The modular multilevel matrix converter (M3C) is a key device for the low-frequency transmission system (LFTS) of offshore wind power. Its stable operation under asymmetric faults is crucial. Currently, M3C controllers are mainly based on PID control. However, the M3C is a complex, multivariable, nonlinear system, and fault conditions introduce additional uncertainties, making it difficult for PID control to meet the high-performance requirements of fast tracking and disturbance rejection. To address this challenge, this paper proposes a fuzzy improved linear active disturbance rejection control (LADRC) strategy for the M3C current inner loop. The strategy enhances the improved LADRC with fuzzy adaptive control, enabling the controller to better compensate for fault-induced uncertainties. Finally, on MATLAB/Simulink, compared with PID control under different fault conditions, the research results show that the proposed strategy reduces the d-axis current overshoot by 14.9

This paper proposes a novel, dual-output, hybrid-clamped, quasi-five-level inverter (DO-HC-FLI) topology, capable of providing two independent AC voltage outputs with adjustable frequency and amplitude. Derived from a dual-output, active, neutral-point-clamped, three-level inverter, the proposed topology introduces three additional switches per phase to create dynamic switching paths. This expands the available range of DC-side voltage outputs and significantly improves the utilization rate of the DC–link voltage. Additionally, by adopting an asymmetric DC–link voltage configuration, the output line voltage levels of the conventional four-level inverter are increased to a number comparable to that of a five-level inverter. The front-end stage employs a hybrid series-parallel architecture, integrating dual Buck circuits with DC power sources. This configuration supplies the subsequent inverter stage with DC voltage levels at an optimal asymmetric ratio. In conjunction with a dual-output space vector pulse width modulation (SVPWM) strategy, the proposed system can collaboratively optimize the output voltage level characteristics of the inverter stage. Furthermore, a comprehensive analysis and comparison with other multilevel inverters are presented to demonstrate the superiority of the proposed topology. Finally, simulations and experiments are conducted to validate the effectiveness and feasibility of the proposed topology and modulation strategy.

With the accelerating urbanization process, traditional wastewater treatment plants are facing dual challenges of high energy consumption and high carbon emissions. To address the current research gaps in studies regarding the overlooked synergistic potential of sludge, the unclear quantification of regulation capacity, and the insufficient analysis of multi-scenario adaptability in wastewater treatment plants, this paper integrates carbon emission costs, wastewater grading, and a multi-energy complementary mechanism to establish a VPP dispatch optimization model incorporating sewage–sludge co-treatment. The superiority and robustness of the co-dispatch model are validated through simulations across multiple seasonal scenarios (dry, wet, and normal seasons) and various water quality parameters. The results indicate that the co-treatment mode can significantly enhance system revenue (with an increase of up to 34.3% in the wet season), reduce carbon emissions (with a reduction rate exceeding 57% across all seasons), and improve grid regulation potential (with upward and downward regulation potentials increasing by 248% and 288%, respectively, in the wet season). Furthermore, variations in water quality exert a notable nonlinear impact on the system’s economic performance, environmental benefits, and regulation capacity. As the water quality concentration increases, the system’s dispatch strategy gradually shifts from prioritizing “peak-shaving benefits” to prioritizing “carbon cost control”.

Driven by the low-carbon transition, hydrogen is vital; however, most existing studies on hydrogen-blended combustion rely on deterministic models with fixed blending ratios, overlooking the benefits of diversified hydrogen allocation. Furthermore, the traditional power-to-gas (P2G) process suffers from excessive energy conversion losses. To address these limitations, this article proposes a low-carbon economic dispatch model for a virtual power plant (VPP). The primary innovation lies in decoupling the traditional P2G process into a bi-level architecture-comprising an upper layer for hydrogen production and a lower layer for diversified utilization. Additionally, liquid-based carbon capture and storage (CCS) and hydrogen storage units are introduced. On this basis, a dynamic hydrogen allocation model based on a multipriority strategy is established. Combined with an reward-penalty tiered carbon trading mechanism, the model coordinately optimizes hydrogen pathways including hydrogen fuel cell (HFC) power generation, hydrogen-blended combustion, methanation, and hydrogen storage. Simulation results show that the P2G-CCS decoupling reduces system costs by 9.73% (337,660 CNY) and carbon emissions by 17.76%. Furthermore, transitioning to variable blending ratios with HFC integration yields an additional 158,000 CNY in savings and a 402.8 tons reduction in CO2 emissions. These findings demonstrate the model's effectiveness in achieving multienergy coordination and deep decarbonization.

