Overview
MHO-type distance protection on parallel 735-kV transmission lines with zone logic, fault studies, and permissive trip signaling.
This example demonstrates distance protection on high-voltage transmission lines using digital MHO-type relays. It is a strong protection-focused seed post that broadens the initial community beyond converter and DER topics.
Two 735-kV, 200-km transmission lines connect two network equivalents. Line 1 is protected by two distance relays with first- and second-zone logic. The relays evaluate phase and loop impedances using Fourier-based phasor estimation and support permissive trip signaling.
Protection engineers are a major community audience. This model creates room for practical discussions around reach settings, sampling rates, accelerated tripping logic, and how simulation supports relay validation before field use.
Key Features
- Zone 1 and Zone 2 protection behavior
- Phase-to-ground and phase-to-phase fault handling
- Earth-return compensation factor
- Send Permissive Trip and Received Permissive Trip logic
- Multiple built-in test cases
Getting Started
- Program a fault on Line 1 and run a 0.3 s simulation.
- Explore impedance trajectories from Relay B1.
- Re-run the published test cases to compare zone operation and trip logic.
Model Specifications
| Parameter | Value |
|---|---|
| Product | SPS Software |
| Simulation type | Real-time |
| Software version | SPS Software 2026+ (with RT-LAB) |
| Recommended time step | Ts_Control = 16 × Ts_Power (32 samples/cycle); confirm Ts_Power in model |
| Real-time solver | ARTEMiS (CPU real-time) |
| Compatible hardware | OP4605XG2, OP4610XG2, OP5020XG2, OP5025XG2, OP5033XG2, OP5707XG2 |
| Model file | Coming soon |
Downloads
The downloadable model package is coming soon.
power_DistanceProtectionRelay (1).slx (604.7 KB)
