The Small Current Grounding System Fault Line Selection Research In Thermal Power Plant Of Daqing Petrochemical Company

Thermal power plant of daqing petrochemical company 35 kv electrical workshop and the 6 kv system now are all neutral point via arc suppression coil grounding mode, the fault current is small, the small current grounding system single-phase earth fault system can bring to continue running 1～2 hours, without affecting the continuous power supply to the user. But this small due to system fault current, and arc instability caused by the transition resistance instability factors, such as the small current grounding system of single-phase grounding line selection accuracy has been unsatisfactory, the small current grounding system of single-phase earth fault line selection this problem has also been a power workers continued attention and the difficulties of the study.The small current grounding system at home and abroad were introduced in this paper the development of single-phase earth fault line selection, and according to the thermal power plant of daqing petrochemical company electrical workshop electrical system at a time, into ever use a neutral point grounding system are introduced and are using the knowledge of the neutral point via arc suppression coil grounded system; Analyses the fault characteristics of the single-phase grounding fault occurs, the transient electric parameters and static electricity characteristic; For the existing main line selection method and thermal power plant of daqing petrochemical company use YH-B811the basic principle and limitations of device are analyzed and compared; Using MATLAB simulation platform, according to the actual setting up of a 6 kv electrical workshop three loop simulation model of the small current grounding system of neutral point grounding and single-phase grounding by arc suppression coil grounded system is simulated, and the line selection method than amplitude method of zero sequence current and zero sequence current direction method, first half wave method, the transient zero sequence current characteristic frequency method, five line selection methods, such as harmonic method, injecting signal method, the simulation research and analysis the waveform simulation, obtained their respective applicable conditions and dead zone; This article also combined with the thermal power plant of daqing petrochemical company electrical workshop the practical operation of the small current grounding system, summarized a set of small current line selection and fault wave record of equipment used, the combination of comprehensive judgment fault line method, and the field grounding phenomenon, fault judgment and handling in detail, which is order thermal power plant of daqi ng petroche ni cal company deal wththeopti mal scheme of single-phase earth fault.