PV-PCS Ground Switching to Balance PID and Fault Current
Find Innovative SolutionsGenerate Solutions
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 photovoltaic system and power conversion system that employs a switch controller to dynamically change grounding structures based on the power generation state of the photovoltaic system, using ground fault detectors to monitor for faults while minimizing Potential Induced Degradation (PID) and fault currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large number of battery modules are arranged in parallel to increase power output, then the power output of the energy storage system is improved, but the heat dissipation difficulty increases and the system structure becomes more complex
Solution Approach 1:
The energy storage system is divided into multiple independent energy storage units, each containing a complete set of battery modules, conversion modules, and heat dissipation components. This segmentation allows each unit to operate independently with its own thermal management, reducing the overall system complexity while maintaining high power output through parallel configuration of multiple units.
Solution Approach 2:
The patent implements a nested structure where battery modules are arranged in series within each energy storage unit to achieve high voltage, and multiple such units are connected in parallel to achieve high power. Each unit contains nested components including battery modules, conversion modules, and heat dissipation elements, creating a scalable architecture that manages complexity through hierarchical organization.
2Power
If battery modules are arranged in parallel to increase power, then the power output is improved, but the heat dissipation becomes more difficult
Solution Approach 1:
Each energy storage unit is equipped with independent heat dissipation components including heat sinks and cooling channels, allowing thermal management to be handled at the unit level rather than requiring a centralized complex cooling system for the entire parallel array of battery modules.
Solution Approach 2:
The patent introduces heat sinks as intermediary thermal management components between the battery modules and the environment. These heat sinks with integrated cooling channels serve as mediators that efficiently transfer heat from multiple parallel battery modules, facilitating heat dissipation without requiring direct complex thermal coupling between all modules.
3Temperature
If series connection is used to increase voltage, then the voltage output is improved, but the reliability decreases due to higher risk of module failure
Solution Approach 1:
The system segments the high-voltage requirement across multiple energy storage units connected in parallel. Each unit contains battery modules connected in series to achieve the required voltage level, while the parallel connection of multiple units provides redundancy. This segmentation ensures that a failure in one unit does not compromise the entire system, maintaining reliability while achieving high voltage output.
4Stability of the object's composition
If the ground structure is not stable, then the structural support is insufficient, but increasing the ground structure may increase cost and complexity
Solution Approach 1:
The patent implements a reinforced ground structure with embedded grounding electrodes and grounding wires installed beforehand. This preliminary action ensures proper grounding and electrical stability before the energy storage units are deployed, preventing future reliability issues without requiring complex modifications later. The grounding system is integrated into the ground structure during initial installation.
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
According to embodiments of the present disclosure, an energy storage system, including a photovoltaic (PV) system and connected with a power grid, may comprise: a power conversion system (PCS) configured to be connected with the power grid and 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 the ground; a second switch selectively configured to connect the photovoltaic system and the other terminal of the first ground fault detector, wherein the second switch is located between the first switch and the photovoltaic system; and a switch controller configured to change a ground structure of at least one of the photovoltaic system, the power conversion system, and a battery system included in the energy storage system and to selectively connect the photovoltaic system and the DC link of the power conversion system, by controlling the first switch and the second switch based on a power generation state of the photovoltaic system.