Online Monitoring of Electrical Energy – A step towards

Modern Energy Management System

in Durgapur Steel Plant

Somak Dasgupta

CET, SAIL, Durgapur Sub Centre, Ispat Bhawan - 7th Floor,

Durgapur Steel Plant, Durgapur-713203

Tel: +91-343-2582687

Email:somak.dasgupta@sailcet.co.in

Electrical Energy Management System (EEMS) refers to a system designed specifically for

automated control and monitoring of electric power and utility system.

As per directive of Bureau of Energy Efficiency, all steel plants of SAIL are required to

fulfil the energy consumption target as per Perform, Achieve and Trade (PAT) scheme. The

present practice of Power Management Department of Durgapur Steel Plant (DSP) is to

note down the energy consumption readings from the conventional electromagnetic type

meters and calculate them manually. Need was felt for an automated system to monitor

and subsequently control the electrical energy consumption of different units of the plant.

The proposed paper describes the scheme of setting up of an online energy monitoring

system (OLEMS) connecting 146 nos. of panels with retrofitted multifunction meters

(MFM) spread over 16 nos. sub-stations throughout the plant. The existing DSP Local

Area Network (LAN) will be utilized as the media for data communication from different

substations to OLEMS server at Main Receiving Station (MRS) control room.

Key Words: EMS, energy, online, monitor

INTRODUCTION

Electrical Energy Management System (EEMS) widely refers to a computer system which

is specifically designed for the automated control and monitoring of electric power and

utility system.

ABSTRACT

Energy Management System (EMS) is a collection of computerized tools used to monitor,

control and optimize the performance of generation and transmission systems. The

intelligent energy management software control system utilizes real time system data and

is designed to reduce energy consumption, improve the utilization of the system, increase

reliability and predict electrical system performance as well as optimize energy usage to

reduce cost.Energy Management System had its origin in the need for electric utility

companies to operate their generators as economically as possible. It involved efficient

on/off scheduling of generating units. Energy Management Systems can also provide

metering, sub metering, and monitoring functions that allow facility and building managers

to gather data and insight that allows them to make more informed decisions about energy

activities across their sites.

EMS IN POWER SYSTEMS

EMS is related to the real time monitoring, operation and control of a power system. The

information from the power system is read through Remote Terminal Units (RTU), an

integral part of SCADA to an EMS system or Energy Control Centre (ECC). EMS consists

of both hardware and software. Hardware part of EMS consists of RTU, Intelligent

Electronic Device (IED), Protection, Computer networking, etc. Software part of EMS

consists of Application programs for network analysis of power systems. In EMS,

application programs are run in a real time as well as extended real time environment to

keep the power system in a secure operating state. Now-a day’s EMS is an integral part of

any power system. It is used as a part of Substation Automation System (SAS), Demand

Side Management (DSM), Protection and Distribution Management Systems (DMS), for

renewable energy and so on.

OBJECTIVES

Primary objectives are maintaining the power system in a secure and stable operating state

by continuously monitoring the power flow and voltage magnitudes, maintaining the

frequency and the tie line power close to the scheduled values.

Secondary objectives are economic operation of power system through real time dispatch

and control and optimal control through preventive and corrective actions.

Tertiary objectives are optimization of the power system for normal and abnormal

operating scenarios and maintenance scheduling.

The three objectives are executed at different levels by the operator in a control centre.

While the first objective is automatic or closed loop control without manual intervention

the other objectives performed with the aid of the operator.

EVOLUTION OF EMS

The evolution of EMS has a long past. It has started with control centres in 1960s to fully

developed energy management systems.

During 60’s, the Control Centres (CC) were introduced to control and the power generation

and load demand so as to match the generation with load demand.

During 70’s, Energy Control Centres (ECC) came into existence to mainly manage the

energy rather than power.

During 90’s EMS were formed to manage the energy through various techniques like Load

Management, Demand Side Management, etc. EMS uses computer based programs that

perform both computational tasks as well as decision making tasks to assist the operator for

real time and control.

The evolution of SCADA started with monitoring and data acquisition systems of plants

followed by control. These have been used prior to EMS. The main tasks of SCADA were

to continuously measure and monitor parameters for checking limit violations and to

ensure reliable and safe operation of the system. It becomes more beneficial when EMS

and SCADA are used together.

