ECE  4600  Group  Design  Project  Proposal  

 Group  14  Chen  Chen  Lyle  Motluk  Hang  Li  

Jingwei  Liu  Yingyang  Huo  

   

Academic  Supervisor  Dr.  Aniruddha  Gole  

Electrical  and  Computer  Engineering  Department  University  of  Manitoba  

 Industrial  Supervisor  

Arash  Darbandi  Manitoba  HVDC  Research  Centre  

       

Date  of  Submission  September  26th,  2014

Design  and  Implementation  of  a  low  power  Line-­‐Commutated  Converter  

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Table of Contents

1 Introduction ................................................................................................................. 1

2 Project Details .............................................................................................................. 2

3 Project Specifications .................................................................................................. 3 3.1 Converters (rectifier and inverter) ..................................................................... 4 3.2 Harmonic Filters ................................................................................................ 5 3.3 Three phase Thyristor Driver with Opto-Isolator .............................................. 5 3.4 RTDS (Real Time Digital Simulator) ................................................................ 5

4 Milestones, Tasks and Division of Labor ................................................................... 6

5 Gantt Chart .................................................................................................................. 7

6 Budget ........................................................................................................................... 8

7 Conclusion .................................................................................................................... 9

8 References ................................................................................................................... 10        

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1. Introduction

High Voltage Direct Current (HVDC) converters are used in power transmission to

convert high voltage alternating current (AC) to high voltage direct current. HVDC provides

an alternative to AC for electrical energy transmission over long distances or between

multiple AC power systems of different frequencies. Two categories of HVDC converters

exist: line-commutated converters (LCC) and voltage-sourced converters (VSC). This project

will focus on HVDC-LCC systems that are implemented where very high power capacity and

efficiency are required.

The goal of this project is to develop an accurate low power HVDC system to

represent the concepts of a HVDC and implement the design with standard laboratory

equipment (Lab-Volt). HVDC-LCC systems implemented in power transmission require

voltage and power in the kilovolt and megawatt range, which cannot be implemented safely

in laboratory settings. Therefore the low voltage HVDC-LCC design will represent a scaled

down version of the CIGRE (International Council on Large Electric Systems) developed

model of an HVDC-LCC. The lower power HVDC-LCC will first be designed using PSCAD

software before transferring the controllers to RTDS and assembling the final design on Lab-

Volt equipment.

This project was chosen because HVDC systems are widely used in the high voltage

industry therefore this will provide valuable insight into equipment that electrical engineers

are constantly improving. The final product will provide instructors an accurate model to

educate students on HVDC systems with the goal of improving the design in a safe low

power lab environment to be implemented in industry.

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2. Project Details

The whole project was divided into two phases; phase I is the design and assemble of

rectifier side, phase II is to implement inverter and verify the back-to-back line commutated

converter system.

To be more detailed, the process can be divided into several steps:

(i) Studying the existing PSCAD case for CIGRÉ (in French: Conseil International

des Grands Réseaux Électriques; in English: International Council on Large

Electric Systems) model.

(ii) Scaling all the units to W and V range.

(iii) Transferring controllers from PSCAD into RTDS for a real time simulation.

(iv) Deciding what additional equipment or tools we need.

(v) Designing and assembling rectifier side of the system.

(vi) Performing set of tests for verification.

(vii) Designing and assembling inverter side and verify the whole back-to-back Line

Commutated Converter system.

The entire back-to-back system should be built as the figure shown below.

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Figure 1. Basic HVDC Transimission.[2]

3. Project Specifications

The specifications of the project were determined by discussing the feasibility of

building high voltage system. CIGRE developed a benchmark for HVDC-LCC system, which

will help us to understand the operation of HVDC-LCC. However, the developed model is in

the range of MW and kV, which are not suitable for laboratory application. Therefore, the

goal of this project will focus on low power HVDC system which can be implemented in

laboratory. The low power HVDC system includes: i) a step-down transformer, ii) AC filters,

iii) a three phase Thyristor driver along with an opto-isolator to control the block of Thyristor,

iv) two identical Thyristor blocks on each side of the system act as rectifier and inverter, and

v) some additional resistors, inductors, capacitors will be needed.

The input AC voltage is three phase, 208V line to line. Design requirement for DC

bus voltage is in the range of 306 Volts to 374 Volts. All system specifications are

summarized in Table 1.

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Table 1. System Specifications

Parameter Value

Rectifier AC side input voltage 208 +/- 10% Volt

Rectifier DC side output voltage 340 +/- 10% Volt

DC bus current and power 2 +/- 10% Amp and 680 +/- 10% Watt

3.1 Converters (rectifier and inverter)

Rectifier is a power electronic device that converts energy between AC and DC. In

realistic HVDC system, 12-pulse arrangement rectifier was usually used. [4] In our project,

we are going to use two blocks of 6-pulse bridge Thyristor as rectifier and inverter on each

side of the system. The figure below shows a scheme of 6-pulse controlled bridge rectifier.

