| Wind power is the most mature technology of the new energy at present, which iseconomical and one of the most potential energy for large-scale power generation. However,the stochastic of wind power makes it difficult in connecting to the power grid. ElectronicPower Transformer(EPT) has a certain flow control capability, but it brings harmonicpollution to the grid. This paper chooses the wind power grid-connect system with EPT as atypical case and studies the stochastic optimal harmonic power flow. This study isimportant for power system optimization operation with new energy generation intheoretical and practical.First, this paper analyses the gird connection of wind power system which is based onEPT, and then introduces the wind power and EPT briefly. After that this paper establishesthe steady-state model of power flow, and proposes a modified power flow calculationprogram considering the EPT wind power system. This program is the foundation for theharmonic analysis and optimization in the following research.Second, this paper studies the stochastic power flow of the wind power generation andEPT harmonic, introduces the harmonic probability index of the STHD95and the voltageprobability index of the SV95based on the traditional index of which is, in order tomeasure the stochastic quantitative. This paper describes the stochastic power flow by3-parameter Weibull distribution as well as the expectation and variance of the measuredwind speed. and describes the EPT harmonic by normal distribution. This paper calculatesthe basic operation state by alternating direction iterative, and stochastic harmonic powerflow by Gram-Charlier expansion theory based on semi-invariant. Furthermore this papergets the probability index of harmonic power flow of wind power from the calculation,besides, this paper takes the random characteristics assessment of voltage and harmonic ofthe grid.At last, this paper establishes the model of stochastic optimal harmonic power flowbased on wind power grid-connect system with EPT. The objective function has penaltyfunction formed by STHD95and SV95along with active power loss. This paper uses thegenetic algorithm and makes the stochastic constraint conditions of harmonic power flow clear in the control strategy by the active penalty function. This paper uses the IEEE14anddoes the programming and calculation on its stochastic optimal harmonic power flow inwind power grid-connect with EPT. Moreover, this paper brings in the rationalityassessment through overall indicators, and verifies the availability of the model andalgorithm. |
