minnesota power - umn ccaps · 2015-09-15 · minnesota power system upgrades for phase angle...

Minnesota Power System Upgrades for Phase Angle Regulating Transformers

September 6, 2015

Ken Sletten & Benjamin Fameree

30 West Superior Street

Duluth, MN 55802

(Ken 218-355-3456) (Ben 218-355-2907)

[email protected] [email protected]

Table of Contents

I. Introduction……………………………………………………………………………….. 1

II. Planning and Overview…………………………………………………………………... 1

III. Phase 1 – Background ………………………………………………………………….... 2

IV. Phase 1 – Execution and Commissioning……………………………………………….. 2

V. Phase 1 – Lessons Learned and Summary……………………………………………… 3

VI. Phase 2 – Background……………………………………………………………………. 4

VII. Phase 2 – Execution and Commissioning……………………………………………….. 4

VIII. Phase 2 – Lessons Learned and Summary……………………………………………… 5

IX. Conclusion………………………………………………………………………………… 5

X. Resources………………………………………………………………………………….. 6

XI. Appendix…………………………………………………………………………………... 7-15

mailto:[email protected]

mailto:[email protected]

System Upgrades for Phase

Angle Regulating Transformers

September 6, 2015

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1. http://www.reinhausen.com/ Motor Drive TAPMOTION® ED flyer 2. http://www.ifallscoldtesting.com/

Introduction

Minnesota Power (MP) and Ontario Hydro share a 115kV interconnection transmission line from

International Falls substation to Fort Francis substation respectively. Due to the large phase regulation

difference that can take place both daily and seasonally, an unusual configuration of phase angle

regulating transformers (PAR) was installed at the International Falls substation and put into service in

1995. Two Siemens (150MVA) PAR transformers were installed in series; their internal design housed a

delta exciting winding and series quadrature legs with Reinhausen tap changers. Their design allows the

series units to operate with a +/- 70 degree phase shift allowing a combined range of 140 degree phase

shifting capability at full load rating. Each PAR transformer had four individual motor drives split on

each side of the transformer labeled the source and load terminal. All eight motor drives were replaced in

2013, a difficult task with an outage window of one week per transformer. Due to the aging existing

control system, a new replacement system was undertaken in 2014. A high need for monitoring

capability was stressed for this project as past tap changing errors had created headaches with no ability to

remotely diagnose issues. A field visit was needed each time. As error time increased, coupled with a

remote site location for our personnel, remote monitoring and diagnostic analysis was needed for the new

controller system. A Reinhausen controller system was installed in December 2014. The importance of

this line allows Minnesota Power energy transactions with Ontario Hydro that allow the diversity of fuel

and load between the power systems grids, a great economic benefit for both parties. A twelve day

outage was requested; a daunting task of installing new wires in sub-zero temperatures was required to

ensure the system was fully operational. The combined effort of contracted engineering, internal

planning, and a great effort on the part of our technicians and field crew along with Reinhausen support

personnel, allowed the controller replacement project to be completed in the allotted outage time.

Planning and Overview

With the original 10 & 11 PAR transformers installed in 1995 including the original Reinhausen motor

drives and VANSCO controller system, the approximately 20 year old system was due for an upgrade.

With the complexity on both the engineering and technician installation, the project was split into two

phases. Phase 1 was to be executed in 2013 and would consist of upgrading all eight motor drives for

both 10 & 11 PAR transformers with new Reinhausen TAPMOTION® ED 1 motor drives. Phase 2 was

to be executed in 2014 and would consist of upgrading the controller system with new Reinhausen

TAPCON® 260 controllers. Each project had unique challenges and obstacles to overcome and will be

highlighted separately with respect to the chronological timeline of the project. International Falls

substation is located in International Falls, MN and located on the Minnesota, Ontario border (see

Appendix – Figure 1). International Falls, MN is known nationally as “The Ice Box of the Nation” 2 this

northern climate location makes for an ideal condition for extreme cold weather testing in the United

States. International Fall’s substation is located 160 miles north of MP’s main Herbert Service Center

(HSC) in Duluth, MN and 100 miles north of MP’s branch service center located in Eveleth, MN. With

the remote and cold location, careful planning was taken to ensure all material, tools, food and overnight

accommodations where provided to all personal for both phases of the projects. Overtime was expected

and a “can do” and “must finish” attitude was planned by all personal.

