High Power Transmission Research Articles

Power Grid Reliability Estimation via Adaptive Importance Sampling

Electricity production currently generates approximately 25% of greenhouse gas emissions in the USA. Thus, increasing the amount of renewable energy is a key step to carbon neutrality. However, integrating a large amount of fluctuating renewable generation is a significant challenge for power grid operating and planning. Grid reliability, i.e., an ability to meet operational constraints under power fluctuations, is probably the most important of them. In this letter, we propose computationally efficient and accurate methods to estimate the probability of line overflow, i.e., reliability constraints violation, under a known distribution of renewable energy generation. To this end, we investigate an importance sampling approach, a flexible extension of Monte-Carlo methods, which adaptively changes the sampling distribution to generate more samples near the reliability boundary. The approach allows to estimate overload probability in real-time based only on a few dozens of random samples, compared to thousands required by the plain Monte-Carlo. Our study focuses on high voltage direct current power transmission grids with linear reliability constraints on power injections and line currents. We propose a novel theoretically justified physics-informed adaptive importance sampling algorithm and compare its performance to state-of-the-art methods on multiple IEEE power grid test cases.

Wireless Energy Transmission System for Capsule Endoscopy Based on Image Processing Technology

The current capsule endoscopy power supply generally uses a battery, which has security risks and will affect the efficiency of capsule endoscopy to a large extent. Therefore, this paper constructs a wireless energy transmission system for capsule endoscopy based on high power and low loss transmission of image processing technology. By improving the merging mode of image processing, image processing is combined with wireless transmission to achieve efficient image processing in wireless transmission. Given the two-dimensional structure of the image, this paper also configures the block in the kernel as a two-dimensional structure. To obtain the best energy transfer performance, this paper tests all the possible combinations of the two dimensions. Then point-to-point high-frequency mode is used for inductive transmission of energy. Research shows that the wireless energy transmission system based on image processing technology can transmit energy in the frequency of 50 Hz-60 Hz, the loss rate is between 11% - 19%, and the overall efficiency has small fluctuations in different modes. Compared with wired power transmission, this system has only a small loss increase, but its efficiency is more than 30% higher than that of battery. And after 100 groups of image testing, this system takes a short time and can meet the wireless power transmission effect of capsule endoscopy.

Preparation and mode conversion application of narrowband hollow-core anti-resonant fiber

Owing to the unique characteristics of the hollow core fiber(HCF), more and more researchers pay attention to its application. Because the mode field is mainly limited to the core region of the fiber, which results in low non-linearity, ultra-low group velocity dispersion, low temperature sensitivity, and high material damage threshold. Based on the above, the HCF possesses some attractive nonlinear applications such as in transmission of high-power laser beams, sensing, ultra-wide band low-loss transmission, pulse compression and super-continuum generation. Besides, the HCFs can be further divided into the transmitting band-gap photonic crystal fiber(PBG-PCF) and the hollow-core anti-resonant fiber(HC-ARF). Compared with the PBG-PCF, the latter has wide light guiding characteristics caused by leaking modes. According to the research in the recent year, the HC-ARF has gradually approached to the performance of the PBG-PCF in its transmission loss, showing that it has potential applications in communications, sensing, aerospace, high-power laser transmission and other fields in the future. In addition, the HC-ARF with the special light-guiding properties has also become the important photonic device in the fields of fiber filters, mode conversion, etc. In this paper, a hollow-core anti-resonance fiber is studied and its light transmission performance in the spectral range of 500–1500 nm is verified. The optical loss measured at 980 nm wavelength is about 0.32 dB/m. It is found that a 980 nm multi-mode laser beam can be converted into a single-mode one after transmitting through the hollow core fiber we designed.

