Backup PV Curtailment With Autonomous Load Breaking
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Solution Overview
Problem
Existing backup power supply systems face challenges in effectively curtailing PV power output to prevent over-generation and meeting high load demands, especially when large loads are connected to the backup side, which can overload or drain the storage system, and installation of these loads is cumbersome and expensive.
Innovation Solution
The system includes an autonomous smart load breaker and a storage converter that dynamically adjust power frequency to curtail PV output and disconnect large loads during backup mode, ensuring the energy storage system's capacity is not exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PV panels are moved to the non-backup side to curtail over-generation, then PV power output is reduced to match storage capacity, but the total power output capacity of the backup PV power supply is reduced, inhibiting the ability to meet high load demands
Solution Approach 1:
The system dynamically switches PV panels between backup and non-backup sides based on real-time conditions. The controller monitors storage capacity and load demands, automatically reconfiguring the electrical connection to optimize both over-generation prevention and power output capacity availability.
Solution Approach 2:
The PV power supply system is divided into separate backup and non-backup sides with independent control. This segmentation allows selective connection of PV panels to different system sides, enabling flexible management of power distribution and storage charging without compromising overall system capacity.
2Productivity
If large loads are connected to the backup side, then load demand is met, but the storage system is rapidly drained or the AC bus is overloaded
Solution Approach 1:
The controller continuously monitors storage system state of charge, AC bus voltage, and current levels. When thresholds are approached, the controller automatically disconnects large loads from the backup side to prevent overloading or rapid drainage, then reconnects them when conditions improve, maintaining both load fulfillment and system stability.
Solution Approach 2:
Large loads are dynamically connected or disconnected from the backup side based on real-time system conditions. This dynamic load management allows the system to meet high load demands when capacity is available while protecting the storage system from overload or rapid depletion.
3Reliability
If existing storage inverters use frequency-watt control to curtail PV generation, then PV power output is reduced to match storage capability, but the curtailment is not quick enough to proactively prevent over-generating the AC bus
Solution Approach 1:
The controller proactively monitors PV power output and storage capacity in advance, detecting potential over-generation conditions before they occur. When the risk of exceeding storage capacity or AC bus limits is detected, the controller preemptively curtails PV generation or disconnects large loads, preventing over-generation rather than reacting after it occurs.
Solution Approach 2:
The system uses real-time feedback from monitors tracking PV output, storage state of charge, and AC bus conditions. This continuous feedback enables the controller to detect approaching capacity limits and execute curtailment actions quickly, significantly faster than traditional frequency-watt control methods.
Data Source
AI summary
The present disclosure provides curtailing photovoltaic (PV) power output and autonomous load breaking in a backup mode of an electrical system. The electrical system includes a PV system, an energy storage system having a storage converter, and an energy control system. The energy control system is electrically coupled to the PV system, the energy storage system, and a plurality of backup loads. The electrical system includes an autonomous load breaker electrically coupled to a first backup load. When the energy control system switches from an on-grid mode to the backup mode, the storage converter adjusts the frequency of the power supplied to the backup side of the energy control system to a setpoint frequency that curtails PV power output, and the autonomous load breaker electrically disconnects the first backup load from the energy control system.