# Fix Power Flow Divergence and TDS Initialization Error in ANDES

Published:

As dsicussed in ANDES Discussions #386, the user may run into power flow divergence or TDS initialization error when revising cases file from given cases. In this blog, we will discuss how to fix these errors. The case files and source code can be found at andes_init_debug.

# Power flow divergence

AC power flow resutls are used as the initialization points of TDS. In ANDES, devices Bus, PQ, PV, Slack, Shunt, Line are used to solve AC power flow. Usually, the user may revise the system topology, such as adding new devices (Bus) or changing load (PQ). Belows are some possible reasons for failed power flow:

1. Power load unbalance is too large;
2. Bus initial voltage and angle are inapproriate.

# TDS initialization error

After solving the AC power flow, the dynamic device can be initialized from the power flow results. Belows list some possible reasons for failed TDS initialization:

1. Inapproriate limiter values, usually occurs in TurbineGov, Exciter if power flow is changed significantly;
2. Inapproriate dynamic devcie parameters;
3. Inapproriate equations in dynamic model, usually happens when developing new models.

Tags: