Study On Influence Of Power Quality In Wind Power Connection Grid

In recent years, with the proportion of wind power in the global total continue to increase, the power quality problems caused by wind power grid also has attracted much attention.A large number of nonlinear electric equipment and impact load connected to the power grid has seriously deteriorate the power quality,it reduces the power grid safe.Among that the harmonic and transient disturbance are the main grid power quality problems.Harmonic increased grid power.The random and moments of transient disturbance can cause a serious impact to the power grid.It is very important to improve the power quality,which research real-time accurate detection methods that to detection harmonic and disturbance signal.In this paper, for the problem of transient disturbance caused by wind power grid,propose a comprehensive algorithm that based on FFT algorithm and Wavelet packet analysis.Firstly,Identify the frequency range of signal by FFT.Then, evenly divide band use the excellent time-frequency characteristics of wavelet.Finally,select the optimal wavelet,and then get harmonic component by use the wavelet to decompose the signal within a certain frequency band.Simulation experiments showed that the algorithm can accurately detect every harmonic component, has the advantage of high real time capability.In this paper,for the problem of transient disturbance caused by wind power grid,put forward a method to detect the disturbance signal based on Daubechies wavelet.By analyzing the characteristics of several typical wavelet bases,selects db4 as the optimal wavelet basis that because db4 has orthogonality and time domain compactly supported.Then according to the relationship of signal singularity and it's WT modulus maximum.Using db4 wavelet fast and accurate positioning the beginning and ending time of signal mutationUsing db4 wavelet fast and accurate positioning the beginning and ending time of signal mutation.MATLAB simulation results show that the algorithm can quickly locate disturbance begin-end time, identify all kinds of disturbance signal, it solved the low problem of transient disturbance signal recognition.In order to achieve the assessment of power quality problems caused by the wind power connection grid,set up a multi-index comprehensive evaluation model of entropy weight fuzzy,and designed the real-time monitoring system of power quality,wind power harmonic testing solutions and disturbance identification scheme.Experimental testing datas shows that the scheme can accurately detect the harmonic and transient disturbance signal, and has made an objective power quality evaluation.The assessment scheme is feasible.