"Comparison Analysis of AC Voltage Controllers Based on Experimental and Simulated Application Studies" Hamdy. A. Ashour and Rania. A. Ibrahim Arab Academy for Science & Technology Department of Electrical & Computer Control Engineering, 1029 Miami, Alexandria, Egypt hashourgaast.edu, rania assemgalexseeds.com Abstract- This paper introduces a detailed comparison between possible connections of AC voltage controllers. For each configuration, the experimental setup is implemented and the corresponding simulation program is presented using Simulink under Matlab. The simulated and experimental instantaneous voltage and current waveforms in case of resistive and inductive loads are matched well, validating the simulation comparison for analysis. The comparison analysis includes the required number of devices and isolated gate signals, which determines the complexity and the size, hence the overall cost. Also harmonic spectrum, total harmonic distortion, effective rms value, dc offset and the control range are compared to specify the performance. The implementation of a fixed- capacitor thyristor controlled reactor (FC-TCR) and three phase induction motor starters (SOFT STARTER) as two application case studies of AC voltage regulators has been discussed. Experimental and simulation results have been obtained and well correlated, showing the effectiveness of such configurations in the fields of control of reactive power flow and in the field of controlling the starting performance of three phase induction motor. LIST OF SYMBOLS VO rms VS n, m k a '3 0 IFC-TCR, VFC- BFC -TCR BC BTCR Bmax Co C,L : rms output load voltage : rms supply voltage : Number of ON & OFF cycles : Duty cycle : Delay angle : Extinction angle Load angle Conduction angle (8 =,8 - a) -TCR FC-TCR current and voltage Compensator susceptance Capacitor susceptance Inductor susceptance as a function of delay angle Maximum inductor susceptance Angular frequency Capacitance & inductance value I. INTRODUCTION: The AC voltage controller can be considered as a voltage regulator device by which the root mean square load voltage (rms), hence the power flow, can be set and maintained constant at a certain desired value. The recent developments achieved in the field of power electronics, control techniques and microprocessors have introduced such AC voltage controllers for the applications of power ranges from few watts up to fractions of megawatts, such as light dimmers, heating, melting, arc furnace, transformer tap changing, cycloconverters, wind turbines, power factor improvement, flexible transmission systems (FACTS), static switches, AC motors control and operation [1-13]. The operation of the AC voltage controllers have been explained in literatures [5-8]. This paper introduces a comparison between eleven possible configurations of the AC voltage controllers based on experimental and simulation analysis. Principle of operation is reviewed, experimental setup and software simulation are introduced, a detailed comparison has been carried out and two different application case studies have been discussed for practical validation. II. AC VOLTAGE CONTROLLERS: If a thyristor switch is connected between an AC supply and load, the power flow can be controlled by varying the rms value of the AC voltage applied to the load. This type of power circuit is known as an AC voltage controller (regulator). Since the input voltage is AC, the thyristor is line commutated, so there is no need of extra commutation circuitry and the circuits for AC voltage controllers are simple and relatively inexpensive. AC switch can be implemented either using a single triac with a single isolated gate circuit but for lower power applications, using two back to back thyristors with two isolated gate circuits, using two diodes and two thyristors with a single isolated gate circuit, or with four diodes and a single thyristor with a single isolated gate circuit. The power flow to the load can be controlled by the ON-OFF or phase angle control techniques. For the ON-OFF control, the rms output voltage for resistive load can be expressed as [6]: Vorms L22(n+) f m)s m+n t) =VSmn = VSk While for the phase control VO can be expressed as: rm) (1) 1 F1( Si 2 - f 2f§ Sir?II 1 7-a/-v (2) V°rms 021- I 0 i 4t)1 =V / (T_ 2il The ON-OFF type of control can be applied in applications having mechanical inertia and high thermal time constant such as industrial heating and speed control of small motors, while the phase control can be utilized in many industrial applications such as motor starters, transformer tap changing and static VAR compensators. In case of inductive load, the current will not be in phase with the controlled voltage. In this case, in order to ensure full control of the AC voltage, a single gate pulse should be replaced with continuous train of pulses and the range of delay angle a is limited within the range of: 1-4244-0272-7/06/$20.00 ©2006 IEEE i: 79