Examination of long-distance high-power microwave power transmission system

Examination of long-distance high-power microwave power transmission system

Experimental Verification of Multipactor Suppression in Microstripline Using High Porosity Surfaces

We report computational and experimental research results confirming that surfaces with porosity exceeding a certain threshold will fully suppress multipactor in parallel-plate microstripline structures, while negligibly perturbing the RF transmission properties. Our research also identified a practical arrangement of nonuniform pores that provided the required high-porosity for multipactor suppression, but with enhanced mechanical rigidity. This alternative layout facilitates the fabrication process using commercially-available manufacturing methods. Porous, multipactor-resistant surfaces can be used in a wide range of high-power components including high-power microwave sources, antennas, filters, and transmission lines (TLs).

Research on Preparation and Mode Conversion Application of Narrowband Hollow-core Anti-resonant Fiber

Due to the unique characteristics of the hollow core fiber(HCF), more and more researchers pay attention to its application. Because the mode field is mainly limited to the core region of the fiber, which results in low non-linearity, ultra-low group velocity dispersion, low temperature sensitivity, and high material damage threshold. Based on above, there are some attractive nonlinear applications of the HCF, such as transmission of high-power laser beams, sensing, ultra-wide band low-loss transmission, pulse compression and super-continuum generation. Besides, the HCF can be further divided into the transmitting band-gap photonic crystal fiber(PBG-PCF) and the hollow-core anti-resonant fiber(HC-ARF). Compared with the PBG-PCF, the latter has wider light guiding characteristics caused by leaking modes. According to the research in the recent year, the HC-ARF has gradually approached the performance of the PBG-PCF in its transmission loss which shows that it has potential applications of communications, sensing, aerospace, high-power laser transmission and other fields in the future. In addition, the HC-ARF with the special light-guiding properties has also become the important photonic devices in the fields of fiber filters, mode conversion, etc. In this paper, a hollow-core anti-resonance fiber is studied and its light transmission performance in the spectral range of 500 ~ 1500 nm is verified. The optical loss measured at 980 nm wavelength is about 0.32 db/m. It is founded that a 980nm multi-mode laser beam can be converted into a singe-mode one after transmitting through the hollow core fiber we designed.

Investigations on noise emission from functionally graded materials based polymer spur gears

There is tremendous growth in the polymer gearing field. Polymer gears have replaced the metal gears in various fields. Polymer gears are now used for low, medium, and even for high power transmission systems, especially in automotive engineering. Noise emission from polymer gears is much less than metal gears in an application. In the present work, homogeneous and functionally graded materials (FGMs) gears are fabricated by glass fiber reinforced high-density polyethylene (HDPE) material via traditional and centrifugal casting techniques, respectively. Gears are manufactured by HDPE granules reinforced with fifteen weight percent and thirty weight percent of glass fibers. The focus of this experimental study is to examine the noise generation from the fabricated gears during the operation. Fabricated gears are run for 2 lakh cycles at different speeds and torque. The value of torque and speed are chosen within the range of 0.8–2.6 Nm and 500–1400 rpm, respectively. Experiments are performed on the polymer gear test rig. Noise emission from fabricated polymer gears is investigated for various running combinations of torque and speed.

Exciting Circular TM11 Mode Using Symmetric Probes Based on Ridge Gap Waveguide

This article proposes a method to excite the TM $_{11}$ mode in circular waveguides. The principle of synthesizing a circular TM mode is deduced based on the electric dipole moment theory first, and the output mode and its purity are analyzed theoretically. Then, a mode conversion scheme to convert the rectangular TE $_{10}$ into circular TM $_{11}$ mode via a pair of out-of-phase quasi-TEM mode is proposed. In order to achieve the broadband excitation in a compact size, the ridge gap waveguide is used as a medium between the rectangular and cylindrical waveguide. Simulation results present that the proposed exciter has a propagation bandwidth up to 10 GHz in Ka-band with a mode purity over 98%. A prototype is manufactured and measured, and the presence of TM $_{11}$ mode and the mode purity are confirmed by a port radiation pattern measurement. The mode exciter features high mode purity, broad bandwidth, and a compact size, which provides a low-power generator for the research of novel gyrobackward-wave devices and devices in the high-power transmission line.

