Intelligent Systems in Power System

Information for:

Security Assessment

Fault Analysis

Power System Protection

Protection Logic

Figure 1. 3 bus system with a fault

Consider the 3-bus system in figure 1. Vignole, Castelnuov, and Bagio are substations. The breaker are represented by B1 to B4.

Suppose we have a fault between the substations at Castelnuov and Vignole

Substations Castelnuov and Vignole see the fault in the 1st zone

Substation Baggio sees the fault in the 2nd zone

The two substations that see the fault in the first zone will trip the associated relays, and under normal conditions, the breakers (B1 & B2) will open.

B4 should be opened if there is a relay or breaker malfunction at Castelnuov which results in B2 not opening.

Now observe the system below:

Figure 2.

Now what would happen if there is a fault between Castelnuov and Vignole B?
The relays at Castelnuov and Vignole will trip the breaker to isolate the fault.

Can you show which substation that sees the fault in 1st, 2nd or 3rd zone?

Castelnuov and Vignole see the fault in zone 1

Spezia, Baggio, and Vado Term see the fault in zone 2.

Magliano, Margione, Parma Vigh, Ospiate, Lacchiarel, and Turbigo St see the fault in zone 3.

Suppose the breaker at Vignole B failed to open what would happen?
Breakers at Vado Term, Spezia , Castelnuov should be opened to isolate the fault.

Suppose we have a fault in the system, and we use GAAM to ease our job in solving an event. Below is the hypothesis generated by GAAM for a fault between Castelnuov and Vignole B.

Figure 3.

Now look at the SER report data below:

Date	Time	Time (msec)	Substation Name	Volt (kV)	Line Name	Line No.	Status	Component

Figure 4.

We can see that after the relay tripped at both ends (Castelnuov-Vignole), the telepilot send a signal to open the breaker. The breakers at both ends will be opened after receiving the telepilot.Next the reclosure will try to close the breakers at both ends.

Something happened after the reclosure action?
When it recloses the fault is still not clear, then the breakers for all three phases are opened.

Can you tell what type of fault is it?
Phase A Single Line to Ground

Is it permanent or temporary fault?
It is a permanent fault since the fault was still there after the reclosure action.

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