UPGRADATION OF POWER DISTRIBUTION NETWORK AT A-F BLAST FURNACES A PROJECT REPORT Submitted In Partial Fulfillment of The Requirements for Completion of Summer Training at Tata Steel (May 2005-June 2005)
By
Smarak Swain Department of Electrical Engineering Indian Institute of Technology Kharagpur
Under The Guidance of
Mr. P.K.Basu Head Integrated Electrical Maintenance, A-F Blast Furnaces Division Tata Steel
A-F Blast Furnaces Division Tata Steel Jamshedpur
Dated: 07-06-2005.
CERTIFICATE This is to certify that the project entitled “Upgradation of Power Distribution Network in A-F Blast Furnaces” being submitted by Smarak Swain, is in partial fulfillment of the requirement for completion of summer training at Tata Steel. This is a record of candidate’s work carried out by him under my supervision and guidance.
Mr. Pradyot K. Basu A-F Blast Furnaces Division Tata Steel, Jamshedpur
ACKNOWLEDGEMENTS
I am extremely thankful to Mr. Sanjay Kumar, Chief, A-F Blast Furnaces, for his encouragement and support. I am very much indebted to my guide Mr. PK Basu, head, IEM, A-F Blast Furnaces whose sincere comments, motivations and expert advise during various stages of this project work helped me immensely in completing my project work. My special thanks to Mr. Subash Chakraborty, Manager, IEM for his timely guidance and help. I am also greatly indebted to Mr. Abhishek Kumar of Automation Development Centre (ADC) for helping me with practical networking problems and Mr. R.S. Sah of Load Dispatch Centre (LDC) for giving me a holistic view of power automation at Tata Steel. I am also thankful to all the officers in Blast Furnace office for giving me their help and support. Last but not the least, I am thankful to Arunanshu Chatterjee of HR Implementation for his support.
Smarak Swain
ABSTRACT
The fast changing world of technology demands better efficiency and up-gradation from ageold processes in order to stay in the fray of competition. Power is an important resource in iron making process. Efficient management of power consumption can greatly enhance productivity at the same time reducing cost. Power automation helps in efficient energy management and also monitoring power quality. Basic power problems faced and up-gradation of power distribution network required at A-F Blast Furnaces is studied.
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Contents: 1.
Introduction
2. Problem Statement
6 7
2.1. Energy Management
7
2.2. Quality Monitoring
8
2.3. Fault Detection
9
3. Automation
10
3.1. Theory
10
3.2. Cost Estimates
14
3.3. Tapping Points
15
3.4. Design and Optimization
17
4. Instrument Specifications
5.
19
4.1. Relays and Sensors
19
4.2. Data Acquisition System
20
4.3. Intelligent Energy Meters
21
4.4. SCADA Features
22
Advantages
23
6. Future Improvements
24
APPENDIX
25
I. Power Interruptions in A-F Fce II. Existing Networking: A Mock Diagram
26 27
III. List of Incoming & Outgoing Feeders
28
IV. Power Distribution Network: Block Diagram
30
V. Sub-Stations: Geographical Mapping VI.
The Proposal: Topology Design Plan
31 33
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INTRODUCTION Aim of this two months long summer project is to study the power distribution network of A-F Blast Furnaces in Tata Steel and recommend possible up-gradation. Even though Tata Steel has some of the most modernised machinery and state-ofthe-art steel making procedures in the country, some areas of the blast furnaces region remain very outdated. Steps are being taken to modernize this crucial process in steel-making, for example, F blast furnace is now completely automated and modernized. Power is an essential utility for any industry and its significance increases many fold at a place like Tata Steel where power consumption level is very high. Unlike many resources power is consumed as soon as it is generated. It cannot be stored to be analyzed for quality in the future. If power quality is unsatisfactory it cannot be recycled or repaired and returned to the process. It must be monitored continuously and its quality established in “real-time”. Major breakdowns in the past have occurred due to either power failure or abrupt changes in power quality. Production lines can be extremely sensitive to power quality — we need flawless control over timing, temperature, blending, and assembly. A disturbance in quality can lead to equipment failure and a loss of
production time, plus maintenance or repair costs. Hence the need to monitor power quality. An estimation of total raw materials consumed is essential for any operational researcher to optimize resource allocations. We need to maximize the use of resources, run equipment at optimal levels and minimizing downtime. Hence, the need to monitor power online.
