Dynamic line rating determination apparatus and associated method

• US 10,447,041 B2
• Filed: 05/17/2016
• Issued: 10/15/2019
• Est. Priority Date: 05/18/2015
• Status: Active Grant

• Current Assignee: General Electric Technology GmbH (GE Aerospace)
• Original Assignee: General Electric Technology GmbH (GE Aerospace)
• Inventors: Ha, Hengxu, Na, Deng
• Primary Examiner(s): Donovan, Lincoln D
• Assistant Examiner(s): Almo, Khareem E
• Application Number:
  US15/574,854
• Publication Number:
  US 20180131189A1
• Time in Patent Office: 1,246 Days
• Field of Search: None
• CPC Class Codes: H02J 2203/20 Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
• CPC Class Codes: H02J 3/00 Circuit arrangements for ac mains or ac distribution networks
• CPC Class Codes: H02J 3/003 Load forecast, e.g. methods or systems for forecasting future load demand
• CPC Class Codes: H02J 3/20 in long overhead lines
• CPC Class Codes: H02J 3/22 in cables
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

A dynamic line rating determination apparatus configured to control the current applied to a power line conductor by determining a dynamic maximum current rating for said power line conductor, based on measured voltage and current phase vectors taken at two temporally spaced sample times, the phase vectors including a voltage and current phase vector for each phase of electrical power carried by the power line conductor at a first and second end of the power line conductor; and determining the dynamic maximum current rating by; applying the phase vectors to a power line model to estimate the conductor temperature, applying the estimate to a thermal model to predict a steady state temperature that the power line conductor will reach, and calculate the dynamic maximum current rating based on the prediction of the steady state temperature, a power line conductor current, and a maximum temperature limitation value.

Claims

1. A dynamic line rating determination apparatus configured to provide for the control of the current applied to a power line conductor by determination of a dynamic maximum current rating for said power line conductor, the apparatus configured to;

based on a set of measured voltage and current phase vectors taken at, at least two temporally spaced sample times, the voltage and current phase vectors comprising;

a voltage phase vector for each phase of electrical power carried by the power line conductor at a first end of the power line conductor;

a voltage phase vector for each phase of electrical power carried by the power line conductor at a second end of the power line conductor;

a current phase vector for each phase of electrical power carried by the power line conductor at a first end of the power line conductor; and

a current phase vector for each phase of electrical power carried by the power line conductor at a second end of the power line conductor;

determine the dynamic maximum current rating by;

applying said set of voltage and current phase vectors to a predetermined power line model to determine an estimate of the real time conductor temperature,

applying said estimate of the real time conductor temperature to a predetermined thermal model to determine a prediction of a steady state temperature that the power line conductor will reach over time, and

calculating the dynamic maximum current rating based on at least said prediction of the steady state temperature, a power line conductor current, and a maximum temperature limitation value.

2. An apparatus according to claim 1, wherein a set of positive sequence components, derived by a method of symmetrical components, of the voltage and current phase vectors is applied to the predetermined power line model, the set of positive sequence components comprising;

a positive sequence voltage component for the first end;

a positive sequence voltage component for the second end;

a positive sequence current component for the first end; and

a positive sequence current component for the second end.

3. An apparatus according to claim 1, wherein the set of positive sequence components are determined based on the following equation;

4. The apparatus of claim 1 wherein the apparatus is configured to;

determine the estimate of the real time conductor temperature Tc based on the predetermined power line model represented in the equation below;

5. The apparatus of claim 2, wherein the apparatus is configured to determine the power line conductor current, I, as an average of a power line conductor current, by the following equation;

6. An apparatus according to claim 5, wherein the apparatus is configured to determine the elongation parameter by any one of the following methods;

7. An apparatus according to claim 4, wherein, based on the power line model, the estimate of the real time conductor temperature Tc is derived using a non-linear least squares method.

