Heuristic optimization of clusters of heat pumps: A simulation and case study of residential frequency reserve

The technological challenges of adapting energy systems to the addition of more renewables are intricately interrelated with the ways in which markets incentivize their development and deployment. Households with own onsite distributed generation augmented by electrical and thermal storage capacities (prosumers), can adjust energy use based on the current needs of the electricity grid. Heat pumps, as an established technology for enhancing energy efficiency, are increasingly seen as having potential for shifting electricity use and contributing to Demand Response (DR). Using a model developed and validated with monitoring data of a household in a plus-energy neighborhood in southern Germany, the technical and financial viability of utilizing household heat pumps to provide power in the market for Frequency Restoration Reserve (FRR) are studied. The research aims to evaluate the flexible electrical load offered by a cluster of buildings whose heat pumps are activated depending on selected rule-based participation strategies. Given the prevailing prices for FRR in Germany, the modelled cluster was unable to reduce overall electricity costs and thus was unable to show that DR participation as a cluster with the heat pumps is financially viable. Five strategies that differed in the respective contractual requirements that would need to be agreed upon between the cluster manager and the aggregator were studied. The relatively high degree of flexibility necessary for the heat pumps to participate in FRR activations could be provided to varying extents in all strategies, but the minimum running time of the heat pumps turned out to be the primary limiting physical (and financial) factor. The frequency, price and duration of the activation calls from the FRR are also vital to compensate the increase of the heat pumps’ energy use. With respect to thermal comfort and self-sufficiency constraints, the buildings were only able to accept up to 34% of the activation calls while remaining within set comfort parameters. This, however, also depends on the characteristics of the buildings. Finally, a sensitivity analysis showed that if the FRR market changed and the energy prices were more advantageous, the proposed approaches could become financially viable. This work suggests the need for further study of the role of heat pumps in flexibility markets and research questions concerning the aggregation of local clusters of such flexible technologies.Comisión Europea 69596

Decentralized Greedy-Based Algorithm for Smart Energy Management in Plug-in Electric Vehicle Energy Distribution Systems

Variations in electricity tariffs arising due to stochastic demand loads on the power grids have stimulated research in finding optimal charging/discharging scheduling solutions for electric vehicles (EVs). Most of the current EV scheduling solutions are either centralized, which suffer from low reliability and high complexity, while existing decentralized solutions do not facilitate the efficient scheduling of on-move EVs in large-scale networks considering a smart energy distribution system. Motivated by smart cities applications, we consider in this paper the optimal scheduling of EVs in a geographically large-scale smart energy distribution system where EVs have the flexibility of charging/discharging at spatially-deployed smart charging stations (CSs) operated by individual aggregators. In such a scenario, we define the social welfare maximization problem as the total profit of both supply and demand sides in the form of a mixed integer non-linear programming (MINLP) model. Due to the intractability, we then propose an online decentralized algorithm with low complexity which utilizes effective heuristics to forward each EV to the most profitable CS in a smart manner. Results of simulations on the IEEE 37 bus distribution network verify that the proposed algorithm improves the social welfare by about 30% on average with respect to an alternative scheduling strategy under the equal participation of EVs in charging and discharging operations. Considering the best-case performance where only EV profit maximization is concerned, our solution also achieves upto 20% improvement in flatting the final electricity load. Furthermore, the results reveal the existence of an optimal number of CSs and an optimal vehicle-to-grid penetration threshold for which the overall profit can be maximized. Our findings serve as guidelines for V2G system designers in smart city scenarios to plan a cost-effective strategy for large-scale EVs distributed energy management

Towards flexibility trading at TSO-DSO-customer levels : a review

The serious problem of climate change has led the energy sector to modify its generation resources from fuel-based power plants to environmentally friendly renewable resources. However, these green resources are highly intermittent due to weather dependency and they produce increased risks of stability issues in power systems. The deployment of different flexible resources can help the system to become more resilient and secure against uncertainties caused by renewables. Flexible resources can be located at different levels in power systems like, for example, at the transmission-level (TSO), distribution-level (DSO) and customer-level. Each of these levels may have different structures of flexibility trading as well. This paper conducts a comprehensive review from the recent research related to flexible resources at various system levels in smart grids and assesses the trading structures of these resources. Finally, it analyzes the application of a newly emerged ICT technology, blockchain, in the context of flexibility trading.fi=vertaisarvioitu|en=peerReviewed

Towards Flexibility Trading at TSO-DSO-Customer Levels: A Review

The serious problem of climate change has led the energy sector to modify its generation resources from fuel-based power plants to environmentally friendly renewable resources. However, these green resources are highly intermittent due to weather dependency and they produce increased risks of stability issues in power systems. The deployment of different flexible resources can help the system to become more resilient and secure against uncertainties caused by renewables. Flexible resources can be located at different levels in power systems like, for example, at the transmission-level (TSO), distribution-level (DSO) and customer-level. Each of these levels may have different structures of flexibility trading as well. This paper conducts a comprehensive review from the recent research related to flexible resources at various system levels in smart grids and assesses the trading structures of these resources. Finally, it analyzes the application of a newly emerged ICT technology, blockchain, in the context of flexibility trading

