Research On 10kVSVG Control Technology And Application In Coal Mine

As the power load of coal mines in our country becomes larger and larger,the types of loads are becoming more and more complex.In particular,the access of a large number of non-linear and impact loads worsens the power quality of the power grid.Among the power quality problems,reactive power impact is the most Outstanding,therefore,it is of great significance to study the installation of reactive power compensation devices in coal mine power grids to improve power quality.Static var generator(SVG),as the latest generation of power system reactive power compensation device,has the advantages of good dynamic performance,high continuous control accuracy,and wide application range.Therefore,the main research object of this thesis is SVG in coal mine power supply system.After in-depth study of the basic principles of SVG compensation for reactive power in power systems,this subject designs the high-voltage SVG in Fengjiata Coal Mine to achieve the goal of quickly and effectively compensating reactive power and suppressing harmonic currents.The main contents include:First of all,I thoroughly studied the command current extraction technology of the SVG system,compared the two current detection methods,and finally chose the ip-iq current detection method,which has a simple structure and is more suitable for the harsh power grid voltage conditions of coal mines,as the command current extraction method of this SVG.And improve it to make it have the function of extracting harmonic current components.Aiming at the difficulty of phase locking caused by the asymmetrical distortion of the grid voltage of the coal mine power supply system,which affects the command current extraction effect,and then affects the SVG compensation effect,a phase-locked loop(DSOGI-PLL)based on a dual second-order generalized integrator is proposed to replace The traditional phase-locked loop based on the synchronous selection of the coordinate system realizes the effective phase-locking of the system and overcomes the influence of the asymmetrical distortion of the grid voltage of the coal mine power supply system on the SVG compensation effect.Simulate and analyze the proposed DSOGI-PLL to verify its effectiveness.Secondly,conduct in-depth research on SVG in high-voltage power supply systems.It is proposed to use modular multilevel converter(MMC)as the main topology of Fengjiata high-voltage coal mine SVG system to solve the problem that traditional two-level and three-level bridge converters are not suitable for 10 k V highvoltage systems.A hierarchical model predictive control strategy is proposed as the current tracking control strategy of MMC-SVG.This control strategy inherits the excellent dynamic performance and compensation accuracy of the model predictive control strategy,while greatly reducing the computational complexity of the model predictive control.And it performs well in suppressing the circulating current between MMC phases and balancing the voltage of the bridge arm sub-modules.The entire SVG system is simulated and analyzed through the Matlab/Simulink simulation platform to verify the effectiveness and feasibility of the overall scheme.Then,according to the actual load situation of Fengjiata Coal Mine in Shaanxi Province,the installation location and compensation capacity of the SVG system were planned,and on this basis,the main circuit and control loop of the hardware part were designed.Finally,the actual application of the designed scheme is carried out,the monitoring system interface of the SVG system is designed,and the actual operation effect of the power system after the SVG device is installed is analyzed to prove the practical value of the design.