Demand Flexibility of Residential Buildings:Definitions,Flexible Loads,and Quantification Methods

This paper reviews recent research on the demand flexibility of residential buildings in regard to definitions,flexible loads,and quantification methods.A systematic distinction of the terminology is made,including the demand flexibility,operation flexibility,and energy flexibility of buildings.A comprehensive definition of building demand flexibility is proposed based on an analysis of the existing definitions.Moreover,the flexibility capabilities and operation characteristics of the main residential flexible loads are summarized and compared.Models and evaluation indicators to quantify the flexibility of these flexible loads are reviewed and summarized.Current research gaps and challenges are identified and analyzed as well.The results indicate that previous studies have focused on the flexibility of central air conditioning,electric water heaters,wet appliances,refrigerators,and lighting,where the proportion of studies focusing on each of these subjects is 36.7%,25.7%,14.7%,9.2%,and 8.3%,respectively.These flexible loads are different in running modes,usage frequencies,seasons,and capabilities for shedding,shifting,and modulation,while their response characteristics are not yet clear.Furthermore,recommendations are given for the application of white-,black-,and grey-box models for modeling flexible loads in different situations.Numerous static flexibility evaluation indicators that are based on the aspects of power,temporality,energy,efficiency,economics,and the environment have been proposed in previous publications,but a consensus and standardized evaluation framework is lacking.This review can help readers better understand building demand flexibility and learn about the characteristics of different residential flexible loads,while also providing suggestions for future research on the modeling techniques and evaluation metrics of residential building demand flexibility.

A Simulation of Market-based Non-frequency Ancillary Service Procurement Based on Demand Flexibility

This paper proposes a novel approach for the provision of non-frequency ancillary service(AS)by consumers connected to low-voltage distribution networks.The proposed approach considers an asymmetric pool-based local market for AS negotiation,allowing consumers to set a flexibility quantity and desired price to trade.A case study with 98 consumers illustrates the proposed market-based non-frequency AS provision approach.Also,three different strategies of consumers’participation are implemented and tested in a real low-voltage distribution network with radial topology.It is shown that consumers can make a profit from the sale of their flexibility while contributing to keeping the network power losses,voltage,and current within pre-defined limits.Ultimately,the results demonstrate the value of AS coming directly from end-users.

Transactive Energy and Flexibility Provision in Multi-microgrids Using Stackelberg Game

Aggregating demand side flexibility is essential to complementing the inflexible and variable renewable energy supply in achieving low carbon energy systems.Sources of demand side flexibility,e.g.,dispatchable generators,storage,and flexible loads,can be structured in a form of microgrids and collectively provided to utility grids through transactive energy in local energy markets.This paper proposes a framework of local energy markets to manage this transactive energy and facilitate the flexibility provision.The distribution system operator aims to achieve local energy balance by scheduling the operation of multi-microgrids and determining the imbalance prices.Multiple microgrid traders aim to maximize profits for their prosumers through dispatching flexibility sources and participating in localised energy trading.The decision making and interactions between a distribution system operator and multiple microgrid traders are formulated as the Stackelberg game-theoretic problem.Case studies using the IEEE 69-bus distribution system demonstrate the effectiveness of the developed model in terms of facilitating local energy balance and reducing dependency on the utility grids.

A Review on Active Customers'Participation in Smart Grids

Industrial,commercial,and residential facilities are progressively adopting automation and generation capabilities.By having flexible demand and renewable energy generation,traditional passive customers are becoming active participants in electric power system operations.Through profound coordination among grid operators and active customers,the facilities’capability for demand response(DR)and distributed energy resource(DER)management will be valuable asset for ancillary services(ASs).To comply with the increasing demand and flexible energy,utilities urgently require standards,regulations,and programs to efficiently handle load-side resources without trading off stability and reliability.This study reviews different types of customers’flexibilities for DR,highlighting their capabilities and limitations in performing local ancillary services(LASs),which should benefit the power grid by profiting from it through incentive mechanisms.Different financial incentives and techniques employed around the world are presented and discussed.The potential barriers in technical and regulatory aspects are successfully identified and potential solutions along with future guidance are discussed.

Review of Market Power Assessment and Mitigation in Reshaping of Power Systems

The deregulation of the power industry requires avoiding market power abuse to maintain the market competitiveness. To this end, a sequence of assessment measurements or mitigation mechanisms is required. Meanwhile, the increasing renewable energy resources(RESs) and flexible demand response resources(DRSs) are changing the behaviors of market participants and creating new cases of market power abuse.Such new circumstances bring the new evaluation and control methods of market power to the forefront. This paper provides a comprehensive review of market power in the reshaping of power systems due to the increasing RES and the development of DRS. The market power at the supply side, demand side,and in the multi-energy system is categorized and reviewed. In addition, the applications of market power supervision measures in the US, the Nordics, UK, and China are summarized.Furthermore, the unsolved issues, possible key technologies,and potential research topics on market power are discussed.