lessons learned from phil experiments with power converters … · lessons learned from phil...

Tallahassee, FL, November 5-6, 2015

Lessons Learned from PHIL Experiments with Power Converters and Fault Current

Limiters

3rd Annual International Workshop on Grid Simulator Testing

of Energy Systems and Wind Turbine Power Trains

J. Langston, M. Steurer, K. Schoder Center for Advanced Power Systems

Florida State University

Overview

I. PHIL II. Lessons Learned

I. Stability II. Engagement of PHIL Interfaces III. Accuracy IV. Flexibility of PHIL Interfaces V. Protection of PHIL Experiments VI. Other Points

III. Conclusion

Nov. 5-6, 2015 Grid Simulator Testing Workshop 2

HIL Simulation Approach


• A device under test (DUT) is interfaced to a simulated environment through HIL interfaces to a real-time simulation model

• Allows – DUT to be exercised in a wide range of

potentially realistic environments – Execution of extreme conditions within

controlled lab environment – DUT to be tested with systems not yet

constructed – DUT to be exercised to extremes of

interface specifications including controlled transients

• Controller HIL (CHIL) – HIL Interfaces use control level (low

voltage) signals for I/O • Power HIL (PHIL)

– Power amplifiers and/or actuators are used for interfacing

– Power flow over PHIL interface

Interface

Algorithm

G Interface

AlgorithmMRG

A

B

C

DUT

A

B

C

Amplifier Dynamometer

References

andFeedback

References

andFeedback

Real Time Simulation

SimulatedDUT

GMRG

DUTController

ControlSignalsSimulated

VabcandIabc

SimulatedTand

Real Time Simulation

Challenges Associated with HIL Simulation


• Restrictions of real-time simulation – Typically fixed time-step size simulations with minimum achievable time-step size – Limitations on the size and complexity of simulated systems due to finite

computational resources • Limitations of amplifiers and actuators (max power, torque, speed, etc.) • Assessment of the impact of HIL Interfaces (particularly PHIL) • Accuracy of models used for surroundings

– Common issue with modeling and simulation activities, in general – establishing confidence in the models.

– Synergy between model verification and validation (V&V) and HIL simulation

DUT

DUT

Controller

Amplif ier

Amplif ier

Controller

PHILInterface

Controls

Interface

ComponentROS

RealTime

Simulator

PHIL

Interface

• Non-ideal interfaces – Time delays associated with

I/O, controllers for actuators and amplifiers, etc.

– Limited bandwidth of amplifiers and actuators

Stability of PHIL Experiments


[1] Wei Ren, M. Steurer, and T.L. Baldwin. Improve the stability and the accuracy of power hardware-in-the-loop simulation by selecting appropriate interface algorithms. Industry Applications, IEEE Transactions on, 44(4):1286-1294, July 2008. [2] Alexander Viehweider, Felix Lehfuss, and Georg Lauss. Interface and stability issues for SISO and MIMO power hardware in the loop simulation of distribution networks with photovoltaic generation. International Journal of Renewable Energy Research (IJRER), 2(4):631-639, 2012.

PHIL System [1] Example ROS and DUT

Voltage Type Ideal Transformer Model Interface Algorithm

𝑊𝑊 = −1 + det (𝐼𝐼 + 𝐺𝐺𝑂𝑂𝑂𝑂)

𝐺𝐺𝑂𝑂𝑂𝑂−𝐼𝐼𝐼𝐼𝐼𝐼−𝑉𝑉𝐼𝐼 = −𝑍𝑍𝐴𝐴𝑍𝑍𝐵𝐵

𝑇𝑇𝑚𝑚𝐼𝐼𝑇𝑇𝐴𝐴

𝐺𝐺𝑂𝑂𝑂𝑂−𝐼𝐼𝐼𝐼𝐼𝐼−𝐼𝐼𝐼𝐼 = −𝑍𝑍𝐵𝐵𝑍𝑍𝐴𝐴

𝑇𝑇𝑚𝑚𝑉𝑉𝑇𝑇𝐴𝐴

[2]

