Enhanced Power Supply Research Articles

Cable Incipient Fault Identification Method Using Power Disturbance Waveform Feature Learning

Cable incipient fault (CIF) is a potential fault which may recur over time and evolve into permanent fault eventually. The identification of CIF can help to reduce the likelihood of a permanent fault and enhance power supply reliability. This paper fully considers the randomness and uncertainty of CIF waveforms, and proposes a CIF identification method using power disturbance waveform feature learning. Firstly, the shallow features are extracted to characterize the transient components of different disturbance current waveforms, by conducting a stationary wavelet transform. Then, a dropout deep belief network (DDBN) is constructed using the extracted shallow features by pre-training and fine-tuning. Finally, the well- constructed DDBN model is used to identify CIF from other similar disturbance events. The performance of the proposed method is verified by simulation data and experimental data, for different disturbance events, such as sub-cycle cable incipient fault and multi-cycle cable incipient fault, as well as other over-current disturbance events such as capacitor switching and inrush current. Both the accuracy and generalization ability are higher than other methods. The proposed method provides new insights on possible applications on monitoring of cable status and timely warning of cable faults.

Application of the method of dynamic programming for solving the optimal unit commitment problem in distribution networks with local distributed generation

The continuous growth of communities leads to an increase in electrical energy usage. Besides the technological advance of power systems, still, there are outages which lead to an interruption in the power supply. The implementation of distributed generation provides usage of the local renewable energy sources for satisfying local power needs which in good manner complexes the distribution networks. However, because the distributed energy resources depend on the weather conditions, the islanded work is not quite reliable. Grid-connected distributed energy resources have enhanced power supply reliability. In this paper, a dynamic programming model is used for the optimisation of power generation by the local distributed energy resources. Assuming the distributed energy resources have storage systems, the model takes into account the battery charge at the moment and the availability of the distributed energy resources depending on the weather conditions and whether is day or night. It is assumed that the distributed energy resources have equal power capacities. Case study reviews a low voltage distribution network with plenty of distributed energy resources from different renewable energy sources implemented and a cluster of household consumers.

A Low-Dropout Regulator with PSRR Enhancement through Feed-Forward Ripple Cancellation Technique in 65 nm CMOS Process

In this paper, a low-dropout (LDO) regulator with an enhanced power supply rejection ratio (PSRR) is proposed with a feed-forward ripple cancellation technique (FFRC) in 65 nm CMOS technology. This technique significantly improves the PSRR over a wide range of frequencies, compared to a conventional LDO regulator. The LDO regulator provides 35–76.8 dB of PSRR in the range of 1 MHz–1 GHz, which shows up to 30 dB of PSRR improvement, compared with that of the conventional LDO regulator. The implemented LDO regulator has a dropout voltage of 0.22 V and a maximum load current of 20 mA. It can also provide an output voltage of 0.98 V at a range of 1–1.3 V of the input voltage. The load regulation is 2.3 mV/mA while the line regulation is 0.05 V/V. The circuit consumes 385 μA with an input voltage of 1.2 V. The total area without pads is 0.092 mm2.

Ultralow power voltage reference circuit for implantable devices in standard CMOS technology

SummaryAn ultralow power CMOS voltage reference for body implantable devices is presented in this paper. The circuit core consists of only regular threshold voltage PMOS transistors, thus leading to a very reduced output voltage dispersion, defined as σ/μ, and extremely low power consumption. A mathematical model of the generated reference voltage was obtained by solving circuit equations, and its numerical solution has been validated by extensive electrical simulations using a commercial circuit simulator. The proposed solution incorporates a passive RC low‐pass filter, to enhance power supply rejection (PSR) over a wide frequency range, and a speed‐up section, to accelerate the switching‐on of the circuit. The prototype was implemented in 0.18 μm standard CMOS technology and is able to operate with supply voltages ranging from 0.7 to 1.8 V providing a measured output voltage value of 584.2 mV at the target temperature of 36° C. The measured σ/μ dispersion of the reference voltage generated is 0.65% without the need of trimming. At the minimum supply of 0.7 V, the experimental power consumption is 64.5 pW, while the measured PSR is kept below –60 dB from DC up to the MHz frequency range.

