With a fixed-rate energy plan, the price you pay for electricity each billing period will not change for the duration of your contract.
However, the price that your TDSP charges to deliver electricity to your home may change. This can only happen if the Public Utility Commission approves the change. If that happens, the TDSP charges on your bill would increase, but all the other charges (energy charge, base charge or usage charge) have to remain the same – those are fixed.
You can see all these elements of your price broken down at the top of your EFL.