Input-Series-Output-Parallel DC Transformer Impedance Modeling and Phase Reshaping for Rapid Stabilization of MVDC Distribution Systems

This paper focuses on the instability problem of the medium-voltage DC (MVDC) distribution system and proposes an impedance phase reshaping (IPR) method. To obtain the load impedance model of the MVDC distribution system, the input impedance of the input-series-output-parallel (ISOP) DC transformer (DCT) is derived by the generalized average modeling (GAM). Based on the obtained model, the traditional ISOP DCT controller optimization (IDCO) approach is discussed and the IPR method is developed. An impedance phase controller is introduced based on the original control method. According to the optimized impedance stability criterion, the parameters of the impedance phase controller are determined. Compared with the IDCO approach, the proposed method weakens the negative resistance characteristic of the load impedance at the resonant frequency. Therefore, the MV bus voltage oscillation is rapidly mitigated. Besides, the dynamic performance of the system using the IPR method can be classified as good. The simulation results show that the mathematical model is correct, and the proposed method is effective for the rapid stabilization of MVDC distribution systems.

A type-2 fuzzy control for active/reactive power control and energy storage management

This paper presents a new type-2 fuzzy logic control (T2FLC) for active/reactive power (AP/RP) regulation and energy storage management of an independent microgrid (MG). The case-study MG includes sporadic renewable sources that lead to significant frequency and voltage fluctuations in the network. The rules of suggested T2FLCs are tuned such that a fractional-order sliding condition can be satisfied. Also a new approach using square-root-cubature Kalman filter is designed to optimize the membership parameters of T2FLCs. Beside AP/RP power regulation, an electrical storage system (battery energy storage system (BESS)) is managed to produce the rated power, rather than a conventional generator. It makes the device frequency separate from the synchronous generator’s mechanical inertia. Nevertheless, a BESS has a power limit – it uses a synchronous generator to sustain the BESS charge state at a certain value. Sustainable energies achieve a voltage-damping impact by supplementing an AP/RP droop strategy procedure that considerably reduces voltage oscillation created by variation of its own output power. In various disturbed scenarios the good performance of the suggested controller and energy management system is shown.

Organelle calcium-derived voltage oscillations in pacemaker neurons drive the motor program for food-seeking behavior in Aplysia

The expression of motivated behaviors depends on both external and internally-arising neural stimuli, yet the intrinsic releasing mechanisms for such variably occurring behaviors remain elusive. In isolated nervous system preparations of Aplysia, we have found that irregularly expressed cycles of motor output underlying food-seeking behavior arise from regular membrane potential oscillations of varying magnitude in an identified pair of interneurons (B63) in the bilateral buccal ganglia. This rhythmic signal, which is specific to the B63 cells, is generated by organelle-derived intracellular calcium fluxes that activate voltage-independent plasma membrane channels. The resulting voltage oscillation spreads throughout a subset of gap junction-coupled buccal network neurons and by triggering plateau potential-mediated bursts in B63, can initiate motor output driving food-seeking action. Thus, an atypical neuronal pacemaker mechanism, based on rhythmic intracellular calcium store release and intercellular propagation, can act as an autonomous intrinsic releaser for the occurrence of a motivated behavior.

Organelle calcium-derived voltage oscillations in pacemaker neurons drive food-seeking behavior in Aplysia

The expression of motivated behaviors depends on both external and internally-arising neural stimuli, yet the intrinsic releasing mechanisms for such variably occurring behaviors remain elusive. In isolated nervous system preparations of Aplysia, we have found that irregularly expressed cycles of motor output underlying food-seeking behavior arise from regular membrane potential oscillations of varying magnitude in an identified pair of interneurons (B63) in the bilateral buccal ganglia. This rhythmic signal, which is endogenous and specific to the B63 cells, is generated by organelle-derived intracellular calcium fluxes that activate voltage-independent plasma membrane channels. The resulting voltage oscillation spreads throughout a subset of gap junction-coupled buccal network neurons and by triggering plateau potential-mediated bursts in B63, can initiate motor output driving food-seeking action. Thus, an atypical neuronal pacemaker mechanism, based on rhythmic intracellular calcium store release and intercellular propagation, can act as an autonomous intrinsic releaser for the occurrence of a motivated behavior.

Optimization of PSVR parameters of condenser based on MATLAB/Simulink simulation

Installing a power system voltage regulator (PSVR) on the condenser can enhance the dynamic voltage control capability of the local high-voltage bus voltage, but there are still few studies on the optimization of PSVR parameters. The dynamic model of the condenser is built to determine the analytical expression between the system voltage disturbance and the change of the control target, and the influence trend of PSVR on the dynamic voltage characteristics of the condenser is analyzed. Furthermore, in the MATLAB/Simulink environment, a PSVR-containing condenser model is built, and a quantitative index for evaluating the phase-frequency characteristics of the condenser is proposed. Based on this index, the PSVR time constant is optimized through the simulation of the dynamic voltage characteristics of the condenser, and using eigenvalue root locus method combined with dynamic simulation to coordinate PSVR gain coefficient, achieve PSVR parameter optimization. The simulation results under the single-machine and three-machine systems show that after the PSVR parameter optimization, the voltage oscillation mode of the condenser is effectively improved.