A method for choosing the optimal quantity of short-circuit indicating devices to enhance power supply reliability

This article considers a method for solving the problem of choosing the optimal quantity of short-circuit indicating devices for providing a required reliability of the 6(10) kV distribution power grid. Compatibility of the equipment powered was taken into account. An outcome of the problem solution became a mathematical model; an optimization task, limiting and boundary conditions were formulated.

Joint PEV Charging Network and Distributed PV Generation Planning Based on Accelerated Generalized Benders Decomposition

Integration of plug-in electric vehicles (PEVs) with distributed renewable power sources will reduce PEVs’ well-to-wheels greenhouse gas emissions, promote renewable power adoption, and defer power system investments. This paper proposes a multidisciplinary approach to jointly plan PEV charging stations and distributed photovoltaic (PV) power plants on a coupled transportation and power network. We formulate a two-stage stochastic programming model to determine the sites and sizes of: 1) PEV charging stations and 2) PV power plants. This proposed method incorporates comprehensive models of: 1) transportation networks with explicit PEV driving range constraints; 2) PEV charging stations with probabilistic quality of service constraints; 3) PV power generation with reactive power control; and 4) alternating current distribution power flow. The formulation results in a mixed-integer second-order cone program. We then design a generalized Benders decomposition algorithm to efficiently solve it. Numerical experiments show that investing in distributed PV power plants with PEV charging stations has multiple benefits, e.g., reducing social costs, promoting renewable power integration, and alleviating power congestion. The benefits become more prominent when utilizing PV generation with reactive power control, which can also help to enhance power supply quality.

The Utilization of Digital Platforms for Marketing in the Nigerian Entertainment and Media (E&M) Industry: Prospects and Challenges

The National Bureau of Statistics recently announced that the entertainment and media (E&M) industry in Nigeria recorded growth of 1.86% to 12.81%; contributing N54bn to the country’s GDP. The industry’s revenue is projected to reach an estimated $8.5bn in 2018, from $4bn in 2013, with internet as one of the key drivers (PwC report, 2016, p.14). This comes at a time when Nigeria’s economy has shrunk by 2.24% since 2015 and receded by 0.18% from the previous quarter. Therefore, this study unpacks the possibilities and challenges of the impact of e-marketing tools on the growth of the Nigerian E&M industry. E-marketing tools provide “a unique combination of powerful capabilities for marketers” (Parsons et al., 2015). E-marketing suitability for the E&M industry lies in its lower capital demand, and a convenient and online means of disseminating marketing messages across a heterogeneous population at an unlimited geographical space. E-marketing is a reality in Nigeria as a study by Mathew, Ogedebe & Ogedebe (2013, p. 549) shows that “Many Nigerians who used (sic) the internet as one form of communication or another are bombarded daily with advertisements of products and services from industries in the country.” This reality has brought a shift from mechanical to electronic and from analogue to digital; ultimately impacting the marketing realms. The internet enables these electronic/digital platforms; which marketers (E&M industry) and customers (content consumers) rely on to effectively reach and receive communication content and feedback respectively. However, this study examined the challenges that have possibly hindered the full realization of the e-marketing tools of the Nigerian E&M industry and noted among others; poor power supply and unreliable network infrastructure in the country. There is also an increased customer expectation, security, content copyright and privacy issues as well as the challenge of compliance demand in the industry as influenced by ever dynamic digital boundaries. There is a huge economic need for the Nigerian government to live up to its obligation and enhance power supply and boost network infrastructure. The Nigerian E&M industry needs to continually integrate different digital platforms to reach targets and attract more content consumers. Both the government and industry should increasingly learn and bring a global perspective that can help the nation adapt to the constantly changing digital environment.

