UPS-ESS Power Flow Control for Peak Shaving and Backup Readiness
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Solution Overview
Problem
Existing UPS systems face inefficiencies and high costs due to the integration of Energy Storage Systems (ESS) for backup and peak-shaving operations, while ESS systems lack protection from instantaneous power fluctuations, necessitating a unified solution for simultaneous backup and peak-shaving services.
Innovation Solution
A combined UPS and ESS system with an Energy Management System (EMS) that dynamically controls power flow between the power source and load, enabling Peak-Shaving and energy time shifting functions through multiple operating stages, including charge, discharge, recharge, and standby modes, using rectifiers, inverters, and DC/DC converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ESS capacity is increased to provide longer backup duration, then reliability during power outages is improved, but system cost increases prohibitively
Solution Approach 1:
The system dynamically adjusts the ESS state of charge (SOC) based on real-time conditions. During peak-shaving operations, the ESS is discharged to reduce grid demand, and during off-peak hours, it is recharged. This dynamic operation allows the system to provide backup capability when needed while utilizing the ESS for cost-saving operations at other times, effectively stretching the backup duration without proportionally increasing ESS capacity.
Solution Approach 2:
The system changes the operating parameters of the ESS by adjusting the state of charge thresholds and power flow directions based on grid conditions and pricing signals. By flexibly changing these parameters, the system maximizes the utility of the existing ESS capacity, providing both backup and peak-shaving functions without requiring oversized energy storage.
2Loss of energy
If ESS is used for peak-shaving operations, then energy cost is reduced, but backup capability during outages is compromised
Solution Approach 1:
The system incorporates a control mechanism that continuously monitors the ESS state of charge, grid conditions, and pricing signals. Based on this feedback, the controller dynamically adjusts the power flow to balance peak-shaving operations with maintaining adequate backup capability. When the ESS SOC drops below a threshold, the system prioritizes backup readiness over peak-shaving, ensuring both objectives are met.
Solution Approach 2:
The system dynamically switches between different operating modes (peak-shaving, recharging, backup standby) based on real-time conditions. This dynamic operation allows the ESS to serve dual purposes: reducing peak demand charges while maintaining sufficient charge for backup operations, thereby resolving the contradiction between cost savings and reliability.
3Adaptability or versatility
If bidirectional PCS is used for peak-shaving, then energy management flexibility is improved, but instantaneous power fluctuation protection is lost
Solution Approach 1:
The patent combines the bidirectional PCS architecture (which enables peak-shaving and flexible energy management) with a UPS system (which provides instantaneous power fluctuation protection). The merging of these two systems allows the load to receive both the flexibility of bidirectional energy flow and the protection of instantaneous response to power quality events, resolving the contradiction between adaptability and reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system optimizes energy use by dynamically adjusting power consumption based on load requirements and market rates, reducing costs and enhancing system longevity, while providing uninterrupted power and peak demand management.
Implementation Method 1
power electronics converters that take the Alternating Current (AC) from the main supply and transform it to Direct Current (DC) of the battery (this converter is called a rectifier)
Implementation Method 2
vice-versa from the DC bus to the AC load (this converter is called an inverter)
Implementation Method 3
DC/DC converter controlling the power flow between the rectifier and the inverter and/or ESS
Data Source
AI summary
The current invention relates to an uninterruptible power supply (UPS) with PeakShaving and energy time shifting functions system comprising at least one UPS comprising an AC/DC conversion stage, a DC/AC conversion stage, and at least one Energy Storage System (ESS); an Energy Management System (EMS) configured to control the system: at least one processor, and at least one non-transitory computer readable media comprising software; wherein the software causes the processor to configure the system to operate according to different operating stages.