I'm evaluating the short-circuit currents of all busbars in a power systems for 4 types of short-circuits and the levels do not change with and without the presence of the PV generator.
Regards
The contribution of PVs with inverters on any type of short circuit exist but is not high and can be negligible , mabye (1.2 - 1.4) xIn of inverter depending of inveerter types. So when it passes through transformers on HV side it is very small contribution. The reason is since the model of PV and inverter in fault analysis is Norton equivalent element and PV has no inertia X", and other reactances like SM. or AM..
Andreas is in right since inverters very fast disconnect the PV if SC occured in the network since voltage decrease-coplapse and time undervoltage fast step U
The reason why a PV generator does not provide current fault, is because they do not have a mechanical coupling with the system which react in the presence of a fault. The integration of these generators to the system is through electronic inverters, so they are decoupled system.
the maximum contribution is limited to 1.5-2 In. increase PV capacity and try to calculate fault current near to PV.
Dear Tohid
You are in right but contribution of PV via inverter is about 1,2-1,5 In
Srete
Dear Srete
you are right. it depends on IGBT overloading and overheating characteristic. generally in comparison to grid contribution , it is negligible for small and medium size PVs.
Dear Tohid
I am not expert in power electronic but related to power protection of different type of RES I am follow the knowlege of some expersts from USA and Germany. In attachemnt is what you and me confirm. I do not know what is about thyristor inverters ovreloading but for IGBT technology see the dialox box of one software.
Srete
Inverter plays a vital role in grid synchronized PV generation systems. whenever an abnormality is sensed by the inverter it will directly go out of synchronism that means it will disconnect PV generation from grid.
That is the truth Pavan since almost all of them are network leading inverters :-) When network is lost (Lost of Mains ) PV will be disconnected.
Mean to say Islanding....but this is not allowed in power systems.for that reason anti-islanding protection is placed in inverter.
Yes anti islanding protection is placed in inverters!!!
One way of detection is in inverter of PV since it deliver only P-active power with power factor closed to or equal to 1, So if feeder breaker open and LOM- Lost of Mains happened PV need to supply some amount of Q (inductive or capaciive) depending of the feeder loads and inverter of PV recognized that since it can not deliver Q to network and transfer such signals to digital information which disconnect PV from the grid
Srete
The PVPPs are based on solar panels - they convert immediately, without any delay the solar energy to electrical. The circuit is DC - there are no AC effects of the reactance - no L or C, no stored energy, no magnetic flux. The Short circuit ratio is around 1.1-1.2 (you can check in catalogs of producers). It does not matter at which point the short circuit (Between the + and the – of the system) will occur – the current in the respective point will increase with appr. 1.1-1.2. The grid can’t feed back current as there is DC/AC decoupling in the PVPP inverter.
The synchronous generators have inductive character with stored energy and operate on the base of electromagnetic fields interaction. The transient (xd’) and subtransient (xd”) reactance define the short circuit current of the generator, naturally with the respective impact of the excitation system.
In fact, that contribution will depend on the eletronic interface. Usually the inverters of the PV generator limit the contribution of those generators to the short-circuit current.
For more information, have a look at the following presentation (a brief version of IEC 60909 Standard) especially the part Type IV of DGs:
Impact of Distributed Generation Units on Short-Circuit Capacity (SCC) Calculations
https://www.researchgate.net/publication/260228951_Impact_of_Distributed_Generation_Units_on_Short-Circuit_Capacity_SCC_Calculations
The contribution depends on type of inverters (for PV), but it is not more then 1.2 -1.3 of rated current of inverters. It can be seen on inverters namplate.
kindly help me .Why the wind turbine do not contribute to the short-circuit current if this event occurs in any bus of a given power system?
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