In this paper we present a new value proposition for load flexibility. This value is derived through enabling a congestion free dispatch, which brings economic benefits to the market participants (loads and generators), subject to certain conditions on the network. If participant classes are considered as collectives, then no class of participants is economically disadvantaged. We show that load flexibility increases the opportunity for congestion free dispatch. The economic implications of this new paradigm are studied using a simple two bus example.

%B 2015 American Control Conference (ACC) %I IEEE %C Chicago, IL, USA %P 5002 - 5009 %8 07/2015 %R 10.1109/ACC.2015.7172118 %0 Journal Article %J IEEE Transactions on Smart Grid %D 2013 %T Real-Time Scheduling of Distributed Resources %A Anand Subramanian %A Manuel J. Garcia %A Duncan S. Callaway %A Kameshwar Poolla %A Pravin Varaiya %K CERTS %K distributed energy resources (der) %K load modeling %K optimization %K reliability and markets %K renewables integration %K RM11-006 %X We develop and analyze real-time scheduling algorithms for coordinated aggregation of deferrable loads and storage. These distributed resources offer flexibility that can enable the integration of renewable generation by reducing reserve costs. We present three scheduling policies: earliest deadline first (EDF), least laxity first (LLF), and receding horizon control (RHC). We offer a novel cost metric for RHC-based scheduling that explicitly accounts for reserve costs. We study the performance of these algorithms in the metrics of reserve energy and capacity through simulation studies. We conclude that the benefits of coordinated aggregation can be realized from modest levels of both deferrable load participation and flexibility. %B IEEE Transactions on Smart Grid %V 4 %P 2122 - 2130 %8 12/2013 %N 4 %! IEEE Trans. Smart Grid %R 10.1109/TSG.2013.2262508 %0 Journal Article %J International Journal of Electrical Power & Energy Systems %D 2013 %T Risk-limiting dispatch for integrating renewable power %A Ram Rajagopal %A Eilyan Bitar %A Pravin Varaiya %A Felix Wu %K CERTS %K reliability and markets %K renewables integration %K reserve markets %K RM11-006 %X Risk-limiting dispatch or RLD is formulated as the optimal solution to a multi-stage, stochastic decision problem. At each stage, the system operator (SO) purchases forward energy and reserve capacity over a block or interval of time. The blocks get shorter as operations approach real time. Each decision is based on the most recent available information, including demand, renewable power, weather forecasts. The accumulated energy blocks must at each time t match the net demand D(t) = L(t) − W(t). The load L and renewable power W are both random processes. The expected cost of a dispatch is the sum of the costs of the energy and reserve capacity and the penalty or risk from mismatch between net demand and energy supply. The paper derives computable ‘closed-form’ formulas for RLD. Numerical examples demonstrate that the minimum expected cost can be substantially reduced by recognizing that risk from current decisions can be mitigated by future decisions; by additional intra-day energy and reserve capacity markets; and by better forecasts. These reductions are quantified and can be used to explore changes in the SO’s decision structure, forecasting technology, and renewable penetration. %B International Journal of Electrical Power & Energy Systems %V 44 %P 615 - 628 %8 01/2013 %N 1 %! International Journal of Electrical Power & Energy Systems %R 10.1016/j.ijepes.2012.07.048 %0 Conference Paper %B 2012 American Control Conference (ACC) %D 2012 %T Real-time scheduling of deferrable electric loads %A Anand Subramanian %A Manuel J. Garcia %A Alejandro D. Dominguez-Garcia %A Duncan S. Callaway %A Kameshwar Poolla %A Pravin Varaiya %K distributed energy resources (der) %K PEVs %K renewables integration %K RM11-006 %K Thermostatically controlled loads %XWe consider a collection of distributed energy resources [DERs] such as electric vehicles and thermostatically controlled loads. These resources are flexible: they require delivery of a certain total energy over a specified service interval. This flexibility can facilitate the integration of renewable generation by absorbing variability, and reducing the reserve capacity and reserve energy requirements. We first model the energy needs of these resources as tasks, parameterized by arrival time, departure time, energy requirement, and maximum allowable servicing power. We consider the problem of servicing these resources by allocating available power using real-time scheduling policies. The available generation consists of a mix of renewable energy [from utility-scale wind-farms or distributed rooftop photovoltaics], and load-following reserves. Reserve capacity is purchased in advance, but reserve energy use must be scheduled in real-time to meet the energy requirements of the resources. We show that there does not exist a causal optimal scheduling policy that respects servicing power constraints. We then present three heuristic causal scheduling policies: Earliest Deadline First [EDF], Least Laxity First [LLF], and Receding Horizon Control [RHC]. We show that EDF is optimal in the absence of power constraints. We explore, via simulation studies, the performance of these three scheduling policies in the metrics of required reserve energy and reserve capacity.

%B 2012 American Control Conference (ACC) %I IEEE %C Montreal, QC %P 3643 - 3650 %8 06/2012 %@ 978-1-4577-1095-7 %R 10.1109/ACC.2012.6315670 %0 Conference Paper %B 2012 American Control Conference (ACC) %D 2012 %T Risk limiting dispatch of wind power %A Ram Rajagopal %A Eilyan Bitar %A Felix Wu %A Pravin Varaiya %K CERTS %K reliability and markets %K reserve generation %K risk-limiting dispatch %K RM11-006 %K wind power %XIntegrating wind and solar power into the grid requires dispatching various types of reserve generation to compensate for the randomness of renewable power. The dispatch is usually determined by a system operator (SO) or an aggregator who `firms' variable energy by bundling it with conventional power. The optimal dispatch is formulated as the solution to a stochastic control problem and shown to have a closed form that can be quickly computed. Different objectives and risk constraints can be included in the formulation and trade-offs can be evaluated. In particular one can quantify the influence of sequential forecasts on the total integration cost and the choice of dispatched generation. When the forecast error is Gaussian, the optimal dispatch policy can be precomputed.

%B 2012 American Control Conference (ACC) %I IEEE %C Montreal, QC %P 4417 - 4422 %8 06/2012 %@ 978-1-4577-1095-7 %R 10.1109/ACC.2012.6315239 %0 Report %D 1999 %T Real Time Security Monitoring and Control of Power Systems %A George Gross %A Anjan Bose %A Chris DeMarco %A Mangalore Pai %A James S. Thorp %A Pravin Varaiya %K consortium for electric reliability technology solutions (certs) %K Grid of the Future %K power system operations %K RTINA %XThis white paper outlines the scope of issues, challenges and opportunities in the area of real-time security monitoring and control (RTSMC) of power systems in the restructured electricity industry. The counterpart of power system reliability in real-time operations is *security* – the ability of the power system to withstand contingencies. This White Paper is part of a set of six papers on reliability aspects of the electric power system prepared for the U.S. Department of Energy by the Consortium of Electric Reliability Technology Solutions (CERTS).