Метод распознавания тренда графика нагрузки в автоматике отключения силовых трансформаторов

For reducing the technical losses ar ising duetolow loading of transformers, part of them should be disconnected with subsequently transferring the load to the transformers that remained in operation. To avoidexcessive switching operations, achange in the load should be taken into account. Prediction of the load curve trendisatopical issue. However, the known load prediction methods ar enotsuitable for solving the above-mentioned problem be cause they are either not applicable or excessively complex. Indeed, itissufficient to predictjust the load curvetr end to determine whether it will increase or decrease in the nearest hours. Th earticle considers a statistical method based on checking hypotheses for predicting the load curve trend. The developed statistical method for recognizing the load curvetr end features high accuracy and represents an efficient means for reducing losses in a transformer group of step-down substation and for enhancing power supply reliability.

A Metamaterial-Based Energy Harvester Design for Enhanced Power Supply to Wireless Sensor Network

Health sensing module in prognostics and health management (PHM) requires accurate acquisition of sensory signal and optimal deployment of sensor nodes. To this end, wireless sensor network (WSN) is widely utilized by virtue of the ease of the sensor deployments and the advances in the wireless communication. However, periodic replacements of the batteries are demanded for continuous operation of the WSN, which incurs additional costs and temporary suspension. To overcome these drawbacks, vibration energy harvesting (VEH) has emerged as a possible solution to realize self-powered/sustainable WSN operation. The VEH converts ambient vibration into electric power through an energy conversion medium. Low output power density, however, is still a critical issue in the VEH for its feasible application. Metamaterial-based energy harvesting (MBEH) has recently been proposed as a breakthrough technology to drastically improve output power generation. Metamaterials are engineered structures to exhibit exotic properties such as a bandgap. The bandgap refers to a certain frequency range within which elastic waves are prohibited to propagate. It can be used to enlarge elastic wave energy going into the energy conversion medium. While various mechanism for the MBEH has been introduced, only a few research has considered detail factors that can degrade the metamaterial’s performance. In this study, we propose a new phononic crystal design which prevents wave cancellation to improve the metamaterial’s performance. In building the model, the multiphysics finite element method are used to analyze dispersion and energy harvesting performance. Finally, the energy harvesting performance of the proposed design is compared with the design without the consideration of the wave cancellation.

The Effect of Control Measures in the Power Sector Reforms on Electricity Development in Nigeria

This work examined the effect of the control measures available for project evaluation and monitoring in power sector reforms on electricity development in Nigeria. Electric power reforms are necessary for private sector participation in electricity development in Nigeria in order to break monopoly in that sector of the economy. In the course of this study, we employed fairly closed-ended and few open-ended questionnaire as research instrument. Also, data were gotten through personal interview with top management staff of Enugu Electricity Distribution Company (EEDC) at Corporate Headquarters, Enugu. While secondary data were collected from in-house News journal (NEPA Profile), Journal articles, Publications on national Newspapers and Magazines. Data collected from both primary and secondary sources were analysed using the spearman Rank correlation co-efficient, percentages, frequency tables, and Chi-square. We postulated three hypotheses and the results of the test revealed that there is positive and significant relationship between internal control measures in power sector reforms and electricity generation and distribution on one hand and efficient and effective project evaluation and monitoring on another hand. Our finding also revealed that there are internal control measures available for management in the power sector but political office holders normally compel the staff to ignore such control. We therefore recommend that investors should make fund available for generation and distribution companies to enable them complete on-going projects in order to enhance power supply in the country. There should be effective monitoring and evaluation of projects by ensuring that oversight function of the National Assembly is operational without executive interference. Government should not protect any public office holder found diverting project funds. This study contributes to knowledge gap on the challenges of electricity development in Nigeria. It is of worthy to note that electricity is the drivers of all sectors of the economy and as such all users of electricity and government stand to benefit from this work. The importance of the study cannot be over emphasized. We would be able to ascertain from this study the problem associated with electricity development in Nigeria. This study apart from providing solution to power outage that affects the households, the firms and government, would assist further researches in the related areas of the study.

