Two six pulse converters used for bipolar HVDC transmission system, are rated at 1000 MW, +- 200 kV. Find the rms current rating required for the SCRs.

To find the RMS current rating required for the SCRs in a bipolar HVDC transmission system with two six-pulse converters rated at 1000 MW and ±200 kV, we can use the following relationship.

For a six-pulse converter, the output power (P) is given by the formula:

[ P = frac{3 sqrt{3}}{2} V_{dc} I_{dc} ]

Where:

– ( P ) = output power in watts (1000 MW = ( 1000 times 10^6 ) W)

– ( V_{dc} ) = DC voltage (±200 kV = 200,000 V)

– ( I_{dc} ) = DC current (the current we want to find)

### Step 1: Find the DC current (I_dc)

Rearranging the formula to solve for ( I_{dc} ):

[ I_{dc} = frac{P}{frac{3 sqrt{3}}{2} V_{dc}} ]

Substituting the values in:

[ I_{dc} = frac{1000 times 10^6}{frac{3 sqrt{3}}{2} times 200,000} ]

Calculating ( frac{3 sqrt{3}}{2} ):

[ frac{3 sqrt{3}}{2} approx 2.598