OPERATION AND FUNCTIONS OF EMS

EMS consists of several application programs which are used by the operator in a control

centre for effective decision making in the operation and control of a power system. These

application programs are specific programs like load forecasting, security assessment,

contingency analysis, optimal power flow etc. which monitor and calculate the operating

states of the power system.

All of these programs are networked together in such a way the output of one program is

the input to another. This continues till all the programs form a closed loop. The output of

each program provides a result which can be used by the operator for decision makingfor

controlling the power system.

The working of an EMS is divided into two categories, namely “online” or “offline”

corresponding to the problem being addressed and the application it is handling.

The operation has three main classifications namely

i) Online closed loop control like load frequency control, automatic generation

control, reactive power control, voltage control

ii) Online open loop control like active & reactive power dispatch

iii) Offline study or simulation model

The following are the important functions which are carried out by EMS:

Control functions:

1. Real time monitoring and control functions

2. Automatic control and automation of a power system like automated interfaces and

electronic tagging

3. Efficient automatic generation control and load frequency control

4. Optimal automatic generation control across multiple areas

5. Tie line control

Operating functions:

1. Economic and optimal operation of the generating system

2. Efficient operator decision making

Optimization functions:

1. Optimal utilization of transmission network

2. Power scheduling interchange between areas

3. Optimal allocation of resources

4. Immediate overview of power generation, interchanges and reserves

Planning functions:

1. Improved quality of supply and system reliability

2. Forecasting of loads and load patterns

3. Generation scheduling based on load forecast

4. Maintaining reserves and committed transactions

5. Calculation of fuel consumption, production cost and emissions

The functionsof an EMS are illustrated in Figure-1 and 2. Figure-1 shows the measurement

of voltage and current through current transformer (CT) and voltage transformer (PT) or

through remote terminal units (RTU). These are inputs to the EMS of the control centre.

Figure-2 illustrates the various EMS functions in an EMS. State estimation forms the first

and foremost function that is executed based on SCADA measurements. The output is used

by many other programs.

Fig.1.0: Measurement and monitoring

Fig.2.0: EMS functions

ENERGY MANAGEMENT SYSTEM IN DSP

BACKGROUND

DSP receives bulk power from DVC. The balance power is obtained through self-

generation from Old Power Plant (OPP) and NSPCL. The power from DVC is received at

Main Receiving Station at 220 KV and stepped down to 33KV through 80MVA

transformers for onward distribution. Step down substations are situated at various load

centres to feed power to different units of the plant like Coke Oven complex, Sinter plant,

Blast furnace, SMS complex and Rolling Mill complex together with associated auxiliary.

As per directive of Bureau of Energy Efficiency, all steel plants of SAIL are required to

fulfil the energy consumption target as per Perform, Achieve and Trade (PAT) scheme.

The present practice of Power Management Department of Durgapur Steel Plant (DSP) is

to note down the energy consumption readings from the conventional electromagnetic type

meters and calculate them manually. Readings are taken once in a month. Continuous

monitoring is not possible as number of monitoring points is very high and involves

manpower. Need was felt for an automated system to monitor and subsequently control the

electrical energy consumption of different units of the plant.

PROJECT OVERVIEW

The EMS system will collect data from Multifunction meters (MFM), for the 33kV, 11kV,

& 3.3kV power distribution network, over MODBUS RTU protocol via DSP LAN from

sixteen substations of DSP. Multifunction meters will be retrofitted in 146 breaker panels

throughout the plant for which the energy monitoring will be done. The existing DSP

Local Area Network (LAN) will be utilized as the media for data communication from

different substations to OLEMS server at Main Receiving Station (MRS) control room.

A new Local Area Network (LAN) will be set up in Main Receiving Station (MRS)for

communication between Online Energy Monitoring System (OLEMS) server, clients,

printers, existing SCADA (ECIL) and existing network switch of DSP LAN in the control

room.

PROJECT ARCHITECTURE

The existing substations, for which the EMS will be implemented, are distributed

throughout the plant. An existing network switch of DSP LAN may either be located inside

or far from a sub-station.Accordingly, the architecture will be different in both the cases.

