Generator Protection

 A STUDY STUDY ON PROTECTIONS PROTECTIONS OF 60MW  TURBO GENERATORS OF CAPTIVE POWER PLANT IN VSP  Internal Guide Mr. MANOFAR ALI, Assistant Professor EEE DEPARTMENT

SUBMITED BY K.SIVA K.SIVA GOVINDARAO

(09U41AO264)

L.THARUN KUMAR

(09U41A0272)

M.CHAITANYA M.CHAITANYA DEEPTHI (09U41A0277) A.AJAY A.AJAY KRISHNA

(09U41A0248)

 ABSTRA  ABST RACT  CT  This project covers the complete electric protections of Turbo Turbo generator in a Thermal Power Plant of o f Visakhapatnam Visakhapatnam Steel Plant. The main objective of the project is to study the various protections provided for the alternator and the necessity of  each. Normally the faults in Generator can occur either inside like stator, rotor or external to it in the bus-ducts of feeders.

INTRODUCTION INTRO DUCTION TO VSP  Steel industry is both a basic and a core industry. industry. Visakhapatnam isakhapatn am Steel Plant (VSP), a public sector undertaking, is a subsidiary of Rashtriya Ispat Nigam Limited. It is one of the the most sophisticated sophisticated modern plants. plants. The plant is designed to produce 3.0 Million tones of liquid steel. It possesses possesse s thestate-of-the-art technology and a strong well trained manpower of 17,000 employees.Nearly 40% of the South Indian domestic market has been captured for the steel products. International customers are from from the countries of China, Singapore, Russia, Nepal, Sri Lanka, USA, Japan, UAE etc.

 ACHIEVEMENT  ACHIE VEMENT AND AW AWARDS Indira Priya Darshini Vrikshamitra for massive afforestation efforts of RINL : 1992-93.  Award from Ministry of heavy industries for achieving MoU targets for 2000-01. award-2002 -- First Prize in  National Energy conservation award-2002 Integrated sector.  Certificate of appreciation for achieving OHSAS 18001 from department of Factories, Govt. of Andhra Andhra Pradesh. 

INTRODUCTION TO TPP  Power requirement of VSP is met through captive generation as well as supply from ABSEB grid. The captive capacity of 270 MW is sufficient to meet all the plant needs in normal operation time we have 3 units of each 60 MW and one unit of 67.5 MW capacity.

BOILERS: 

Thermal Power Plant has 5 Boilers each of 330 T/hr. steam capacity at 101 KSCA and 540 O C.



The boilers are of BHEL make, capable of firing combination of fuels namely, namely, Coal, Coke Oven Gas, Blast Furnace Gas and Oil

TURBO GENERATORS Thermal Power Plant has 4 Turbo Generators, three of 60 MW capacity each and the fourth 67.5 MW

CHEMICAL WATER TREATMENT PLANT PLA NT Chemical Chemic al Water Water Treatment Treatment Plant Pl ant located in TPP zone produces high purity De-mineralised De-mine ralised Water and Soft S oft Water Water..

CHILLED WATER PLANT The chilled water wa ter is supplied to TPP, TPP, Blast Bla st Furnace and Sinter Plant for air conditioning conditioning purpose

COKE DRY COOLING PLANT (CDCP) BOILERS In VSP, hot coke produced in the Coke Oven Batteries is cooled by circulating Nitrogen in Coke Dry Cooling Plant .

ISLAND OPERATION SCHEME A scheme has been envisaged at TPP to get isolated form the grid in case of  system disturbance or low frequency condition with ABB make relay type FCX 103b relay with following settings:

POWER REQUIREMENT Integrated Steel Plants are major consumers of electricity, electricity, with specific consumption of power at around 600-650 kWh/Ton of liquid steel.

POWER DISTRIBUTION IN POWER PLANT Integrated Steel Plants are major consumers of electricity, with specific consumption of power at around 600-650 kWh/Ton kWh/Ton of liquid steel. The estimated annual power requirement of Visakhapatnam Steel Plant, at full level of production in each shop (corresponding to 3.0 MT of liquid steel), is 1932 million kWh. Power requirement of VSP is met through captive generation generatio n as well as supply from AP TRANSCO grid. The captive capacity of 270 MW is sufficient to meet all the plant needs in normal operation time.

SYNCHRONISATION The operation of connecting an alternator in parallel with another alternator alternat or or with common bus-bars is kwon as Synchronizing. Generally Generall y, alternators are used in a power system where they are in parallel with many other alternators. alternators. It means that the alternator is connected to a live system of constant voltage and constant frequency.

THEORETICAL REVIEW OF RELAYS TYPES OF PROTECTIONS Two types of protection: 1. 2.

Primary protection Backup protection

Primary protection Primary protection is the first line of defence and primary relays clear faults in the protected section as fast as possible.

Backup protection Backup relays operate if the primary relays fail and cover not only the local station but the next one also and have a time delay long enough for the primary relays to operate if they can.

ELECTROMAGNETIC RELA RELAYS YS

These are earliest form of relays devices used for power system protection and till now they are the most widely used variety relays. ATTRACTED ARMATURE TYPE

The type includes plunger, hinged armature relays. These are the simplest type  which respond respond to AC as well well as DC. The electromagnetic electrom agnetic force is given by F = KI2 INDUCTION RELAYS

Induction type relays are the most widely used for protective relaying purposed involving involving A.C. quantities. The Actuating Actuati ng force is given by F = K 1  2 Sin

GENERATOR DIFFERENTIAL RELAY

 A differential differential relay relay is defined as the relay  that operates when the vector difference of two or more similar electrical quantities exceeds a predetermined  value.

GENERATOR GENERA TOR RESTRICTED EARTH FAULT RELAY

In circulating current protection schemes, the sudden and often asymmetrical growth growth of the system current during external fault conditions can cause the protective current transformers to go into saturation resulting in a high unbalance current.

GENERATOR VOLTAGE RESTRAINED OVER CURRENT RELAY

Fault conditions cause a greater drop in bus bar  voltage  voltage than normal over load, and this fact has been utilised in  voltage  voltage restrained restrained over current relay.  An over over load characteristics determine by the operation of  instantaneous under  voltage  voltage unit unit monitoring monitoring the generator voltage.

GENERATOR VOLTAGE RESTRAINED OVER CURRENT RELAY

Fault conditions cause a greater drop in bus bar  voltage  voltage than normal over load, and this fact has been utilised in  voltage  voltage restrained restrained over current relay.  An over over load characteristics determine by the operation of  instantaneous under  voltage  voltage unit unit monitoring monitoring the generator voltage.

Time / current characteristics of Voltage restrained over current relay 

GENERATOR DIRECTIONAL OVER CURRENT RELAY

 When fault current can flow in both directions through the relay  location, it is necessary  to make the response of  the relay directional by  the introduction of  directional control elements.

GENERAL FIELD FAILURE RELAY

Under current relays connected in the field circuit have been extensively but the most selective type of  loss-excitation relay is a directional-distance type operating from the  A.C. current current and  voltage  voltage at the main generator field.

EARTH FAULT PROTECTION

 A single single earth earth fault is is not in itself dangerous since it does not cause any fault current, but a second fault effectively  short circuits or all parts of the field system and the unbalancing of  the magnetic force caused there by may be sufficient to spring the shaft and make it eccentric.

GENERATOR DIRECTIONAL EARTH FAULT RELAY  The relay is used for directional directi onal earth fault protection protect ion for generator. generator. Typical external externa l and internal connection. Since the current may be derived from any  phase, in order to obtain directional response it is necessary to obtain a related voltage. Such a voltage is the residual voltage of the system.

ROTOR EARTH FAULT RELAY   When a single earth fault is detected in the d.c field circuit circuit of a Machine, the Machine has to be taken out of service at the first opportunity.

PROTECTION AGAINEST PRIME MOVER FAILURE The effect of prime mover failure is to cause the machine to motor by taking power from the system which may result in severe mechanical mechanica l damage and, in addition will impose a heavy motoring load on the generator.

GENERATOR SENSITIVE EARTH FAULT PROTECTION This protection is especially provided in the generator to sense any earth leakage near to the neutral. Question Questio n may come why separate earth fault relays is used. Reason is that other earth fault relay senses earth current of  higher magnitude.

GENERATOR OUT OF STEP RELAY  A CAG CAG 19 relay serves as an over current starter and this is set at between 50 and 20% of nominal current. Based on 5 A CTs CTs below the current no operation can occur. occur. Both character look into into the source and consequently ignore ignore all conditions of load other than those which produce a reversal of power flow such as would occur with a condition of pole slip or power swing exceeding 90 O.

CONCLUSION  The purpose of protection system is to monitor the unwanted conditions and when such conditions arise, to remove remove the fault in the shortest time possible, leaving unaffected are operational. In this project proje ct we have studied the protection provided to 60 MW Turbo Turbo generator in Thermal Power Plant of Visakhapatnam Steel Plant. Plan t. In this we have studied both symmetrical symmetr ical and unsymmetrical unsymmet rical faults and response of different relays for these faults with the existing settings.