【正文】 are closed (or SI and S2) and the output voltage is equal to zero. When there is a voltage mg, the switch S4 is closed, and SI and S, are operated with a duty cycle D, generating a v, for pensation. When there is a voltage swell, the switch S3 is closed, and SI and S4 generate a v, with a polarity inverted for pensation. Switches S*S3 and S2amp。The 30th Annual Conference of the IEEE industrial Electronics Society, November 2 6,2020, Busan, Korea Compensation of Voltage Sags and Swells using a Singlephase ACAC Converter JOrge PhZ, Student member, IEEE, Victor Ciirdenas, Member, IEEE, Homero Miranda, Student member, lEEE and Ricardo AIvNeZ, Member,lEEE Centro de Investigacibn y Estudios de Posgrado, Facultad de Ingenieria, Universidad Autonoma de San Luis Potosi. Manuel Nava 8, Zona Universitaria 78290, San Luis Potosi, . MEXICO. Phone /Fax: 52(444) 8173381 : , , , . AbstractIn this paper, a topology to pensate voltage sags and swells simultaneously in critical loads is proposed. It consists in a singlephase ACAC converter in a matrix arrangement, which keeps a continuous regulation in the output voltage. The proposed scheme has the capability to pensate up to 25% voltage sags and 50% voltage swells. Energy storage devices are not required by the ACAC converter and it is connected between the AC mains and the load by using a series transformer. One of the advantages of this topology is that taps for the coupling transformer are no necessary to change the polarity of the pensation voltage. A four step switching technique is used to drive the ACAC converter switches, executing snubberless operation. The reference signal is generated using singlephase dq theory, obtaining a fast response time and bigh regulation. Simulation and experimental results of a 5kW capacity, 127V, 60Hz equipment are presented. I. INTRODUC~ON The quality of the AC mains has been affected by the use of new semiconductordevices technologies. Nowadays, it is mon to find disturbances in the amplitude or waveform shape of current and voltage in the electric systems. These conditions could produce fails in the equipments, raising the possibility of an energy interruption. The voltage fast variations that appear in the AC mains during 10 seconds or less are monly known as voltage sags and swells. These variations are produced by normal operation of high power loads as well as theirs connection and disconnection。 the voltage fast variation effects are function of the amplitude and the duration of the event. Some studies show that 92% of all disturbances in the electrical power distribution systems are produced by voltage sags [ 11. It is important to eliminate the voltage fast variations because they are the most frequently cause of disrupted operations for many industrial processes, particularly those using modem electronic equipment, which are highly sensitive to short duration source variations [2]. Dynamic Voltage Restorer (DVR) and Uninterrupted Power Supply (UPS) systems had been researched and developed along the last decades and they are capable to pensate voltage sugs and swells. Nevertheless, they depend on devices to store energy, like large capacitors or batteries bank. The nominal power operation is a function of size and capacity of those devices。 never should be closed at the same time in order to avoid a shortcircuit in the AC mains side. The switches are driven using a signal pattern which incorporate a fourstep switching strategy, reducing the switching losses and eliminating the use of snubbers circuits. 111. MODULATION TECHNIQUE The function of the singlephase ACAC converter is to reproduce a voltage with a peak amplitude lower or equal than the AC mains value. To achieve this, the voltage of the AC mains is modulated by using a switching pattem. The amplitude of the fundamental voltage will depend on the modulation index of the switching pattern. Fig. 3 shows the scheme used to obtain a pulsed pattern. In this case, it is used a Digital Signal Processor (DSP) to generate the duty cycle D and to control the PWM of the switching devices. The operation mode of the scheme consists in to obtain a reference signal that represents the pensation voltag