This paper presents the dynamic simulation and testing to verify the smart substation solutions designed for a brown field 110 kV retrofitting project. An IEC 61850 based aotomation design, transitioning the conventional substation into a smart substation, where existing current/voltage transformers remain in service, and smart Field Apparatus Interface Units (FAIUs) are utilised to bridge the conventional primary system to the IEC 61850 based secondary system. While outdoor switchgears and field instrument transformers are equipped with FAIUs, MV indoor switchgears are installed with IEDs mounted on the top. Direct point-to-point connections serve as process buses, and a single PRP/RSTP LAN is employed at station bus level. Extensive dynamic simulation and testing were conducted in the Smart Substation Technologies Lab, and test results show the smart substation performance meets and exceeds the substation reliability requirement.