ANALISIS MOTIVASI PETUGAS KESEHATAN TERHADAP PENANGGULANGAN COVID-19 DI PUSKESMAS JAKABARING

A study on work motivation needs to be carried out because during the Covid-19 pandemic it takes work encouragement from health workers so that they can work optimally so that the role of puskesmas during the Covid-19 pandemic can be optimal. The high transmission power of this disease causes health workers, especially in health centers to be vulnerable to this disease. The purpose of this study was to find out the analysis of the work motivation of health workers against Covid-19 at the Jakabaring Health Center, Banyuasin Regency. The method in this research is this research is quantitative research and the approach used in this research is descriptive analytical approach, on the grounds that this research uses numbers or calculations in data collection and provides an overview of the object under study through sample or population data as existence. The research design used Cross Sectional. The results showed that working conditions (p=0.001), interpersonal relationships (p=0.004) and the responsibility of health workers (p=0.007). ada hubungan antara kondisi kerja, hubungan interpersonal, dan tanggung jawab terhadap penanggulangan covid-19. It is recommended that the Puskesmas which is the front line, is expected to be able to maintain and create working conditions and interpersonal relationships between subordinates and superiors by means of regular meetings, such as scientific meetings. So that effective communication can be established in solving patient health problems

PERFORMANCE INDICATORS OF CONCHOIDAL STRAIGHT SPUR GEARS WITH INCREASED LOADING CAPACITY. THE THEORY

The article is devoted to the actual problem of increasing the performance indicators of machine gear drives. To solve this problem, in the article proposed to use a conchoidal engagement made with a shifting of the reference profile and special contact conditions. A feature of the proposed engagement is that it is less sensitive to manufacturing and assembly errors compared to conventional conchoidal engagement. As a result of theoretical studies, the performance indicators of such an engagement were determined. This made it possible to determine the level of load during further experimental tests of new gears. Contact strength and meshing losses were selected as performance indicators subject to further experimental verification. The ratios of these indicators, calculated for conchoidal spur gears with convex-convex contact, made with a shifting of the reference profile, with similar involute ones, are theoretically determined. Comparative analysis of performance indicators was carried out for gears of involute and conchoidal engagement with the same parameters and shifting of the reference profile. It was found that for experimental conchoidal drives with shifting, the maximum load is 1.2 times higher than that of a similar involute drive with shifting, and the loss in engagement is 21% less. A rational area of application of the new gearing is machine drives for high power transmissions.
 Keywords: spur gears, conchoidal gearing, profile shift, convex-convex contact, meshing characteristics, teeth surface strength, gearing power loss

Optimization for Compact and High Output LED-Based Optical Wireless Power Transmission System

Optical wireless power transmission (OWPT) is a technology that supplies energy remotely. Due to the great advantages of long transmission distances, high directionality, no electromagnetic interference noise, and loose safety regulations, light emitting diode (LED) based OWPT systems become appropriate candidates for powering various applications, especially for the Internet of things (IoT). In this paper, improved LED-OWPT systems are proposed based on a collimation scheme for optimizing the system dimension and output. In a single LED configuration, the system dimension is compressed by 46% while the high transmission efficiency is maintained. As for the LED-array system, the dimension is compressed by 56%, and the output is enhanced by 40%. In the experiment, a high electricity output of 532 mW is achieved at 1 m transmission distance. In addition, the effect of misalignment between LED and lens and the potential of long-distance transmission are clarified in the LED-array OWPT system.

Unlocking the Hidden Dimension of the World’s Transmission and Distribution Power Losses through Fractal Statistical Inference

Various studies on the transmission and distribution power losses had been conducted but a global view of the transmission and distribution power loss rates had not been explored yet. This paper explained the fractal dimension of the global distribution and transmission power losses using fractal statistical analysis. Findings revealed that the computed fractal dimension of 1.08 means that power losses of countries across the globe deviated from uniformity by about 8 percent. The upper and bottom eight (8) percent of the dataset were analyzed and findings revealed that the ruggedness of the phenomenon was attributable to political and economic dimensions. The extreme high distribution and transmission power losses may be traced back to chaos, pilferage, and substandard materials. On the other hand, the economic stability and state control capacity contributed much to the extreme low distribution and transmission power losses. Keywords: fractal analysis, power loss, power transmission and distribution, xfractal.