http://www.reinhausen.com/

http://www.ifallscoldtesting.com/



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Phase 1 – Background

Each transformer’s motor drive had numerous issues that started to affect the overall reliability and

operation of the transformer. Aged mechanical drive shafts along with deteriorating cam shafts and

failing contacts became progressively worse from 2008 to 2013. A project team was assembled in

January of 2013 and an initial budget of 1.4 million was approved by upper management for the

replacement and installation for all eight motor drives to be replaced in the fall of 2013. With only one tie

line between Minnesota Power and Ontario Hydro, careful planning was needed for coordinating outage

requirements for construction. Winter provided the best off peak loading time for outage coordination.

Each transformer was given a one week outage split by a one week gap. With the amount of unwiring,

disassembling, and installation of all four motor drives on each transformer, the weekends were planned

as flow over days. With the original motor drives installed and commissioned by Reinhausen, it was

decided to contract the bulk of the work to Reinhausen technicians and have a small MP crew as added

support with the intent for oversite and training purposes on the new motor drives. Each PAR

transformer was split into two halves, load and source with each side operated by two motor drives acting

as a unit; an on load tap changer (OLTC) and advance retard switch (ARS) motor drive (see appendix –

Figure 2). The interlocking wires between OLTC and ARS motor drives would have to be completely

replaced. With phase 2 of the project to replace the controllers next year, the wiring from the control

house to each motor drive was re-used for phase 1 with the plan to replace with all new cables in phase 2.

Phase 1 – Execution and Commissioning

Plans were put in place to begin the week long outage for 11 PAR transformer September 16th – 20

th,

2013 and 10 PAR transformer the week of September 30th – October 4

th, 2013. The first week consisted

of numerous tasks for 11 PAR transformer (see appendix – Figure 3). With a late fall construction

schedule and a small control house, onsite logistical planning for an all-weather headquarters facility on

site was recommended. Two large 30 feet x 15 feet construction trailers were used to shelter all personal

on site. A total of fourteen Reinhausen personal including ten technicians, two engineering leads, and

two designers were flown in, coming as far away as Germany. A total of twelve MP personal including

six construction & maintenance (C&M) technicians, two communication technicians, two relay

technicians, and two engineers were on site the entire week. Work was broken up into two teams, five

Reinhausen technicians, two MP C&M technicians, and one MP relay technician. Each team worked on

the load and source side of 11 PAR transformer at the same time. Demolition of all four motor drives

went quickly and the construction schedule became a day ahead of schedule. Work progressed with the

installation of the OLTC motor drives onto the side of the transformer. The new drive shaft was installed

but due to the physical location of the new motor drive cabinet and permanent location of the drive shaft

gear box located at the top of the transformer, an angle was introduced with the vertical motor drive shaft

leaving the cabinet (see Appendix – Figure 4). The ARS motor drive cabinets were installed, next and

this same issue was present. The angle for the vertical drive shaft was great enough for a mid-point

coupler to be installed on the vertical shaft to relieve pressure off the shaft. The new OLTC and ARS

motor drives required a sophisticated interlocking wiring system and all new cable and conduit were

wired between the drives. Thirty interconnections were needed between each OLTC and ARS motor

drives. Control cable coming from the control house Automatic Power Flow



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3. www.Reinhausen.com Dehydrating Breathers DB 200

Control (APFC) panel used for alarm and control was determined to be in good condition and re-used for

this phase of the project. The main control cabinet on each transformer housed the AC distribution feeds

for the motor drives and the cable leads from the main cabinet to the motor drives was also re-used. As

both motor drives were getting ready to be commissioned, an error was found with the drive shaft ratio.

The ARS motor drive was not able to make a full rotation to change the tap changer from position 1 to

position 2. This error was found Wednesday evening. A call was made to Germany to inquire on the

mistake, and to see if a drive shaft with the correct ratio was available at one of the Reinhausen facilities

in the United States. No spare part could be found but thanks to Reinhausen support personal, a gear box

with the correct ratio was found in Germany and arrived the next night in Minneapolis, MN. A crew was

assembled to drive from International Falls to the Minneapolis International Airport to pick up the

equipment and head straight back. Once the equipment was received and installed, a second issue was

discovered. The original thermal overload protection breakers in each new motor drive were found to be

undersized as increased heating capacity in each motor drive was needed for the cold winters.

