Comparison of Contracts in Vehicle-to-Load to Benefit Both Retailers and Electric Bus Operators

Price fluctuations in the electricity market are becoming a major risk for retailers, and appropriate retail contracts with customers who have controllable demand-side equipment are becoming increasingly important. The aim of this paper is to identify a suitable contract that benefits both the retailer and the electric bus operator to promote Vehicle-to-Load as demand response. The electric bus operator optimizes the charging/discharging operations in various retail contracts, and the characteristics of the revenue for the retailer and the cost of the electric bus operator are analyzed in each case. By optimizing the charging/discharging operations of the electric bus with various retail prices in mixed-integer programming, it is possible to benefit both the retailer and the electric bus operator. The result shows that the two-step price for stimulating demand is found to be the best in terms of appropriate risk allocation between the retailer and the electric bus operator.