Mahnoosh Alizadeh

Real-Time Power Balancing Via Decentralized Coordinated Home Energy Scheduling

It is anticipated that an uncoordinated operation of individual home energy management (HEM) systems in a neighborhood would have a rebound effect on the aggregate demand profile. To address this issue, this paper proposes a coordinated home energy management (CoHEM) architecture in which distributed HEM units collaborate with each other in order to keep the demand and supply balanced in their neighborhood. Assuming the energy requests by customers are random in time, we formulate the proposed CoHEM design as a multi-stage stochastic optimization problem. We propose novel models to describe the deferrable appliance load [e.g., plug-in (hybrid) electric vehicles (PHEV)], and apply approximation and decomposition techniques to handle the considered design problem in a decentralized fashion. The developed decentralized CoHEM algorithm allow the customers to locally compute their scheduling solutions using domestic user information and with message exchange between their neighbors only. Extensive simulation results demonstrate that the proposed CoHEM architecture can effectively improve real-time power balancing. Extensions to joint power procurement and real-time CoHEM scheduling are also presented.

Demand-Side Management in the Smart Grid: Information Processing for the Power Switch

Over the course of several decades after their introduction, power systems merged into large interconnected grids to introduce redundancy and to leverage on a wider pool of generation resources and reserves. As the system grew in size and complexity, a cyberphysical infrastructure was progressively developed to manage it. Traditionally, general-purpose computing and communication resources have been used in power systems, specifically to serve two needs: 1) that of monitoring the safe operation of the grid and logistics of power delivery, and 2) that of gathering information required to dispatch the generation optimally and, later on, to operate the energy market.

A Scalable Stochastic Model for the Electricity Demand of Electric and Plug-In Hybrid Vehicles

In this paper we propose a stochastic model, based on queueing theory, for electric vehicle (EV) and plug-in hybrid electric vehicle (PHEV) charging demand. Compared to previous studies, our model can provide 1) more accurate forecasts of the load using real-time sub-metering data, along with the level of uncertainty that accompanies these forecasts; 2) a mathematical description of load, along with the level of demand flexibility that accompanies this load, at the wholesale level. This can be useful when designing demand response and dynamic pricing schemes. Our numerical experiments tune the proposed statistics on real PHEV charging data and demonstrate that the forecasting method we propose is more accurate than standard load prediction techniques.

Coordinated home energy management for real-time power balancing

This paper proposes a coordinated home energy management system (HEMS) architecture where the distributed residential units cooperate with each other to achieve real-time power balancing. The economic benefits for the retailer and incentives for the customers to participate in the proposed coordinated HEMS program are given. We formulate the coordinated HEMS design problem as a dynamic programming (DP) and use approximate DP approaches to efficiently handle the design problem. A distributed implementation algorithm based on the convex optimization based dual decomposition technique is also presented. Our focus in the current paper is on the deferrable appliances, such as Plug-in (Hybrid) Electric Vehicles (PHEV), in view of their higher impact on the grid stability. Simulation results shows that the proposed coordinated HEMS architecture can efficiently improve the real-time power balancing.

Information infrastructure for cellular load management in green power delivery systems

In this paper, we outline a specific communication framework to support a novel demand management program on the edge of the power distribution network. We suggest a model where the arrival process of the smart appliances is made visible to control centers, forming a cellular Microgrid infrastructure, through Home Energy Management Systems (HEMS). These appliances then wait to receive an authorization message before starting to function. The cell control center uses this information to choose an optimal departure process that serves the waiting appliances while minimizing its operational costs. The described information exchange strategy gives the cell the ability to better match the load to the available green energy supply and its day ahead energy bid. We show that this model will allow to increase the integration of intermittent resources in the power grid, with modest communication rate requirements.1

Grid integration of distributed renewables through coordinated demand response

There is a growing interest in developing solutions to facilitate large scale integration of distributed renewable energy resources and, in particular, contain the adverse effects of their volatility. In this paper, we introduce a neighborhood-level demand response program that aims at coordinating the Home Energy Management Systems (HEMS) of residential customers in order to opportunistically consume spikes of locally generated renewable energy. We refer to this technique as Coordinated Home Energy Management (CoHEM). Our model predictive control technique modulates the aggregate load to follow a dynamically forecasted generation supply. Both centralized and decentralized deployments of CoHEM are considered. The decentralized version requires a more demanding communication backbone to connect individual HEMS but, it is more resilient to failures of individual computational units or communication links and, compared to the centralized model, it preserves consumers privacy. In our numerical results section, we compare the scenario where individual HEMS optimize their energy use selfishly, under a hypothetical dynamic pricing program, to the performance of the centralized and decentralized versions of our proposed CoHEM architecture. The results highlight the advantages of using the CoHEM model in absorbing the fluctuations in the generation output of distributed renewables.

