1 July 2001 SMES Modeling and Simulation Benchmarking Paulo F.Ribeiro Calvin College / BWX Technologies, Inc

2 July 2001 Outline SMES Coil Modeling Chopper / SMES Coil Transient Interaction Chopper Modeling + Coil Inverter + Chopper Modeling + Coil Modeling Integrated Energy Storage/Power Electronics/ Supply System Integrated System: Performance / Site Sensitivity Integrated System: CAPS Facility - STATCOM Impact Observations Conclusions

3 July 2001 Overall System Perspective

4 July 2001 Coil Modeling - Parameters Computation

5 July 2001 Coil Modeling - Assumptions  The dielectric constant of the insulating material does not vary with frequency  The thermal enclosure and the tank does not carry current, and they were represented as ground plane  A small value of resistor represents skin effect and eddy current losses.  Parallel plate model is employed to calculate ground and series capacitances of each turn.  To reduce the computing cost, each double pancake (two single pancakes) is represented by its series inductance, capacitance, mutual inductance and ground capacitances.

6 July 2001 Coil Modeling - Matrix Organization Cad= Capacitance between adjacent turns within a disk coil Cax= Capacitance between axially separated turns Cg= Capacitance between a turn and ground N= number of turns in a single pancake Nsp= Number of single pancakes in a coil

7 July 2001 Coil Modeling

8 July 2001 Coil Simulation Initial Voltage Distribution Frequency Response

9 July 2001 Chopper Modeling + Coil Transient Analysis and Protection

10 July 2001 Transients under Normal Operation Condition Chopper Modeling + Coil Transient Analysis and Protection

11 July 2001 Inverter + Chopper Modeling + Coil Modeling Basic Controls Have been developed Controls is a major task in order to guarantee optimum performance (for the several demonstration functions) and avoid negative power quality impact on the supply system

12 July 2001 Utility / Shipboard Supply System Considerations

13 July 2001 Integrated Energy Storage/Power Electronics/ Supply System

14 July 2001 Integrated System: Performance / Site Sensitivity SMES Close to Load Center SMES Close to Generation

15 July 2001 Observations The performance of an integrated STATCOM + SMES, and its dynamic response to system oscillations can be well observed and accurately determined by proper modeling and simulation using adequate EMTP Type programs. It has been observed that energy storage can enhance the performance of a STACOM and possibly reduce the MVA ratings requirements of the STACOM operating alone. This is an important finding for cost/ benefit analysis of FACTS / Power Quality devices. Also the combination of other FACTS / Power Electronics Devices should be investigated in order to increase performance and reduce cost. It has been also verified that a Voltage Source Inverter / STATCOM provides a real power flow path for SMES and that the SMES Coil chopper-controller can be controlled independently of the STATCOM controller. It was also observed that the location where the combined compensator is connected is important for improvement of the overall system dynamic performance. Although the use of a reactive power controller seems more effective in a load area, this simulation study shows that a STATCOM with real power capability can damp the power system oscillations more effectively, and therefore stabilize the system faster if the STATCOM - SMES controller is located near a generation area rather than a load area.

16 July 2001 Conclusions The development and implementation models for the simulation of high power electronics devices and associated energy storage systems such as a Superconducting Magnetic Energy Storage (SMES) system (SMES Coil and DC-DC Chopper) have been performed. Additional studies and verifications are required for better validation of benchmarking models The models/simulations are intended to provide a basis for verifying performance and developing functional specifications for the power electronics devices and associated interfaces subsystems. Power electronics devices topologies, technologies, protection and control strategies will be discussed and evaluated for its optimum performance on a specific location. EMTP and Dynamic Stability programs are required for the proper modeling and simulation of a SMES system for utility application.