The MFMs will be serially connected through RS485 cable and connected to the Ethernet

gateway which in turn will be hooked up to the existing network switch. The connection

arrangement of MFM using the existing CT/PT/Auxiliary is given in Figure-3.

In case the network switch is located outside the sub-station, optical fiber cable will be

used for hooking up. The architecture of sub-station MFMs is shown in Figure-4.

The MFM data will be dumped into the LAN andthe data will be fetched from the network

switch located in the MRS control room. A LAN will be set up in MRS control room to

accommodate the server hardware. The architecture of server hardware is shown in Figure-

5.

PROJECT WARE

Following items will be installed for EMS:

SL

No Item Name

Make/

Model Descriptions Qty

1 MFM 0.5s

CMS RM705

L4

Bi-Directional revenue energy metering. Voltage &

Current, KW, KVA &KVAR, Power Factor,

Frequency Energy: Import & Export KWH,KVARH

Lag, Voltage & Current unbalance %, Display

current Date & Time, Phase Wise KWh 150

2

RS485 to

Ethernet

Converter Netex 103

Interface for Modbus TCP and Modbus RTU

22

3

Media

Converter

D-Link DFE

855S-15i

Media converter converts 10/100BASE-TX Ethernet

twisted –pair signals to 100BASE-FX fast Ethernet

fibre signals. 18

4

UPS

Offline

APC

BR1000 G

1.0kVA, Supply : 210-230VAC, 50Hz, Output:

220VAC, 50Hz, 5

5 FL 9U rack WQ 600mmW x 500mmD and 9U usable Height 15

6

Network

Enclosure

Box WQ

600mmW x 500mmD and 9U usable Height

18

7 LIU Molex 12 Port LIU box fully loaded 18

8

Network

Switch

CISCO

SG300-10P

8 Port, 19” Rack Mountable, 10/100/1000BaseTx

RJ45, RS232 Console port and GBIC/ SFP Slot 5

9

N/W

Firewall

CYBEROA

M Cyber roam DPU CR 25iNG 1

10 Server PC

HP

ML350T09 HP ML350T09 G9 1

11 Client PC

DELL

OptiPlex

3020 Intel I3 Processor of latest architecture 2

12 Laptop

LENOVO

B40 80 Intel I3 500SU 1

13 Printer

CANON

LBP6230DN

LAN interface, Resolution-1200 X 1200 dpi, Paper

Size-A4 2

14 UPS Online

Emerson

Liebert GXT

MT

1.0kVA, Supply : 210-230VAC, 50Hz, Output :

220VAC, 50Hz 3

15

UPS for

Switch APC

Supply : 210-230VAC, 50Hz, Output : 220VAC,

50Hz 2

16

EMS

Server

Software CMS Envisage EMS software 1

17

EMS Client

Software CMS Envisage EMS software 2

18 Furniture Standard Computer Table & Chair 3

19 UTP Cable Molex Cat6 UTP Cable

1500

Mtr

20

RS 485

Cable

KabirInfosol

ution Pvt

Ltd. RS 485 Armoured Cable

2000

Mtr

21 GI Conduit UTKARSH 0.5” GI Conduit

800

Mtr

22

PVC

Conduit UTKARSH 0.5” PVC Conduit

1200

Mtr

23 HDPE Pipe UTKARSH 1.00” HDPE pipe for FO Cable

2000

Mtr

24 FO Cable Molex 6 Core Armoured Single core FO Cable

2000

Mtr

25

Power

Cable Finolex 2.5sq. mm (Red, Yellow, Blue & Black) Power cable

4500

Mtr

CONCLUSION

The introduction of EMS in DSP will result in continuous monitoring and analysis of

electrical energy consumption of selected load points throughout the plant. It is a stepping

stone for introduction of automated electrical energy control which in turn will optimize

the energy utilization in future.

REFERENCES

1. Steve Doty & Wayne C Turner - Energy Management Handbook, Eighth edition, Nov 2012

2. SaniaAman, Yogesg S and Prasanna V.K - Energy Management Systems: State of the art and

Emerging Trends- IEEE Communications Magazine, Vol.50, No. 1, 2013

Somak Dasgupta