Additionally, new MESSKO® MTraB® DB 200 3 devices were installed for both load and source OLTC

oil tanks. These devices replaced the existing conventional breather devices and had a built in

microprocessor for continuous monitoring of the vapor in the oil conservator tank. Due to the cold

climate, heaters in each unit were needed. The extra heaters in the motor drives along with the heating

circuit for the dehydrating breathers, prompted an increase in circuit protection breakers size. The nearest

warehouse with the correct breakers was Minneapolis, MN. Another team was sent on an overnight

pickup down to Minneapolis, MN to pick up the breakers and drive them back to International Falls. It

was not until Saturday morning when everything passed point to point checks and commissioning and

testing were able to begin. Luckily, all testing was finished Saturday evening and 10 PAR transformer

was put back into service. A week later, 11 PAR transformer was scheduled for it’s week outage.

Everything went well and 11 PAR was able to be placed into service on the scheduled Friday of the week.

Phase 1 – Lessons Learned and Summary

Even with all the preparation beforehand, problems arose that were not foreseen to be an issue. Incorrect

gear ratios on the motor drive shaft presented a difficult challenge that could have halted the project for

weeks if it wasn’t for Reinhausen’s support personal that determined the correct ratio, tracked down the

correct parts in Germany, and oversaw the speedy transportation for an overnight delivery through United

States customs, thus ensuring we received the parts within 24 hours. Increasing the size of the motor

protective circuit breaker in each motor drive was another issue solved. New parts were located and

quickly transported to the job site, all in part to Reinhausen support personal. Since the motor drive would

rotate half way through its 32 position rotation and would automatically rotate back to the original

position, the motor drive clutch required stiffer springs for increased friction. This would cause an

incomplete or tap change error ever time this happened. A temporary fix was installed on each motor

drive until new springs could be installed in early December 2013. The source ARS local remote switch

broke on 11 PAR transformer. Spare parts were ordered and temporary switch from 10 PAR motor drives

was used. With multiple issues arising during the motor drive replacement project, one thing was for sure,

MP and Reinhausen’s work crew were able to keep focus, work together, and finish the project as

scheduled and on time.




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4. http://www.cai-engr.com/ 5. www.Reinhausen.com TAPCON 260 controllers

Phase 2 – Background

The original controller system was from VANSCO, which utilized an Allen Bradley programmable logic

controller. When the original system was commissioned in 1995, a logic controller was the only option,

as the complex power flow calculations and continuous error checking was needed. With original

engineers from the project retired, expert help was needed in order to complete phase 2 of the project.

Minnesota Power reached out to Commonwealth Associates Inc., 4 as they have used their consultants and

expertise in the past to design a phase shifter controller for another substation just a few years prior. The

complexity of the design rested on the shoulders of Commonwealth. The design for an upgrade in

sophistication was required. With the current controller system, any alarms triggered by the controller

would have to be field inspected and analyzed on site. MP could have field technicians on site within two

hours from our Eveleth service branch and many times occurring in the middle of the night and in the

cold of winter. Main engineering support was based out of the HSC in Duluth, MN for any issues with

the PAR transformers. It would require a lot of phone calls for troubleshooting with technicians remotely

to evaluate the ladder logic (see Appendix – Figure 6). The original VANSCO controller used a CRT

monitor on site to view alarms (See Appendix – Figure 7). The aging communications card in each

controller only allowed viewing access from one of the controller based systems. Each transformer is

controlled by the same controller by either the primary unit, and has a completely redundant system that

can be switched over at any time on a secondary unit. The secondary unit had a failed communication

card and diagnosis for reading alarms was through the LED light ups on the back of the system (see

Appendix – Figure 8). The control was switched over on a set schedule between primary and secondary.

