1. School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, China; 2. State Grid Energy Research Institute, Beijing 102209, China

Decision-making and risk assessment of electricity purchasing and selling business is the major activities of electricity retailers in electricity market. In order to enrich the electricity purchasing and selling business modes, the possible power purchasing and selling business are classified and combined to acquire the different business mode in the medium and long term and spot electricity market. Some random variables such as spot prices and electricity demand are simulated by the scenario method. The conditional value at risk(CVaR)of profit is used as the financial risk assessment indicator. A comprehensive model of risk decision and assessment for purchasing and selling business is built to maximize the comprehensive utility of the electricity retailer. The influence of different factors on the electricity retailers risk decision and assessment is analyzed with different business models. Three different power purchasing and selling business mode are presented as examples in this paper. The validity of the model is verified in the example 1 by analyzing the influence of the risk preference of retailer and different types of selling contracts on the selling behavior and the financial risk. Based on the power purchasing and selling business modes of example 1, example 2 and example 3, the influence of the unit cost and scale for the decision and risk of electricity retailers is assessed when respectively introducing medium- and long-term renewable power business and energy storage leasing business.