Indian Power Sector: 220 KV and above transmission lines and substations

Showing posts with label 220 KV and above transmission lines and substations. Show all posts

Sunday, November 29, 2009

Growth in Transmission Lines and substations in India

Wondered how much we added in our transmission lines in Xth plan? Here are the data:-
765 KV : 1700 Circuit KM
HVDC +-500KV : 60000 Circuit KM
HVDC 2200KV monoploe : 160 Circuit KM
400 KV : 75000 Circuit KM
220KV : 1,15,000 Circuit KM
Addition in substations during these 5 years was:-
HVDC Back to Back : 3000MW
HVDC Bipole+Monopole : 5000MW
765 KV :2000MVA
400 KV :90,000MVA
220 KV : 1,50,000 MVA

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How to construct EHV grid subsatation?

To evacuate power from generating station we need first a Step Up substation since the generation voltage is in the range of 11 KV only. This needs to be stepped up to 400 KV or 220 KV or 132 KV.
Then at the load centres it is again stepped down to 33 KV or 11 KV before final conversion into 440 V.
1.We need suiatble land for subsation.
2.Based upon load growth, operation speed, busbar arrangement, and fauld clearance , the layout and design is prepared.
3. Civil work starts with foundation of structures, equipements and cable trenches. Control room,quarters, fencing, road water supply , drainage and sewerage is contsructed thereafter.
4.Then power transformers, isolators,CTs, PTs, LAs, Control and relay panels, battery chargers abttery sets and shunt capacitors are installed.
5.After planning and laying the control wiring, testing is carried out.
Structures:- ( 220 KV ) all Black steel/ GI
AT1, AT8 for Column
AB 1, AB2 for Beam
AO, AO1 for isolators.
AO3 for CT/PT
AO4 for LA.
Busbars:-
ACSR conductors or pipes strung by tension disc insulators at the ends having tension of 750 kg. They are protected by earth wire at an angle of 30.
Various arrangements of busbars are given in the pictures below.
Earthing:-
Depending upon earth resistivity mesh isdesigned and layed. 200 mm MS rod or 50x10mm MS flat is trenched in 300 mm deep trenches. Mesh is connected to the ground with 28mm dia 3 m long earth electrode. Transformer tanks and neutarl needs separate earth electrodes. Final earth resistance should be < 0.2 ohms.
Safe IR :-
33 KV ( 1000), 132 KV ( 1400 ), 220 KV ( 6000 ).

Small Note on Acounting and Finance

While given a problem of preparing Profit & Loss Account and Balance Sheet from Trial Balance , follwoing tips were given by a friend:-

P & L Account :- What we have done during the year ? Credit ( in ) and Debit ( out ) is part of it.

Balance Sheet :- What is the statement at the end of year? It has two parts- Liability ( share holder ; which has 3 parts: capital, Reserves and Debt , Long Term Loans and Current Liabilty ; which includes short term debt , debtors and Provisions ) and Assets ( Fixed Assesta and Capital assets ; which includes Base, Liquid investment, receivables and Stock/inventory , NCA which means Long Term Investments Loans and Advances)

Expenses are of 3 types:- Cost of Material, Cost of Labour and Admin or Marketing. Further they can be booked as direct expenses( raw material, labour, wages, rent Maint of P&M ) and indirect expenses ( Directors Remun. , clerk's salary, Insurance, Bldg Maint, Heat & Power, Canteen, Welfare, Motor, Prof Charges, Postage and Telegr., Books and stationary, Packing etc )

Net Sales - expenses = PBDIT / EBITDA

PBDIT - DEP - Int = PBT

Op. Profit = Op. Income - Expenses - Dep.

PBT - taxes = PAT ( it has two parts:- Share Holdera and Reserves )

Sales - ST - Discounts = Net Sales

Now the question is , which part of Trial Balance is to be booked under which head?
Well some go into Trading ( raw material, Labour, Insurances, Sales, Discounts ), Some P&L ( salaries, Bldg Maint, Lab, Canteen, Rent, ST ) , some Balance Sheet ( Capital equity, Creditors, Taxation , P & L Account, Xerox Machine, Motor car) .