ECEN 460 Power System Operation and Control Lecture

ECEN 460 Power System Operation and Control Lecture 19: PV Buses, Generator Limits, and Power Flow Example 2 Prof. Adam Birchfield Dept. of Electrical and Computer Engineering Texas A&M University abirchfield@tamu. edu

2 Announcements • Homework and reading assignment due Thursday, March 18 – – • • Thursday, March 18 is a redefined Friday Lab 4 this week This week office hours moved to today 9 -11 am Exam 2 on March 24 – • Read book Chapter 6. 3 -6. 6 Book problems 6. 9, 6. 12, 6. 18, 6. 25, 6. 38, 6. 43 For extra practice: 6. 39, 6. 40, 6. 44 Quiz 6 will be on Gauss and Newton-Raphson Mainly covers Y-bus, Gauss, Newton-Raphson, Power Flow No lab next week due to exam

3 Power Flow Problem Variables •

4 Power Flow Bus Types • For slack bus: no power balance equations (P, Q pick up the slack) For Load (PQ) buses: 2 power balance equations (P, Q must balance) For Generator (PV) buses: only need 1 power balance equation (P must balance, V magnitude remains fixed by controlling generator reactive power)

5 Generator Reactive Power Limits • • The reactive power output of generators varies to maintain the terminal voltage; on a real generator this is done by the exciter To maintain higher voltages requires more reactive power Generators have reactive power limits, which are dependent upon the generator's MW output These limits must be considered during the power flow solution – – During power flow, once a solution is obtained, check to make generator reactive power output is within its limits If the reactive power is outside of the limits, fix Q at the max or min value, and resolve treating the generator as a PQ bus • • • this is know as "type-switching" also need to check if a PQ generator can again regulate Rule of thumb: to raise system voltage we need to supply more vars

6 Power Flow Example #2 • • Bus 1 contains a large generating unit operating at V=1. 0 pu Bus 2 has a load consuming 200 MW and 100 MVR Bus 3 has a generator that is set to produce 30 MW and control its terminal voltage to 1. 0 pu Want to solve for all bus voltages and line flows

7 Newton-Raphson Power Flow Procedure •

Power Flow Example #2 8

Power Flow Example #2 9

Power Flow Example #2 10

11 Power Flow Example #2, Solution • Bus Type Known 1 Slack 2 PQ P, Q 3 PV P, V Unknown P, Q

12 Power Flow Example #2, Solution Bus Type Known 1 Slack 2 PQ P, Q 3 PV P, V Unknown P, Q •

13 Power Flow Example #2, Solution •