Virtual Power Plant Concepts for Ancillary Market - Demonstration, Development, and Validation

The increased penetration of distributed energy resources and renewables open up issues in power systems as a whole. Chapter 1 discusses these issues, and highlights the literature solutions. The concept of VPP is highlighted, different options are explored, and the use of VPP is motivated. The chapter further discusses different ancillary services, with both technical and market perspectives. It makes a clear demarcation amongst transmission and distribution level VPPs, and their economic and technical aspects. Different components within VPP are also highlighted in this chapter. The models of VPP, based on SGAM, are presented in Chapter 2, with detailed test cases. The models characterize VPP as an aggregator at TSO, VPP as DER-Aggregator/DERMS at DSO-DMS, and VPP as business case for flexibility to DSO-DMS. It includes the VPP actors, their characteristics, and a compact architecture based on SGAM. It further splits VPP participants in different software: MATLAB/Simulink, DIgSILENT, and LabVIEW for defined test cases. These are further elaborated in detail in the next chapters, and all are discussed w.r.t regulatory, technical, and economic aspects. Chapter 3 co-simulates VPP-DERMS (Distributed Energy Resource Management System as a Virtual Power Plant) based customers' DR through LabVIEW. It develops interface to customers' meters for reactive power visibility, and then develops a HMI and recording tool at VPP controller. The performance of the tool is analyzed in the chapter, which is in fact the modeling of Modbus based customers' interaction for reactive power. Chapter 4 co-simulates effects of DER on a distribution grid in DIgSILENT. A distribution grid is modelled in DIgSILENT, and then DERs are added to the network. Node voltages and line loading are analyzed in the absence and presence of unplanned DERs. Then the network is seen from two perspectives \u2013 flexibility that can be provided to TSO with STATCOM at transmission node, and flexibility that can be provided to DSO with planned DGs at distribution node. Chapter 5 co-simulates storage model in MATLAB/Simulink. It starts with the techno-economic analysis of potential storage systems, and then to realize the storage model for simulation. The model of selected storage system is implemented in MATLAB/Simulink, and then a explicit service test case is developed within VPP-aggregator to analyze the flexibility margin by storage. Next step is the integration of these co-simulators within different service platform levels. The objective of Chapter 6 is to develop an interface amongst co-simulators to simulate the VPP chain. At first step, the co-simulators are realized within tags: wind farm tags are created in DIgSILENT, customers' based tags are built in LabVIEW, and storage tags are located inside MATLAB/Simulink. Then communication amongst the co-interfaces is done by the development of Matrikon OPC server and explorer platform. The master platform is implemented in LabVIEW-RT tool. Then test cases are defined for the validation of platform, which is performed in Chapter 7. Chapter 7 is dedicated to the validation of the formulated VPPs \u2013 DERMS, business VPP, and aggregator. DERMS based model is validated within DIgSILENT, by using a portion of the Italian distribution grid. Aggregator based model is validated within DIgSILENT, by using the IEEE 9 bus transmission test model. Business VPP model is validated using IEC 61850 compliant feature of DIgSILENT for the same distribution grid in a translational manner. The validated VPP is used as an application for power system reliability, which is presented in Chapter 8. It describes the conventional schemes for power system protection, and the issues with DER penetration. It then models a VPP, and verifies its functionality for power system protection. Chapter 9 concludes the thesis

A Comprehensive Review of Congestion Management in Power System

In recent decades, restructuring has cut across all probable domains, involving the power supply industry. The restructuring has brought about considerable changes whereby electricity is now a commodity and has become a deregulated one. These competitive markets have paved the way for countless entrants. This has caused overload and congestion on transmission lines. In addition, the open access transmission network has created a more intensified congestion issue. Therefore, congestion management on power systems is relevant and central significance to the power industry. This manuscript review few congestion management techniques, consists of Reprogramming Generation (GR), Load Shedding, Optimal Distributed Generation (DG) Location, Nodal Pricing, Free Methods, Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Fuzzy Logic System Method, as well as Additional Renewable Energy Sources. In this manuscript a review work is performed to unite the entire publications on congestion management

Opening of Ancillary Service Markets to Distributed Energy Resources: A Review

Electric power systems are moving toward more decentralized models, where energy generation is performed by small and distributed power plants, often from renewables. With the gradual phase out from fossil fuels, however, Distribution Energy Resources (DERs) are expected to take over in the provision of all regulation services required to operate the grid. To this purpose, the opening of national Ancillary Service Markets (ASMs) to DERs is considered an essential passage. In order to allow this transition to happen, current opportunities and barriers to market participation of DERs must be clearly identified. In this work, a comprehensive review is provided of the state-of-the-art of research on DER integration into ASMs. The topic at hand is analyzed from different perspectives. First, the current situation and main trends regarding the reformation processes of national ASMs are analyzed to get a clear picture of the evolutions expected and adjustment required in the future, according to the scientific community. Then, the focus is moved to the strategies to be adopted by aggregators for the effective control and coordination of DERs, exploring the challenges posed by the uncertainties affecting the problem. Coordination schemes between transmission and distribution system operators, and the implications on the grid infrastructure operation and planning, are also investigated. Finally, the review deepens the control capabilities required for DER technologies to perform the needed control actions