The dual-dc-port dual-output converter for photovoltaic (PV)-battery hybrid system is proposed in this article. Two dc ports, in which one is interfaced with the battery and other one is interfaced with PV, two outputs, in which can be interfaced with different ac loads, are provided simultaneously by the dual-dc-port dual-output converter, which presents high efficiency and low cost with single-stage power conversion. First, the operating modes of PV and battery for the dual-dc-port dual-output converter are analyzed, and the effective switching states of two sets of outputs are analyzed. Then, to achieve the flexible power management between PV, battery and two sets of ac loads, the virtual space vector pulsewidth modulation is proposed. In order to reduce the voltage vector arrangement combinations between two sets of outputs, the idea of topological decoupling and switch driving signal splicing is proposed, which can greatly reduce computational complexity and program programming. Finally, the effectiveness of the proposed scheme is verified through experimental results.

As the grid-connection voltage level of the cascaded H-bridge (CHB) STATCOM increases, the number of cascaded cells also increases, and the switch fault leads to a higher risk of STATCOM operation. For instance, the open-circuit (OC) switch fault will deteriorate the power quality of the STATCOM output current. Therefore, the high efficiency and precision of OC switch fault localization are an assurance of STATCOM operation safety. Using the actual output voltage acquired from the AC voltage sensor installed at the output side of the CHB STATCOM, the fault characteristic of the voltage is obtained through comparison with the expected output voltage of the CHB STATCOM, and then combined with the mapping relationship of the switch trigger signals, a novel OC switch fault localization method based on timing logic is proposed. The proposed method, while ensuring rapid localization, eliminates the misjudgment caused by traditional methods and is not limited by the number of cells and faulty switches. Finally, the effectiveness of this method in the application of CHB STATCOM was verified through simulation and experiments.

The widespread adoption of renewable energy generation and diversified end-user equipment has significantly enhanced user benefits, attracting sustained attention from the research community. As energy systems become increasingly decentralized, traditional centralized optimization methods struggle to effectively capture the interactions among multiple agents. Achieving efficient interaction between diversified energy devices and load demands has emerged as a key challenge in current research. This study first outlines the system operation architecture and the involved game-theoretic agents, clarifying the roles of all participating entities. Subsequently, optimization models are established for the Virtual Power Plant (VPP) and the user aggregator, respectively, incorporating an integrated electro-thermal demand response mechanism under multi-device scenarios. By analyzing the Stackelberg game between the VPP and end-users, the existence of a unique equilibrium solution for this game is demonstrated. Simulations are conducted on the MATLAB R2021b platform using the YALMIP 20210331 toolbox and the CPLEX solver, with heuristic algorithms applied to further optimize the results. The proposed model effectively balances the interests of both parties while maintaining robust privacy protection for critical data.

A dual-output neutral-point-clamped CLLC resonant converter (DO-NPC-CLLC) based on flying capacitor neutral-point clamping topology is proposed in this paper. By adding two switches, this topology can realize dual-channel output voltage while completely retaining the inherent bidirectional power flow capability of the CLLC resonant converter. In this paper, the structure of the dual-output topology is described in detail, and its working principle under various working conditions is analyzed. Based on first harmonic approximation (FHA), an optimized FHA model is proposed to solve the problem of the low precision in a parameter solution when it works under resonance. In addition, the current path, resonance current characteristics, and soft switching realization capability under different modulation strategies are studied. According to this topological characteristic, a hybrid modulation strategy combining pulse frequency modulation (PFM) and primary-side phase-shift modulation (PSPSM) is proposed. This strategy effectively supports the stable operation of the converter under a variety of working conditions and a wide range of dual output voltages. Finally, the feasibility of the proposed dual-output topology and the effectiveness of the hybrid modulation strategy are fully verified on an experimental prototype.

