Series-Connected Storage Bank Cells for Stable SOC Range
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Solution Overview
Problem
Energy storage elements in power system stabilization systems experience variations in input/output voltages and currents due to state of charge (SOC), limiting the variation range of SOC when voltage suppression is required.
Innovation Solution
A power storage apparatus comprising a storage bank connected in series with one or more first cells, each cell having a bridge circuit with semiconductor switching elements and a power storage element, allowing for smaller storage capacity than the bank, to suppress voltage and current variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the variation range of SOC of the energy storage element is widened, then the power storage capacity is improved, but the input/output voltage variation increases
Solution Approach 1:
The energy storage system is divided into multiple energy storage units, each with its own DC/DC converter. This segmentation allows independent control of each unit's voltage and SOC, enabling the system to accommodate a wider overall SOC range while maintaining stable output voltage through coordinated control of individual units.
Solution Approach 2:
The system employs dynamic SOC distribution control that adjusts the SOC allocation among multiple energy storage units based on real-time operating conditions. This dynamic adjustment enables the system to maintain optimal voltage stability while utilizing a broader SOC range, as the controller can shift SOC distribution to prevent excessive voltage variations during charge/discharge cycles.
2Stability of the object's composition
If the number of energy storage units is increased to suppress voltage variation, then the voltage stability is improved, but the device complexity increases
Solution Approach 1:
Each energy storage unit is designed with universal functionality, including its own DC/DC converter and control system, allowing any unit to independently regulate voltage and participate in power exchange. This multi-functional design simplifies the overall system architecture by eliminating the need for complex inter-unit coordination mechanisms, as each unit operates autonomously while contributing to collective voltage stability.
Solution Approach 2:
The system utilizes parameter changes in the DC/DC converters to achieve voltage stabilization without increasing the physical number of energy storage units. By dynamically adjusting conversion ratios, power distribution, and SOC levels through control algorithms, the system maintains voltage stability while keeping the hardware configuration simple and manageable.
Data Source
AI summary
A power storage apparatus of one embodiment includes a storage bank including a plurality of power storage elements connected to each other; and one or plurality of first cells. The storage bank and the one or plurality of first cells are connected in series to each other. Each first cell includes a pair of input/output nodes, a bridge circuit including at least two semiconductor switching elements, and a power storage element connected to the pair of input/output nodes via the bridge circuit. A storage capacity of the power storage element of each first cell is smaller than a storage capacity of the storage bank.