When the secondary system was activated, alarms were read using the LEDs instead of the CRT monitor

and ladder logic prints were used for diagnostics along with helpful cheat sheets taped on the panel (see

Appendix – Figure 9). Usually a field visit was required from engineering when difficult issues arose

after troubleshooting. As the frequency of difficult issues increased, a three hour drive from Duluth, it

was becoming more and more prevalent a remote diagnostic system would be of more value. The digital

fault recorder DFR, originally commissioned with 10 & 11 PAR transformers back in 1995, was due also

for an upgrade for the same remote diagnostic improvements needed with the controllers. It was decided

to perform both projects at the same time as outages could be coordinated together.

Phase 2 – Executing and Commissioning

Preparation work for phase 2 began the beginning of October 2014, as according to the planned

construction schedule (see Appendix – Figure 10). A two week outage for construction and

commissioning was needed for phase two. MP planned to replace all cabling from the controller panel to

10 & 11 PAR transformer motor drives. As all existing conduit was filled, we needed to install and extend

the cable trench to both transformers. This allowed for easy access for installation and any future planned

additions for both 10 and 11 PAR transformers (see Appendix – Figure 11). Eighteen thousand feet of

new control cable was used for both DFR and controller projects. The new TAPCON® 260 4 controllers

from Reinhausen needed fully customized input output cards and software to meet and replace the

existing controllers (see Appendix – Figure 12). As the previous system had a primary and secondary

system, so the new system also had a completely redundant system for reliability reasons. A two week

outage was set for December 1st – 12

th, 2015. MP had planned to test the new software for the controllers

http://www.cai-engr.com/




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the week of November 17-21st at HSC. Reinhausen representatives flew from Germany to deliver and

install the new software but were delayed by 1 week, this added stress on the entire project. Thankfully,

testing of the new software went smoothly and completed the Thursday before the scheduled outage.

Shelters were constructed around each motor drive cabinet the week before the outage; they consisted of

heaters, foam insulation and a tarp for rain (see Appendix – Figure 13). On the first day of the outage,

morning temperatures reached -20 degrees Fahrenheit and crews were extra happy to have heated shelters

as they started unwiring hundreds of connections. The total amount of connects for the entire project was

under a thousand. Demolition and installation of the new controller panel went quickly and the project

was a day ahead of schedule coming into the second week of the outage. Once all wires and connections

were checked by our relay technicians, the long process of testing every function in the controllers took

place. During the commissioning and testing process, problems started to surface. Many long days of

testing and commissioning were needed the final week in order to complete phase 2 project on time (see

Appendix – Figure 14).

Phase 2 – Lessons Learned and Summary

New current transformers were installed on the motor to be recorded by the DFR. Due to the long

distance of the cables, not a strong enough signal was able to be brought back. A quick in the field fix of

double wrapping the primary connection to increase the secondary current output of the current

transformers at the motor drive was performed. We placed temperature transducers in each OLTC motor

drive cabinet to remotely monitor the inside temperature next to the motor. These transducers needed to

be externally powered and another fix in the field was performed by installing 24 volt DC power supplies

on each circuit. Originally 10 PAR and 11PAR transformers were positioned with the original crane

installation in 1994 back to back. This original placement of the transformers is in contrast to both MP’s

energy control center (EMS) and tap changer controller definitions of power flow. As defined by our

EMS, positive power flow is defined as power flow from Minnesota Power to Canada; negative power

flow is defined as power flow from Canada to Minnesota Power. Power flow defined by the designers of

the Tapcon controller originally was backwards to MP’s definition. The Reinhausen controllers were

quickly reprogrammed in the field to meet MP’s definition. The controller expects an increase positive

power or decrease negative power flow when transformer taps go in advance direction; vice versa the

controller expects an decrease positive power or increase in negative power flow when transformer taps

go in retard direction. With the transformers faced back to back correct raise and lower commands were

needed in order for the transformers to cooperate when advance or retard tap positions. With the finish of

adding the new digital fault recorder, individual alarms for each motor drive can now be viewed remotely

and can be time stamped for added troubleshooting ability.

Conclusion

Monitoring on both the DFR and controller panel has greatly improved remote troubleshooting ability.

Alarms for each motor drive are now able to be viewed remotely through the DFR. An event trigger is set

with the tripping of the motor protective switch on each motor drive. Each alarm on every motor drive is

recorded with the time stamp when activated. MP’s approach of splitting up the work into two phases,

allowed for successful individual projects. Both phases needed outside engineering expertise, planning,

equipment coordination, and a “can do” attitude from the work crew, resulting in both projects finishing

on time.



