1July 2001

SMES Modeling and Simulation

Benchmarking

Paulo F.RibeiroCalvin College / BWX Technologies, Inc

2July 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

3July 2001

ControllerCoil Protection

CryogenicSystem

VCoil

ICoil

DewarPower ConversionSystem CSC

orVSC + dc-dcchopper

Transformer BypassSwitch Coil

ACLine

Overall System Perspective

4July 2001

Coil Modeling - Parameters Computation

, )21

8(ln(2

0 R

RRNL

12

25tan

3

2tan

3

2)1ln(

12)1ln(

12)ln(

2

11ln 11

2

2

2

2

2

2

2

222

a

b

b

a

b

a

a

b

a

b

b

a

b

a

a

bbaR

)(

4

)](2

)()2

[()(

2221

21

21021

dRR

RRk

kEk

kKkk

RRM

d

AC r0

d

5July 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.

6July 2001

Cad

Cg

Cax

1 2 N

1

2

Nsp

Coil Modeling - Matrix Organization

Cad = Capacitance between adjacent turns within a disk coilCax = Capacitance between axially separated turns Cg = Capacitance between a turn and groundN = number of turns in a single pancakeNsp = Number of single pancakes in a coil

NNsxNNsNxNNxNNxNNxN

NxNNxNNxNNxN

NxNNxNNxNNxN

NxNNxNNxNNxN

NxNNxNNxNNxN

NxNNxNNxNNxN

AJKL

HCDE

IBCD

JABC

KBAB

LCBA

Lturn

..............

.........................................................................................

.........................................................................................

..............

..............

..............

..............

..............

NsNsxABABsumKJKLsum

CBCDsumEDEFsum

ABABsumCBCDsum

KJKLsumCBCDsumABABsum

Ldb

22)(........................................)(

...............................................................................

........................................)()(

........................................)()(

)(....................)()(

7July 2001

Cad1 Cad2 CadN-1

Cax1

Ca-2

CaxN

Cax1

Cax2

CadN-1 Cad2 Cad1 CadN--2 CadN-1

1st Single Pancake 2nd Single Pancake 3rd Single Pancake

CaxN

1st Double Pancake

Cad1

Cad1 Cad2 CadN-1 CadN-1 Cad2 Cad1 CadN-1Cad1 CadN-2

a1 a1 a1 a1 a1 a1 bN a1

a2 a2 a2 a2 bN-1 bN-1 bN-1

aN

aN-1aN-1

b1 b1

b2

a1

b1 b1 b1

a1

a2

aN-1

b1

Coil Modeling

8July 2001

Coil Simulation

Initial Voltage Distribution

Frequency Response

9July 2001

Chopper Modeling + Coil Transient Analysis and Protection

10July 2001

Transients under Normal Operation Condition

Chopper Modeling + Coil Transient Analysis and Protection

11July 2001

Inverter + Chopper Modeling + Coil Modeling

Basic ControlsHave 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

12July 2001

Utility / Shipboard Supply System Considerations

13July 2001

Integrated Energy Storage/Power Electronics/ Supply System

14July 2001

Integrated System: Performance / Site Sensitivity

SMES Close to Load Center

SMES Close to Generation

15July 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.

16July 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.