With the increasing scale of urban power grids and the application of various advanced power equipment, the comprehensive efficiency of the power system depends on the cooperation and synergy between various power equipment. Aiming at the physical entities with dynamic and real-time changes in the state of power equipment, constructing an efficient mathematical model is essential in system-level simulation of power systems and integrated design of large electromagnetic equipment. Taking the magnetically-saturated controllable reactor (MSCR) as the object, this paper proposes a nonlinear dynamic electromagnetic network model, considering the accuracy of theoretical analysis and the efficiency of parameter calculation.

Firstly, according to the structural characteristics and magnetic field distribution characteristics of MSCR, the MSCR solution domain is meshed by domain discretization. Considering the nonlinearity of the iron core, the magnetization curve model of the MSCR iron core is established by the piecewise interpolation method. The nonlinear grid parameters are calculated according to the principle of the flux tube. The MSCR equivalent magnetic network model is generated based on the loop current method.

Secondly, the electromagnetic model of circuit-magnetic circuit separation is established. The electromagnetic coupling equivalent circuit is established using the controlled source to realize the coupling connection between the circuit and the magnetic circuit. The nonlinear dynamic electromagnetic network model of MSCR is generated. Combined with the nonlinear iterative solution of the chord-cut method, the MSCR winding current and the core flux under different magnetic saturations are calculated.

Finally, a three-dimensional finite element model of MSCR is established based on the finite element method, and field-circuit coupling joint simulation is carried out. Experimental measurements are also performed on the MSCR winding current. The MSCR nonlinear dynamic electromagnetic network model is compared with the three-dimensional finite element model and experimental measurements. The MSCR nonlinear dynamic electromagnetic network model is verified.

(1) The proposed model's calculated winding current and core flux agree with the finite element model and experimental results under different magnetic saturations. (2) The calculation speed and the storage space of the proposed model in electromagnetic parameter calculation are approximately 50~240 times and 1/10 000~1/7 000 of the finite element model. The model can improve calculation efficiency and reduce cost while meeting computational accuracy. It has unique advantages in the initial design of controllable reactors and system-level simulation of power systems.