In this study, an optimal meta-heuristic optimization algorithm for load frequency control (LFC) is utilized in two-area power systems. This metaheuristic algorithm is called harmony search (HS), it is used to tune PI controller parameters ( , ) automatically. The developed controller (HS-PI) with LFC loop is very important to minimize the system frequency and keep the system power is maintained at scheduled values under sudden loads changes. Integral absolute error (IAE) is used as an objective function to enhance the overall system performance in terms of settling time, maximum deviation, and peak time. The two-area power systems and developed controller are modelled using MATLAB software (Simulink/Code). As a result, the developed control algorithm (HS-PI) is more robustness and efficient as compared to PSO-PI control algorithm under same operation conditions. Keyword:LFC Meta-heuristic optimization Algorithm (HS) Integral absolute error (IAE) MATLAB environment

This research implements a PI controller based on harmony search (HS) optimization algorithm for voltage source inverter to improve the output performance under step load change conditions. The HS algorithm aims to handle the trial and error procedure used in finding the PI parameters and then apply the proposed control algorithm via the eZdsp TMS320F28355 board to link the inverter prototype with the Matlab Simulink. The mean absolute error (MAE) is used as an optimization problem to minimize the output voltage error for the developed controller (PI-HS) as compared to the PI controller based particale swarm optimization algorithm (PI-PSO). Based on the experimental results obtained, it is noted that the proposed controller (PI-HS) provides a good dynamic performance, robustness, constant voltage amplitude, and fast response in terms of overshoot, transient, and steadystate. Keyword:eZdsp TMS320F28335 board Harmony search PI controller SPWM with its C code Voltage source inverter Copyright © 2017 Institute of Advanced Engineering and Science.All rights reserved. Corresponding Author:Mushtaq Najeeb, Faculty of Electrical and Electronics Engineering, Pekan Campus, Universiti Malaysia Pahang, 26600, Pekan, Pahang, Malaysia. Email: eng.mushtaq2004@gmail.com INTRODUCTIONThe topic of the voltage source inverter is playing an important role nowadays in research area to generate an AC output for different applications [1]- [5]. An inverter device is required to convert a DC to an AC source because of the most applications are connected to the AC loads [6]- [9]. So, the main important feature of the inverter design is its controller improvement. In addition, the controller ability is to provide a good dynamic performance, keep a constant output voltage waveform and frequency regardless of different loads are connected [10]- [11].Therefore, there are a lot of various control algorithms have been carried out in the literature to solve the voltage control problems. The author in [12] has implemented a PI controller with a PWM algorithm for the PV inverter system using eZdsp F2812 board to keep the voltage waveform as a sinusoidal. Similarly, the researchers in [13] have also proposed a conventional controller of proportional-integral design to control the boost converter for the inverter system in order to get a good performance. In a related research, a field programmable gate array (FPGA) has been used in the PV inverter systems to develop the control algorithm described in [14]-[15] but it considered a time consuming task because it needs a wide knowledge in software programming. For a real time hardware setup, the reference [16] has used the platform of dSPACE DS1104 control unit to implement the PI controller of three-phase PV inverter system for a good dynamic performance. Also, same control unit has been used in [17] to enable the user to develop the control

Direction finding systems applying phase interferometer of long baseline gives high accuracy of the angle of arrival measurements; however, they are suffering from phase ambiguity and phase error due to antenna spacing greater than half wavelength of the intercepted signals. In this paper, the simple two-antenna interferometer system has been adopted with the zero-crossing technique used to solve the phase measurement ambiguities in the processing unit. The zeros-crossing of both channels (lead and lag) were extracted using electronic circuitry. A count gate was formed to count the zeros throughout the phase difference between the two channels. The ambiguity factor was taken to be half of the even count which will be added to the output of the phase comparator to estimate the total phase difference. Multisim software has been used to simulate the proposed processing unit and the ambiguity was calculated for different values of phase difference. Antenna spaces (D/λ) of (1/2, 1, 2, 4, 8, 12, 14, and 16) were applied to the system and the corresponding ambiguity factors have been measured to be (zero, 1, 2, 4, 8, 12, 14 and 16) respectively. Therefore for antenna spaces (D ≤ λ/2) there is no ambiguity. These simulated results show a coincidence with the theoretical values. The lead-lag channels were also solved without the need to add other antennas to the system since the first zero detected by either antenna refers to the lead channel. The proposed technique has advantages over others since it solves ambiguities on the basis of real-time processing without the need for complex, expensive, heavy, and slower response systems.