Suggested grid code modifications to ensure wide-scale adoption of photovoltaic energy in distributed power generation systems

Abstract

Abstract-Current grid standards seem to largely require low power (e.g. several kilowatts) single-phase photovoltaic (PV) systems to operate at unity power factor with maximum power point tracking, and disconnect from the grid under grid faults. However, in case of wide-scale penetration of single-phase PV systems in the distributed grid, the disconnection under grid faults can contribute to: a) voltage flickers, b) power outages, and c) system instability. In this paper, grid code modifications are explored for wide-scale adoption of PV systems in the distribution grid. More recently, Italy and Japan, have undertaken a major review of standards for PV power conversion systems connected to low voltage networks. In view of this, the importance of low voltage ride-through for singlephase PV power systems under grid faults along with reactive power injection is studied in this paper. Three reactive power injection strategies are discussed in detail. Simulations are presented for a PV power system with low voltage ride-through capability and ancillary services. An example of a full-bridge single-phase grid-connected system is tested experimentally to demonstrate the potential benefits.

Mission profile translation to capacitor stresses in grid-connected photovoltaic systems

“…During fault ride-through, the system is operating at low voltage ride through mode instead of MPPT mode at unity power factor, where the active power is reduced in order to inject sufficient reactive power for grid support and also prevent the inverter from over-current trip-off [26]. It can be observed in Fig.…”

“…The next-generation PV inverters have to be of much power controllability and flexibility in order to integrate into the conventional grid smoothly with reduced cost of PV energy [26], [27]. One of the advanced features for PV inverters is to statically support the grid by appropriately controlling the active power and exchanging the reactive power [4], and also to ride-through transient grid disturbances [27]- [29].…”

Constant power generation of photovoltaic systems considering the distributed grid capacity

“…Regarding PV systems, they still account for a minor share of the overall electricity production in most countries. Therefore, it is required PV systems to operate with Maximum Power Point Tracking (MPPT) control, and they are not allowed to participate in the grid voltage regulation [6], [13]- [15]. As aforementioned, the increasing adoption of PV systems poses more challenges for the distributed grid, which requires infrastructure upgrades.…”

“…As aforementioned, the increasing adoption of PV systems poses more challenges for the distributed grid, which requires infrastructure upgrades. Thus, some of the grid codes are undergoing a major revision to enable the grid support capability for PV systems at a high penetration level [15]- [22]. In that case, similar to wind power systems, the PV systems should be able to flexibly control the active power, e.g.…”

Improved reliability of single-phase PV inverters by limiting the maximum feed-in power

“…Regarding the reliability of PV inverters, it has become of intense importance and involves multiple disciplines [5], [7], [12]- [19]. The lifetime prediction research on power devices is transitioning from handbook-based approaches [18], [19] to more physics-based methods, which require in-depth understanding of various failure mechanisms and thus dedicated lifetime models, e.g.…”