserved by using the alternating direction method of multipliers (ADMM) to decompose a stochastic network-secure bidding problem into bidding and network subproblems and solve them separately and in parallel. The uncertainty of the prosumers is incorporated in the bidding problem through scenarios of load, renewable generation, and DER preferences. Our experiments show that the proposed bidding strategy computes robust bids against distribution network problems, outperforming deterministic and stochastic state-of-the-art bidding strategies in terms of cost and network observability.

Realizing the Value of DERs: A Utility Perspective

Across the world, policy makers are encouraging the deployment of large quantities of distributed energy resources (DERs), including photovoltaics (PVs) and battery energy storage, to mitigate the effects of climate change and implement resiliency-enhancing grid technologies. As part of this effort, many have emphasized the potential value that DERs can provide directly to the distribution grid, thereby increasing their total social, environmental, and infrastructure value stack. However, these same DERs pose integration challenges to electric utilities, particularly as utilities seek to ensure that grid benefits can be affordably and equitably leveraged by all communities the utilities serve. Fairly and accurately quantifying the value that each DER provides to the grid is critical to developing a sustainable economic model for the integration of future DERs.

Guest Editorial: Enhancing hosting capability for renewable energy generation in active distribution networks

Guest Editorial: Enhancing hosting capability for renewable energy generation in active distribution networks

Robust Scheduling of Virtual Power Plant Under Exogenous and Endogenous Uncertainties

Virtual power plant (VPP) provides a flexible solution to distributed energy resources integration by aggregating renewable generation units, conventional power plants, energy storages, and flexible demands. This paper proposes a novel stochastic adaptive robust optimization (SARO) model for determining the optimal self-scheduling plan for VPP’s participation in the day-ahead energy-reserve market. We consider exogenous uncertainties (or called decision-independent uncertainties, DIUs) associated with market clearing prices and available wind generation, as well as endogenous uncertainties (or called decision-dependent uncertainties, DDUs) pertaining to real-time reserve deployment requests. A tractable solution methodology based on modified Benders dual decomposition is developed to effectively solve the proposed SARO model with both DIUs and DDUs. Case studies are conducted to verify the efficiency and applicability of the proposed approach. Comparative results show that the proposed method can mitigate the conservatism of robust strategy by capturing a satisfactory trade-off between profitability and real-time operation feasibility.

Nonwire alternatives: Much ado about nothing? [Guest Editorial

The growing proliferation of distributed energy resources (DERs) is perceived as both a challenge and an opportunity for electric utilities. DER integration requires a modernized power grid capable of addressing the two-way flow of power as well as managing increased energy usage, availability uncertainty, and potentially higher feeder hosting capacity to ensure these new additions do not cause network congestion.

DC Energy Hubs for Integration of Community DERs, EVs, and Subway Systems

In this paper, a DC microgrid solution is proposed to mitigate the high penetration levels of distributed energy resources (DERs) and electric vehicles (EVs). The microgrid is designed to integrate the regenerative energy available as a result of trains braking at adjacent subway lines. Therefore, the proposed configuration not only helps the distribution network accommodate more renewable energy, but also reduces the energy consumption and peak demand associated with the nearby electrified transportation system. A framework for DC microgrid control has been developed and evaluated using a case study. The results prove the validity and effectiveness of the proposed control framework.

Community-Based Microgrids: Literature Review and Pathways to Decarbonise the Local Electricity Network

This article addresses the suitable approaches for empowering energy citizens and smart energy communities through the development of community-based microgrid (C-MG) solutions while taking into consideration the functional architectural layers and system integration topologies, interoperability issues, strategies for consumer-centric energy trading under the local electricity market (LEM) mechanism, and socio-economic aspects. Thus, this article presents state-of-the-art microgrid solutions for the smart energy community along with their motivation, advantages and challenges, comprehensibly contrasted between the recommended generic architecture and every other reported structure. The notion of LEM for peer-to-peer (P2P) energy exchange inside a transactive energy system based on a flexible consumer-centric and bottom-up perspective towards the participation in the wholesale electricity market (WEM) is also reviewed and critically explored. Furthermore, the article reviews the interoperability issues in relation to the development of C-MG including energy trading facilities. The article’s overall contribution is that it paves the path for advanced research and industrialisation in the field of smart energy communities through the analytical recommendations of the C-MG architecture and DER (distributed energy resource) integration structure, considering the future trend of local energy markets and socio-economic aspects.

Applications, Operational Architectures and Development of Virtual Power Plants as a Strategy to Facilitate the Integration of Distributed Energy Resources

In this article, we focus on the development and scope of virtual power plants (VPPs) as a strategy to facilitate the integration of distributed energy resources (DERs) in the power system. Firstly, the concepts about VPPs and their scope and limitations are introduced. Secondly, smart management systems for the integration of DERs are considered and a scheme of DER management through a bottom-up strategy is proposed. Then, we analyze the coordination of VPPs with the system operators and their commercial integration in the electricity markets. Finally, the challenges that must be overcome to achieve the large-scale implementation of VPPs in the power system are identified and discussed.

