Energy Storage Valve Submodule RC Damping for Switching Oscillation
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Solution Overview
Problem
The reliability of energy storage valve submodules in high-voltage direct-connected energy storage systems is low due to underdamped oscillation currents generated during connection and disconnection state switching, which can cause overcurrent, damage, and reduced lifespan.
Innovation Solution
An energy storage valve submodule is enhanced with a suppression circuit connected in series with a capacitor to form a resistance-capacitance branch, which is parallel with the power conversion unit and energy storage unit, using a resistor element to adjust impedance and suppress underdamped oscillation currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If energy storage valve submodule is used in high-voltage direct-connected energy storage system, then energy storage capability is improved, but underdamped oscillation current is generated during switching which reduces reliability
Solution Approach 1:
A suppression circuit is introduced as an intermediary component between the power conversion unit and the energy storage unit. This circuit includes a suppression resistor connected in series with a capacitor, forming a resistance-capacitance branch that is connected in parallel with the power conversion unit and energy storage unit. The suppression circuit acts as a mediator to dampen the underdamped oscillation current generated during connection and disconnection state switching, thereby reducing harmful effects on the energy storage valve submodule while maintaining its energy storage capability.
Solution Approach 2:
The suppression circuit changes the impedance parameters of the energy storage valve submodule by introducing a suppression resistor with a specific resistance value. This resistor adjusts the overall impedance characteristics of the module, transforming the underdamped oscillation response into a critically damped or overdamped response. The parameter change in resistance directly affects the damping ratio of the system, eliminating the harmful oscillation current while preserving the energy storage function.
2Reliability
If suppression circuit is added to reduce underdamped oscillation current, then reliability is improved, but device complexity increases
Solution Approach 1:
The suppression circuit is designed to serve multiple functions within a single integrated structure. The resistance-capacitance branch not only suppresses underdamped oscillation current but also maintains parallel connection with both the power conversion unit and energy storage unit, allowing it to function across different operating states. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity while achieving improved 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 suppression circuit significantly reduces underdamped oscillation currents, minimizing harm to the submodule and improving its reliability by maintaining a critical or overdamped state, thus enhancing operational stability and safety.
Implementation Method 1
The suppression circuit can suppress an underdamped oscillation current generated in the energy storage valve submodule at a connection and disconnection state switching moment by adjusting a resistance value of an impedance in the energy storage valve submodule
Data Source
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AI summary
This application relates to an energy storage valve submodule and a high-voltage direct-connected energy storage system, where a suppression circuit for underdamped oscillation is additionally provided in the energy storage valve submodule. The suppression circuit is connected in series with a first capacitor, and a resistance-capacitance branch formed by the suppression circuit and the first capacitor connected in series is connected in parallel with a power conversion unit and an energy storage unit, respectively. The suppression circuit can suppress an underdamped oscillation current generated in the energy storage valve submodule at a connection and disconnection state switching moment by adjusting a resistance value of an impedance in the energy storage valve submodule, reducing the underdamped oscillation current generated in the energy storage valve submodule at the connection and disconnection state switching moment, thereby reducing harm caused by the underdamped oscillation current to the energy storage valve submodule, and thus improving reliability of the energy storage valve submodule.