Transmission System Unbalanced Three-Phase Power Flow
Use of DEW/ISM to perform three phase unbalanced power flow to evaluate the impact of EHV/HV transmission system voltage imbalances on distribution systems. Project work included:
- Build three-phase, unbalanced model of a portion of the TVA power system.
- Perform quasi-steady state power flow analysis and compare calculated results of unbalanced voltages of unbalanced voltages against field measurements of the unbalanced voltages.
- Demonstrated that calculated unbalanced voltages as a function of time matched well against TVA unbalanced measurements on 500 kV/161 kV transformers.
- Demonstrated that phase rotations within substations could be used to improve the imbalance.
Comparison of Measured Values with DEW Calculated Results
|Variable||Measured Value||DEW Calculated Value|
|Max Spread in % of VRMS for phases A, B, and C||3.2%||3.2%|
|Negative Sequence Voltage / Positive Sequence Voltage||1.75%||1.84%|
|ANSI C84.1 Standard Imbalance||1.84%||1.85%|