Online FIDVR Alert |
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Figure 1 Schematic diagram of the online FIDVR alert
Fault-Induced Delayed Voltage Recovery (FIDVR) is caused by wide-spread stalling of residential single-phase air conditioners, which can stall in less than two cycles and faster than fault clearance [1]-[2]. Once it stalls, a locked rotor current with four to six times the rated current is induced, thereby depressing voltages that can be observed in distribution, sub-transmission and transmission sides of the power grid [2]. Air conditioners trip because of their internal thermal protection, so there is a risk of over-voltages and equipment damage. One can visualize stalled air-conditioners as a wide-area high impedance distributed fault. Prolonged voltage depression represents a reliability threat due to an increased risk of losing power plants, SVCs, HVDC lines and ultimately disturbance cascading. Prolonged voltage depression can also result in the interruption of the customer's power consumption. In order to implement the online detection of FIDVR, we developed the online FIDVR alert using the FNET/GridEye [1]-[2]:
Alert.1: A voltage dip larger than 0.2pu within 3 cycles triggers the fault alert.
Alert.2: A under-voltage period longer than 5 sec triggers the air condition stall alert.
Alert.3: In the next two minutes after the air condition stall alert, any over-voltage period longer than 1 sec triggers the overvoltage alert.
With the help of the online FIDVR alert, we can see where and when a FIDVR event occurs and the historical data will help us to carry out further research. We are now trying to embed the online alert functions in FNET/Grideye system.
References
[1] Zhuohong PAN, Jidong Chai and Yilu Liu, “Fault–Induced Delayed Voltage Recovery Detection Using PMUs and FDRs Measurement Data”, in Advanced Grid Modeling 2014 Peer Review, 2014 AGM, April 2014, Knoxville, Tennessee, USA.
[2] Zhuohong PAN and Yilu Liu, "Fault-Induced Delayed Voltage Recovery Detection from Historical PMU and FDR Measurement Data", technical report, 2014.