PV Ground Switching Control for PID and Ground Fault Balance
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Solution Overview
Problem
Existing energy storage systems face a trade-off between system efficiency and safety due to differing grounding methods used by photovoltaic and battery systems, leading to inefficiencies and potential ground faults.
Innovation Solution
An energy storage system with a switch controller that dynamically adjusts grounding structures based on the photovoltaic system's power generation state, using a combination of grounding and floating ground configurations to minimize ground faults and PID, while employing ground fault detectors for continuous monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a grounding method is used for the photovoltaic system, then system efficiency is improved, but safety deteriorates due to potential ground faults
Solution Approach 1:
The patent implements dynamic switching between grounding and floating ground configurations based on the photovoltaic system's operational state. A switch controller changes the ground structure from a fixed configuration to a dynamic one that adapts between daytime (power generation) and nighttime (non-power generation) modes, resolving the contradiction by making the grounding method flexible rather than static
Solution Approach 2:
The patent changes the electrical parameter of the ground structure by switching between two distinct grounding configurations: a first ground structure during power generation that prioritizes efficiency, and a second ground structure during non-power generation that prioritizes safety. This parameter change allows the system to optimize for different operational requirements at different times
2Reliability
If a floating ground structure is used, then safety is improved, but system efficiency deteriorates due to Potential Induced Degradation (PID)
Solution Approach 1:
The system dynamically selects the appropriate ground structure based on operational needs. During daytime power generation, the first ground structure is applied to prevent PID and maintain efficiency. During nighttime non-power generation, the system switches to the second ground structure to provide safety benefits, thus avoiding the efficiency loss that would occur with a permanent floating ground configuration
Solution Approach 2:
The patent implements periodic switching between grounding configurations corresponding to the daily operational cycle of the photovoltaic system. The ground structure is changed periodically between daytime (efficiency-oriented) and nighttime (safety-oriented) modes, allowing the system to capture the benefits of both configurations without suffering from their respective drawbacks continuously
3Productivity
If different grounding methods are used for photovoltaic and battery systems, then each system operates optimally, but system complexity increases and ground faults may occur
Solution Approach 1:
The patent merges the grounding control of the photovoltaic system and battery system into a unified switch controller that manages both ground structures. By coordinating the switching of multiple switches (first switch, second switch, third switch) under a single controller, the system reduces operational complexity while maintaining the ability to optimize each subsystem's grounding configuration
Solution Approach 2:
The switch controller serves multiple functions: it controls the grounding configuration for both the photovoltaic system and battery system, monitors ground faults through ground fault detectors, and coordinates the switching operations of multiple switches. This multi-functionality reduces overall system complexity by consolidating control functions
Data Source
AI summary
Discussed is a switch control apparatus in an energy storage system connected with a power grid. The energy storage system includes a photovoltaic (PV) system, a power conversion system (PCS) selectively connected to the photovoltaic system, a first switch configured to selectively connect the photovoltaic system and a direct current (DC) link of the power conversion system, a first ground fault detector including a terminal which is connected to a ground, a second switch selectively configured to connect the photovoltaic system and another terminal of the first ground fault detector. A second switch is located between the first switch and the photovoltaic system, the switch control apparatus includes at least one processor; and a memory configured to store at least one instruction executed by the at least one processor.