ROS DUT+

-

Examples of PHIL Experiments Presenting Challenges in Terms of Stability


Fault Current Limiters

Island Detection Tests for PV Inverters

ROS DUT

PHIL Interface

RLC Load Bank

PV Inverter

ROS DUT

PHIL Interface

Engagement of PHIL Interfaces


• Allow PHIL interfaces to be gradually engaged to couple DUT and simulated ROS

• Can allow stability issues to be detected prior to full instability • Bring systems to steady state and allow for smooth transition to PHIL

experiment • Example: Testing a 1.2 MW, 4.16 kV AC / 1 kV DC Power

Conversion Module for Shipboard Applications ([1] on next slide)

Surrounding System [1] Current with ITM IA [1]

DC ITM-IT IA







0 0.005 0.01 0.015 0.02 0.025 0.030

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Time (s)

Cur

rent

(kA

)


DC ITM-IT IA







0 0.005 0.01 0.015 0.02 0.025 0.030

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Time (s)

Cur

rent

(kA

)

AC

Source

Source

DUTAC

Amp

DC

Amp

AC

HILIA

DC

HILIA

DC

Load

Load 3

DC

Load

Load 4

S4

S6

S7

AC

Source

Source

AC DC

PCM

PCM 2

S2 S3S5

S1

AC

LoadLoad 1

T1

AC

LoadLoad 2

T2

AC Bus 1

AC Bus 2

DC Bus

Hardware

Simulated Surrounding System


DC ITM-IT IA







0 0.005 0.01 0.015 0.02 0.025 0.030

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Time (s)

Cur

rent

(kA

)


DC ITM-IT IA



• Example: Testing a 1.2 MW, 4.16 kV AC / 1 kV DC Power Conversion Module for Shipboard Applications [1]

• Employed current-type Damping Impedance Method (DIM) IA [2]

0 0.005 0.01 0.015 0.02 0.025 0.030

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Time (s)

Cur

rent

(kA

)

[1] J. Langston, F. Bogdan, J. Hauer, K. Schoder, M. Steurer, D. Dalessandro, T. Fikse, J. Cherry, and S. Gonstead, “Megawatt-scale power hardware-in-the-loop simulation testing of a power conversion module for naval applications," Electric Ship Technologies Symposium (ESTS), 2015 IEEE, pp.268,275, 21-24 June 2015. [2] Richard Mack Mersenski. Evaluation of a new power-hardware-in-the-loop (PHIL) interface algorithm for current controlled amplifiers. Master's thesis, University of South Carolina, 2011.

DC DIM-IT IA Current with DIM IA [1]



• Example: PHIL Testing of Air Core Superconducting FCL [1] • Used Modified DIM IA [2] • Initialized damping impedance to known pre-quench impedance • Used a few cycles of pre-fault, load current to allow the

impedance to be estimated and all feedback of the IA engaged

[1] Naeckel, O.; Langston, J.; Steurer, M.; Fleming, F.; Paran, S.; Edrington, C.; Noe, M., "Power Hardware-in-the-Loop Testing of an Air Coil Superconducting Fault Current Limiter Demonstrator," Applied Superconductivity, IEEE Transactions on , vol.25, no.3, pp.1,7, June 2015. [2] Sanaz Paran and CS Edrington. Improved power hardware in the loop interface methods via impedance matching. In Electric Ship Technologies Symposium (ESTS), 2013 IEEE, pages 342-346. IEEE, 2013.

PHIL Setup and ROS [1] Voltage and DUT Impedance [1]

Accuracy


• Example: Load Rejection Test with 1.2 MW, 4.16 kV AC / 1 kV DC Power Conversion Module for Shipboard Applications ([1] on next slide)

Surrounding System [1]

[1] J. Langston, F. Bogdan, J. Hauer, K. Schoder, M. Steurer, D. Dalessandro, T. Fikse, J. Cherry, and S. Gonstead, “Megawatt-scale power hardware-in-the-loop simulation testing of a power conversion module for naval applications," Electric Ship Technologies Symposium (ESTS), 2015 IEEE, pp.268,275, 21-24 June 2015.

