Abstract

Large-scale wind power integrated into power grids brings serious uncertainties and risks for power system safe operation, and it is imperative to evaluate power system security risk pertinent to high-level of uncertainties. In this paper, a comprehensive source–network–load probabilistic model, representing the typical uncertainties penetrated in power generation transmission consumption portion, is firstly set for power system operation. Afterwards an integrated LHS–CD approach based on the Latin hypercube sampling (LHS) and Cholesky decomposition (CD) is tailored to effectively conduct the security risk assessment, in which the LHS is utilized to stratified sample the uncertainties of wind power and thermal power, transmission line outage, and load demands, while the CD part is adopted to address the correlations of uncertainties by rearranging the sampled matrix generated by LHS. Moreover, static voltage risk and transmission line overloaded risk index are properly defined for quantitatively evaluating power system operational security risk. Simulation results of a modified New England 39-bus system confirm that the proposed integrated LHS–CD approach is effective and efficient for power system security risk assessment with consideration of source–network–load demand uncertainties.

Highlights

  • Power system operation usually involves various uncertainties stemming from, for instance, stochastic load demands, power source output fluctuations, and transmission line failure, etc

  • With the rapid increase of wind power generation worldwide, the variability and uncertainty of wind power bring heavy power fluctuations into power networks and increase power system operation risk, such as the voltage fluctuations and transmission line overloaded caused by the high level of wind power penetration [1,2]

  • Based on effective combinations of the Latin hypercube sampling (LHS) and Cholesky decomposition (CD) strategy, an integrated LHS–Cholesky decomposition (LHS–CD) approach is proposed for power system security risk assessment with the advantages of high efficiency

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Summary

Introduction

Power system operation usually involves various uncertainties stemming from, for instance, stochastic load demands, power source output fluctuations, and transmission line failure, etc. The LHS method is used to sample the uncertainties of wind power and thermal generators, probabilistic transmission line outages, and load demands; the Cholesky decomposition is adopted in order to rearrange the sampling matrix for dealing with wind power correlations and load demand correlations. With the help of introducing LHS to sample the source–network–load demand uncertainties and adopting CD to handle wind power and load demand correlations by rearranging the sampling matrix, an integrated LHS–CD approach is tailored to handle power system generation–transmission–consumption uncertainties for security risk assessment. We present the source–network–load probabilistic model for describing the uncertainties uncertainties of transmission line outages, load demands, wind power generation, and thermal of transmission line outages, load demands, wind power generation, and thermal power generation power generation for power system security risk assessment.

Discrete
Probabilistic Model of Correlated Wind Power Output
A Bv Cv 2 Prate vin vof any vrate
Probabilistic Model of Thermal Generator Operation State
Probabilistic Model of Correlated Load Demands
Integrated LHS–CD Approach for Power System Security Risk Assessment
Sampling Based on LHS
Permutation Based on CD
CD-Based Permutation for Independent Random Input Variables
CD-Based Permutation for Correlated Random Input Variables
Static Voltage Risk Index
Transmission Line Overloaded Risk Index
Simulation Results
Comparison of MC and for for Wind
Comparison
LHS–CD for Powerthe
Influence of Wind
Accuracy of Security Risk Assessment
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