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2 PROBLEM STATEMENT
2.1 Energy Management
Power consumption at A-F blast furnaces is measured on a weekly basis by the manual method i.e. move from sub-station to sub-station taking energy-meter readings. This has many disadvantages.
First, it doesn’t give any accurate value of power consumption at any instant. Secondly, we can never know the peak times i.e. time when load requirement is
high/low. Load requirements fluctuate over the day. Online power monitoring can help us plan extra-load activities at off-load time.
Third, we can detect which area/machinery in blast furnaces has become inefficient over time and replace/ repair them for better efficiency. Finally, this will reduce man-power. Fifty man-days in a year is required to collect the data from various sub-stations.
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2.2 Quality Monitoring
Many electro-mechanical equipments in heavy industries need constant power supply to operate. These equipments are extremely sensitive to even small power fluctuations and may lead us to a major breakdown. Variations like spikes, sags and power dip have to be monitored if we want to prevent them. Hence the need for continuous power quality monitoring.
Power quality problems have been faced quite a number of times at A-F Furnaces. A power dip of 100 milliseconds leads to a shutdown of 7-8 minutes, in turn harming productivity. It should be pointed out that spikes and power dip are mostly sub-
cycle events. We need very efficient relays and data acquisition systems so as to monitor every cycle continuously. A list of power interruptions in last one year at AF Blast Furnaces is given in the appendices.
After studying the distribution network, I have come to the conclusion that such power quality monitoring needs to be done only at 6.6 KV HT sub-stations that supply power to other sub-stations and critical equipments. The places are A Fce SS, New Fce SS and F Fce HT SS. F -9furnace sub-station has high-speed microprocessor based relays but A Fce SS and New Fce SS are not equiped with modern instruments. Oil Circuit Breakers (OCB) and electromechanical relays are still being used there. The relays and CBs of atleast the incoming feeders of these sub-stations have to be replaced by modern numerical relays in order to measure quality
2.3 Fault Detection
Faults are the most unpredictable of all. Faults can be in the incoming sources (PH#3, PH#4, Golmuri SS & WSS) or can occur anywhere in the distribution lines.
Faults can be easily detected and alarm sounded in the control room if the power distribution network is automated. To detect faults, we need to monitor the CT transducers for current variations. Since the energy meters will be measuring power (V*I*Pf), we can easily monitor both voltage and current transducers. There is no need to monitor power factor as it is centrally maintained and varied at Load Dispatch Center (LDC).
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3 AUTOMATION
Many companies –likes of Siemens, Alstom and Honeywell –provide products (with varied features) for power system automation for the purpose of monitoring. However, they being oblivious to the needs of our department (A-F BF), the purpose of this project is to provide them a guideline as to our requirements and also to propose an ethernet networking that is optimized. Optimized in the sense, it costs lower than any outsider’s design and takes into consideration all constraints in networking.
3.1 Theory There are many factors to be taken into consideration while installing the system:
•
Ethernet Specifications
•
Ethernet Topology
•
Ethernet Media
•
Media Converters
•
Location of sub-stations on map of A-F furnaces
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Ethernet Specification:
10Base-F and 10Base-T specifications make use of LAN networks that have 10Mbps speed. Since we at Tata Steel have 100Mbps speed, we will be using 100Base-T specification. 100Base-T sends link pulses over a network segment, but these pulses contain more data than those in 10Base-T. ‘Fast Ethernet’, as it is called, raises Ethernet transfer rates with only minimal changes to the existing cable structure.
