Abstract
The ever increasing demand on the electrical energy has led to the diversification on the electrical energy generation technologies especially from the renewable energy sources like the wind and the solar PV. Micro-grids powered by distributed generators utilizing renewable energy sources are on the increase across the globe due to the natural abundance of the resources, the favorable government policies and the resources being environmentally friendly. However, since the electrical power distribution networks have always been passive networks, the connection of the distributed generations (DGs) into the network has associated several technical implications with distribution network protection and Over-Current Protective Devices (OCPDs) miss-coordination being one of the major issues. The need for a detailed assessment of the impacts of the wind turbine generation (WTGs) on the distribution networks operations has become critical. The penetration of the WTGs into a distribution network has great impacts on the short circuit current levels of the distribution network hence eventually affecting the OCPDs coordination time margins. The factors which contribute to these impacts are: The size of the WTG penetrating the distribution network, the location at which the WTG is connected on to the network and the Type of the WTG interfacing technology used. An important aspect of the WTGs impacts studies is to evaluate their short circuit current contribution into the distribution network under different fault conditions. The magnitudes of these short circuit currents, both the three phase and the single-line-to-ground (SLG) faults, are needed for sizing the various Over-Current Protective Devices (OCPDs) utilized in protecting the distribution network. The sizing of the OCPDs entails among other procedures coordinating them with both the upstream and the downstream OCPDs so that there is sufficient time margin between their Time Current Characteristic (TCC) curves. For Fuse-Fuse protection coordination, the ANSI/NEC rules stipulate that a minimum of 0.025seconds or more time margin should be maintained between the primary/downstream fuse and the secondary/upstream/back-up fuse. Due to the topological and operational differences between the different types of WTGs interfacing technologies, the electrical generators design industry has divided wind turbine generators into four different types labeled as Type I, Type II, Type III and Type IV. This paper presents a detailed study of the impacts brought upon by integrating wind turbine generators on a conventional Fuse-Fuse protection coordination scheme. A conventional Fuse-Fuse protection coordination scheme was modeled in Electrical Transients Analysis Program (ETAP) software and WTG with different interfacing technologies connected. A study of the impacts brought by the integration of the WTGs on Fuse-Fuse Miss-coordination was performed. IEEE 13 Node Radial Distribution Test Feeder was used for the study.
Highlights
The ever increasing demand on the electrical energy has led to the diversification on the electrical energy generation technologies especially from the renewable energy sources like the wind and the solar PV
Fuse-Fuse selective coordination shall be generally achieved by using the following minimum recommended margins as per ANSI/NEC rules which says that the total clearing time of the downstream fuse curve must be less than 75% of the minimum melting time of the upstream fuse curve to account for pre-loading; compensates for effects such as load current and ambient temperature, or fatigue in the fuse element caused by the heating effect of fault currents that passes through the fuse to a fault downstream but were not sufficiently large enough to melt the fuse This translates to a minimum of 0.025seconds time margin between the downstream Fuse total clearing time (TCT) curve and the upstream fuse minimum melting time (MMT) curve
Fault currents in critical conditions with an Interfaced Distributed Generators (IIDG) connected into the power grid are limited by the inverters having current limiting ranges, the fault current share injected by IIDGs is not as much as Distributed Generators (DIDG) which shares most of their fault currents with the main utility grid [5][6]
Summary
A fuse is a thermal tripping device in an electric circuit, the operation of which depends on the thermal capacity of the fusing element, its melting temperature and the current flow previous to the fault condition. For currents with time durations below and to the left of the Fuse TCC band, the fuse will not blow or be damaged. Currents with time duration above and to the right of the Fuse TCC band, the fuse will blow within a minimum time given by the Minimum Melting Time characteristics and a maximum time given by the Total Clearing Time characteristics. The continuous current rating of a fuse should be equal to or slightly less than the current carrying capacity of the circuit it is protecting [1]. The TCC Curve for a fuse is much simpler in appearance and easier to coordinate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