Noise reduction of ultrasonic Doppler velocimetry in liquid metal experiments with high magnetic fields

The last decades have seen a number of liquid metal experiments on the interaction of magnetic fields with the flow of electrically conducting fluids. The opaqueness of liquid metals requires non-optical methods for inferring the velocity structure of the flow. Quite often, such experiments are carried out in the presence of high electrical currents to generate the necessary magnetic fields. Depending on the specific purpose, these currents can reach several kiloamperes. The utilized switching mode power supply can then influence seriously the measurement system by electromagnetic interference. A recent experiment on the azimuthal magnetorotational instability (AMRI) has shown that a hydrodynamically stable Taylor–Couette flow becomes unstable under the influence of a high azimuthal magnetic field. An electrical current along the axis of the experiment with up to 20kA generates the necessary field to destabilize the flow. We present experimental results of this AMRI experiment carried out at the PROMISE facility with an enhanced power supply. For this setup, we discuss the elaborate measures that were needed to obtain a reasonable signal-to-noise ratio of the ultrasonic Doppler velocimetry (UDV) system. In dependence on various parameter variations, some typical features of the observed instability, such as the energy content, the wavelength, and the frequency are analyzed and compared with theoretical predictions.

A Capacitor-less Low Dropout Regulator for Enhanced Power Supply Rejection

Various power supply noise sources in a system integrated circuit degrade the performance of a low dropout (LDO) regulator. In this paper, a capacitor-less low dropout regulator for enhanced power supply rejection is proposed to provide good power supply rejection (PSR) performance. The proposed scheme is implemented by an additional capacitor at a gate node of a pass transistor. Simulation results show that the PSR performance of the proposed LDO regulator depends on the capacitance value at the gate node of the pass transistor, that it can be maximized, and that it outperforms a conventional LDO regulator.

H/V linear regulator with enhanced power supply rejection

H/V linear regulator with enhanced power supply rejection

Power System Security in a Meshed North Sea HVDC Grid

There are very ambitious plans in Europe for changing the energy infrastructure in order to reduce greenhouse gas emissions. This involves scenarios where renewable energy sources by 2050 will meet almost 100% of the electric power demand. This has spurred offshore wind farm development activities in the North Sea due to the vast wind energy potential in this region and the potential lack of suitable onshore sites in the future. Large-scale wind farms in the North Sea pose grid integration challenges such as the need for long-distance subsea power transmission and tackling the impact of wind power variation on alternating current (ac) grids. These challenges can be properly managed by the use of meshed high-voltage direct current (HVDC) grids. Three of the regional groups (RGs) in the European Network of Transmission System Operators for Electricity (ENTSO-E), namely Regional Group Great Britain (RG-GB), Regional Group Nordic (RG-N), and Regional Group Continental Europe (RG-CE), surround the North Sea area. A meshed North Sea HVDC interconnection between offshore wind farms and these three asynchronous ac grids can also enable market integration of the otherwise separate regions. This, in turn, results in better utilization of generation and transmission infrastructures, improved security of power supply, and maximized utilization of renewable energy resources. In this paper, a test scenario of a meshed North Sea HVDC grid is studied to demonstrate the potential of such a system for enhancing power supply security of the ac grids. Simulation studies of the test case show that with proper control techniques, a meshed North Sea HVDC grid can mitigate the effect of wind power variation by facilitating exchange of primary and secondary reserves between asynchronous ac grids.

A 0.38 V near/sub‐ V T digitally controlled low‐dropout regulator with enhanced power supply noise rejection in 90 nm CMOS process

This study describes a 0.38 V digitally controlled low-dropout (LDO) voltage regulator enabling dynamic voltage scaling (DVS) for near/sub-threshold applications. For operating at an ultra-low supply voltage, analogue components are replaced in conventional LDOs with digital counterparts. Especially, a digital reference control that is based on a replica circuit is proposed to improve power supply noise rejection and line regulation of the LDO. The proposed LDO has been designed in a 90 nm regular V T complementary metal oxide semiconductor technology. The LDO can regulate the output voltage from 0.12 to 0.32 V with a supply voltage of 0.38 V. Furthermore, it reaches the current efficiency of 99.3% and the power efficiency of 83.6%, respectively, at a load current of 1 mA. The digitally controllable DVS with 3 mV resolution is achieved.