A split-source dual-output two-stage matrix converter (SSDO-TSMC) is proposed to address the problems of the conventional two-stage matrix converter, which is not able to have dual outputs and has a low voltage transfer ratio. First, the topology of the proposed SSDO-TSMC is introduced. A zero-vector-free modulation strategy is applied to the rectifier stage of the SSDO-TSMC and an improved space vector pulse width modulation strategy is applied to the inverter stage in terms of the modulation strategy, which can remarkably improve the voltage transfer ratio. Second, a carrier-based pulse width modulation (CBPWM) strategy is proposed to optimize the switching modulation sequence of the inverter stage by fixing the discharging time of the inductor of the split-source network, which can be combined with the operating state of the dual-output inverter stage to derive a stable boost ratio. The modulating waveforms of the rectifier and inverter stages are deduced from the duty cycle and carrier waveform expressions. The proposed CBPWM strategy is easy to implement and only needs to use a symmetric triangular carrier to generate the pulse width modulation signals of the rectifier and inverter stages. Finally, the effectiveness of the topology and the improved modulation strategy proposed in this study is verified experimentally.

As an emerging power electronics topology, the quasi-single-stage four port three-phase converter (QSS-FPTPC) has two DC voltage ports and two three-phase AC voltage ports. Due to the function of its internal DC-DC converter, the voltage at its low-voltage DC port can vary over a wide range. This paper introduces the topology structure of the QSS-FPTPC and analyzes the effective working states corresponding to the two sets of outputs of the four-port three-phase DC-AC converter. To achieve the transmission of as much power as possible through the low-voltage port and reduce the number of power conversion stages, an improved SVPWM strategy is proposed. Based on the improved SVPWM strategy, an output-integrated improved SVPWM strategy is proposed, which can flexibly adjust the voltage transmission ratio of the two groups of outputs to meet different voltage requirements and achieve a wide range voltage output. Finally, the effectiveness of the proposed modulation strategy is verified through experiments.

In addition to achieving maximum power capture, photovoltaic (PV) grid-connected inverters have remaining capacity that can be utilized for harmonic compensation. However, due to the variable nature of PV power generation, this remaining inverter capacity fluctuates. Enhancing the harmonic compensation of PV grid-connected inverters under these limited and fluctuating margins is a critical issue. This study proposes an optimal harmonic compensation method that flexibly adjusts the compensation coefficients for each harmonic current, solved by constructing the minimization of the total harmonic distortion (THD) as the objective equation. Compared to conventional methods, the proposed approach improves harmonic compensation performance and reduces the THD at the point of common coupling (PCC). The method is effectively validated through comparative hardware-in-the-loop (HIL) simulation on a StarSim experimental platform.

Integrated energy systems (IESs) can realize the conversion and complementarity of various energy sources, which provides opportunities and challenges for the energy market. Considering that the user's energy consumption is affected by the energy price difference, there is a problem that the new energy output in the comprehensive energy system does not fully match the user's energy demand period. In order to solve the above problems, this paper proposes a two-stage optimization model of "open source and reducing expenditure" to give full play to the potential of multiple energy sources on the load side to participate in demand response (DR) and combine low-carbon technology and market mechanisms to realize the low-carbon economic operation of the comprehensive energy system. In the first stage, a collaborative optimization strategy for electric and thermal DR is constructed from the aspect of "reducing expenditure," a comprehensive load fuzzy DR mechanism based on the logistic function is constructed for electric load, and the load curve and time-of-use (TOU) energy price are optimized considering the coupling characteristics of user energy consumption, and nondominated sorting genetic algorithm (NSGA-II) solution to achieve peak shaving and valley filling. In the second stage, a joint operation model of carbon capture power plant (CCPP) and power-to-gas (P2G) equipment is built from the aspect of "open source," and the ladder-type carbon trading mechanism is considered to rationalize the unit output and achieve low-carbon emission reduction. The calculation results obtained through examples show that the total cost of the model is slightly reduced by 5.44%, but the actual total carbon emission of the system is greatly increased by 50.73%. It proves that the high-carbon power plant transformation and TOU energy price optimization strategy are effective for the low-carbon economic operation of the system and realize both economic benefits and benefits of the system.