8. An apparatus according to claim 1, wherein the apparatus being configured to apply said estimate of the real time conductor temperature to the predetermined thermal model to determine a prediction of a steady state temperature that the power line conductor will reach over time comprises;

determining a time constant representative of a predicted change in real time conductor temperature over time based on a time derivative of at least two calculated real time conductor temperatures at different times and using said time constant to determine the steady state temperature.

9. An apparatus according to claim 8, wherein the apparatus is configured to determine the steady state conductor temperature Tcss by the following process;

1) If |Δ

T_cI<

ε

T_css(k)=T_cv(k)

2) If not

10. An apparatus according to claim 1 wherein, the apparatus is configured to calculate the dynamic maximum current rating based on one or more of the following;

i. the predicted steady state temperature value T_css relative to the predetermined maximum temperature limitation value T_max;

ii. the difference between the predetermined maximum temperature limitation value T_max and a first steady state temperature value T_c0, relative to the difference between a subsequent steady state temperature value and the first steady state temperature value T_c0;

iii. the difference between the predetermined maximum temperature limitation value T_max and a first steady state temperature value T_css(k−

g), relative to the difference between a subsequent steady state temperature value T_css(k) and the first steady state temperature value and a change in the average conductor current, I, between the time of the first steady state temperature value and the time of the subsequent steady state temperature value.

11. An apparatus according to claim 1 wherein the apparatus is configured to calculate the dynamic maximum current rating, I max(k), based on one or more of the following equations;

12. An apparatus according to claim 1 wherein the apparatus is configured to calculate the dynamic maximum current rating, I_max, based on;

determination of one or more of the following variables for use as judgment conditions in one or more of three different cases, wherein,

Δ

I is a difference between two successively determined conductor currents, where k−

1 represents a first determined value and k a subsequent determined value;

Δ

I=I_k−

I_k-1

Δ

T_css is a difference between two successively determined steady state conductor temperatures where k−

1 represents a first determined value and k a subsequent determined value;

Δ

T_css=T_css(k)−

T_css(k−

1)

T_c0 is an initial steady state conductor temperature when there is no current flowing in the power line;

Δ

T_c0 is the difference between two successive initial steady state conductor temperature,

Δ

T_c0=T_c0(k)−

T_c0(k−

1)

ε

1, ε

2, ε

3 and ε

4 are all predetermined threshold values that control the determination of I_max; and

the dynamic maximum current rating I_max is calculated by one or more of the following equations;

i) if |Δ

I|≤

ε

1, I_max(k) is calculated using the following equation;

13. An apparatus according to claim 1 wherein the apparatus is configured to check that the calculated dynamic maximum current rating I_max(k) value lies within predetermined bounds prior to the apparatus providing it for control of current applied to the power line conductor.

15. An electricity distribution grid or an electricity transmission grid including at least one power line conductor for carrying electrical power around said grid, the grid including the apparatus of claim 1 for controlling the power applied to said at least one power line conductor.

14. A method of providing for the control of the current applied to a power line conductor by determination of a dynamic maximum current rating for said power line conductor, the method comprising;

based on a set of measured voltage and current phase vectors taken at, at least two, temporally spaced sample times, the voltage and current phase vectors comprising;

a voltage phase vector for each phase of electrical power carried by the power line conductor at a first end of the power line conductor;

a voltage phase vector for each phase of electrical power carried by the power line conductor at a second end of the power line conductor;

a current phase vector for each phase of electrical power carried by the power line conductor at a first end of the power line conductor; and

a current phase vector for each phase of electrical power carried by the power line conductor at a second end of the power line conductor;

determining the dynamic maximum current rating by;

applying said voltage and current phase vectors to a predetermined power line model to determine an estimate of the real time conductor temperature,

applying said estimate of the real time conductor temperature to a predetermined thermal model to determine a prediction of a steady state temperature that the power line conductor will reach over time, and

calculating the dynamic maximum current rating based on at least said prediction of a steady state temperature, a power, line conductor current, and a maximum temperature limitation value.