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IEC standard does not specify any switching impulse test value below 245kV. There has been a debate about whether the switching impulse test should be performed in a large wind farm below 245kV. Basically, I hope to find out if there is any quick hand calculation method that can give me a rough...

hi, is there any hand calculation method available that can roughly determine the switching overvoltage at different voltage level and its propagation in a network? I know the value can be determined via the simulation program. Any document you can refer me to will be greatly appreciated. Many...

sorry, i was away.. thanks for all the comments. Jghrist, to answer questions: You have to define what you mean by "Xc is made exactly equal to the source reactance." Is it the source reactance seen during normal operation, during a 3Ø fault or during a Ø-grd fault? Actually, I'm hoping to...

if R=0

if R = and the fault is the ground fault, would the potential seen by generator is zero as the effective/equivalent impedance in between the fault and the generator is zero, Z=0 (as compensated fully by the capacitor)?

hi, i'd like to ask a question that perhaps sound a bit stupid. i don't know why, i seem to get clogged up easily with this simple and basic stuff. Assume a lossless transmission system connecting one single generator (on the left) to a load center (on the right). Assume a series capacitor is...

Hi, Thank you for an interesting posting about Three Winding Transformer. I have an question regarding the choice of the transformers used at 150kV offshore wind farm. Hope some experts out there can enlighten me as I'm pretty new in this area. I've encountered commonly in several wind farm...

thanks for posting this interesting question.. I have another question in relation to this. If the transmission line is equipped with a series capacitor compensation, how the line charging capacitance will likely be affected? How the magnitude of the charging and discharge current are likely...

thanks for all comments. I appreciate that. It has been really helpful!!

sorry redfurry, it's a typo. Should be +/-12%, +/-6 steps (12 steps) 2%. Some suggests to have 1.5% or twice of the tap size. If it is possible to calculate the absolute difference between upper limit voltage and the reference voltage, lower limit voltage and the reference to define the...

hi, can anyone tell me how to determine the deadband of the tap changer correctly, given that the tap changer is +/- 12%, +/-6 steps (12 steps) 1%. your help is greatly appreciated. Many thanks

thanks rasevskii. my question is actually referring to an offshore wind farm project equipped with the mechanically switched capacitors and STATCOM. In order to comply with the grid code, a continuous voltage control must be ensured. However, the capacitor is not possible to re-use for a period...

hi, due to a requirement to discharge the capacitor in between operations, the capacitor is not possible to re-use it for reactive VAR control for a period of 10 mins after the first switching in and out. Hence, the power utility claims that it does not comply to the continuous voltage control...

most of the catalogues i found do not have the short circuit current and nominal current loading capacity. i wonder if you or anyone have seen one with these information as i need to refer this catalogue so that i'm able to tell roughly the size of cable should be considered.

Hi, i wonder if anyone can tell me anywhere I can get hold of the short circuit and loading capacity of different types of power cables used for offshore wind farm. typical voltage range are 33kV, 150kV, 132kV. look forward to hearing from you. Many thanks,

thank you for sending me all the information. I really appreciate that. the transformer capacity is around 200MVA. Distance to the hv switchgear is approx. 20m, and distance to lv switchgear is approx. 30m. Can distance also be the factor to determine the choice between cable and busduct? I used...

hello, has everyone come across this type of bus duct? any information i can get? This busduct has been proposed to an offshore wind farm main transformer rated at 150/33kV. HV primary connection we use gas insulated busbar and LV connection is the duresca bus duct. I'm wondering what are the...

i have a question and hope somebody can enlighten me about an offshore wind farm with a three winding transformer(yd1d1) on the offshore platform. The client requested the star winding of the 150/33kV offshore transformer NOT to be unearthed as the system is already earthed at the onshore...

Hi, I wonder if someone could explain me what is meant by the quasi-dynamic and quasi steady state simulation? I was reading through some papers from the internet about these and still have not been able to understand how this methodology is formed. Can we consider it a statistical approach or...

hi, i wonder if any expert in wind turbines can help me to clear my doubts. at a very low wind speed, i understand it's sensible to disconnect the wind turbine generator (WTG) from the grid to reduce the losses. one of the papers that I have recently read about wind farm connection has however...