Mitigation of Rooftop Solar PV Impacts and Evening Peak Support by Managing Available Capacity of Distributed Energy Storage Systems

Abstract

A high penetration of rooftop solar photovoltaic (PV) resources into low-voltage (LV) distribution networks creates reverse power-flow and voltage-rise problems. This generally occurs when the generation from PV resources substantially exceeds the load demand during high insolation period. This paper has investigated the solar PV impacts and developed a mitigation strategy by an effective use of distributed energy storage systems integrated with solar PV units in LV networks. The storage is used to consume surplus solar PV power locally during PV peak, and the stored energy is utilized in the evening for the peak-load support. A charging/ discharging control strategy is developed taking into account the current state of charge (SoC) of the storage and the intended length of charging/discharging period to effectively utilize the available capacity of the storage. The proposed strategy can also mitigate the impact of sudden changes in PV output, due to unstable weather conditions, by putting the storage into a short-term discharge mode. The charging rate is adjusted dynamically to recover the charge drained during the short-term discharge to ensure that the level of SoC is as close to the desired SoC as possible. A comprehensive battery model is used to capture the realistic behavior of the distributed energy storage units in a distribution feeder. The proposed PV impact mitigation strategy is tested on a practical distribution network in Australia and validated through simulations. 2013 IEEE.

Active Management of Low-Voltage Networks for Mitigating Overvoltages Due to Photovoltaic Units

“…Alternatively, the use of active power curtailment [19] or storage of the excess energy in batteries [20] have been suggested. In Refs.…”

A Centralized Energy Coordinator Reliant on BESS and DER-PV Operation

“…The usable energy capacity for the upcoming cycle can be found by the initial DoD, with the BESS peak load shaving controller directly responsible for energy level. As presented in [6], a simultaneous solution of Equations (2 & 3) which model the total energy differentials from implementing a trapezoidal charge rate (CR) profile is conducted to arrive at the Slope of Charge Rate (SCR) and h 2 required to ensure 100% SoC. A SoC schedule was constructed directly from the CR profile (CR r ) based on BESS energy capacity (C B,rated ) and charging efficiency (η CH ).…”

“…Acceleration gains (A1 or A2) are applied to the observed PV derivative and either added to CR (k) or subtracted from DR (k) as shown in Equation (11). If this event extends for a long period of time, then there is a chance the controller will switch to short term discharging mode [6] when the BESS becomes a generator and injects power. After when the DER-PV's generation finally begins to ramp up, the derivative becomes positive.…”

“…Onto the second situation when the DER-PV power deviation does not violate the threshold and the BESS SoC is below the SoC schedule, the CR will be adjusted by a factor determined by Equation (13) [6]. This will continue until the SoC is again within 1% of the scheduled level.…”

Optimal placement, sizing, and daily charge/discharge of battery energy storage in low voltage distribution network with high photovoltaic penetration

“…In [21], the storage is utilized to compensate long-term and short-term voltage variations originated from sudden change of PV output. The strategy of charge/discharge is presented without any optimization.…”