Abstract:In the past, transmission line planning based on standard designs suffered from inefficiency and capital wastage. Economic studies show that employing optimal design and scientific cost management for transmission line construction is crucial for saving capital investment. So the review of research efforts in transmission expansion planning is given to facilitate more informed decision-making regarding the construction and operation of transmission lines. By surveying domestic and international research articles, the fundamental theories of transmission line planning are outlined. The methods for transmission line planning, including deterministic, heuristic and metaheuristic approaches, are systematically delineated and their respective strengths and weaknesses are analyzed. Then, for economic evaluation, a life cycle cost analysis is proposed to account for expenses across multiple phases such as line construction, operation and maintenance, which can more comprehensively evaluate the cost-effectiveness of any given transmission planning scheme.