Review of technical issues influencing the decoupling of DG converter design from the distribution system protection strategy

Abstract

Several issues need to be considered in the design and control of converters for converter-interfaced distributed generators (DGs). Under fault conditions, the semiconductor devices withstand ratings must not be exceeded. The converter control strategy is also required to facilitate fault ride through (FRT) capability. On the other hand, protection against fault is better served by employing control strategies that allow the converter-interfaced DGs to contribute short duration fault current sufficient to aid the detection of faults. Semiconductor devices protection and FRT capability have the same objective of limiting the magnitude of the fault current. Protection coordination in the complex DG-integrated network is difficult and may result in protection settings that are not optimal or contribute to long relay operating times that may impact FRT support. On this basis, this study proposes the de-coupling of the protection solution from FRT and semiconductor device considerations. This study critically reviews various strategies proposed in the literature for the protection of the DG-integrated distribution system and develops an argument that aims to influence a paradigm shift towards voltage-based protection that may see protection design decoupled from inverter design and control, since fault current contribution may not be required to achieve effective protection.

Anoff‐linealgorithm forfuse‐reclosercoordination in distribution networks with photovoltaic resources

“…If DERs are prevalent in distribution networks, there will be several technical challenges for distribution network operators: voltage deviation, short‐circuit level increment, power flow reversal, and emergence of island networks as well as miscoordination of protective devices 1‐3 . By increasing the penetration rate of DERs, the fault current profile changes significantly in different points of the network as a consequence of increasing the share of inverter‐based resources, which can affect the operation of protection system 4‐6 . When a fault occurs, the current share of DERs may be sufficient to change the operating points of the protective relays and fuses.…”

Integration of wind turbines in distribution systems and development of an adaptive overcurrent relay coordination scheme with considerations for wind speed forecast uncertainty

“…The integration of renewable energy (RE)‐based distributed generation (DG) units with electric power distribution systems (DSs) in association with smart grid introduces many benefits, including emission reduction, power quality and reliability enhancement, transmission and distribution loss reduction, peak shaving, and voltage regulation [1, 2]. However, the integration of DG units into the DSs results in a higher level of complexity in control and the protection of DSs [3]. The effects of DG on the protection of DSs have been widely evaluated in the literature [3, 4], and may be divided into three categories.…”

“…However, the integration of DG units into the DSs results in a higher level of complexity in control and the protection of DSs [3]. The effects of DG on the protection of DSs have been widely evaluated in the literature [3, 4], and may be divided into three categories.…”

“…For RE‐based DG units, such as wind and photovoltaic (PV) energy systems that have inherent intermittent characteristics, where they may disconnect from the grid several times a day, the noted complications may be further magnified. One of the approaches that have been suggested under the concept of a smart grid for solving the above‐mentioned issues, is introduced in the literature as adaptive protection [3]. Adaptive protection tracks any changes in the DS condition and provides an appropriate response to them by modifying the setting parameters of protective devices for the fast and correct operation of protective devices while maintaining the coordination constraints [3].…”

“…However, the integration of DG units into the DSs results in a higher level of complexity in control and the protection of DSs [3]. The effects of DG on the protection of DSs have been widely evaluated in the literature [3,4], and may be divided into three categories. First, with DG units, power flow in many branches of DS becomes bi-directional, and therefore, the conventional protection schemes are inadequate because these schemes only consider unidirectional power flow [5].…”