The growing penetration of renewable energy in power system and the increasing adoption of demand response have brought about the challenges of operation in distribution systems with more uncertainty. Due to the intermittency of distributed generation, the centralized control of distribution systems must coordinate the operation of distributed generation and responsive load in a fast and reliable manner, while still attempting to achieve the profit maximization. This paper proposes a market based operation method for distribution companies, by smoothing out the fluctuating renewable generation with responsive load to ensure the reliable feeding of ordinary load. By going through the proposed steps which consists of responsive load grouping, mapping and shedding in an optimal way, the distribution company is able to perform the most economical control over the distributed sources and load. A case study demonstrated the use of the proposed method.