Technology Planning for Electric Power Supply in Critical Events Considering a Bulk Grid, Backup Power Plants, and Micro-Grids

This paper discusses a risk assessment approach to infrastructure technology planning aimed at improving power supply resiliency to natural disasters or other critical events. Cost as well as power supply availability are both fundamental decision factors considered in the study. The proposed planning process spans three phases during which the critical loads under study are subject to the effects of the extreme event: during the event, the immediate aftermath until potential infrastructure damage is repaired, and the long term aftermath until the load has recovered the same level existing before the critical event. The combined risk of these three phases is calculated considering likelihood of the critical event to occur, expected impact, and system vulnerability. This risk is then added to the system capital and normal operational costs to yield a lifetime cost that is used to compare technological options. Micro-grids are identified as a relevant technology with potential to achieve enhanced power supply during critical events. The analysis provides indications on how to better configure micro-grids in order to achieve high availability through diverse local distributed generation sources.

Electret microphone buffer circuit with significantly enhanced power supply rejection

A microphone buffer circuit being adaptable for connection to a power source is disclosed. The microphone buffer circuit includes an input transistor operably connected between an input and an output for buffering an input signal. The microphone buffer circuit includes a means for reducing power supply noise capable of being coupled to the input transistor wherein the means being operably connected to the input transistor and the power source.

A 5 GHz, 192.6 dBc/Hz/mW FOM, LC–VCO System With Amplitude Control Loop and LDO Voltage Regulator in 0.18 <formula formulatype="inline"> <tex>$\mu$</tex> </formula>m CMOS

To reduce phase noise degradation from oscillator tail current sources, this letter presents an inductor-capacitor voltage-controlled oscillator (LC-VCO) biased by triode metal-oxide-semiconductor transistors. The VCO system also includes an amplitude control loop and a voltage regulator to endure process, voltage, and temperature variations and to enhance power supply rejection ratio. Fabricated in a 0.18 mum CMOS process, the measured results show the adopted topology achieves a better phase noise than the conventional saturation current source. At 5.181 GHz, the VCO system demonstrates a phase noise of -104.8 dBc/Hz at 100-kHz offset, and -127.1 dBc/Hz at 1 MHz offset, while dissipating 4.2 mA from a 1.8 V supply voltage. The corresponding figures of merit at 100 kHz and 1 MHz offset are 190.3 and 192.6 dBc/Hz/mW, respectively.

Enhancing power supply adequacy in Spain: Migrating from capacity payments to reliability options

There has been total unanimity about the vital importance of reliability of supply since the beginning of the electricity sector deregulation process. This paper describes the procedure proposed by Pérez-Arriaga et al. [2005. White paper for the reform of the regulatory scheme of the power generation in Spain. For the Ministry of Industry, Tourism and Trade of Spain (in Spanish)] to improve upon the current scheme to guarantee a reasonable reserve margin, the capacity payment mechanism. This alternative design introduces improvements aimed at guaranteeing at least a minimum capacity reserve margin, as well as at providing a strong incentive for generating units to be available when needed, namely, in situations when supply is likely to be insufficient to meet the total demand.

Power quality in high-tech campus: A case study

This paper presents preliminary results from a power-quality audit conducted at a high-tech campus over the last year. Voltage and current were measured at various R&D buildings; it was found that the main problems for the equipment installed were voltage sags and surges. The paper examines the causes and effects of power disturbances that affect computer or any other microprocessor-based equipment and analyses the auto-protection capabilities of modern power supplies. The convenience of ‘enhanced power supply’ or ‘low-cost customer-side’ protection solutions is also discussed. Finally, it addresses the role of the standards on the protection of electronic equipment and the implications for the final customer.