Demand response for chemical manufacturing using Economic MPC

Abstract

The notion of demand response in electric power systems is to use time varying electricity price structures to encourage consumers to track generation availability. Specifically, when available generation is low, either due to high demand or a lack of renewable sources, an increase in electricity rates is intended to encourage smart grid participants to reduce consumption. Similarly, when on-line generation is higher than demand, smart grid participants may benefit from low electricity rates. While many think of smart grid participants as residential consumers, the commercial building and industrial sectors will likely result in a higher grid impact to implementation cost ratio. In this work we investigate potential demand response mechanisms from the chemical manufacturing industry. It will be shown that depending on the type of upgrade hardware selected the smart grid operating policy will either be an application of Real-Time Optimization (RTO) or Economic Model Predictive Control (EMPC). In the case of EMPC the impact of prediction horizon size will be highlighted.

Demand response in smart grids: Participants, challenges, and a taxonomy

“…In the industrial sector, [17] shows data centers able to save 30% on monetary costs by participation in the regulation services without significant loss in QoS. Further, [12] shows reduced power consumption of industrial refrigeration systems and [14] presents examples indicating as much as a 30% increase in operating profits for a chemical manufacturing site.…”

“…Each one of them consumes more than 100 TWh making them ideal candidates for DR [13]. The DR potential of the chemical manufacturing industry has been investigated in [14] where it is shown how the type of participation depends on the hardware installed, as large manufacturing sites have the potential to participate in the reserve energy market with the correct investments. In [15], Alcoa Power Generating Inc. (APGI) show that they can provide fast regulative service for the power grid.…”

Economic Model Predictive Control - A Review

“…The research in smart grid and energy saving has started flourishing from economic MPCs, as has been found in recent works including those from [1,15,17,18,26,30]. Unlike the rigorous developments in the previous three papers, these application-oriented papers simply prolong the predictive horizon for feasibility or applies an infinitehorizon approximation, while emphasizing the effectiveness of the economic MPC approach in power systems and energy saving problems.…”

“…[31], an EMPC "directly and dynamically optimizes the economic operating cost of the process, doing so without reference to any steady state". EMPC has been successfully implemented for HVAC energy saving applications, and started flourishing in power systems, as has been found in recent works, including those from [17,18,15,27,1,26,30,33,5]. For chemical process systems, the review in [10] has also pointed out that "while steady-state operation is typically adopted in chemical process industries, steady-state operation may not necessarily be the economically best operation strategy".…”

“…The stability proof is supported by a Lipschitz continuous property, plus an assumption on the weak controllability of the cyclic steady state. Different strategies for the infinite-horizon EMPCs have also been proposed in [40,19,27,26,41,30]. However, these are only the preliminary results or EMPC alike formulations, thus will not be given a review herein.…”