At the core of the battery storage energy system lies a bidirectional converter that acts as a bridge between the passive end-user and the energy storage. This converter comprises an AC/DC rectifier (battery charger) and a DC/AC inverter. The energy storage system efficiently operates within this framework to capitalize on economic benefits for the customer. By employing a load-shifting strategy, excess energy is stored during periods of low demand and released during high-demand periods. This approach not only optimizes energy usage but also aligns with the dynamics of dynamic pricing tariffs.
Great Power's battery storage energy systems function within three distinct operating modes, each tailored to leverage the fluctuating electricity prices of dynamic pricing tariffs. The charging mode comes to life during low electricity prices, allowing the battery to accumulate energy. Conversely, the standby mode bypasses the battery's involvement, relying solely on grid power supply to the end-user. The discharging mode, on the other hand, activates during periods of high electricity prices. In this mode, the battery steps in to supply a portion of the load, thereby mitigating the cost impact of peak pricing.
Several assumptions form the bedrock of effective battery storage energy system operation:
Hourly Tariff Structure: The end-user interacts with an hourly tariff, with rates reflective of the System Marginal Price (SMP) and adjusted for utility benefits and taxes.
Grid-Load Power Flow: Energy flows from the grid to the load, and the stored energy cannot be sold back to the utility.
Predictable Hourly Prices: Electricity prices are known in advance for a finite period, and the storage device's usage does not influence market prices.
Disregarding Battery Self-Discharge: Battery self-discharge is not factored into the system's operation.
Constant Battery Capacity: The battery's capacity remains consistent over its lifecycle, without degradation.
Frictions and Efficiency: Charging and discharging efficiency account for common operational frictions, ensuring practical representation.
Constant Charge/Discharge Rate: The charge/discharge rate is fixed and equal to the battery's rated power capacity, ensuring the energy and power constraints are met.
Equal Charging/Discharging Time: Equal time is allocated for both charging and discharging cycles, enabling the battery to return to its initial state-of-charge at the end of each cycle.
Variable Depth of Discharge (DOD): Different discrete DOD states are considered based on the objective function's value.
Sizing for Optimal Cost: The battery's capacity is chosen to minimize upfront investment while ensuring it can meet peak load demands during specific hours.