Minimizing Unserved Energy Using Heterogeneous Storage Units

Abstract

This paper considers the optimal dispatch of energyconstrained heterogeneous storage units to maximise security of supply. A policy, requiring no knowledge of the future, is presented and shown to minimise unserved energy during supplyshortfall events, regardless of the supply and demand profiles. It is accompanied by a graphical means to rapidly determine unavoidable energy shortfalls, which can then be used to compare different device fleets. The policy is well-suited for use within the framework of system adequacy assessment; for this purpose, a discrete time optimal policy is conceived, in both analytic and algorithmic forms, such that these results can be applied to discrete time systems and simulation studies. This is exemplified via a generation adequacy study of the British system.

Assessing operational benefits of large‐scale energy storage in power system: Comprehensive framework, quantitative analysis, and decoupling method

“…Assessment framework is first proposed to evaluate ESS's impact on the traditional power system. Based on different utilized functions of ESS, the traditional framework divides its benefits into two parts: (a) energy transfer benefits, 1‐11 and (b) ancillary services benefits 12‐39 . Since the RE penetration in the traditional power system is relatively low, the evaluation of traditional energy transfer benefits mainly focuses on ESS's benefits in reducing the system operation cost.…”

“…There is no unified division standard because of the different definitions and understandings of the ESS's ancillary services benefits. The most widely accepted classification method is formed based on the International Symposium discussion on “dynamic benefits of energy storage plant operation” 40 According to different application scenarios, ancillary services benefits in the traditional framework can be classified into five categories: Emergency reserve benefit 12‐17 : ESS can provide emergency or spinning reserve to enhance system reliability. Load following benefit 27‐29 : ESS can follow the load fluctuation when the load changes rapidly on a minute to an hour timescale. Frequency regulation benefit 24‐26 : ESS is capable of fast responding in several seconds. Therefore, it can replace the function of thermal units in frequency regulation at a high quality and a relatively low cost. Var regulation benefit 18‐20 : ESS can be used for var compensation operation.…”

“…First, some works have studied ESS usage in enhancing system reserve. Various reserve allocation methods of ESS are designed to provide required flexibility reserves,, 12,13 ensuring supply security against supply shortfall events 14 or contingencies 15 . Moreover, the revenue of ESS can be settled by the reserve market 16,17 .…”

Chance-Constrained Ancillary Service Specification for Heterogeneous Storage Devices

“…We now investigate the speed-up achieved in using the Ep transform to determine the maximum service magnitude for a given sample-state, in place of straightforward timesequential simulation using the discrete time policy of [16]. We assume that the trapezoidal request is implemented as a piecewise constant signal of period 1 min, and for increased efficiency configure the routine so that it terminates as soon as the current value of the request cannot be met.…”

“…We therefore investigate the speed-up achieved in using the E-p transform for such a check. In prior work we presented a policy, in both continuous [15] and discrete [16] time, with a one-to-one mapping between feasible requests and those that will be met under the implementation of the policy. It will therefore be this that we will use to perform a procedural check.…”