Ethernet Topology:
There are three types of topologies, ring, bus and star topology.
In a bus topology, all devices are linked together in series with each device
connected to a long cable or bus. Any device can communicate with all other devices on the bus. Bus networks are relatively inexpensive and
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easy to install, but a break anywhere in the cable causes the entire segment to be inoperable until the break is repaired.
In a star topology, all devices are connected to a central hub that controls access. The primary advantage of this type of network is reliability, because if one of the “pointto-point” segments has a break, other segments continue to operate. Star networks are also relatively easy to install and manage, but bottlenecks may occur because all data must pass through a hub
In a ring topology, all devices are connected to one another in a closed loop. Ring topologies are relatively expensive and difficult to install, but offer high bandwidth and can span large distances.
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A proper selection (combination) of topologies can optimize the network and can lead to lower installation costs and better efficiency. However, it should be noted
that ring topology is already outdated. Nowadays, star and hybrid of stars interconnected by bus are mostly used.
Ethernet Media:
There are two types of Ethernet media –fiber optic cable and UTP. Fiber optic cables are pretty expensive and are a substitute only at places having large degree of electromagnetic interference (EMI). For 100Base-T specification, UTP is a better bet.
Since the energy-meters will be placed in sub-stations, the shielding ability of UTP cables against 6.6KV and 415V have also to be examined. Another drawback of UTP cables is that they can’t be connected beyond 100 meters from nearest switch.
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Media Converters:
The energy meters need to be TCP/IP compatible in order to get connected to the LAN with an IP address that could be recognized in the control room. Else, a media converter, depending on the protocol of device of communication of energy meter, has to be used.
Location of Sub-Stations:
Location of equipments helps us to decide on the type of connection to make i.e. on network topology. We will obviously be integrating bus, ring and star connections for better performance. A crude map (not to scale) of A-F Blast Furnaces sub-stations is attached.
Our plan is to imbibe the power networking to existing switches. In such a situation, sub-stations can be connected to nearest control rooms. We also note that D and F coal-injection SS are isolated from others due to tracks for carrying ladles and slag. There is another sub-station, LRH sub-station. It doesn’t figure in the diagram because it will be shut down very soon.
3.2 Cost Estimates
Fibre Optic (Raw Price)
: Rs. 300/m - 15 -
Fibre Optic (Including Laying and Termination charges) UTP (Raw Price)
: Rs. 475/m (approx.) : Rs. 10/m
UTP (Including Laying and termination charges)
: Rs. 25/m (approx.)
Central Switch
: Rs. 2.5 Lacs (around)
Branch Switch
: Rs. 50,000 each
3.3 Tapping Points
Our primary motive is to measure power, at the same time detecting faults. Hence, power measurement at incoming feeders and outgoing feeders can do the task. Accordingly, tapping points are recognized. A complete list of in-comers and outgoers to be tapped is given below. Please refer to the geographical figure of A-F Furnaces and individual furnace line diagrams in appendices also.
Selection Of Tapping Points: Incoming feeders in all sub-stations need to be tapped. Incomings to OGP, NSGP and Slag Dump SS being outgoings from New BF SS and F Fce HT SS, we don’t need physical ethernet connectivity at these places.
Similarly, Bosh Cooling SS also gets power from New Fce SS and doesn’t need a special physical ethernet connectivity. These can be tapped from source sub-stations
All (with the exception of SGDP) outgoing feeders supplying power to other departments have to be tapped so that we know how much power is consumed, in total, in blast furnaces.
Outgoing feeder from Slag Dump SS to SGDP isn’t tapped from economy point of view. It is the only outgoing feeder at slag dump SS. SGDP takes power only during an emergency and doesn’t take any power in normal times. A normal energy-meter can give an estimate of power consumption there.
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As per geographical location, we have prepared an optimized design for the network topology. Central switches are available at all control rooms. With a maximum of one or two branch switches, all tapping points can be connected to nearby control rooms.
