In modern power systems, renewable energy resources are becoming more relevant due to their eco-friendly nature and sustainable electrification. Therefore, it is important to consider the effects of the renewable energy resources (RERs) on the generation expansion planning and transmission expansion planning (GTEP) simultaneously. The proper assessment of power losses is essential in order to adequately evaluate the consequence of renewable energy resources in power systems. This paper presents multi-objective optimization problems that are solved using DC, modified DC and AC modelling methods in order to accurately and efficiently compute electrical losses and its impacts on the expansion planning procedure. This paper develops a Mixed Integer Non-linear Programming (MINLP) problem and was solved using CONOPT and CPLEX solvers embedded in Algebraic Modelling Language. The proposed methods are evaluated and validated on three case studies: IEEE Garver’s 6 bus system, IEEE 24 bus test system and a real-world Nigeria Power System. A comparative analysis of the three modelling approaches and a sensitivity analysis of the simulation results indicate that AC solution method provide an accurate computation of power losses and efficient optimal planning strategy as compared to the modified DC method.

在现代电力系统中，可再生能源由于其生态友好的性质和可持续的电气化而变得越来越重要。因此，重要的是要同时考虑可再生能源（RER）对发电扩展计划和输电扩展计划（GTEP）的影响。为了充分评估电力系统中可再生能源的后果，正确评估功率损耗至关重要。本文提出了使用直流，改进的直流和交流建模方法解决的多目标优化问题，以便准确，高效地计算电气损耗及其对扩展计划程序的影响。本文提出了一个混合整数非线性规划（MINLP）问题，并使用嵌入在代数建模语言中的CONOPT和CPLEX求解器进行了求解。在三个案例研究中对提出的方法进行了评估和验证：IEEE Garver的6总线系统，IEEE 24总线测试系统和现实世界的尼日利亚电力系统。对三种建模方法的比较分析以及对仿真结果的敏感性分析表明，与改进的直流方法相比，交流解决方案方法可提供精确的功率损耗计算和有效的最佳规划策略。