Designs Of Magnect-Geared Speed Regulator For Energy Storage Condenser System

With the increase of the penetration of new energy,the frequency regulation capability,voltage support and inertia support of power system are gradually weakened.In order to improve the regulation capability of new energy stations,it is necessary to use equipment of dynamic reactive power regulation and increase energy storage.However,traditional synchronous condensers do not have the capability of primary frequency regulation.In order to increase the active power support of the system,the synchronous condensers and flywheel energy storages can be combined in the new energy power system to form a condenser-flywheel energy storage system(CFESS)that participates in the regulation of the power grid for stable operation.One of the key technologies for realizing the CFESS is the speed regulator that connects the synchronous condenser with a fixed speed and the flywheel with a continuously varying speed.A magnetic-geared speed regulator(MGSR)is suitable for this application with the variable speed ratio.The MGSR has two mechanical ports and one electrical port,and it can make bidirectional energy transfer between the two mechanical ports.For the main purpose of improving torque density,this thesis proposes dozens of structural designs of MGSR for the CFESS.On the basis of comparing and analyzing the torque densities,electromagnetic losses and efficiencies of these designs,the best design is chosen.The main work of this thesis is detailed as follows.This thesis analyzes the basic condition for stable transmission of magnetic torque based on the field modulation theory that a coaxial magnetic gear(CMG)relies on to transmit torque,and it verifies this theory through the analysis of the flux density harmonics in the air gap.The basic composition of the CFESS is introduced,and the operation theory of CMG is extended to the MGSR used for the CFESS.The thesis also develops the basic equations that describes the different working states of the MGSR,and the power flow between the ports of the MGSR under each working state is analyzed based on these equations.It is also revealed that the capacity of the inverter is proportional to the speed range of the flywheel.The thesis builds the finite element model of the MGSR,determines the range of the power supply frequency according to the speed range of the flywheel,calculates and analyzes the torque curve and loss characteristics of 6 typical charge/discharge states.These simulation results verify the operation principle of MGSR.The thesis investigates the impacts of structural designs,such as permanent magnets,modulators,stator slots,on the torque and loss performances.With equal amount of permanent magnet,the thesis adopts surface-mounted,consequent pole,V-shaped arrangements of permanent magnets,and applies radial and Halbach array magnetizations for the surface-mounted permanent magnets,in order to compare the electromagnetic performances of these arrangements and magnetizations of permanent magnets.Based on the surface-mounted and V-shaped permanent magnets,the thickness and width of the modulators and the shape of the stator slots are adjusted to form 26 electromagnetic designs.By comparing the torque and loss performances of these designs,a preferred design is selected.This design of MGSR significantly improves the torque density and yields a high operating efficiency.The thesis explores the feasibility of the MGSR for CFESS,reveals the impacts of key structure designs on the electromagnetic performances of MGSR,and provides technical ideas for the design optimization of MGSR.