3.4 Design & Optimization
Following points need consideration:
It should be noted that sub-stations like OGP, NSGP and Bosh cooling (refer network diagram) get their power from other sub-stations ( F Fce HT SS, A Fce SS, New Fce SS). Hence, incomers for these are outgoing feeders for other substations. If outgoings of one supplying SS is tapped, no need to tap the SS it supplies power to.
There are underground HT lines to prevent human interference to HT wires. In normal situations, we can install fibre optics (with no EM interference) in these underground path in case of geographical barriers overground. But maintenance problems arise here. At some places, it is not possible to use underground as well as overground routes. In such a situation, wireless communication can be used.
We have central switches in all control rooms. The existing LAN network can be extended to meet our purpose
UTP cabling is far cheaper that fibre optics cables. Since UTP isn’t immune to electromagnetic interference, it can’t be used in 6.6 KV sub-stations. With proper shielding, UTP can be used in 415 V sub-stations. This must also be noted that UTP cables are effective only for a maximum distance of 100 metres from nearest switch. For longer distances, fibre optics is preferred.
D and F Fce Coal Injection Sub-Stations are close to F Furnace control room. Yet, it is not possible to connect these sub-stations to any control room by overhead cables. These are surrounded by hot metal line and railway lines on both sides and we don’t have any existing cable tray. Rather than construction of overhead cable trays, wireless communication is a better alternative.
A complete mapping of A-F Blast Furnaces Sub-Stations with topology plan of automation is attached.
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4 INSTRUMENT SPECIFICATIONS 4.1 Relays & Sensors
There are electromechanical relays, solid-state relays and numerical relays with increasing level of accuracy and price. After proper inspection of the sub-stations, we have found out that most relays in the sub-stations are electromechanical relays (OCB, VCB & MOCBs). Relays in F Fce HT SS and New F Fce SS are modern micro-
processor based relays that are pretty fast. Numerical relays are pretty costly and aren’t used unless quality monitoring is required.
We plan to monitor quality as well. Most sub-stations getting power from the A Fce SS, F Fce HT SS and New Fce SS, it is okay if we replace the relays on incoming feeders in these sub-stations by numerical relays. Since D Fce Coal Injection SS and F Fce Coal Injection SS get power directly from SP#2 sub-station, feeder relays of these need to be replaced by numerical relays.
At this point, it is worth mentioning that the energy monitoring system used to measure power consumption can be used in place of numerical relays to detect faults and quality variations. Energy - 20 meters measuring sub-cycle events are costlier than normal energy meters, but are a better substitute for normal energy meter + Numerical relays. Besides, we need to install them at selected points. Normal intelligent energy meters can be placed at places where quality monitoring isn’t crucial.
Sensors required for the up-gradation are CT and PT only. Standard PTs in Tata Steel have secondary voltage of 100V rating and turns ratio are
accordingly selected. CTs have secondary current of 1 Ampere rating. We don’t need power factor transducers as P.F is centrally controlled by LDC using capacitor banks and SVC.
4.2 Data Acquisition System
Fast fault detection (FFD) is defined as “fault detection for systems that require fault removal or limitation before the first current peak after the initiation of the shortcircuit.” For a fast fault detection and archiving of such data, we need a data acquisition system. Fast Data Acquisition Systems (FDAS) have been installed in Golmuri Sub-Station and MPDS. These are pretty costly but greatly enhance quality monitoring and enterprise energy management. - 21 In our system, FDAS has to be installed not with numerical relays but with energy meters; at incomings of three sub-stations, namely A Fce SS, New Fce HT SS and F Fce HT SS. They should have the ability of detecting and storing sub-cycle events.
4.3 Intelligent Energy Meters
The primary duty of our energy meters will be to measure and process each cycle. Some monitors sample for a limited period and suspend monitoring while they perform the power and harmonics calculations. These are called “blind spots”. Our energy meter shouldn’t have this disadvantage. A high speed sampling can both capture transients and display their waveforms.