In this paper, the transient response characteristics of microgrid containing virtual synchronous generator (VSG) and synchronous generator (SG) and their coordinated control methods under load fluctuations when they operate together are investigated and the instability in the transient process caused by the different mechanical structures and operation modes of heterogeneous micro-sources is analyzed. On this basis, a coordinated control strategy of SG-VSG based on power coupling is proposed to effectively reduce the overshooting and oscillation in the active power and frequency of the VSG. Meanwhile, in a microgrid containing energy storage, a low-pass filtered hybrid energy storage coordinated control strategy considering power equalization within the system is proposed to improve the power regulation capability and frequency stability of the system based on the principle of energy conservation at the input and output sides of the inverter. Finally, the proposed strategy is verified on the MATLAB/Simulink simulation platform.

Aiming at the grid-connected instability of converters induced by the inherent resonant peaking in T-type filters, this paper presents a parameter optimization method based on a resistive-capacitive series passive damping branch (RC-PD). First, a dq-frame admittance model of the T-type grid-connected voltage-source converter (VSC) system with RC-PD is established. By deriving the system stability conditions using passivity theory and simplifying through admittance decomposition, the non-passive regions requiring compensation are identified via parameter impact comparison. Building on this, combined with the compensation capability of RC-PD, a PD parameter optimization method is constructed to enforce full-frequency passivity of the output admittance, thereby satisfying stability requirements. This method demonstrates universality for a class of grid-connected VSC systems equipped with T-type filters. Finally, a real-time simulation platform for grid-connected VSC is established to verify the effectiveness and correctness of the proposed method.

To address the challenges of grid instability and economic risks from intermittent wind power, the research developed a hybrid electrolyzer hydrogen generation system (HE-HGS). This system leverages the complementary dynamic characteristics of alkaline electrolyzer (AEL) and proton exchange membrane electrolyzers (PEMEL) for large-scale green hydrogen production. A method for wind power distribution, utilizing adaptive wavelet packet decomposition (AWPD), is introduced. This approach separates wind power into a stable grid-connected component and an input component for the HE-HGS. Wind power fluctuations are smoothed through the HE-HGS. Based on the distinct features of the two electrolyzers, a power distribution strategy for the electrolyzers is proposed to achieve flexible consumption of fluctuating energy. On this basis, the capacity of the electrolytic hydrogen production plant is optimally configured. The results show that when the proportion of AEL and PEMEL is 67.76% and 32.24%, respectively, the hybrid system achieves a 46.47% improvement in energy efficiency and a 10.90% increase in annual hydrogen output compared to the standalone AEL system, with the unit hydrogen production cost rising by just 10.55%.The HE-HGS enables superior adaptability to wind fluctuations and dynamic response by leveraging electrolyzer complementarity, all while preserving economic viability.

This paper addresses the transient stability of grid-connected inverters under high renewable energy penetration by proposing a dual-objective coordinated control strategy for power angle stabilization and fault current limitation. A third-order active supporting virtual synchronous generator model is developed, integrating a control architecture with virtual power angle compensation in the power loop and dynamic voltage regulation in the voltage loop. The innovative Kon triggering coefficient enables adaptive switching between control modes. Transient power angle dynamics analysis and the equal-area criterion validate large-disturbance stability, while circuit equation modeling and vector analysis reveal the synergy between enhanced voltage support and fault current limitation. Case studies on a photovoltaic plant demonstrate the proposed transient control strategy's excellent effectiveness in mitigating three-phase symmetrical short-circuit faults.

