In this paper, an extensive literature survey on critical research areas of various load frequency control (LFC) methods in a deregulated power system with conventional and distributed power generators are emphasized. The main goal of LFC is to ensure zero steady state error for frequency and tie-line power deviations. This paper provides an overview of different types of deregulated power system structures, market models, contracts agreements and various control methodologies/techniques for mitigating the various LFC issues in a deregulated power system. Detailed analysis of various control methodologies based on classical control, robust and self tuning control and various soft computing control techniques are discussed. Finally, the investigations on incorporating fast acting energy storage devices such as Battery energy storage system (BESS), superconducting magnetic energy storage (SMES), Redox flow batteries (RFB) and Flexible AC transmission systems (FACTS) devices for mitigating the LFC problems in a deregulated power system are also addressed.