Location

This example model can be found in the software under the category "Benchmarks" with the file name "HVAC_230kV_8Bus.ecf".

Description

Such models can be used to evaluate electromagnetic transient overvoltage caused by line switching, fault initiation, and clearing. It can also be used to test the performance of real protection relays interfaced with the simulators through digital to analog converters and power amplifiers or with the new IEC61850 Ethernet communication protocol used with model relays. This benchmark model contains five synchronous machines with built-in voltage and speed regulators, five two-winding transformers, six constant parameters lines, one load and works at three voltage levels 13.8 kV, and 230 kV. During the simulation, any kind of fault, including single-line-to-ground, three-phase, and two-phase-to-ground faults, can be introduced in different locations. For this example, three three-phase faults are considered on Buses 3, 6, 7, 11, and 12. The fault times can be modified as required by the user, and new faults can also be added on other buses.
All the machines of the generation system are controlled by internal exciters, governors (speed regulators), and stabilizers. The user can change this configuration by double-clicking on the machine subsystem and changing the values in the mask. The following is a snapshot of the machine configuration:

Figure 1: Synchronous machine configuration settings

Simulation and Results

As part of the example model setup, the user can perform three types of scenarios. The user can enable or disable five three-phase faults on different model buses. In this case, only two of the five three-phase faults equipped in this model will show the results, each fault is applied independently in different buses. The other 3 three-phase faults can be activated or deactivated following the same instructions given below.

Scenario 1: Three-phase fault on Bus 6

The first scenario is about introducing a three-phase fault on Bus 6 at 0.1s by 0.1s. This scenario gives the user an idea of reliability in power systems, and how it reacts after clearing a fault. The user can change these settings by going into the fault subsystem and changing the values of T1 and T2, configuring the fault activation and clear times, respectively. By default only this fault is enabled,  it is necessary to check the Enable option within the fault subsystem called Fault4 and also check the disable option within the faults subsystem called Fault1, Fault2, Fault3, and Fault5.

Figure 2: Fault configuration settings

The following are the results from ScopeView following the first scenario, a three-phase fault on Bus 6.

Figure 3: Bus Voltage on Buses 4 and 8 with a three-phase to ground fault at Bus 6

Figure 4: Primary and secondary current of transformer 4 with a three-phase to ground fault at Bus 6

Figure 5. Machine 1 Terminal Voltages and Speeds with a three-phase to-ground fault at Bus 6

Scenario 2: Three-phase fault on Bus 7

The model is also equipped with a three-phase fault on Bus 7. Similar to scenario 1, the default times for this fault are set to activate at 0.1s and clear 0.1s later. By default this fault is disabled and only the three-phase Fault4 described in scenario1 is enabled. To activate only this fault it is necessary to check the Enable option within the fault subsystem called Fault5 and also check the disable option within the faults subsystem called Fault1, Fault2, Fault3, and Fault4. 

The following are the results from ScopeView following the three-phase fault on Bus 7.

Figure 6: Bus Voltage on Buses 4 and 8 with a three-phase to ground fault at Bus 7

Figure 7: Primary and secondary current of transformer 4 with a three-phase to ground fault at Bus 7

Figure 8. Machine 1 Terminal Voltages and Speeds with a three-phase to-ground fault at Bus 7