Due to the injection of energetic particles, such as electrons in space environment, the internal charging–discharging characteristics of spacecraft dielectrics need to be evaluated for the safety of spacecraft, and the evaluation results from experiments and simulations should be comparatively validated. An in-site pulsed electroacoustic (PEA) measurement system under high-energy electron radiation was established for evaluating the charging characteristics of thick plate samples about 3 mm, while a joint simulation method based on Geant4 and COMSOL was also proposed. The deposited charge distributions were compared through experiment and joint simulation method under 0.7, 1.0 and 1.3 MeV for 30 min and 1.0 MeV for 10, 60 and 120 min, respectively. Meanwhile, the electrostatic discharging characteristics were also comparative evaluated by both methods under 0.3 MeV for 20 min under 5, 10 and 15 µA beam current, and the total discharging times and initial discharging time were compared and analyzed. Overall, a good consistency existed between experimental and simulation results of charging–discharging characteristics under electron radiation while the difference was also analyzed in the perspective of dielectric properties, such as charge leakage by conduction. Through the comparative study, both evaluation methods are validated, which offers effective reference for the safety evaluation of spacecraft dielectrics in future.

The “closed-loop design, open-loop operation” scheme traditionally adopted by distribution networks results in limited power-flow regulation capability and insufficient supply reliability. Existing flexible interconnection solutions mostly employ AC–DC–AC back-to-back converter architectures, which suffer from high cost, large footprint, and low efficiency. To address these issues, this paper proposes a flexible AC controllable interconnection device based on a hybrid series–parallel structure. The device couples series voltage injection through cascaded H-bridge (CHB) submodules with parallel feeding through a multi-winding transformer: the series side synthesizes a controllable AC voltage source from the cascaded submodules, enabling independent regulation of the active and reactive power of the line, while the parallel side supplies isolated power to the DC sides of all submodules via the multi-winding transformer, thereby fundamentally resolving the DC-side energy-balance problem of series-connected converters. A decoupled vector control strategy in the dq synchronous rotating reference frame, together with an individual-phase control scheme, is developed, and the device supports both interconnected and islanded operation modes. An RTDS simulation model is established on the basis of 10 kV/5 MW rated parameters, and three groups of tests are conducted: steady-state active power control, steady-state reactive power compensation, and dynamic active power control. The simulation results show that the steady-state active power control error is below 1.5%, the reactive power compensation error is approximately 5%, and the dynamic power step response time is 12–13 ms, with the power settling at the target value within 30 ms, verifying the technical feasibility and effectiveness of the proposed scheme for power-flow regulation and reactive power compensation in distribution networks.

Unplanned islanding and off-grid issues of photovoltaic (PV) power stations caused by tie-line faults have seriously undermined the power supply reliability and operational stability of PV plants. Furthermore, it takes a relatively long time to restore normal operation after an off-grid event, leading to substantial power losses. To address this problem, this paper proposes a tie-line fault ride-through control strategy based on the coordinated control of on-site energy storage units. After a fault on the tie-line occurs, the control mode of PV inverters is switched to achieve source–load balance, and the control mode of energy storage inverters is switched to VF control mode, which supports the stability of voltage and frequency in the islanded system. Subsequently, the strategy coordinates with the tie-line recloser device to perform synchronous checking and grid reconnection. Simulation results show that, for transient tie-line faults, the proposed method can achieve stable control of the islanded system and grid reconnection within 2 s after a fault on the tie-line occurs. It successfully realizes fault ride-through within the operation time limit of anti-islanding protection, effectively preventing the PV plant from disconnecting from the grid. Finally, a connection scheme for the control strategy of a typical PV plant is presented, providing technical reference for on-site engineering.