GABRIEL NICOLAE POPA, CORINA MARIA DINI, SORIN IOAN DEACONU, ANGELA IAGĂR Department of Electrotechnical Engineering and Industrial Informatics “Politechnica” University of Timisoara Revolutiei str., no.5, 331128, Hunedoara ROMANIA gabriel.popa@fih.upt.ro http://www.fih.upt.ro/v3/ In the paper is present power quality measurement analysis of three sections plate7type electrostatic precipitators supplied with traditional d.c. energization with analogical controlled anti parallel thyristors. The control of constant firing angle of thyristors is set depending on the secondary reference current. Analysis of the measure electrical parameters is done according with power quality standards EN 50160 (for voltage) and IEC 610007374 (for current). The measures were made in two regimes: a long period of time and short period of time. plate7type electrostatic precipitators, power supplies, power quality, total harmonic distortion The plate7type electrostatic precipitators (ESPs) are used for collecting fly ash from gases in thermal power plants that used pulverized coal as a fuel. Today, in industry, there are a lot of plate7type electrostatic precipitators that operate with traditional d.c. energization. From this reason it is imposed a power quality analyzer for that type of consumers that are fed from power supplies, running at 50 Hz, with two anti parallel thyristors [1,2]. The power electronics have detrimental effects on the power quality of a.c. supplies. The main problems on the quality of a.c. supplies are: communication interference, insulation failures (because over7heating and over7voltages), malfunction of commutation and protective equipments. Using correction capacitors, if power factor is low, the problems increase (amplify the current harmonics) [3]. The power supply of ESP must operate according with standards. Many industrial ESP section are fed by a single line commutated anti parallel thyristors that affect the power quality. The main advantage of using of that type of supply is the simplicity with implication in the lower cost. There are other types of supplies with better performance that can be used to sections supplies [4]. A device with a nonlinear current7voltage characteristic that is supply from a sinusoidal electric systems produce harmonic voltages and currents (especially). Harmonic voltages and currents present in electrical systems have some multiple of industrial frequency (50 Hz). The intensity of problems that occur in the presence of harmonics depends on the magnitude of distortion waveforms and the sensitivity of existing equipments [2,3]. Through using other type of supplies (i.e. intermittent energization, pulse energization) strongly reduce total ESP energy consumption (especially for high resistivity dust) and it is possible to improve collection efficiency [5,6] Industrial ESP that de7dusting large flow of gas are divided into several sections (that are supplied independently) in order to increase their collection efficiency. The typical output power range are tens kW and the secondary voltages are tens kV [4]. The power quality of power supplies that fed an ESP with three sections was presented in the paper. The power quality was investigated for d.c. traditional operation. The main structure of a power plant is in fig.1. Many power plants used coal that is transported to mills and then is burned in the boiler. A dirty gas is passed through an ESP (with few sections, usually three or four), and then is evacuated in the atmosphere through a high stack (2007250 m). Recent Researches in Circuits, Systems, Multimedia and Automatic Control ISBN: 978-1-61804-085-5 49