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To study the impact of faults on the enrichment and mobility of shale oil in the Gulong area, representative rock samples were selected in this paper. Based on geochemical data and chemical kinetics methods, coupled with shale oil enrichment and mobility analysis techniques, the shale oil generation quantity and in situ oil content were evaluated from the perspectives of shale oil generation and micro migration, and the mobility of shale oil was revealed. At the same time, the hydrocarbon expulsion efficiency (HEE) of shale was qualitatively and quantitatively characterized, combined with the development of faults. The research results indicate that the study area mainly develops organic-rich felsic (ORF)/organic-containing felsic (OCF) shale, their proportion in both wells exceeds 65%, and the resource amount is the largest in this type of lithofacies. The development of a fault controls the enrichment of shale oil, and the in situ oil content and oil saturation index (OSI) of the shale in well Y58, which is close to the fault, are significantly worse than those in well S2. Well Y58 has 9.52 mg/g and 424.83 mg/g TOC respectively, while well S2 has 11.34 mg/g and 488.73 mg/g TOC respectively. The fault enhanced the migration of shale oil, increasing the efficiency of oil expulsion. As a result, the components with weak polarity or small molecules, such as saturated hydrocarbons and low carbon number n-alkanes, are prone to migration, reducing the mobility of shale oil.

Hydrothermal activity is widespread in sedimentary basins, but its dual effects (chemistry and temperature) on shale reservoirs are rarely discussed. In this research, we systematically collected 33 well core samples from Q1 to Q9 units in Gulong Sag, Songliao Basin, and analyzed them using a variety of analytical techniques, including a field emission scanning electron microscopy (FE-SEM), an energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), and stable C-O isotopes. Combined with the collected vitrinite reflectance (Ro), total organic carbon (TOC), and soluble hydrocarbon content data, which is the sum of free oil (pyrolysis S1) and sorb oil content (pyrolysis S2), the results show that (1) Q4 and Q8 units have large amounts of hydrothermal minerals, and its C-O isotope obviously shifts to negative, which implied those units are the main hydrothermal fluid influence area; (2) the hydrothermal activity occurred in the late depositional period of Q1–Q9 units such that its geochemistry has little effect on the proliferation of algae blooms, but its high temperature calculated by δ18O temperature formulas (around 208 °C) promoted the organic matter maturation process around Q4 and Q8; and (3) the overpressure caused by hydrothermal activity protected the shale reservoir and minimized the decrease in mineral reservoir brittleness index caused by hydrothermal fluid influence. We suggest that the shale reservoir affected by hydrothermal fluid will become a good geology “dessert”, and its upper and/or lower bounds can form an engineering “dessert” due to the precipitation of large amounts of brittle carbonate minerals.

With the increasing participation of wind generation in the power system, a wind power plant (WPP) with an energy storage system (ESS) has become one of the options available for a black-start power source. In this article, a method for the energy storage configuration used for black-start is proposed. First, the energy storage capacity for starting a single turbine was determined. Then, a hierarchical planning model was established. This model did not consider the starting efficiency of the WPP, but it did consider the layout of the energy storage in the WPP and the balance of the terminal voltage when starting the WPP. Finally, the feasibility and value of the proposed method and model were verified in a 49.5 MW WPP with an ESS (a power rating of 2.24 MW and energy capacity of about 1.68 MWh). The result suggests that configuring an ESS with a small capacity on the side of the turbine can achieve black-start for a WPP with an ESS as the power source.

Large scale wind power integration has a negative influence on the frequency response. Assistant measurement improves the frequency stability of power systems under high wind penetration. The Proportional Curtailment Strategy (PCS) for wind turbines provides a primary frequency reserve for power systems. To solve the worthless curtailed wind power, the PCS is used to improve the utilization of wind power curtailment. Then the wind turbine and the lithium battery Energy Storage System (ESS) provide primary frequency reserves together. Different control strategies of ESS have been proposed based on the different methods for selecting valid reserves. The economic benefits of different control strategies have been compared based on the same frequency regulation reserve. The optimal control strategy is the maximum method. The economic benefit of the maximum value method is ¥4,445,300.