Secondly, the protocol of communication of available energy meter has to be checked. If the device is TCP/IP compatible, we don’t need a media converter. Else, the need for a media converter arises –in order to give the energy meters an IP address.
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Above facts and SCADA Features given below should be taken into consideration before selecting a vendor to buy the automation product.
4.4 SCADA Features
The attached software with our automation system must have certain features in order to facilitate analysis and storage of data. Based on industry demands at A-F blast furnaces, following features must be available at the control room: Production of aggregated load profile, cost allocation and power quality reports Sound alarm in case of emergency/ fault in the control room Archive data in a database that can be retrieved at a future time Facility to correlate, filter and compare energy and power quality variables over time. Should display KPIs, trends, tables, real-time data, power quality indicators and alerts in one easy-to-use dashboard; Graphics should be customizable.
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5 ADVANTAGES Accurate determination of amount and cost of energy consumed. Determination of peak and off-peak hours and efficient energy management to reduce load variations over time.
Data Collection; this data is required to determine how and where events were caused, leading to an understanding of how they may be avoided in future. Power consumption data also useful for planning future plant expansion and for ensuring existing and future feeder capacities adequately Predictive Maintenance; archiving of power reports helps to predict when a failure (in what situations) may occur in future. Fault detection; Normal meters can measure cycle-to-cycle faults. Total disclosure meters even monitor sub-cycle events and detect sub-cycle faults. Power Quality Monitoring; Detection of voltage sags, swells, outages etc. Also detect voltage transients and imbalance. Alarm system that sends alarm to the control system in case of faults at the sub-station level.
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6 FUTURE IMPROVEMENTS The system can be extended to monitor circuit breakers. Switches of circuit breakers have an auxiliary switch attached. When the CB is NC, the auxiliary switch is NO and vice versa. Auxiliary switches can be tapped to monitor
CBs. Also, automation is available to close/ trip CBs at the click of a mouse in the control room.
Harmonics can also be monitored on a continuous basis. This can ensure that over time, the incremental addition of loads doesn’t cause excessive heating. It will suffice to detect 3rd, 5th and 7th harmonics
Most relays in A-F Blast Furnace Sub-Stations are electromechanical relays. Relays at crucial feeders need to be changed for better and faster operation. Fast energy meters with ‘Full Disclosure’ facility can work as a good substitute for ‘numerical relays with FDAS’ wherever placed.
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APPENDIX
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I. Power Interruptions in A-F Fce DATE
PROBLEM
REASON TISCO isolated from DVC and flashover at MPDS - 1 S/S. due to Total power failure and 1/2 bus power rain water entry. After restoration of power again NBF S/S. 1/2 1/5/2004 failure of NBF s/s.from WSS for bus bus failed due to malfunctioning of bus zone relay at WSS end. zone relay operation Total Delay of all the furnaces --- 4 Hrs. 05 Min. Cooling Pp. trippwed on NPS indication due to voltage dip in the system because of CT brusting at Golmuri S/S.
16/05/04 D Fce. Cooling Pp. tripped. 26/06/04 Total power failure
Total power failure of JSR. All Fce. Were down. Due to Total power failure at PH # 3 Total power of A Fce. Has failed. A & B Fce. Has suffered. Voltage dip occurred in the system due to flash over of DG fdr. # 2 at MPDS S/S. D & F Fce. Suffered for 7 min. Due to flas over of 33 KV feeder oat HSM voltage dip occurred in the system and F Furnace and high line PCC's drives tripped and delay occurred at F Fce. and CT car.
30/06/04 Total power failure of A fce. S/S. 19/07/04 Voltage dip in the system 31/07/04 Voltage dip in the system
22/11/04 Voltage dip in the system
Due to tripping of B-73 Feeder at CP due to grounding of compressor motor,A Fce. Power failed and DELAY occurred for 3 min.
