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Background: Four members of N,N-disulfo-1,1,3,3-tetramethylguanidinium chlorometallates [DSTMG]n[X], where n= 1 or 2; X= FeCl4 -, Zn2Cl6 2-, NiCl4 2-, MnCl4 2- were synthesized as solid Brønsted-Lewis acidic compounds and studied the catalytic activity with the most acidic salt for threecomponent synthesis of 1,2-dihydro-1-aryl-3H-naphth[1,2-e][1,3]oxazin-3-ones. Methods: N,N-disulfo-1,1,3,3-tetramethylguanidinium chlorometallates of the four transition metal cations such as Fe(III), Zn(II), Ni(II) and Mn(II) were prepared after treatment of the parent ionic liquid N,N-disulfo-1,1,3,3-tetramethylguanidinium chloride [DSTMG][Cl] with the respective metal chlorides in different mole fractions at 75 ºC. The synthesis of 1,2-dihydro-1-aryl-3H-naphth[1,2- e][1,3]oxazin-3-ones was carried out via three-component reaction of 2-naphthol, aromatic aldehydes and urea under neat condition at 90 ºC using 7 mol% of the [DSTMG][FeCl4] catalyst. Results: The characterization of synthesized chlorometallates was done using spectroscopic and other analytical techniques, including thermogravimetric analysis and Hammett acidity studies. Among the four salts, the salt of Fe(III) ion was observed as the strong Brønsted acidic hydrophobic salt and thus chosen for the catalytic study. Conclusion: A new type of chlorometallates of guanidinium cation with composition [DSTMG]n[X], where X= FeCl4-/Zn2Cl6 2-/NiCl4 2-/MnCl4 2- and n= 1 or 2 were developed as –SO3H functionalized solid acids with varied thermal stability (150-250 ºC) and physisorbed water (0-20%) as observed from the thermogravimetric study. From them, the most Brønsted acidic Fe(III) salt was employed as an efficient recyclable heterogeneous catalyst for the one-pot synthesis of 1,2-dihydro-1-aryl-3Hnaphth[ 1,2-e][1,3]oxazin-3-ones in neat condition.

Background: The Remote Terminal Units (RTUs) in the Distribution Automation System (DAS) are widely used in the field in recent years. It is lack of sample data in different operation status that makes the RTU maintenance improper. The weight allocation for the monitoring indicators in the health status evaluation needs to be identified efficiently and properly. Methods: A systematic health status assessment indicator system is constructed firstly. Then, a hybrid indicator weight allocation algorithm based on the Attribute Hierarchy Model (AHM) and grey relational degree (GRA) is proposed to identify the elementary item in the weight allocation under small sample condition. The final indicator weight would be dynamically adjusted according to the equilibrium coefficient, which is determined by the indicator condition parameter. Results: The simulation results show that the weight allocation can be effectively and reasonably adjusted according to the indicator value even under small sample condition. Conclusion: The expert experience and objective data laws are combined and used in our proposed dynamic weight allocation method. It can be used to assess the health status of RTU in the electrical power distribution network.

The main shortcomings of the software-based power engineering education are a lack of physical understanding of phenomena and hands-on experience. Existing scaled-down analogous educational power system platforms cannot be widely used for experiments in universities due to the high cost, complicated operation, and huge size. An integrated power distribution system laboratory platform (PDSLP) using modular miniature physical elements is proposed in this paper. The printed circuit board (PCB) and microelectronic technology are proposed to construct each physical element. Furthermore, the constructed physical elements are used to set up an integrated PDSLP based on modular assembly technology. The size of the proposed cost-efficient PDSLP is significantly reduced, and the reliability of the proposed PDSLP can be improved greatly because the signal transmission path is shortened and a number of welding points are reduced. A PDSLP for fault location in neutral non-effectively grounded distribution systems (NGDSs) is selected as a typical experimental scenario and one scaled-down distribution network with three feeders is subsequently implemented and discussed. The measured zero-sequence currents by our proposed PDSLP when a single-phase earth fault occurred can reveal the true features of the fault-generated signals, including steady-state and transient characteristics of zero-sequence currents. They can be readily observed and used for students to design corresponding fault location algorithms. Modular renewable energy sources and other elements can be designed, implemented and integrated into the proposed platform for the laboratory education of the active distribution networks in the future.

Traditional communication technologies based on 2G and 4G cannot meet the requirements of low-power wide-area data transmission in electricity distribution network. Ubiquitous power Internet of things (UPIoT) has thus been proposed by the State Grid of China and it can be used to transmit energy information requested from any location. Narrowband Internet of things (NB-IoT) and LoRa are two promising low-power wide-area communication technologies, which are capable of providing good performance to transmit data collected from the devices installed in the distribution network. In this paper, taking the fault indicator as an example, we combine LoRa and NB-IoT to construct a wireless network to transmit the operation status of fault indicator, which can improve the transmission distance and reduce the operating cost of the system. It adopts a communication mode including a master node and a plurality of child nodes to meet the needs of large-scale information monitoring. Among them, the design of the master node uses NB-IoT and LoRa communication technologies. The design of the child node uses LoRa communication technology and sensor technology. The control chip STM32F103C8T6 is used for data transmission, and the data is finally managed by a centralized means through upper computer software.