Important Considerations Of Substation Design

IMPORTANT CONSIDERATIONS OF SUBSTATION DESIGN

  Necessary Conditions of Substation Design

1. Safety of personnel and equipment

2. Reliability and Security

3. Electrical design considerations

4. Statutory obligations as per I.E. rules, Environmental aspects

5. Structural design considerations

6. Easy of maintenance

7. Possibility to Expand

 System parameters

System parameters are as shown below in table-8.1.

Table-8.1 System Parameters

Sr.	Descriptions	400KV	220 KV
1.	Nominal System Voltage	400KV	220KV
2.	Max. Operating Voltage	420KV	245KV
3.	Rated Frequency	50HZ	50HZ
4.	Number Of Phases	3	3
5.	System Neutral Earthing	Effectively Earthed
6.	Corona Extinction Voltage	320KV	156KV
7.	Min. Creepage Distance	25MM/KV	25MM/KV
8.	Rated Short Ckt. Current For 1 Sec.	40KV	40KV
9.	Radio Interference Voltage At 1MHZ (For Phase To Earth Voltage)	1000MV (320KV)	1000MV (156KV)
10.	Rated Insulation Levels
	A. Full Wave Impulse Withstand Voltage
	For Lines	1550KVP	1050KVP
	For Reactor/ X’mer	1300KVP	950KVP
	For Other Equipments	1425KVP	1050KVP
	B. Switching Impulse Withstand Voltage (Dry/Wet)	1050KVP
	C. One Min. Power Freq. Withstand Voltage (Dry/Wet)
	For Lines	680KV	460KV
	For CB / Isolator	520KV (Line Ground) 610KV (Open Terminals)	460KV 530KV
	For Other Equipments	630KV	460KV

Lightning Design

Adequate lighting is necessary for safety of working personnel and Operation & Maintenance activities

Recommended value of Illumination level

Control & Relay panel area     - 350 Lux (at floor level)

Test laboratory                        - 300 Lux

Battery room                           - 100 Lux

Other indoor area                    - 150 Lux

Switchyard                              - 50   Lux (main equipment)

- 20   Lux (balance Area / road @ ground level)

Minimum Clearances

Minimum clearances are as shown in table 8.2

Table-8.2 minimum clearances

	400KV	220KV
Phase to Earth	3500mm	2100mm
Phase to phase	4200mm(Rod-conductor configuration) 4000mm(Conductor-conductor configuration)	2100mm
Sectional clearance	6400mm	4300mm

Bus Bar Design

a. Continuous current rating. Ampacity calculation as per IEEE:738

b. Short time current rating (40kA for 1 Sec.) IEC-865

c. Stresses in Tubular Busbar

d. Natural frequency of Tubular Busbar

e. Deflection of Tube

f. Cantilever strength of Post Insulator

g. Aeolian Vibrations

Earthing Design

a. Guiding standards – IEEE 80, IS: 3043, CBIP-223.

b. 400kV & 220kV system are designed for 40kA.

c. Basic Objectives:

Step potential within tolerable

Touch Potential limit

Ground Resistance

Adequacy of Ground conductor for fault current (considering corrosion)

Share

Blogger Widget