Research On Control Strategy Based On Three-phase Four-wire DSTATCOM

Due to the fast progress of society,people have more strict demand for power quality.As an advanced reactive power compensation device to improve power quality,the control policy of capacitor split distribution network static synchronous compensator（DSTATCOM）directly affects the compensation performance of the device,and then determines the power quality in the power grid.Therefore,this thesis takes the capacitor split DSTATCOM as the research entity to study its control strategy,for the sake of heightening the compensation function of the device and solving the trouble of the electirc energy quality of electirc energy grid.At the starting of the thesis,it introduces the research background and significance of the subject,as well as the progress course from poles to poles,and expounds the shortcomings of the traditional control strategy of capacitor splitting DSTATCOM.Secondly,the working principle of capacitor split DSTATCOM is introduced,and then the mathematical model is established to simulate the actual running state.Next,the adverse effects of unbalanced operation and noise intrusion on the device are theoretically analyzed.For purpose of diminishing this adverse outcome,the traditional linear active disturbance rejection controller（LADRC）is combined with the current inner loop of the device,and then the performance of capacitor split DSTATCOM is analyzed in frequency domain and time domain under this state.From the analysis,it is found that the compensation precision and speed of the device are not insufficient when using the traditional LADRC control strategy,and the noise suppression ability of the compensation device under the traditional LADRC control strategy is not obvious.Therefore,aiming at these two problems,the novel LADRC with new total disturbance observation deviation and total disturbance differential signal and the noise suppression LADRC with linear tracking differentiator（LTD）filtering and phase compensation are designed respectively.And the two types of controller are independently applied to the current inner ring.The tracking,immunity and stability of the novel LADRC are theoretically analyzed,and the noise suppression ability,phase compensation ability and stability of the noise suppression LADRC are theoretically analyzed.Finally,the simulation model is built through MATLAB,and the comparative simulation examples are verified on the AC and DC sides of the capacitor split DSTATCOM.For the simulation of the insufficient compensation performance of the device,the results show that the system neutral current and current tracking errors under the novel LADRC are less than those under the traditional LADRC.It shows that the compensation performance of the novel LADRC compensation device is better.According to the simulation of noise interference device,the results show that the fluctuation degree of DC side voltage under noise suppression LADRC is less than that under traditional LADRC,and the power factor curve under the noise suppression LADRC is closer to 1,indicating that the anti-noise ability of the compensation device using the noise suppression LADRC is better than that using the traditional LADRC.