Construction change factors of direct current transmission line project and their impact on schedule and costs

Direct Current (DC) transmission is an important part of modern power transmission system. In recent years, large numbers of DC project are under construction. The construction changes in DC projects have become a common issue. Based on the construction changes of the Three Gorges-Guangdong and the Three Gorges-Shanghai DC transmission line construction projects, this paper designs a questionnaire and conducts a questionnaire survey to management and technical staff of project owners, design firms, supervision firms and contractors. The outcome about the importance of changes factors is collected and the main factors impacting transmission line construction changes to its duration and cost are identified. Using agreement analysis method, the agreement degree of the factors impacting on the construction schedule and costs are found. The result may help to control and manage construction changes in transmission line projects.