1. Jeremy Till1, Shutang You2, Yilu Liu2
Impact of high PV penetration on the voltage stability of the ERCOT system
Jeremy Till1, Shutang You2, Yilu Liu2
1 Tennessee Technological University 2 The University of Tennessee, Knoxville
INTRODUCTION
Voltage collapse occurs when the bus voltage becomes unstable. This usually is caused by an increase in load to the point that reactive power is limited. The point the voltage collapses is called the critical point.
Photo-voltaic (PV) generators cannot provide the same reactive power as conventional generators. In theory, they create a greater risk of voltage collapse in the power system.
A power-voltage curve is an effective method to determine the critical point of a system.
Power-Voltage Curve
An example power-voltage curve[1]
CASE STUDY
We developed 0, 20, 40, 60, and 80 percent renewable penetration models of the Electric Reliability Council of Texas (ERCOT) power system for use in simulations. In each simulation, a region of Texas was selected and the load increased in that specific region until reaching the critical point.
Comparing the critical points shows that as renewables increase the system fails under less load. At the same time, the average bus voltage begins to decrease at a heavier load with more renewables.
Average bus voltage at all renewable percentage
Conventional generators have a steady power-voltage curve. PV generators increase voltage until their reactive power limit is reached and the voltage drops more rapidly with each MW of load.
Comparison of conventional and PV bus voltage
The topography map on the right is a study of the Austin, Texas area at voltage collapse. While the voltage in the study region collapses, the voltage in the surrounding areas receive relatively low impact. Voltage stability heavily depends on the generation within the region.
Voltage (pu)
Map view of ERCOT system at critical point
REFERENCES
[1] Kundur, Prabha. “Chapter 14 - Voltage Stability." Power System Stability and Control. Estados Unidos De America: McGraw Hill, N. pag. Print.
This work was supported primarily by the Engineering Research Center Program of the National Science Foundation and the Department of Energy under NSF Award Number EEC and the CURENT Industry Partnership Program