Day-Ahead Scheduling of Integrated Power and Water System Considering a Refined Model of Power-to-Gas

Abstract

To accommodate surplus electricity and decarbonize, power-to-gas (PtG) is being widely considered in the integrated energy system with high proportion of renewable energy. However, the reaction model of PtG should be refined for the sake of making a precise operation strategy and economic evaluation. Compared with the ordinary model of power-to-gas process, this article makes two main improvements. First, an explicit expression of electrolytic process is given according to the usage of electricity. In the refined electrolytic model, the recovery of the extra heat in the electrolytic process and the compression of feed-in gas is explored. Second, the response model of the methanation process to the intermittency of the renewable energy is established. Considering the increasing coupling of power system and water network, we formulate a day-ahead scheduling program for an integrated power and water system (IPWS). Thus, the role of double regulation of power-to-gas is more noticeable. Finally, the accuracy and economical performance of the refined model of power-to-gas is demonstrated through case studies. The results show a significant body of recoverable extra heat reaching 26.6% of the total power consumption. Also, it shows a dramatic growth in PtG's consumption by 61.9% considering compression consumption. Moreover, the information gap decision theory (IGDT) is applied in the unit commitment scheme. Based on IGDT, the impact of the renewable energy uncertainty on the decision-making of IPWS operator is discussed.

Storing Freshwater Versus Storing Electricity in Power Systems with High Freshwater Electric Demand

“…We note that the model for batteries is based on linear constraints ( 4) - (8). Such approximation is valid because the objective function (1) includes non-negative linear operation costs for gas units, and the power output of gas units is bounded by (12) [16]. Constraints ( 9) -( 11) impose the on/off logic constraints for gas units [17].…”

“…Constraints ( 9) -( 11) impose the on/off logic constraints for gas units [17]. Constraint (12) enforces gas units to operate within their maximum and minimum power limits. Constraints ( 13) and ( 14) express the maximum power output of gas units.…”

“…As it is customary in short-term studies, we assume that the pump scheduling states are known and freshwater flows in single direction through pumps. These assumptions are justified in [12], [21], [22]. The constraints are given as:…”

“…A mixed-integer nonlinear programming model for the joint power-freshwater system with wind production uncertainty is reported in [12]. A convex approximation is implemented to represent nonlinear pump operation constraints.…”