Challenges in Future Distribution Grids - A Review

Abstract

The integration of distributed generation facilities and large loads into the electric grid entails power quality issues. Large scale implementation of renewable and other distributed generation as well as relevant loads like heat pumps into the low and medium voltage grid does not longer allow ignoring the influence of those systems on power quality and stability. Grid codes for different regions started to implement the special requirements introduced by distributed generation. Distributed generation is able to reduce but also to increase issues regarding network loading and stability or power quality. Optimised grid control, generator control as well as demand and supply side management are identified as suitable solutions for an optimised integration into the distribution grid.

Reactive power injection strategies for single-phase photovoltaic systems considering grid requirements

“…For example, potential overloading impacts will appear at the distributed feeders, especially when a very high penetration level of PV systems is reached [2], [10], [14]. Due to the intermittent nature of solar PV source and the unbalance between PV supply and load demands, voltage rise has been mostly observed in recent studies [4], [10], [15]- [19]. One possibility to mitigate voltage rises can be achieved by limiting the maximum feedin power from PV systems or by reducing the PV penetration into the grid.…”

Investigations in low voltage distribution grids with a high penetration of distributed generation and heat pumps

“…The main issue regarding the connection of DG and heat pumps (HP) is the voltage level [1]. To evaluate the influence of DG and heat pumps on the low voltage distribution grid, an exemplary German suburban grid, examined and evaluated by Scheffler (2002) [12], is simulated.…”

“…As distribution grids were not designed for such high amount of generators significant challenges will be expected regarding voltage level, network loading, unbalance and other power quality (PQ) aspects. However, distributed generation (DG) can also reduce those issues, if controlled appropriately [1]. This paper reviews the relevant regulation regarding the connection of electrical appliances to the low voltage grid in Europe.…”

Reactive Power Injection Strategies for Single-Phase Photovoltaic Systems Considering Grid Requirements

“…However, a still increasing adoption of PV systems will violate the grid integration. For example, potential overloading or voltage rises may appear at distributed grid feeders, especially when a very high penetration level of PV systems is reached, due to the intermittent nature of solar PV source and the unbalance between PV supply and load demands [2], [4], [10], [15]- [21]. Possibilities to solve those issues include limiting feed-in maximum power from PV systems [22] and reducing installations, which are against the goal of carbon reduction in most countries, e.g.…”

“…Meanwhile, the trip-off of an aggregated PV system owing to anti-islanding protection may induce grid variations, leading to more serious events, e.g. power outage [4], [10], [21], [27]- [29]. Hence, in response to grid disturbances, it is better for next-generation PV systems to provide dynamic grid support in terms of Low-Voltage Ride-Through (LVRT) with Reactive Power Injection (RPI), in order to: a) stabilize the grid in case of failures and b) to avoid loss of massive PV generation systems.…”