Sensitivity based Thevenin index for voltage stability assessment considering N-1 contingency
AssigneeGeiri Co Ltd, State Grid Jiangxi Electric Power Co, State Grid Corp Of China, Geirina Inc.
InventorsXiaohu Zhang, Di Shi, Xiao Lu, Zhehan Yi, Qibing Zhang, Zhiwei Wang
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Abstract
Systems and method are disclosed for monitor long-term voltage stability in a power system by estimating post-contingency operating point(s) considering PV-PQ transitions based on the current operating point; predicting a sensitivity based Thevenin index (STI) for each contingency using the estimated operating condition; and determining a voltage stability assessment (VSA) considering N−1 contingency.
Claims13
A method for determining long-term voltage stability in a power system, comprising:
- estimating post-contingency operating point(s) of the power system considering PV-PQ transitions based on the current operating point;
- predicting a sensitivity based Thevenin index (STI) for each contingency using the estimated operating condition;
- and
- determining a voltage stability assessment (VSA) considering N−1 contingency, wherein the current operating states {tilde over (θ)},{tilde over (V)}, further comprising determining post-contingency operating states as:
- [
- θ
- c
- V
- c
- ]
- =
- [
- θ
- ~
- V
- ~
- ]
-
- [
- f
- θ
- f
- V
- g
- θ
- g
- V
- ]
- -
- 1
-
- Δ
-
-
- F
- inj
- where ({tilde over (θ)}, {tilde over (V)}) is an operating point under base case;
- (θc,Vc) is an operating point following a contingency;
- Δ Finj is a vector containing the active and reactive bus injection changes which are numerically equal to the active and reactive line flow on an outage branch;
- fθ and fV represents the partial derivative of active power injection expression with respect to voltage angle θ and voltage magnitude V;
- gθ and gV denotes the partial derivative of reactive power injection expression with respect to voltage angle θ and voltage magnitude V;
- and
- operating a power generator adapted to be connected to a power grid and controlled by a processor.
A system to control a power system, comprising:
- a power generator;
- a power grid coupled to the power generator;
- and
- a processor to control the power grid with code for:
- estimating post-contingency operating point(s) of the power system considering PV-PQ transitions based on the current operating point;
- predicting a sensitivity based Thevenin index (STI) for each contingency using the estimated operating condition;
- determining a voltage stability assessment (VSA) considering N−1 contingency;
- and
- determining corresponding sensitivities as one predictor when dλ is a continuation parameter with:
- [
- f
- θ
- f
- V
- f
- λ
- P
- g
- θ
- g
- V
- g
- λ
- Q
- 0
- 0
- 1
- ]
-
- [
- d
-
-
- θ
- dV
- d
-
-
- λ
- ]
- =
- [
- 0
- 0
- 1
- ]
- where dλ represents the load increment, dθ and dV denote the change of voltage angle and voltage magnitude respectively, fpλ,gpλ indicate the amount of active and reactive power injection changes as a function of dλ;
- and where fθ and fV represents the partial derivative of active power injection expression with respect to voltage angle θ and voltage magnitude V−gθ and gV denotes the partial derivative of reactive power injection expression with respect to voltage angle θ and voltage magnitude V.
Dependencies are inferred from the claim text.