163 Copyright © 2018, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 6 DOI: 10.4018/978-1-5225-4077-9.ch006 ABSTRACT This chapter gives introduction to evolutionary techniques. Then it presents the problem formulation for load frequency control with evolutionary particle swarm optimization. It gives the application of particle swarm optimization (PSO) in load frequency control; also, it illustrates the use of an adaptive weight particle swarm optimization (AWPSO) and adaptive accelerated coefcients based PSO (AACPSO). Furthermore, it introduces a new modifcation for AACPSO technique (MAACPSO). The new technique is explained. A well-done comparison will be given in this chapter for these above-mentioned techniques. A reasonable discussion on the obtained results will be displayed. The obtained results are promising. 1. INTRODUCTION Frequency is an important factor to describe the stability criterion in power systems (Ismail & Hassan, 2012; Salami et al., 2006). To provide the stability of power system, the balance of power and steady frequency is required. In case of change occurs in active power demand or the generation in power sys- tems, oscillations increase in both power and frequency. Frequency depends on active power balance so it cannot be hold in its rated value (Azar, 2010, 2012a and 2012b). Thus, system suffering from a Load Frequency Control Based on Modern Techniques in Two Areas Power Systems Naglaa Kamel Bahgaat Canadian International College (CIC), Egypt Mohamed Ibrahim Al Azhar University, Egypt Mohamed Ahmed Moustafa Hassan Cairo University, Egypt Fahmy Bendary Benha University, Egypt