Design and Implementation of High Directivity Directional Coupler at VHF Band Using Grounding Composed of Strip Lines Technics

This paper proposes a design of high directivity directional coupler (D.C) based on grounding composed of strip lines for high power Radar transmitter at Very High Frequency (VHF), (150 – 200 MHz). The directional coupler is used to check and verify the transmitter output high power, frequency, and reflected signal from an antenna connected with the Radar transmitter. The performance requirements of directional couplers are a strong coupling to reduce the effect on the transmitted output power and high directivity to suppress the interference of the reflected signal from the antenna. So far, various architectures have been proposed to gain high directivity, and there have been many studies used to obtain a strong coupling and higher directivity. However, the conventional architecture of the directional coupler has a directivity of only about 20 dB, and there have been difficulties to achieve the higher directivity of more than 20 dB. In this paper, the proposed architecture of directional coupler based on grounding composed of strip lines is discussed and compares the test results of the proposed directional coupler with the conventional one. The high directivity directional coupler is designed using a computer-aided design Simulation program; Advance Design System (ADS 2016), using Rogers 4003 substrate. The directional coupler was fabricated on printed circuit board (PCB) technology and measured using a vector network analyzer (VNA). The results show that the proposed directional coupler has directivity between -25 to -24 dB inside the working bandwidth and is adequate for a high-power radar transmitter.

A CASE STUDY OF ELECTROMAGNETIC EXPOSURE FOR HIGH TENSION POWER LINES AND TRANSFORMER WITH AND WITHOUT BASE STATION ANTENNA

With the fast growth of electric activity and the spreading out of town scale, our lives are approached by extremely high voltage power transmission lines. And with the expansion of ultra-high voltage power transmission line, the ultra-high voltage transformer substation will come out in the place with intense inhabitants and the electromagnetic exposure of this transmission and transformer apparatus and its contamination to the inhabitants stimulate the immense anxiety from the civilization. This paper deals with electromagnetic radiation of extremely high voltage power transmission line. Here we have observed the electric and magnetic field beneath the transmission line by the process of equivalent charges and put forward the anticipation rule to the electromagnetic radiation in the engineering of extremely high voltage power dissemination and remodeling. Recognition the safe distance from the EMF produced from the high-tension overhead power lines in the locality of the precise region is the detailed goal of this study. The high-tension transmission lines generated EMF that bounded the projected site has to be underneath 0.2 µT. The safety approval distance has been allotted as 200 m from the active 300-KV high-tension power line.

Optimum energy harvesting model for bidirectional cognitive radio networks

Wireless devices’ energy efficiency and spectrum shortage problem has become a key concern worldwide as the number of wireless devices increases at an unparalleled speed. Wireless energy harvesting technique from traditional radio frequency signals is suitable for extending mobile devices’ battery life. This paper investigates a cognitive radio network model where primary users have their specific licensed band, and secondary users equipped with necessary hardware required for energy harvesting can use the licensed band of the primary user by smart sensing capability. Analytical expressions for considered network metrics, namely data rate, outage probability, and energy efficiency, are derived for uplink and downlink scenarios. In addition, optimal transmission power and energy harvesting power are derived for maximum energy efficiency in downlink and uplink scenarios. Numerical results show that outage probability improves high transmission power in the downlink scenario and high harvested power in the uplink scenario. Finally, the result shows that energy efficiency improves using optimum transmission power and energy harvesting power for downlink and uplink scenarios.