25/11/04 440 Volt power tripped
440 Volt power from PH # 1tripped and stock house power of A & B Fce. Failed. Reason not known as these Brk. Do not have relays which can discreminate fault. DC power from PH # 2 tripped and delay occurred in B Fce. For 3 min. Hoist house equipments tripped due to power swing in the 440 Volt system. C Fce. And bosh cooling power tripped due to voltage dip in the system because of burning of CP motor. Due to cable joint failed at PH # 4 Incoming from WPRS S/S of D Fce. Cooling S/S has failed causing 1/2 bus power failure. Incoming # 2 at NBF S/S has tripped at WSS on E/F indication causing 1/2 bus power failure. A,B,C,E & D Furnaces suffered for this.
26/11/04 250 Volt Dc power failed 28/12/04 Power swing in the system. 29/12/04 Voltage dip in the system 12/2/2005 1/2 bus power failed at NBF /s. 5/3/2005 1/2 bus power of NBF failed. 14/03/05 1/2 bus power failed at F Fce. PCC
440 Volt 1/2 bus power of F fce. Has failed due to E/F of sinter plant motor. This causes delay of 25 min. of F Furnace.
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II. Existing Networking: A Mock Diagram I-Historian E&C ConServer trol Room
A&B Control Room
I-Fix DC
D Control Room
Data Collectors
Data Clients: I-Fix
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III. FEEDERS TO BE TAPPED:
INCOMING FEEDERS: A Blast Furnace SS •
Feeder from PH#1 (6.6KV)(2 Nos.)
New Blast Furnace SS •
Feeder from PH#4 (6.6KV)(2 Nos.)
F Blast Furnace HT SS •
Feeder from PH#4 (6.6KV)(2 Nos.)
D Furnace HT SS • •
Feeder from New Blast Fce SS (1 No.) Feeder from SP#2 (1 No.)
D Fce Coal Injection •
Feeder from SP#2 (1 No.)
F Fce Coal Injection •
Feeder from PH#2 (1 Nos.)
OUTGOING FEEDERS INSIDE A-F FCE POWER DIST. NETWORK: A Blast Furnace SS •
Feeder to Bosh Cooling SS(1 No.)*
New Blast Furnace SS • • • • •
Coke Plant Feeders (3 Nos.) Self Flux SS (1 No.) New Rectifier SS (3 Nos.)* D Fce HT SS (1 No.)* Bosh Cooling SS (2 Nos.)* - 29 -
F Blast Furnace HT SS • • •
OGP SS (1 Nos.)* NSGP SS (1 Nos.)* F BF New PCC (3 Nos.)*
NOTE: Outgoing feeders marked * are incoming feeders to other sub stations. Power consumption in those SS is tapped at above sub-stations. OUTGOING FEEDERS TO OTHER DEPARTMENTS: A Blast Furnace SS • •
Feeder for Energy Mgmt Center from A Bl. Fce. S/S (440 V) feeder (415 volt) for A. Bl. Furnace hearth cooling s/s at BPH area
F Furnace HT SS • •
Service Water Pump Feeder at F Bl. Fce. (6.6 KV) Feeder for ICP # 2 From F Bl. Furnace S/S (6.6 KV)
F Furnace New 415 V Panel • • • •
MCC Feeder # 1 for GCP Ventuary from F Fce. S/S (440 V) MCC Feeder # 2 for GCP Ventuary from F Fce. S/S (440 V) Feeder for GCP MCC # 3 from F Fce. S/S (440 V) Feeder for GCP MCC # 4 from F Fce. S/S (440 V)
New Blast Furnace SS • •
Self Flux Feeder for Sinter Plant from New Bl. Fce S/S (6.6 KV) Feeder for GCP # 1 from New Bl. Fce. S/S (6.6 KV)
New Rectifier SS • •
Feeder to GCP # 2 Pump # 1 from New Rectifier S/S (440 V) Feeder to GCP # 2 Pump # 2 from New Rectifier S/S (440 V)
Slag Dump SS •
Feeder for SGDP from Slag Dump Compressor House ( 440 V)
