In this paper, we described a design scheme for a lead-carbon battery energy storage system (BESS). A two-stage topology of lead-carbon battery energy storage system was adopted. The number and connection structure of battery cells were designed based on the actual demand. The main circuit parameters of the BESS were determined according to the power transfer capability, harmonic suppression, and dynamic response capability. A state feedback linearization method in a nonlinear differential geometry theory was used for dq-axis current decoupling based on the mathematical model used in the dq coordinate system of the BESS. A control strategy based on filter capacitor current inner loop, grid current middle loop, and dc voltage outer loop was adopted to suppress the resonance peak and achieve the independent regulation of active power and reactive power. The PSCAD/EMTDC simulation results and physical prototype experiments showed that the lead-carbon BESS had a good dynamic and steady-state performance. INDEX TERMS Lead-carbon battery, power converter system, power control, battery energy storage system.

In grid-connected photovoltaic (PV) systems, grid inductance greatly influences the performance of grid-connected inverters. However, the grid inductance usually varies with the changes of the grid operation conditions. Therefore, accurate grid inductance detection is one of the key technologies to achieve an adaptive control of the grid-connected inverters under different operation conditions. In this paper, an equivalent circuit model of a grid-connected PV system which includes the controller, filter, and grid impedance is established. The oscillation characteristic of the inverter terminal voltage caused by the sudden change of the inverter output power is analyzed. The oscillation mechanism of the inverter terminal voltage caused by the interaction of the controller, filter, and grid impedance is investigated. A grid inductance detection method based on the oscillation characteristic of the inverter terminal voltage is proposed. The main advantage of the proposed method is that it does not need complicated signal processing and calculation procedures. A 10 kW grid-connected PV system was built for both simulations and the experimental setup. Finally, simulation and experimental results validate the correctness and effectiveness of the proposed method.

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