Some areas in China are facing pressing air pollution problems. Measures from the power sector can be taken to cope with air pollution issues, including reducing emission levels of thermal units and integrating wind and solar power. Social welfare, emission, and renewable integration are three major concerns in modern power system operations. This paper describes three stochastic scheduling models aiming at maximizing social welfare (SW), minimizing emission (EM) and maximizing renewable production (RE).A multi-objective scheduling model (MT) is also proposed that properly balances the above objectives.Wind power uncertainty and dispatchable loads are considered in the model. The outcomes of the three models are compared through an illustrative example and a 57-node case study. Results show that model EM results in 36% of the social welfare of model SW, 27% of its emissions, and 43% of its wind spillage, while model RE results in 55% of the social welfare of model SW, 56% of its emissions and 28% of its wind spillage. Additionally, we analyze how the optimal generation scheduling is affected by the weights in model MT. This work provides insight to policy makers on how to balance social welfare, emissions and renewable production. teristics of wind power increase the possibility of energy curtailment. Wind spillage reached 15% of wind 10 production in China in 2015 [2].Besides deployment of up/down reserves by thermal units, dispatchable loads provide an appropriate mechanism to deal with uncertainty. Dispatchable loads can be scheduled and re-dispatched like generators to achieve the scheduling objective. Dispatchable loads increase the flexibility of the system, which is helpful in system with high renewable production.
15To minimize the operating cost is the main objective for most Independent System Operators (ISO), but nowadays other objectives appear. For some highly-polluted areas, the ISO may seek to minimize emissions to ensure air quality. For areas with high renewable integration, the ISO may seek to maximize renewable production to make electricity production as "green" as possible. These distinct objectives result in different generation scheduling outcomes.
20Considering the pressing problems of air pollution and wind curtailment in China, this paper focuses on the comparison of three stochastic scheduling models taking into account wind power uncertainty and dispatchable loads. The objectives are to maximize social welfare, to minimize emissions, and to maximize renewable integration, respectively. A multi-objective scheduling model that properly combines the above objectives is proposed as well. A similar methodology has not been reported in the technical literature.
25An illustrative example and a 57-node case study are considered to illustrate the proposed models.
Literature ReviewRelevant works pertaining to electricity generation scheduling models with different objectives are reviewed below. Minimizing cost (or maximizing social welfare) is the most common goal [3,4] in unit commitment proble...