Due to the low inertia and weak damping of the dc microgrid, its stability becomes even more serious and has attracted many investigations. However, as its scale and complexity continue to grow, the effectiveness, reliability, and comprehensive-ness of the stability analysis cannot be guaranteed simultaneously. Therefore, this paper proposes a passivity-based stability analysis approach by developing a physically decoupled model. Specifically, for the first time presenting the concept of virtual capacitance in modeling, the dc microgrid is physically decoupled into several low-dimensional subsystems. These subsystems have feedback structures, constituting the physically decoupled model, and the physical meanings of parameters are retained explicitly and completely. Subsequently, a sufficient condition for the stability of the physically decoupled model is derived based on strict passivity and LaSalle's Theorem. Then, by combining optimization theory, the stability domain calculation of multiple subsystems is transformed into a multi-objective optimization problem. The stability impacts of internal circuit and power parameters are evaluated, and the stability boundaries are identified to determine parameter limita-tions. Finally, numerical and time-domain simulations are carried out to validate the effectiveness and accuracy of the theoretical analysis and the superiority of the proposed method than Lyapunov direct method and TS fuzzy model method.

The reliance on fossil fuels poses significant challenges to the environment and sustainable development. To address the heating requirements of the pyrolysis process in a biomass gasification-based multi-generation system, this study explored the use of low-grade solar energy across the full solar spectrum to supply the necessary energy for biomass pyrolysis while leveraging high-grade solar energy in the short-wavelength spectrum for power generation. The proposed multi-generation system integrates the full solar spectrum, biomass gasification, gas turbine, and waste heat recovery unit to produce power, cooling, and heating. A detailed thermodynamic model of this integrated system was developed, and the energy and exergy efficiencies of each subsystem were evaluated. Furthermore, the system’s performance was assessed on both monthly and annual timescales by employing the hourly weather data for Hohhot in 2023. The results showed that the solar subsystem achieved its highest power output of around 2.5 MWh in July and the lowest of 0.7 MWh in December. The annual electrical output peaked at 10 MWh, occurring around noon in July and August, while the winter peak was typically 2–3 MWh. For the wind power subsystem, the power output was maximized in April at 5.17 MWh and minimized in August at 0.7 MWh. Additionally, considering the overall multi-generation system performance, the highest power output of 14.9 MWh was observed in April, with lower outputs of 10.9, 11.3, and 11.4 MWh from August to October, respectively. Overall, the system demonstrated impressive annual average energy and exergy efficiencies of 74.05% and 52.13%, respectively.

When the high voltage cable core passes through the alternating current, the metal sheath will produce induction electricity under the action of electromagnetic induction. When the sheathes are grounded, the induced currents will reduce the transmission capacity of the wire core and increase the power loss. This paper firstly introduces the grounding mode of cable sheath, and then analyzes the grounding mode at both ends of the sheath and the induced current of cross-connected grounding through ATP-EMTP software simulation. The results of the research have shown that: when the cables are in normal operation, the sheathes adopt cross-connected grounding, the induced currents are reduced, and the energy loss caused by induced currents can be neglected. In actual engineering, due to the non-uniform length of each section of cables, when the cable sheathes are cross-connected, there will be residual positive and negative sequence current in each phase of the sheath after complete transposition.

In order to ensure the efficient and stable operation of the electricity market, it is very important to set indexes to measure the market efficiency. In this paper, Herfindahl Hirschman Index (HHI) and social welfare index are used to measure the market efficiency. The article improves the traditional HHI. The HHI and social welfare index are standardized by min-max, and applied to a certain electricity market. The calculating results of each index and the result curve after standardization are given by example analysis.

Aiming at the problem of low redundancy in the structure of the cascaded H-bridge STATCOM. This paper studies and designs a cascaded H-bridge STATCOM device based on STM32 distributed control. The article introduces the basic topology of the device and the realization principle of the control system. The turn-on and turn-off time of the MOSFET in each H-bridge is calculated by using the law of minimum harmonics, realize the output of the fitted sine wave. A simulation model of 12H bridge cascade is built in the EMTP power system electromagnetic transient analysis simulation software. The simulation results show the correctness and reliability of the design.

In the H-bridge inverter, the control and circuit topology parameters are the key factors affecting its dynamic stability, and the changes of each parameter have different effects on the stability of the system. This paper takes the current-controlled first-order H-bridge passive inverter based on PI control as the research object. Firstly, based on the different modal of the circuit, an accurate discrete iterative mapping model of the H-bridge inverter is derived according to the stroboscopic mapping principle. Then iterate through the above iterative formula, after retaining the data of the current peak value, the dynamic bifurcation diagram on the control parameters of the system is obtained, with the bifurcation behavior and stable working area of the system being analysed when the control parameters change, and verified by the current folding diagram the correctness of the analysis. Finally, according to the same method, the influence of other parameters on the system stability is studied. The research results show that when different parameters change, there are critical maximum or minimum values to keep the system running stably.