NSERC Industrial Research Chair in Power Systems Simulation EPEC 2011

RAPID PROTOTYPING OF CONTROL SYSTEMS FROM

ELECTROMAGNETIC TRANSIENT SIMULATOR

PROGRAM By:

Dexter M. T. J. Williams, Esa Nummijoki, Aniruddha M. Gole and Erwin Dirks

University Of Manitoba

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Content •  Introduction •  Background •  PSCAD Code Generator (PSCADCG) •  Example System •  Validation Testing • Conclusion

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INTRODUCTION

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Introduction •  Software based design in power systems

– Grown in popularity with computer processing power

-  Electromagnetic Transient (EMT) simulation models the network in the greatest detail

-  Application: Flexible Alternating Current Transmission System (FACTS), High Voltage Direct Current (HVDC)

-  Exhaustive simulations are done to confirm the controls operate in an appropriate manner

-  However the control model must still be transferred into a useable control code for in-field use

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Introduction •  Solution to Problem

– Automatic code generation from simulation control elements

•  PSCAD Code Generator (PSCADCG)

•  MATLAB’s Real-time Workshop

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BACKGROUND

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Background

Workspace Library

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Background •  PSCAD/EMTDC power system simulator

– 2 main types of Library components: – Electrical

» passive electrical components, power electronic components, machines, transformers, application specific components (EX: HVDC, FACTS)

– Control » arithmetic operations, logical operations, filters,

application specific controls and more

– Problem: To convert the control model to a real-world real-time implementation

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Background •  To allow for prototyping of the controls

the PSCAD Code Generator (PSCADCG) is used – PSCADCG reads the graphic model and

develops embedded software compatible code from the model

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PSCAD CODE GENERATOR (PSCADCG)

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PSCADCG •  The PSCADCG contains 3 main parts involved in the rapid prototyping

process –  Network generation –  C function generation –  C interface generation

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PSCADCG: Network Generation •  Network generation

– Generates a virtual network describing the interconnection of the control elements of the design

•  Reads project and library files to generate and equivalent virtual network of the systems controls

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PSCADCG:C Function Generation •  C function generation

–  Generates the code that describes the control operations modeled •  Sequential orders all elements into a queue based on order of operation •  Elements are sequentially de-queued and the code for each element is sequentially

generated •  Then the code is formatted and used to generate the header and C file

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PSCADCG: C Interface Generator •  C interface

Generator –  Interfaces the C

function to the hardware platform

•  A hardware platform must first be selected

•  The program reads the virtual header file and generates header, configuration and main loop C files

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PSCADCG: C Interface Generator •  C interface

Generator – Main program

•  Configuring all parameters

•  Infinite loop – Reads the A/D

converter values and runs

– Runs the C function generated by the C function generator

– Outputs the values to the ports

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EXAMPLE SYSTEM

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Example System •  Step Down converter

–  Reduces voltage from input to output using pulse width modulation –  Parameters

•  Input = 10 Volts •  Output = 5 Volts •  Voltage Ripple = 0.2% •  Current Ripple = 2.0%

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Example System: Controls •  Step Down converter

–  Control •  Pulse Width Modulation •  Negative feedback •  Proportional-Integral (PI) controller for error reduction

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Example System:PSCAD Simulation •  Step Down converter

– Control system – Optimized controls

•  Controls must be converted to a real time controller

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Real-time Control Implementation •  Cerebot 32MX4

development board –  PIC32MX460F512L

microprocessor •  80 MHz •  32-bit memory. •  PWM •  digital and analog I/O

(Input and outputs) –  8 peripheral ports

•  open collector driver •  A/D •  D/A converters •  Etc.

–  Programmed with C using the MPLAB development

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VALIDATION TESTING

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Validation Testing •  5 volt output test

–  Calculated: 5.00 –  Simulated: 5.00

•  Blue signal represents the PWM signal (Top)

•  Green signal represents PI control signal (Top)

•  Blue signal represents the output voltages (Bottom)

•  Green signal represents the input voltages (Bottom)

–  Hardware: 5.10 •  Blue signal represents the

PWM signal •  Green signal represents

the input voltages •  Orange signal represents

the output voltages

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Validation Testing •  9.90 volt output test

–  Calculated: 9.90 –  Simulated: 9.90

•  Blue signal represents the PWM signal (Top)

•  Green signal represents PI control signal (Top)

•  Blue signal represents the output voltages (Bottom)

•  Green signal represents the input voltages (Bottom)

–  Hardware: 9.53 •  Blue signal represents the

PWM signal •  Green signal represents

the input voltages •  Orange signal represents

the output voltages

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Validation Testing Duty Cycle (%)

Calc. (V)

PSCAD (V)

Actual Hardware

(V)

Error PSCAD

VS Hardware

(%) 1 50 5.00 5.00 5.10 1.00

2 99 9.90 9.90 9.53 3.70

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CONCLUSION

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Conclusion •  PSCADCG capable of:

–  generating control systems for a PSCAD system –  generating most any control system generated by PSCAD

•  PSCADCG can possibly reduce cost and expedite the development of controls

•  Proof of Concept was demonstrated using a simple step-down controller –  It is equally applicable to design arbitrary Power System

Controllers –  Larger scale / power systems may require additional hardware

for isolation, etc. •  Additional code may be needed to interface with these devices

•  Future work –  Support for multiple page modules –  Support for FPGA platforms

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QUESTIONS