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The fault location technique is described by considering a single-phase-to-ground fault on a radial system, shown in Figure 2. The selected system consists of an equivalent source G, the line between nodes M and WN and laterals. Loads are tapped at several nodes and conductors of different types are used on this circuit. The fault location technique consists of six steps. Figure 2. The single line diagram of a radial line experiencing a fault at F.

Figure 2 The fault location technique is described by considering a single-phase-to-ground fault on a radial system, shown in Figure 2. The selected system consists of an equivalent source G, the line between nodes M and WN and laterals. Loads are tapped at several nodes and conductors of different types are used on this circuit. The fault location technique consists of six steps. Figure 2. The single line diagram of a radial line experiencing a fault at F.

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The method was tested on an EMTP model of a typical distribution tapped network (Duke Power, 12.47 kV, three- phase, 4-wire) with approximately 200 fault cases by varying fault locations (main feeder and taps), fault resistances and fault inception angle. Sample results are shown below, where m [%] is calculated fault location:
The method was tested on an EMTP model of a typical distribution tapped network (Duke Power, 12.47 kV, three- phase, 4-wire) with approximately 200 fault cases by varying fault locations (main feeder and taps), fault resistances and fault inception angle. Sample results are shown below, where m [%] is calculated fault location:
Figure 1. Equivalent scheme of the distribution feeder. The method is based on the idea of fault location applied for short transmission lines [3], with all loads, including tapped lines, represented by a lumped-parameter impedance model placed behind the fault. This way of compensating for tapped loads is accurate as tapped load impedances are much larger than feeder impedance.
Figure 1. Equivalent scheme of the distribution feeder. The method is based on the idea of fault location applied for short transmission lines [3], with all loads, including tapped lines, represented by a lumped-parameter impedance model placed behind the fault. This way of compensating for tapped loads is accurate as tapped load impedances are much larger than feeder impedance.
separating this equation into real and imaginary parts., value of m can be obtained from after elimination of R ; using: la The fault type is considered by including the adequate voltages and currents. Unlike other methods using only local data [1, 2], this method is not affected if the fault current at a fault locator is not in phase with current at the fault. In conclusion, immunity to effects of load current and fault resistance is achieved. Compensation for tapped loads enables this method to provide accurate results, although, for heavily tapped feeders, the accuracy may degrade toward the end of the feeder.
separating this equation into real and imaginary parts., value of m can be obtained from after elimination of R ; using: la The fault type is considered by including the adequate voltages and currents. Unlike other methods using only local data [1, 2], this method is not affected if the fault current at a fault locator is not in phase with current at the fault. In conclusion, immunity to effects of load current and fault resistance is achieved. Compensation for tapped loads enables this method to provide accurate results, although, for heavily tapped feeders, the accuracy may degrade toward the end of the feeder.
Figure 3. Fault voltages and currents at nodes F and N. The voltages and currents at nodes F and x are related by
Figure 3. Fault voltages and currents at nodes F and N. The voltages and currents at nodes F and x are related by
As far as only one-end supplied radial networks are considered, the positive sequence fault-loop impedance is calculated according to well known equations depending on the type of fault, as shown in Figure 4.
As far as only one-end supplied radial networks are considered, the positive sequence fault-loop impedance is calculated according to well known equations depending on the type of fault, as shown in Figure 4.
Let us consider the equivalent positive-sequence scheme of the fault-loop. The shunt elements represent loads at successive nodes while the cable impedance is represented by the series elements. Defining an equivalent fault-loop impedance as seen from ith node to the fault point one obtains the following recursive form (Figure 5). Figure 5. Equivalent positive-sequence diagram of the faulty cable. In the above equation Z , , represents the cable segment 1
Let us consider the equivalent positive-sequence scheme of the fault-loop. The shunt elements represent loads at successive nodes while the cable impedance is represented by the series elements. Defining an equivalent fault-loop impedance as seen from ith node to the fault point one obtains the following recursive form (Figure 5). Figure 5. Equivalent positive-sequence diagram of the faulty cable. In the above equation Z , , represents the cable segment 1
Figure 6. Idea of the feeder model representation; dotted lines are for grounding system connection. A 10 kV substation is supplied from 150 kV system. The network contains of rings and sub-rings, containing several 10/0.4 kV transformer-houses. Example of the analysed network is presented in Figure 6.
Figure 6. Idea of the feeder model representation; dotted lines are for grounding system connection. A 10 kV substation is supplied from 150 kV system. The network contains of rings and sub-rings, containing several 10/0.4 kV transformer-houses. Example of the analysed network is presented in Figure 6.
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Electrical EngineeringPower SystemsFault location
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