Power Automation Equipment•2026•DOI: 10.16081/j.epae.202606020
The escalating 'double-high' penetration of power electronics in new-type power systems has rendered conventional electromechanical transient small-signal stability analysis inadequate, necessitating electromagnetic transient (EMT) small-signal stability assessment. Eigenvalue analysis, grounded in rigorous theoretical foundations, is widely applied but faces two critical bottlenecks when scaled to large systems: the construction of EMT linearized state-space equations and the solution of high-order state-matrix eigenvalues. This review examines the urgent demand for EMT model eigenvalue analysis in large-scale new-type power systems. It systematically surveys research status and challenges across three domains: equilibrium-point modeling of EMT models, linearized state-space modeling, and efficient computation of critical eigenvalues. For equilibrium-point modeling, the paper evaluates Park transformation, double Park transformation, shifted frequency analysis (SFA), time-scale transformation, and Floquet-theory-based trajectory linearization. For linearized state-space modeling, it assesses component-level and network-level linearization strategies. For eigenvalue computation, it reviews partial eigenvalue algorithms, sparse matrix techniques, and model-order reduction methods. Key challenges include the inability of Park transformation to handle asymmetric or single-phase systems, the computational burden of Floquet transition matrix eigendecomposition, and the poor scalability of dense eigenvalue solvers for systems exceeding thousands of states. The paper concludes by identifying future research directions, including structure-preserving linearization, GPU-accelerated sparse eigenvalue algorithms, and data-driven model reduction, to enable practical EMT small-signal stability analysis for systems with 18.4 billion kW of installed renewable capacity by 2030.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202507094
To address land waste and poor bearing capacity from sludge landfill, this study developed a composite solidifying agent using loess, fly ash, desulfurized gypsum, and cement. Orthogonal experiments combined strength testing, SEM/XRD microanalysis, permeability and heavy metal leaching tests, and cost accounting. Results show that cement significantly enhances early and mid-term strength, while loess dominates later strength development. Optimal fly ash and desulfurized gypsum content is 12% each. The optimal mix ratio (loess:fly ash:desulfurized gypsum:cement:sludge) is 0.1:0.12:0.12:0.08:1. The solidified matrix forms dense structures via C-S-H gel and ettringite (Aft), effectively controlling heavy metal leaching at low cost. This work enables solid waste resource utilization and provides robust support for sludge solidification engineering.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202408057
Urban waterlogging, exacerbated by climate change and rapid urbanization, poses increasing risks, particularly in coastal low-lying areas with dense river networks. This study simulated waterlogging in the Shajing River drainage area of the Maozhou River basin, Shenzhen, using the SOBEK hydrodynamic model. Under a 5-year return period rainfall, 47 manholes overflowed and 31.29% of stormwater pipes operated at full capacity. Twelve waterlogging-prone points were identified: eight due to insufficient drainage capacity and five due to river backflow from low elevation. Two optimization schemes were compared: enlarging pipe diameters and implementing Low Impact Development (LID) measures. Pipe enlargement reduced overflowing manholes by 32 and full-flow pipe length by 20%, effectively decreasing surface ponding. LID measures reduced overflowing manholes by only 4 and full-flow pipe length by 1.5%, but decreased maximum flooding depth by nearly 1 m, alleviating drainage system burden. The study highlights the complex causes of coastal urban waterlogging, especially river backflow under tidal influence, and recommends considering sea-level rise and storm surge in drainage design. The findings provide valuable references for attributing waterlogging causes and planning drainage network upgrades in coastal cities.