Dynamic Incentive Design for Participation in Direct Load Scheduling Programs

Interruptible Load (IL) programs have long been an accepted measure to intelligently and reliably shed demand in case of contingencies in the power grid. However, the emerging market for Electric Vehicles (EV) and the notion of providing non-emergency ancillary services through the demand side have sparked new interest in designing direct load scheduling programs that manage the consumption of appliances on a day-to-day basis. In this paper, we define a mechanism for a Load Serving Entity (LSE) to strategically compensate customers that allow the LSE to directly schedule their consumption, every time they want to use an eligible appliance. We study how the LSE can compute such incentives by forecasting its profits from shifting the load of recruited appliances to hours when electricity is cheap, or by providing ancillary services, such as regulation and load following. To make the problem scalable and tractable we use a novel clustering approach to describe appliance load and laxity. In our model, customers choose to participate in this program strategically, in response to incentives posted by the LSE in publicly available menus. Since 1) appliances have different levels of demand flexibility; and 2) demand flexibility has a time-varying value to the LSE due to changing wholesale prices, we allow the incentives to vary dynamically with time and appliance cluster. We study the economic effects of the implementation of such program on a population of EVs, using real-world data for vehicle arrival and charge patterns.

Incentive design for Direct Load Control programs

We study the problem of optimal incentive design for voluntary participation of electricity customers in a Direct Load Scheduling (DLS) program, a new form of Direct Load Control (DLC) based on a three way communication protocol between customers, embedded controls in flexible appliances, and the central entity in charge of the program. Participation decisions are made in real-time on an event-based basis, with every customer that needs to use a flexible appliance considering whether to join the program given current incentives. Customers have different interpretations of the level of risk associated with committing to pass over the control over the consumption schedule of their devices to an operator, and these risk levels are only privately known. The operator maximizes his expected profit of operating the DLS program by posting the right participation incentives for different appliance types, in a publicly available and dynamically updated table. Customers are then faced with the dynamic decision making problem of whether to take the incentives and participate or not. We define an optimization framework to determine the profit-maximizing incentives for the operator. In doing so, we also investigate the utility that the operator expects to gain from recruiting different types of devices. These utilities also provide an upper-bound on the benefits that can be attained from any type of demand response program.

How will demand response aggregators affect electricity markets? — A Cournot game analysis

The future electricity grid will include greater and more sophisticated demand side participation. Favored by recent rulings by the Federal Energy Regulatory Commission (FERC), Demand Response (DR) aggregators can combine load requests from a large consumer base and provide load modifications that will be compensated in the wholesale electricity market at the market price. This paper examines the market effects of including Green Energy Management System (GEMS), a future Demand Response (DR) program that will take advantage of operational flexibility of certain types of loads to shape demand profile. Adopting a Cournot game model, we give equilibrium analysis of wholesale electricity market incorporating GEMS as a DR aggregator. The players in the game include traditional generators, the GEMS, and the Independent System Operator (ISO). We provide generalized forms of the optimality conditions for each of these players and show that under certain conditions, the market equilibrium exists and is unique. Our numerical results indicate that the inclusion of GEMS within the power network reduces the average market price of electricity and saves money for customers.

Direct load management of electric vehicles

Electrical Vehicles are gaining increasing attention, due to the opportunities and challenges they present for the energy market. On the one hand, they will allow to drastically reduce the need for oil; on the other hand they may require a significant shift in the day to day management of the electricity generation. This paper is concerned with finding appropriate models for residential load in light of a widespread penetration of electric vehicles. The analysis is aimed at finding a SmartGrid solution that would enable us to optimize the generation dispatch in real time and allow to plug cars in any SmartGrid enabled plug. The key idea is to discriminate between regular load and the load due to the EVs, gathering in real time aggregate information about the sensed EV arrivals and their associated charging times in a demand matrix, that can be readily used to optimize the dispatch, while updating without real time constraints the billing record for the EV.