Energy Storage Valve Submodule RC Branch for Underdamped Switching Currents
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Solution Overview
Problem
The reliability of high-voltage direct-connected energy storage systems is low due to underdamped oscillation currents generated during connection and disconnection state switching in energy storage valve submodules.
Innovation Solution
An energy storage valve submodule is equipped with a suppression circuit connected in series with a capacitor to form a resistance-capacitance branch, which is then connected in 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
1Ease of operation
If energy storage valve submodule switches between connection and disconnection states, then charging and discharging control is achieved, but underdamped oscillation current is generated 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 switch connected in parallel with the energy storage unit, which activates during state transitions to suppress underdamped oscillation currents while allowing normal charging and discharging operations to proceed through the main circuit path.
Solution Approach 2:
The suppression circuit is configured to preemptively counteract underdamped oscillation currents before they can cause harm. The suppression switch is designed to activate automatically upon detection of state transition conditions, applying counter-action to dampen oscillations before they propagate through the system and compromise reliability.
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 merged with the existing power conversion unit structure. The suppression switch is integrated into the circuit topology and shares common connection points with the energy storage unit and power conversion unit, thereby adding suppression functionality without requiring entirely separate independent components or complex additional circuitry.
Solution Approach 2:
The suppression switch serves multiple functions: it suppresses underdamped oscillation currents during state transitions, and it remains dormant during normal operating conditions. This multi-functionality allows a single component to address reliability issues without permanently increasing operational complexity or requiring additional dedicated suppression components for different operating modes.
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
Significantly reduces underdamped oscillation currents, minimizing harm to the energy storage valve submodule and improving its reliability by ensuring a critical or overdamped state, thus enhancing operational stability and safety.
Implementation Method 1
a suppression circuit for underdamped oscillation, the suppression circuit is connected in series with the first capacitor
Data Source
AI summary
An energy storage valve submodule and a high-voltage direct-connected energy storage system having the energy storage valve submodule. A suppression circuit for underdamped oscillation is 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.