Virtual control method applied to Modular Multilevel Converter

The DC transformer based on the Modular Multilevel Converter (MMC) structure has the advantages of robust scalability, low output voltage harmonic content, easy realization of back-to-back connection, and high power transmission efficiency. It is widely used in DC distribution networks. However, traditional control methods hardly provide inertia for the DC distribution network, thereby reducing the stability of the distribution network when new energy output fluctuations, DC distribution network failures, or other disturbances occur. Aiming at the problem that the DC bus voltage is easily affected by power fluctuations, the paper proposes a virtual inertia control method applied to the DC transformer with MMC structure. Similar to the introduction of virtual synchronous generators in the AC distribution network to enhance the system inertia, the paper designs a control strategy for dynamically adjusting the virtual inertia with a virtual capacitor added, which is based on the traditional two-phase shift control. The paper also presents the calculation method of the virtual capacitance. When the power in the DC microgrid fluctuates significantly, the strategy can effectively enhance the inertia of the DC distribution network and suppress the voltage fluctuation of the DC bus. The paper finally establishes a DC distribution network model with distributed power sources in the PLECS simulation software, and verifies the effectiveness of the control strategy compared with the traditional strategy.

Influence of the geomagnetic field on absorption of radiowaves

Exact solutions of Maxwell's equations and the equation of motion of charged particles under the action of a radio wave (for frequencies exceeding the gyro-frequency) and the Earth's magnetic field shows the occurrence of an oscillating polarization current. Using the example of estimates of the HF radio wave amplitude during the operation of the EISCAT high power transmitter, it is shown that the oscillating polarization current can lead to significant losses of radio wave energy. This current allows us to explain the reasons for the efficiency of the high power transmitter on November 6, 2010 (a strong perturbation of the electron density and temperature was observed) and the absence of the effect on March 4, 2011. In the first case, most of the HF radio wave energy reached the height of the reflection point in the F-layer region, and led to noticeable changes in the electron density and temperature. In the second case, most of the HF radio wave energy losses could occur at altitudes below the F-layer due to the appearance of a significant oscillating polarization current, and therefore the HF radio wave could not have a noticeable effect on the F-layer.

EMI radiation of power transmission lines in Malaysia.

Background: There has been rising concern amongst the public regarding their home's proximity to high tension power transmission lines. The primary cause of fear is the impact of the electromagnetic interference (EMI) radiation on the nearby occupants' health. Despite the presence of national permissible limits of EMI radiation, there is still lack of information with regards to the EMI radiation of the types of power lines configuration in Malaysia. Methods: The electric and magnetic fields of several selected power transmission lines were simulated using the EMFACDC software program from the recommendation ITU-T K.90. Five types of power transmission lines available in Malaysia are considered. Results: It was found that the simulated electric and magnetic field levels at all the power lines' right of way (ROW) boundary complies with the prescribed exposure limit. However, the electromagnetic fields (EMF) level increases significantly as the separation distance is reduced from 30m. For a more conservative approach, the ROW can be set at 30m across all transmission voltage level and corridor area condition. Conclusion: It can be concluded that Malaysia's power transmission lines are within the prescribed exposure limits. To further minimize the electric and magnetic field level, it is recommended that the residential building should be built at least 30 meters away from the power transmission lines, especially for the 275kV double circuit, 275/132kV quadruple circuit, and 500kV double circuit lines.

Problems of sub-THz astronomy, radars and telecommunications: development of equipment and methods

Some original results of development methods and equipment for subterahertz astronomy, radars and telecommunications are presented in this paper. There are problems of extremely low sensitivity of receivers, high power transmitters, atmosphere propagation and development of key solid state components for this band: detectors arrays, cooling systems, antennas and so on.

Research on High-power Transmission Technology of Satellite Borne RF Connector

The reliability of the communication link shall be affected severely due to failure modes such as multipactor, low pressure discharge, and thermal damage that are commonly found in the RF connector when it performs high-power microwave signal transmission in the vacuum environment of outer space. This paper proposes supporting measures in respect of design against multipactor, low pressure discharge and thermal damage after analyzing mechanisms of failure modes of the RF connectors when it transmits high-power microwave signals in a vacuum environment. Upon tests, these proposed measures can effectively guarantee the reliability of the RF coaxial connector transmitting high-power signals in vacuum.