Applying Advanced Methods to Power System Planning Studies


Power system planning is a vast and important issue for operation and expansion of power delivery. One of the basic objectives of planning is to determine the right schedule for investment in new devices which ensures secure and economic power delivery for predicted customer demand. Canonical planning issues include generation and transmission planning. In addition, system planning also needs to address the question of reliable and stable operation. Hence, reliability and stability analysis are also included in planning studies. Nowadays power industries worldwide have been undergoing profound changes with deregulation and reconstruction. The separation of generation plants from traditional vertically– integrated utilities results in a situation in which transmission systems have no direct role in deciding generation patterns, both short–term and long–term. This challenge requires that transmission systems must be able to react to the increasing capacities and diverse patterns of generation and load. However, since investment in new transmission links is always restricted by both political and ecological issues, current transmission systems are becoming stressed and operating close to physical limits. Flexible AC transmission systems (FACTS) are developed based on power electronic configurations. So far, most currently used FACTS devices are using thyristor–based technology to achieve fast and continuous control of voltage and current. Plenty studies have proven that FACTS devices can be employed for better utilisation of current system assets. Therefore, given the difficulties of adding new transmission corridors, FACTS devices can present an alternative for system planning. The main objective of this topic is to apply advanced methods to provide a solution for planning issues. Two tasks are included in this topic. One is incorporating FACTS devices into power systems for improvement in network loadability, stability and economy. TCSC is selected as the objective device for its premium power flow controllability. Two sets of advanced methods, mixed–integer programming (MIP) and evolutionary algorithms (EAs) are investigated and discussed in TCSC allocation problem. The former algorithm is an efficient combinatorial optimisation algorithm, which is suitable for large scale planning issues. The latter is a recent member of evolutionary algorithm, differential evolution (DE), which is characterised by its speed and precision as well as robustness. The planning objective includes transmission and economic considerations, which involves the power loss minimisation, reactive power regulation, voltage profile enhancement, as well as the investment minimisation. By exploiting these methods, the number, locations and parameter settings of TCSC can be selected optimally. In addition, detailed power system planning analysis extends to investigation into reliability and stability. In this project, DE and MIP are also applied to system reliability and stability issues. Two issues are involved here, cascading failure analysis and power system stabiliser (PSS) tuning. The former utilises MIP to form a probabilistic–based cascading model followed by further analysis and the latter exploits DE for global PSS parameters tuning. This is an important consideration in the planning topic.