Multiobjective Ant Lion Optimization for Performance Improvement of Modern Distribution Network

Multiobjective ant lion optimization (MALO) is a technique developed to imitate ant foraging behavior. This method has many advantages, including straightforward, scalable, flexible, balanced, and fast response. The MALO technique consists of five stages: ants perform optimization by random walking by updating their position, building traps, inserting ants into traps, capturing prey, and rebuilding traps. MALO has been successfully used to find optimal solutions to power system problems. Computer-assisted operations characterize modern distribution networks to solve complex problems. The complexity of the distribution network problem is owing to the integration of distributed energy resources (DERs). A DER is a renewable energy power plant with a capacity of up to 10 MW that has gained popularity in recent years. In its application, the integration of DERs into the distribution network can cause new problems, namely load imbalances or excessive voltage increases on the buses where the DER is injected. Therefore, good planning is required to place the DER. This study proposes a multiobjective optimization technique based on MALO to determine the optimal DER location and capacity. MALO is a relatively new optimization method that has the potential to improve distribution network performance. Test cases were conducted for an IEEE 33-bus radial power-distribution network. Four scenarios were considered, integrating DER types I, II, III, and IV. In each design, the placement of one DER, two DERs, and three DERs was modeled to optimize the location and capacity. The results of the multiobjective optimization show that the MALO technique can improve the distribution network performance, which is characterized by a significant power loss reduction, an increase in the bus voltage profile, and a balanced load on each feeder.

An Enhanced Approach for Solar PV Hosting Capacity Analysis in Distribution Networks

With the falling cost of Distributed Energy Resources (DERs) and the shift from fossil fuel to renewable energy in many countries, the integration of DERs is expected to grow. This can lead to a wide range of problems in the power system, such as voltage violations, overloading of distribution lines, reverse power flow, etc. Therefore, it is imperative to account for these adverse effects of the integration of DERs on the distribution network and minimize their impact when calculating the Hosting Capacity (HC). Two algorithms are presented in this study derived from a novel modified iterative method and a novel Repeated Particle Swarm Optimization (RPSO) method for determining the HC for multiple DER units simultaneously or a single DER unit integrating into radial or mesh networks. These algorithms calculate the optimal HC based on six scenarios of annual load and DER generation profiles. The developed algorithms were tested on the IEEE 123 bus network, and their results were compared. For a large-scale DER case, the modified iterative method significantly outperforms both the PSO and the normal iterative method in terms of computation time (30 minutes versus 3 hours versus 6 hours, respectively). In the case of multiple DERs, the RPSO method is the only option, as the other two methods cannot simultaneously optimize multiple DERs. As a result, it has been concluded that it is necessary to select HC calculation methods carefully and in accordance with the application, as each method has its own strengths and weaknesses.

Secured energy ecosystems under Distributed Energy Resources penetration

Renewable energy systems have mushroomed in the form of microgrids and Virtual Power Plants (VPP). In Australia itself, there are over three million Distributed Energy Resources (DERs). Integrating these new energy ecosystems into current systems is becoming a horrendous task as multi-dimensional energy flows and new energy business models are evolving. The stakeholders in the energy sector are focused on reducing costs prematurely while integration standards are still evolving, and interoperability of Internet of things (IoT) with legacy systems has outstanding security concerns. In this paper, the changing energy landscape is examined, and cybersecurity issues associated with the operation of VPPs and renewable energy-based microgrids are highlighted. The security and operational scenarios of new ecosystems are outlined, with an emphasis on DER interoperability, security, and integration. The design and development of these evolving standards into these new energy ecosystems is detailed based on observations from experiments on real-world DER installations. This paper is an extension of work originally reported in proceedings of the 31st Australasian Universities Power Engineering Conference [1].

Evaluation of Data-Enhanced Hierarchical Control for Distribution Feeders With High PV Penetration

Reliable and resilient grid operations with high penetration levels of distributed energy resources (DERs) can be achieved with improved situational awareness and seamless integration of DERs with utility enterprise controls. This paper presents the details of the development of a data-enhanced hierarchical control (DEHC) architecture and the results of its evaluation. The DEHC is a hybrid control framework that enables the efficient, reliable, and secure operation of distribution grids with extremely high penetrations of solar photovoltaic (PV) generation by seamlessly integrating centralized utility controls, distributed controls for DERs, and autonomous grid-edge controls. In the DEHC architecture, the advanced distribution management system (ADMS) controls the legacy devices (such as load tap changers and capacitor banks), the PV smart inverters are dispatched by real-time optimal power flow, and the grid-edge devices regulate local voltages in coordination with each other. The DEHC is demonstrated using a commercial ADMS platform, real utility distribution feeder models, and grid-edge devices. The performance of the DEHC architecture is evaluated using simulations and hardware-in-the-loop experiments with voltage regulation as the control objective. The results show that the DEHC enables high penetration levels of PV in distribution feeders by effectively managing system voltages through the synergistic operation of ADMS, distributed PV smart inverter controls, and secondary-level grid-edge device control.