Oscillations in Current with ITM IA [1]

Accuracy



AC

Source

Source

DUTAC

Amp

DC

Amp

AC

HILIA

DC

HILIA

DC

Load

Load 3

DC

Load

Load 4

S4

S6

S7

AC

Source

Source

AC DC

PCM

PCM 2

S2 S3S5

S1

AC

LoadLoad 1

T1

AC

LoadLoad 2

T2

AC Bus 1

AC Bus 2

DC Bus

Hardware





Accuracy






Accuracy





0 0.02 0.04 0.06 0.08

-0.2

-0.1

0

0.1

0.2

Time (s)

Cur

rent

(kA

)

IaIbIc


Accuracy



Currents Using DIM IA (Lower Damping Impedance) [1]


Currents Using DIM IA (Higher Damping Impedance) [1]

Protection Systems


• Important to protect the DUT • Gracefully shut down the experiment if a problem is encountered • Take (only) appropriate actions in response to detected problems • Example: Testing 1.2 MW, 15,000 RPM High Speed Generator [1]

[1] J. Langston, M. Steurer, K. Schoder, J. Hauer, F. Bogdan, I. Leonard, T. Chiocchio, M. Sloderbeck, A. Farrell, J. Vaidya, and K. Yost, “Megawatt Scale Hardware-in-the-Loop Testing of a High Speed Generator,” Proc. 2012 ASNE Day, Arlington, VA, February 9-10, 2012.

Test Setup [1]

• Protection Elements – Over-voltage – Over-current – Over-speed – Over-torque

• Protection Actions – Open closed-loop controls – Open excitation switch – Ramp VVS (load) current to zero – Ramp dynamometer speed to zero – Step dynamometer speed reference to zero

Protection Systems


• Methods to detect the onset of instability – Frequency – Voltage/current distortion – Time-based – Others

• Example: Anti-Islanding Tests of PV Inverters using PHIL [1]

[1] M. Steurer, K. Schoder, J. Langston, J. Hauer, and B. Mather, “Progress on Power Hardware-in-the-Loop Based Anti-Islanding Testing of PV Converters,” Presentation at the Second International Workshop on Grid Simulator Testing of Wind Turbine Drivetrains, September 17-18, 2014, North Charleston, South Carolina, USA.

Stable Case [1]

-50 0 50 100-30

-20

-10

0

10

20

3057 ms40 ms

42 ms

time (ms)

I a (A)

Capture 562: 8 kW, Qf=1, ITM, Rwye, 1/10

mea (C)modelmea (M)

-10 0 10 20 30 40 50 60-6

-4

-2

0

2

4

6

850 ms33 ms

54 ms

time (ms)

I a (A)

Capture 599: 3 kW, Qf=2, ITM, Rwye

mea (C)modelmea (M)

Marginally Stable Case [1]

SwitchPVConverter

AC-Source

Load BankR-L-C

DC-Source

Anti-Island Test Setup [1]

Other Points


• Simulation Mode • Information Collection

– Capture Reference Signals

– Collect Trending Information Including Settings

• Minimize Surrounding System

• Detailed Checklists and Procedures

• Attention to Detail Surrounding System [1]


Other Points







• Attention to Detail

AC

Source

Source

DUTAC

Amp

DC

Amp

AC

HILIA

DC

HILIA

DC

Load

Load 3

DC

Load

Load 4

S4

S6

S7

AC

Source

Source

AC DC

PCM

PCM 2

S2 S3S5

S1

AC

LoadLoad 1

T1

AC

LoadLoad 2

T2

AC Bus 1

AC Bus 2

DC Bus

Hardware




Other Points







• Attention to Detail Surrounding System [1]


Conclusions


• Stability and Accuracy Key for PHIL Experiments

• Points – Stability – Engagement of PHIL Interfaces – Accuracy – Flexibility of PHIL Interfaces – Protection of PHIL Experiments – Simulation Mode – Information Collection – Minimize Surrounding System – Detailed Checklists and Procedures – Attention to Detail

DUT

DUT

Controller

Amplif ier

Amplif ier

Controller

PHILInterface

Controls

Interface

ComponentROS

RealTime

Simulator

PHIL

Interface

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