A novel family of four-port three-phase dc-ac converter (FPTPC) topology is proposed in this article, which has two dc ports and two three-phase ac ports. It can be combined with dc-dc to form the quasi-single-stage FPTPC whose low voltage dc port voltage can be varied over a wide range. The proposed four-port three-phase dc-ac converter topology is first described. Then, its differences with T-type three-level dual output converter are analyzed, and the constraints that should be satisfied for the normal operation of FPTPC, the various operating modes available for the FPTPC, and the key issues such as the dc bias, modulation index range, and displacement angle constraints of the two three-phase ac outputs under different operating modes are discussed. In order to increase the output power of the low voltage (LV) dc port, a sinusoidal carrier-based pulsewidth modulation (CBPWM) strategy for increasing the output power of the LV dc port is proposed by analyzing the effects of the upper bias as well as the lower bias on the output power of the LV dc port, and on the basis of the above mentioned increase of the output power of the LV dc port, three nonsinusoidal CBPWM modulation strategies are also proposed to increase the utilization of the dc bus voltage. Finally, the effectiveness of the proposed topologies and their corresponding modulation schemes are verified through experimental results.

As an advanced power electronic topology, the three-level dual-output converter (TLDOC) combines three-level technology with dual output characteristics, which has significant advantages in industrial, energy, and transportation applications. Achieving capacitor voltage balance and improving dc bus voltage utilization are the key technologies in the application of TLDOC, but it is challenging to satisfy both of them at the same time. In this article, the optimal carrier-based pulsewidth modulation (CBPWM) strategies are proposed to address the above problems. By analyzing the effects of three different zero-sequence voltages on the midpoint voltage of the voltage-divider capacitor, two optimized CBPWM strategies based on the injection of different zero-sequence voltages are proposed, which can effectively improve the dc bus voltage utilization. Based on the above different zero-sequence voltages injection strategies, the capacitor voltage balancing method is proposed to control the average midpoint current, which can realize the capacitor voltage balance within different modulation ranges of two sets of outputs. Finally, the effectiveness of the proposed modulation strategy is verified through experiments.

As an advanced power electronic topology, the three-level dual output converter combines three-level technology with dual output characteristics, which has significant advantages in industrial, energy and transportation applications. Achieving capacitor voltage balance and improving dc bus voltage utilization are the key technologies in the application of three-level dual output converter, but it is challenging to satisfy both of them at the same time. In this paper, the optimal carrier-based pulse width modulation (CBPWM) strategies are proposed to address the above problems. By analyzing the effects of three different zero-sequence voltages on the midpoint voltage of the voltage-divider capacitor, two optimized CBPWM strategies based on the injection of different zero-sequence voltages are proposed, which can effectively improve the dc bus voltage utilization. Based on the above different zero-sequence voltages injection strategies, the capacitor voltage balancing method is proposed to control the average midpoint current, which can realize the capacitor voltage balance within different modulation ranges of two sets of outputs. Finally, the effectiveness of the proposed modulation strategy is verified through experiments.

Most bidirectional isolated DC-AC converters belong to a two-stage structure, which suffers from a degraded efficiency and reliability due to the presence of intermediate-link electrolytic capacitors. In this paper, a bidirectional single-stage DC-AC converter with soft-switching characteristics is proposed. The converter eliminates the need for an intermediate-link capacitor, and enables direct power conversion using a simple modulation scheme that is easy to implement in practice. The paper begins with a description of the converter topology, followed by an explanation of the proposed modulation scheme. Furthermore, detailed discussions of the operating principles and soft-switching conditions are provided. Finally, a 1.5 kW experimental prototype is established to validate the correctness and effectiveness of the proposed topology.