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Resources

1. http://www.reinhausen.com/ Motor Drive TAPMOTION® ED flyer

2. http://www.ifallscoldtesting.com/

3. www.Reinhausen.com Dehydrating Breathers DB 200

4. http://www.cai-engr.com/

5. www.Reinhausen.com TAPCON 260 controllers


http://www.ifallscoldtesting.com/


http://www.cai-engr.com/




September 6, 2015

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Appendix

Figure 1

Figure 2



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Figure 3



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Figure 4

Old Motors with couplers for motor drive shaft angle

New Motors still needing couplers for motor drive shaft angle



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Figure 5 Installation of new motor drives

Setting new motor drive

Aligning new drive shaft



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Figure 6

Figure 7



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Figure 8

Figure 9



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Figure 10

Figure 11

International Falls 115kV Construction Schedule - Replace 10 & 11 PST Controller Project

Date

C&M

Northern

C&M

Central Relay CI

MP

Eng CW MR Description of Work

Special

Equipment Material Notes:

Pre-Outage 1-Oct 2 2 1 Pre-Construction for Trench and Cable install Meeting at HSC

13-Oct 2 Receive Old Castle trench system

ASV to off

load pallets

Oct 13 - 24 4 Install trench system

Compactor,

ASV with

bucket

Geo-textile fabric, Pea

Rock, Sand?, Conduit,

Conduit Caps, 4/0

copper, Steel Cable

clips

Oct 22 - 24 2 Install Cable in trench Shielded Cable

Oct 20 - Nov 7 2 1 1 Install Additional DFR equipment in DFR pnl

Fuse Blocks, Tesla

4000, 5 current

modules

Prints set for Oct 10,

Receive equipment

Oct 10

Nov 10 - 14 2 Install Tapcon software

Panel delivered on

Nov 6 to HSC

Nov 17 - 26 1 1 1 1 1 Tapcon In House Testing

Ken Sletten will need

to come up with a

testing plan

Nov 10 - 21 2 1 Install additional SI board and wire up panel

19-Nov 1 1 1 1 3 1 1 Final Pre Construction Meeting (All leads) Meeting at HSC

13-Nov 2

2 construction trailers delivered and installed

with provisions. Have 2 portable john hualed

to site

Have heat, Wi-fii, and

other provisions

necessary

Nov 3 - 7

Program new TESLA for DFR and additional

TESLA used for PST motor drives

Pete Shommer (Tim

Salmonson)

Nov 17 - 28 4

Install wooden platforms for all 8 motor

drives

Install tarps and

possible heaters for

adequate working

conditions.

30-Nov

Have meeting with crew to go over details of

work for the week and to answer questions

Meeting at hotel

night before outage.



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Figure 12

Figure 13



September 6, 2015

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Figure 14

International Falls 115kV Construction Schedule - Replace 10 & 11 PST Controller Project

December 1 2 3 4 5 WKND 8 9 10 11 12 WKND Description of Work

# of

Guys

Special

Equipment Material Notes:

OutageInstall conduit into all

motor drives 2

Re-wire Motor drives

with new cable/

terminate end into

panel 6 2 days per XFMR, 3 guys per side

Install wiring from

panel to panel inside

control house for

Controller panel 2

2

Remove exisiting DFR 2

DNP conversion for

RTU 2

RTU outage for 10 & 11TR will be for a

couple of hrs

Install new DFR 2

CT circuits 126 line, 134 line have

independent CT's, 10 & 11 Cap bank

neutral CT circuits have relaying and

726 line has watt transducers…

Commision / wire

check DFR 1

Install GPS clock and

RTU points 2

Install CT's in motor

drives / temperture

gauges 2

Commision / wiring

check on Controller pnl 2

Commision / wiring for

all new RTU points 2

install TESLA

programing changes 1

Install New BCD boards 2

Provide Added

Schematic support 1

Commision / testing

Tapcon both Pri & Sec

systems 3

Total # guys during

outage

9

?

2

2

2

1

3Reinhausen

Workforce Color CodeC&M Northern

C&M Central

Relay Technicians

Communications

MP Engineering

CommonWealth

minnesota power - umn ccaps · 2015-09-15 · minnesota power system upgrades for phase angle...

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