Plc Control 2 Genset.pdf

Journal of Electrical Engineering The Institution of Engineers, Bangladesh Vol. EE xx, No. xx, June/December xxxx

PLC Based Operation and Control of Two Diesel Generator Set P. K. Bhowmik1, M. Dey2, and S. K. Dhar3 1

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Department of Instrumentation and Communication, Eastern Refinery Limited, North Potenga, Chittagong, Bangladesh Department of Electrical & Electronic Engineering, Chittagong University of Engineering & Technology, Chittagong, Bangladesh 3 Member IEEE, Chittagong, Bangladesh E-mail: [email protected], [email protected], [email protected] complete set up has the following facilities [4-5]. 1. Programmable Logic Controller (PLC) 2. Interface Unit 3. Power supply for PLC input & output module 4. Power supply for Lamps supply (24V DC) 5. 24V DC Relay and Cables 6. Two contact relay base 7. Push button switch 8. 24V DC Flashing lamps 9. A Personal Computer (PC) 10. Sucosoft V5.02 programming software

Abstract— This paper outlines the operation and control features of a diesel generator of Reactor Operation and Maintenance Unit (ROMU) and discuss about the system, structure and implementation for smooth automatic operation by using programmable logic controller (PLC). All criteria for safe starting, synchronization, protection against electrical and mechanical faults of the generators are taken into consideration in the software used for the PLC. This facility enhances the method of learning of PLC based power systems operation and control at undergraduate level. Over the years the demand of higher quality, greater efficiency & automated system and machines has increased in the globalised world. To cope with this advancement it is anticipated that this paper will be considered very effective effort.

Personal computer Index Terms—PLC, Diesel Generator operation and control, Sucosoft V5.02 Moeller PLC software

Sensor Panel

I. INTRODUCTION

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N order to automate a power generation system and to minimize human intervention, PLC based system will be a good option that monitor the system and help to reduce the error caused by human. The wide applications of PLC in many areas have significantly contributed to the operation and automatic control of electrical and electronic system [24]. The internal storage of instructions for the implementing functions such as logic, sequencing, timing, counting and arithmetic to control through digital or analog input/ output modules various types of machines processes. Similar PLC based automation Systems are also widely used to monitor and control plants or equipment in industries such as power plants, energy, oil and gas refining and transportation.

Input Module

24V dc power supply for PLC

Interfacing Unit

CPU

Output Module

Power circuit Breaker

Load Panel

24V dc power supply for lamp

Main Power Supply Fig. 1. Block diagram of the PLC together with interfacing components III. PROCESS SYSTEM DESCRIPTION

A. Diesel Generator Sets The two diesel generator set defined as Generator-A and Generator-B of ROMU are considered to get an idea of operation for PLC based generator operation and control system development and experimental purpose. Here the two synchronous generator set are driven by diesel engine. The ratings of Generator-A is 3-phase, 650-kVA, 50-Hz, and Generator-B is 3-phase, 250-kVA, 50-Hz. Two generators are connected to a synchronizing panel with which main distribution board are connected. Normally utility supply (REB) is used in ROMU, but in case of load shading the generators are started manually and with the help of synchronizing panel board generators are synchronized [1]. There are specific operating procedures for such activities.

II.PLC MODULE SETUP

A PLC is a 'digital operating system' designed specially for use in an industrial environment, which uses a programmable memory for its internal operation of user-orientated instructions and for implementing specific function such as logic, sequencing, timing, counting and arithmetic. PLC controls digital and analog inputs and outputs in the various types of machines. In a PLC inputs and outputs are not designed for humans, but for use in the control of machines. Machine and operator interact solely by way of limit switches, contact switches, or photoelectric switches [2]. The 43

Author Instructions: J. Elec. Engg., Instn. Engrs., Bangladesh, 36(II), December 2009 D. Protection and Control of Generator

B. Process Block Diagram

Start

Lube oil Measurement Sensor

REB line

Fuel oil Measurement Sensor PLC

GenA

GenB

Water level Measurement Sensor

A C T U A T O R

REB off

Reactor Operating

Yes

Radiator, bearing temp Measurement Sensor

No

Select Gen A

Select Gen B

T1

Generator Cranking

BUS-BAR

Voltage Sensor

Current Sensor

PF Sensor

Frequency Sensor

Reset Alarm T2 No

Fig. 2. Block diagram of automation procedure of two diesel generator set.

All alarm Reset

C. Process Operation Description Successful operation of a process system depends upon careful installation & initial start up. Before start up there should be a thorough check of the system, like valves, control trip, safety device, and all mechanical and electrical systems that should be in good condition. The operating procedure of this diesel generator system is as follows [1]1. Generator automatic selection and starting when utility, named here as “REB” is off and when starting conditions to be fulfilled are ok as mentioned in the operation manual. 2. If Reactor in operating condition higher capacity Generator-A will be selected. Otherwise the lower capacity Generator-B will be selected. 3. Then generator cranking started. 4. All the alarms of the system to be reset condition. After resetting all alarms engine purging started. This checking & purging requires a specific time. 5. Generator starting condition checking (temperature level and pressure of the lube-oil and fuel oil, water level, Radiator and bearing temperature etc) mainly all the mechanical features. This checking takes a specific time. 6. If mechanical fault found then shutdown the engine and then wait for alarm reset. If all mechanical features are ok then generator speeds up gradually. This requires a specific time to accomplish generator rated speed. 7. After achieving the rated speed generator auto synchronism with the bus-bar accomplished. This also requires a specific time. 8. Bus-bar disconnection by disconnecting the circuit breaker while electrical fault occurs (over voltage, over current, power factor or frequency out of desired range) and then again wait for alarm reset.

