Please share some real world examples of outages or contingencies caused in both system that effected them mutually. Thanks
the contingency on the distribution and transport networks is at the origin of the excessive losses observed on these lines. this contingency can create network failure if appropriate arrangements are not made. the contingency contributes to exceeding the margins of electrical and thermal stability of the conductors and can lead to collapse or generalized failures in the electrical systems. Benin for example we had a problem like that on December 24 on one of our 63kV lines. in fact, this line ensures the transit of power from Cotonou to Porto Novo, a city located about 30 km from Cotonou or the economic capital. generally during the end-of-year festivities, people from Benin are used to setting up their various equipment (music machines, freezers, air conditioners, household appliances, etc.) to celebrate the holidays and have fun. on this occasion, the network operators are confronted with the exponential rise of loads on the lines which may exceed the nominal capacities of the links. Also, we have experienced contingency situations on certain sections of MV cables when, as part of the search for sources of energy supply, we asked groups (MRI and aggreko) for rental in decentralized production on our HTA outlets. we had to record flights
a brief answer is: voltage drop caused by faults can slow down induction motors, causing higher demand of reactive power, which causes further drop in voltage, and voltage collapse cascading action ensues.
this is one scenario, out of other possible scenarios
Arouna Oloulade Omar Hazem MOHAMMED Baraa Mohandes Bhupendra Desai Thanks for your kind help. This means that transmission contingency has very less effect on distribution system as it is been dealt by TSO while on DS side, contingency in peak load times, can lead to network failures. Is my understanding right? What if transmission contingencies can cause power flow limit violations on lines connected to TSO substation buses, will this be a case that needs to be explored?
Basically when it is considered that Transmission system supplies the power to the distribution system and normally distribution is not connected to form a loop, it can be said that any disturbance on distribution will affect only distribution system down the line and distribution system when it is closed circuit system. Transmission system will not be affected.
Any disturbance on transmission will have direct impact on distribution systems down the line.
When distribution system has high generating capacity and feeding the network over and above the load of distribution network the said statement will not be applicable. There will be a mutual disturbance depending on the the strength of interconnection.
I agree with DR Arouna
There is a direct relationship between MV and LV network and the HV network in terms of voltage variation and reactive management. In the first place, the voltage level on the HV network directly influences the network underlying the "MV and LV network" as it is generally the source of reactive and voltage driver and control. Secondly the MV and LV network is connected through transformers withTap-changer which automatically controls the MV voltage level. If there is a very large voltage drop on the HV network the Tap-changer of these transformers hangs because it risks the collapse of the voltage, because the motor loads demand more reactive power if the voltage drops to the MT level and the situation becomes irreversible. Today with decentralized renewable production this unidirectional reactive management has changed and the LV and MV network is participating in voltage adjustment and reactive adjustment.!!!!
Outages and contingencies almost every kind in transmission network will reflect somehow on distribution network. Short circuit will reduce power quality on medium voltage level in DSO Company. That is most common event, which affected DSO system. In addition, other events like voltage drop, frequency drop, power swing will be propagate to lover voltage level. Connection transformers between these two networks have nowadays bidirectional power flow. So, distribution network can have also some influence on transmission network, because there is a lot RES connected to medium and low voltage network.
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