Intermittent ground fault detection method for power distribution network

• Main Authors: JIN LIER, YANG SHICHEN, ZHANG JIAN, ZHI YUQING, CHEN QI, XIE JUN, WANG KAI, ZENG ZHENG, LIAO WEN, XIE LEI, ZHANG CHI
• Format: Patent
• Language: English
• Published: 11.03.2015
• Subjects: MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

The invention discloses an intermittent ground fault detection method for a power distribution network in the field of power transmission and distribution. The method comprises the following steps: detecting impact current, starting alarming by a system, and continuously keeping a current running state of the power distribution network; if the impact current exists all the time, judging that an intermittent ground fault is not produced, carrying out corresponding conventional trip-out protection, and returning to a normal state after fault removal; if the impact current disappears within a short time and repeatedly appears within a certain time, judging that the intermittent ground fault is produced, and starting intermittent ground protection to guarantee that the fault is not extended; returning the rest systems which are normal through detection to the normal state; if the impact current disappears and does not appear for multiple times within a certain time or does not appear, judging that a transient fault is produced, and returning the system to the normal state. The method has the technical benefits that the problem of difficult capture of the intermittent ground fault due to difficult setting of the threshold value and time of the intermittent ground fault in conventional instantaneous overcurrent protection and inverse time protection is solved, the running reliability of the power distribution network is improved, and major accidents such as power outage of a whole station caused by the intermittent ground fault are avoided.