Determining status of electric power transmission lines in an electric power transmission system
The present application discloses systems and methods to determine loss of at least one electric power transmission line in an electric power transmission system. In various embodiments, a system consistent with the present disclosure may include an electrical parameter monitoring subsystem configured to receive electrical parameter measurements and to determine a change of the electrical measurements. An analysis subsystem may determine whether a change in the electrical measurements is indicative of loss of at least one transmission line and may calculate a number of transmission lines lost based on the change. In some embodiments, a remedial action subsystem may be configured to implement a remedial action in response to loss of at least one transmission line. The number of transmission lines lost may be determined based on an angle difference ratio and a power ratio between two buses in electrical transmission system.
1. A system configured to determine a status of an electric power transmission line in an electric power transmission system, the system comprising:
an electrical parameter monitoring subsystem configured to:
receive a first plurality of electrical parameter measurements taken at a first location over a first period of time;
receive a second plurality of electrical parameter measurements taken at a second location over the first period of time;
establish at least one rate of change of angle difference threshold and one angle difference threshold;
a threshold adjustment subsystem configured to:
determine a first rate of change based on the first plurality of electrical measurements and the second plurality of electrical measurements over the first period of time;
determine that the first rate of change is within the at least one rate of change of angle difference threshold;
dynamically adjust the angle difference threshold based on the first rate of change;
an analysis subsystem configured to determine that the electric power transmission line is in-service.
2. The system of claim 1 , wherein the angle difference threshold is established using one of a standing angle difference between two points in the electric power transmission system, and a power transfer value between two points in the electric power transmission system.
3. The system of claim 2 , wherein the two points comprise transmission buses in the electric power transmission system separated by the electric power transmission line.
4. The system of claim 1 , wherein:
the electrical parameter monitoring subsystem is further configured to receive a third plurality of electrical parameter measurements taken at the first location and a fourth plurality of electrical parameter measurements taken at the second location over a second period of time;
the threshold adjustment subsystem is further configured to determine a second rate of change based on the third plurality of electrical measurements and the fourth plurality of electrical measurements over the second period of time;
the analysis subsystem is further configured to determine that the second rate of change is outside of the at least one rate of change of angle difference threshold; and
the system further comprises a remedial action subsystem configured to initiate a remedial action based on the determination that the second rate of change is outside of the at least one rate of change threshold.
5. The system of claim 1 , wherein the threshold adjustment subsystem is further configured to establish a margin value preserve transient stability and to compare the margin value to the first rate of change.
6. A method of determining a status of an electric power transmission line in an electric power transmission system, the method comprising:
establishing a threshold value of an electric parameter;
establishing a margin value suitable to maintain stability of the electric power transmission system;
establishing a rate of change range of the electric parameter;
determining a first present value of the electric parameter associated with an electric transmission line;
determining a first rate of change of the electric parameter associated with the electric transmission line;
determining that the first rate of change is within the rate of change range;
determining that the first present value of the electric parameter is below the sum of the threshold value of the electric parameter and the margin value;
dynamically adjusting the threshold value based on the present value of the electric parameter; and
determining that an electric power transmission line is in-service.
7. The method of claim 6 , wherein the initial threshold value comprises one of a standing angle difference between two points in the electric power transmission system, and a power transfer value between two points in the electric power transmission system.
8. The method of claim 7 , wherein the two points comprise transmission buses in the electric power transmission system separated by the electric power transmission line.
9. The method of claim 6 , further comprising:
determining a second present value of the electric parameter;
determining a second rate of change of the electric parameter;
determining that the second rate of change is outside of the rate of change range;
initiating a remedial action.
10. The method of claim 6 , further comprising:
determining a second present value of the electric parameter;
determining that the second present value of the electric parameter exceeds the sum of the threshold value of the electric parameter and the margin value; and
determining that the electric power transmission line is out-of-service.
11. The method of claim 6 , wherein the margin value is established to preserve transient stability.