With the development and application of large-scale renewable energy sources, the electric power grid is becoming huge and complicated; one of the most concerning problems is how to ensure coordination between a large number of varied controllers. Differential games theory is used to solve the problem of collaborative control. However, it is difficult to solve the differential game problem with constraints by using conventional algorithm. Furthermore, simulation models established by existing research are almost linear, which is not conducive to practical engineering application. To solve the above problem, we propose a co-evolutionary algorithm based on the improved weighted fruit fly optimization algorithm (IWFOA) to solve a multi-area frequency collaborative control model with non-linear constraints. Simulation results show that the control strategy can achieve system control targets, and fully utilize the various characteristics of each generator to balance the interests of different areas. Compared with a co-evolutionary genetic algorithm and a collaborative multi-objective particle swarm optimization algorithm, the co-evolutionary algorithm based on the IWFOA has a better suppression effect on the frequency deviation and tie-line power deviation caused by the disturbance and has a shorter adjustment time.

In this work, the adsorption and sensing behavior of Ag-doped MoSe₂/ZnO heterojunctions for H₂, CH₄, CO₂, NO, CO, and C₂H₄ have been studied based on density functional theory (DFT). In gas adsorption analysis, the adsorption energy, adsorption distance, transfer charge, total electron density, density of states (DOS), energy band structure, frontier molecular orbital, and work function (WF) of each gas has been calculated. Furthermore, the reusability and stability of the Ag-doped MoSe₂/ZnO heterojunctions have also been studied. The results showed that Ag-doped MoSe₂/ZnO heterojunctions have great potential to be a candidate of highly selective and responsive gas sensors for NO detection with excellent reusability and stability.

SF ₆ has been recognized worldwide as the main insulating gas for Gas‐Insulated Switchgear (GIS). It is often required to accurately and effectively detect typical SF ₆ decomposition. In this paper, a sub‐ppm‐level SO ₂ F ₂ and SOF ₂ gas sensor based on photoacoustic spectroscopy (PAS) is proposed and demonstrated. The steel resonant photoacoustic cell with a resonant frequency of 1750 Hz was designed and fabricated. The harmonic detection technique in wavelength modulation spectroscopy was applied to improve the signal‐to‐noise ratio. A mercury‐cadmium‐telluride photodetector was added in the PAS system to monitor the input optical power, in order to compensate for the errors caused by power fluctuations. SO ₂ F ₂ and SOF ₂ were measured by using distributed feedback quantum cascade lasers at 6648 and 7463 nm, respectively. The results show that the proposed sensor performed with favourable linearity within the dynamic range, and reached the minimum detection limit of 0.22 ppm for SO ₂ F ₂ and 0.28 ppm for SOF ₂ , which indicated its great potential for monitoring the decomposition process of SF ₆ in GIS.

SO₂F₂ and SOF₂ are the main components from the decomposition of insulation gas SF₆. Photoacoustic spectroscopy (PAS) has been acknowledged as an accurate sensing technique. Polar material adsorption for SO₂F₂ and SOF₂ in the photoacoustic gas cell of PAS may affect detection efficiency. In this paper, the optical gas-cell dynamic adsorptions of four different materials and the detection effects on SO₂F₂ and SOF₂ are theoretically analyzed and experimentally demonstrated. The materials, including grade 304 stainless steel (SUS304), grade 6061 aluminum alloy (Al6061), polyvinylidene difluoride (PVDC), and polytetrafluoroethylene (PTFE), were applied inside the optical gas cell. The results show that, compared with metallic SUS304 and Al6061, plastic PVDC and PTFE would reduce the gas adsorption of SO₂F₂ and SOF₂ by 10 to 20% and shorten the response time during gas exchange. The complete gas defusing period in the experiment was about 30 s. The maximum variations of the 90% rising time between the different adsorption materials were approximately 3 s for SO₂F₂ and 6 s for SOF₂, while the generated photoacoustic magnitudes were identical. This paper explored the material selection for PAS-based gas sensing in practical applications.

As renewable energy sources connecting to power systems continue to improve and new-type loads, such as electric vehicles, grow rapidly, direct current (DC) microgrids are attracting great attention in distribution networks. In order to satisfy the voltage stability requirements of island DC microgrids, the problem of inaccurate load power dispatch caused by line resistance must be solved and the defects of centralized communication and control must be overcome. A hierarchical, coordinated, multiple-mode control strategy based on the switch of different operation modes is proposed in this paper and a three-layer control structure is designed for the control strategy. Based on conventional droop control, a current-sharing layer and a multi-mode switching layer are used to ensure the stable operation of the DC microgrid. Accurate load power dispatch is satisfied using a difference discrete consensus algorithm. Furthermore, virtual bus voltage information is applied to guarantee smooth switching between various modes, which safeguards voltage stability. Simulation verification is carried out for the proposed control strategy by power systems computer aided design/electromagnetic transients including DC (PSCAD/EMTDC). The results indicate that the proposed control strategy guarantees the voltage stability of island DC microgrids and accurate load power dispatch under different operation modes.

SF₆ is a strong greenhouse effect gas, which is widely used in high-voltage electrical equipment such as circuit breakers and high-voltage switchgear because of its excellent insulation performance and arc extinguishing ability. In recent years, the use and emission of SF₆ have been rising, and with the proposal of the dual carbon strategic goal, its harmless degradation has become an urgent problem to be solved. In this paper, SF₆ was degraded by pulsed DBD plasma technology and O₂. Studies have shown that the addition of O₂ can effectively promote the degradation of SF₆. With the increase in the added O₂ content, the DRE and EY of SF₆ first increased and then decreased. Under the conditions of the input power of 50 W, SF₆ concentration of 2%, and gas flow rate of 50 mL/min, the reaction system obtained the highest DRE and EY of 58.40% and 5.24 g/kWh when the O₂ content was 1%, respectively. In the SF₆/Ar/O₂/H₂O system, the addition of H₂O could improve the product selectivity of SO₂F₂, and when the O₂ concentration was 1%, the highest selectivity of SO₂F₂ was 48.96%, and the concentration was 8006.76 ppm. The addition of O₂ inhibited the production of SO₂, and with the addition of the O₂ system, SO₂F₂ and SOF₄ were the main components of degradation products; however, there were also SOF₂, SO₂, SiF_4, SF₄, etc. In this paper, the decomposition path of O₂ under SF₆ was analyzed in detail according to infrared spectroscopy and decomposition products.