In this paper we described the structure and working principle of an interruption generator based on voltage source converters (VSCs). The main circuit parameters of the VSCs are determined according to the target of power transfer capability, harmonic suppression, and dynamic response capability. A state feedback linearization method in nonlinear differential geometry theory was used for dq axis current decoupling, based on the mathematical model used in the dq coordinate system of VSCs. The direct current control strategy was adopted to achieve the independent regulation of active power and reactive power. The proportional integral (PI) link was used to optimize the dynamic performance of the controller, and PI parameters were adjusted. Disturbance voltage waves were generated by the regular sampling method. PSCAD/EMTDC simulation results and physical prototype experiments showed that the device could generate various disturbance voltage waveforms steadily, and had good dynamic and steady-state performance.

With the advancement of distributed power generation technology and the deepening of the low-carbon transformation of energy structure, a high proportion of renewable energy has become an inevitable trend in future energy systems, especially for microgrids. However, the volatility and uncertainty associated with renewable energy pose significant challenges to the secure and stable operation of power systems, necessitating the exploration of the flexible regulation of resources. Energy storage, as a crucial flexible resource characterized by technological diversity and a variety of regulation capabilities, has been extensively studied and applied. Nonetheless, the high investment costs and limited returns of energy storage technology, coupled with the ambiguous utility in different scenarios under the current electricity market’s framework, complicate its broader application. To thoroughly analyze the utility of energy storage in facilitating flexible adjustments in microgrids, this study developed a composite weight-TODIM (an acronym in Portuguese for interactive and multi-criteria decision making) model for assessing the utility of energy storage that incorporates heterogeneity in the risk preferences. This model enabled a comparative analysis of the utility of energy storage technology across multiple scenarios, taking the risk preferences of decision-makers into account, thereby providing strategic insights for the application of multi-temporal energy storage in microgrids. The feasibility and effectiveness of the model were validated through a case study analysis.

In view of the current situation of the global energy crisis and environmental pollution, the energy industry transition and environmental governance are urgently needed. To deal with the problem above, the construction of a power system dominated by renewable energy (PSDRE) with wind turbine (WT), photovoltaic (PV), biomass power (BP), and other clean, low-carbon, renewable energy sources as the principal part has become a consensus all over the world. However, the random and uncertain power output of renewable energy will not only put pressure on the power system but also lead to the unreasonable and insufficient usage of renewable energy. In this context, the energy storage (ES) effects of flexible resources, such as physical energy storage of batteries and demand response (DR), are analyzed first. Next, a modeling method for the operational characteristics of physical and virtual shared energy storage (PVSES) in regional PSDRE (RPSDRE) is proposed. Finally, an optimal scheduling strategy for RPSDRE that considers PVSES is proposed to achieve coordination of WT, PV, PVSES, and other flexible resources. The case study on RPSDRE in Lankao county, Kaifeng city, Henan province of China verifies the effectiveness and practicability of the proposed strategy.

Solar heating technology has the advantages of being high efficiency, energy-saving, and environment protecting; however, the instability of solar energy and its mismatch with the variation characteristics of building heat load have caused great difficulties in the design and the efficient operation strategy of a solar system. A heat storage tank is an important part of a solar hot water system. In order to improve system efficiency, this paper proposes a flat plate PCM storage tank, establishes a mathematical model, and conducts experimental verification under different working conditions. Experiments show that in the heat storage process, the phase change material (PCM) only accounts for less than 20% of the space of the PCM storage tank, and its heat storage can reach 50% of the total heat storage of the tank. In the discharge process, the water temperature of the ordinary tank decreases by 20 °C within 1.5 h, and the phase change process lasts approximately 3 h, with the water temperature remaining at 45~50 °C during this period. In the natural cooling process, the heat discharge of the two water tanks at night was similar, while the temperature of the ordinary water tank decreased by 12 °C and that of the phase change water tank decreased by 7 °C. By simulating the dynamic simulation model of the composite solar phase change thermal storage combined with an air-cooled heat pump system, the results show that the solar heating system with a PCM storage tank (SHS-PCM) saves 34% more energy than a solar heating system with a common tank (SHS-without PCM), and the volume of the PCM storage tank is reduced to 1/5 of the ordinary tank. The investment payback period method of energy saving reconstruction is used to analyze the economy of the SHS-PCM and the SHS-without PCM, the initial investment cost of the SHS-PCM is CNY 9858 higher than the SHS-without PCM, but the annual operation cost is saved by CNY 12,100, and the project investment payback period is 0.81 years, which has energy-saving potential and economic benefits.