Engine Shut down

Yes Engine Purging

T3 Fault T4

Checking lube oil pr, water level, fuel oil pr. temp, Radiator, Bearing temp & others

Generator Speed up T5 Gen rated speed achieved No Disconnecting Circuit Breaker

Yes Gen Synchronizing

Gen Loading according to the demand

T6

T- Indicates Timer

Yes Electrical fault occur No Return

Fig. 3. Process flow diagram for operation and control of two diesel generator set

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Author Instructions: J. Elec. Engg., Instn. Engrs., Bangladesh, 36(II), December 2009 E. Protection and Control of Generator System In this study the starting and protection against both electrical and mechanical faults are automated. When electrical fault occurs (due to over load, over voltage, over and under frequency) and violet the generator protection features according to ANSI the bus bar would be disconnected from load and fault-alert would be made for the operators. The generator protection features according to the ANSI are: differential current(87G), over voltage(59G), under voltage(27G), over current(51G), ground current(51N), loss of excitation(40G), reverse power(67G) and winding temp high. When mechanical fault occurs (due to inappropriate fuel level, lube oil pressure, water level in the radiator and high stack temperature) individual generator would be shut down for individual mechanical faults and also fault alert would be made as usual. An indicator also shows the status whether the fault is cleared or not. Almost all the automation procedure is completed in a program block diagram of which is shown in Figure 2. As the number of input and output address of the PLC module that we used is limited so only some selected control features are considered in developing the PLC ladder program though in the practical case many control and protection feature taken into consideration. The generator is connected to the bus bar through synchronizing panel and the actuator actually starts the generator in reality.

Fig. 4. The process variable declearation for PLC system

F. Program Development Automation software of PLC is programmed in Sucosoft V5.02 programming software and this software is the simulation software of the Moeller PLC which has limited inputs and limited outputs handling capabilities. To overcome these problems many ghost outputs as well as timers are used in programming for convenience and only selected parameter both electrical and mechanical are considered in this study though the practical modern generator system handle many control features. The Ladder Diagram (LD) PLC programming language used easy to understand. Ladder Diagrams are based on graphical representations with contacts, coils and boxes, as per the circuit diagrams. Indicator lights are used as outputs where as push button switches are used as inputs [3].

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Author Instructions: J. Elec. Engg., Instn. Engrs., Bangladesh, 36(II), December 2009 IV. PROGRAM EXECUTION

The ladder logic program execution by Sucosoft V5.02, Moeller PLC software requires the following steps [3]1. Program development in pou editor 2. Topology configaration 3. Program code generation 4. Program transfer from computer to PLC 5. Test and commissioning 6. Program run After following the above mentioned steps then the PLC become ready to run the program. PLC executes the program successfully after pressing the start switch. PLC always scan its input address and give an output signal according the instruction of the program. If the process sequences may need changed or modification only change in the program will sufficient for successful program execution. V. CONCLUSION

The most important aspect of any power generation system is the generation control. Several techniques can be implemented to control the generator in power plant. The method that has to be used relies on varied objectives like superior quality, increased efficiency, high profit and other such points depending upon the purpose. With the prime objective of catering to these necessities and the needs of the industrial sector, significance has been given here to automation. This paper presented here has kept in mind, the ceaseless changes that are relentlessly taking place in the contemporary scenario of the industrial segment. Emphasis has been given to the automation process that is now rapidly taking its place in all the power plants across the globe. The Paper has furnished itself to study the integral parts of the entire process involved, their implementation and the problems that may show up have also been given their due importance. ACKNOWLEDGMENT The authors would like to thank Mr. Sharafat Ali, Assistant General Manager, Department of Instrumentation & Communication, Eastern Refinery Limited, Bangladesh and Md. Ali Zulquarnain, Member, Planning, Bangladesh Atomic Energy Commission (BAEC) for their valuable review and comments. REFERENCES [1] Diesel Generator Operation Guideline, Reactor Operation and Maintenance Unit (ROMU) of Bangladesh Atomic Energy Commission. [2] GUNTE, Equipment for Engineering Education,(04/02/2012) http://www.usdidactic.com/html/p3562.htm [3] Sucosoft S40 V5.02, Moeller PLC Software [4] P. K. Bhowmik and M. Dey, “Protection and Control of Steam Turbine Generator using PLC” First International Conference on Mechanical Engineering and Renewable Energy 2011 (ICMERE2011), Chittagong, Bangladesh, December 22-24, 2011.

Fig. 5. Ladder logic program of diesel generator operation and control

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