On the other side of the system, another 6-pulse controlled Thyristor was connected as an

inverter to convert DC voltage to AC voltage.

Figure 2. A scheme of 6-pulse, controlled bridge rectifier with commutating inductance. [5]

For the project, Thyristor based converter will be used in order to achieve a controlled

three phase rectifier.

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3.2 Harmonic Filters

Certain filters will be needed in the system to filter out the harmonics generated by

conversion operation. To be specific, AC filters are going to be installed on the ac side to

absorb harmonic components. [6]

3.3 Three phase Thyristor Driver with Opto-Isolater

In the project, a three-phase Thyristor driver will be used to turn on and off the

converter. Also, an opto-isolator will be connected with the Thyristor driver to protect both

human and equipment. It is important to notice that everything that connected with the block

of converter will be insulated.

3.4 RTDS (Real Time Digital Simulator)

The control systems of our project can be simulated in RTDS, and used for testing in

the real time environment.

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4. Milestones, Tasks and Division of Labor

The table below shows the team milestones and that every phase that must be

completed in order to achieve the team goals. It also lists team members who are in charge of

the individual task in order to ensure all tasks will be achieved on time.

Table 2. Milestones, Tasks and Division of Labor

Milestones Tasks Individual(s) in charge

Phase 1: Preliminary Works

Ø Study HVDC knowledge

Ø Learn PSCAD software

-­‐ Group -­‐ Group

Phase 2: Rectifier Design

Ø Study emitting PSCAD case for CIGRE model

Ø Scale from MW and KV to W and V (based on LabVolt equipment)

Ø Transfer controllers from PSCAD

Ø Design additional equipment if needed

-­‐ Group

-­‐ Hang

-­‐ Lyle - Group

Phase 3: Rectifier Test Ø Assemble rectifier parts

based on PSCAD design Ø Test desired variables

-­‐ Chen and Huo - Group

Phase 4: Inverter Design

Ø Design inverter side based on rectifier side design

Ø Transfer controllers from PSCAD

Ø Design additional equipment if needed

-­‐ Group

-­‐ Jingwei - Group

Phase 5: Inverter Test Ø Assemble inverter parts

based on PSCAD design Ø Test desired variables

-­‐ Chen and Huo

- Group Phase 6: Final Tests Ø Test entire LCC system - Group

Phase 7: Final Report

Ø Rough draft Ø Final editing /revisions Ø Presentation practice Ø Final presentation

-­‐ Group -­‐ Group -­‐ Group -­‐ Group

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5. Gantt Chart

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6. Budget

The budget for the project is $252,110, but the University of Manitoba supplies most

of the equipment for free. The total budget for the project is $110.

Table 3. Project budget

 

Item Supplier Unit Cost Quantity Total Actual

Cost ($)

PSCAD U of M (free) 1,000 1 1,000 0

RTDS U of M (free) 250,000 1 250,000 0

Six-pulse bridge rectifier U of M (free) 200 2 400 0

Online Gantt chart maker 10 1 10 10

Lab-volt U of M (free) 300 1 300 0

Miscellaneous U of M (free) 100 TBD 100

Total 110

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7. Conclusion

The purposed project is to design and implementation of a low power HVDC in a

laboratory setting. The project structure is organized with limited dependence on ordering

equipment or parts therefore the project will not be halted due to insufficient supplies.

Weekly team meetings and monthly reports to the project supervisors will insure the team

remains on schedule. This project can be achieved according to the timeline outlined in the

Gantt chart and within the proposed budget.

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8. References

[1] Daniel W. Hart, Power Electronics. New Delhi: McGraw Hill Education Private Limited, 2011, pp. 50-447.

[2] Carl Barker. HVDC for beginners and beyond. [Online]. Available: http://www.sarienergy.org/PageFiles/What_We_Do/activities/HVDC_Training/Presentations/Day_7/ALSTOM_HVDC_for_Beginners_and_Beyond.pdf

[3] Steven Pekarek and Timothy Skvarenina. (1998, November). “ACSL/Graphic

Modeller Component Models for Electric Power Education.” IEEE Transactions on Education. [Online]. 41(4), CD-ROM. Available: http://www.ewh.ieee.org/soc/es/Nov1998/08/BEGIN.HTM#INDEX

[4] Kunder, P., Power System Stability and Control. EPRI Power Engineering Series, McGraw-Hill, 1994.

[5] Pekarek, S., ACSL/Graphic Modeller Component Models for Electric Power Education, [Online]. Available:

http://www.ewh.ieee.org/soc/es/Nov1998/08/BEGIN.HTM#INDEX.

[6] Arrillaga, J., High Voltage Direct Current Transmission, 2nd Edition. IEE Power and Energy Series PO 029, 1998.