Capacitor Units Research Articles

An energy-efficient 16 MS/s 10-bit SAR ADC with MSB-block switching scheme

An energy-efficient MSB-block switching scheme without common-mode voltage variation for successive approximation register (SAR) analog-to-digital converters (ADCs) is proposed. Benefit from a pair of extra switches embedded in the capacitive digital-to-analog converter (CDAC), the proposed MSB-block switching scheme can reduce switching energy without further reducing the capacitor unit. The proposed switching scheme can achieve 93.8 % and 49.9 % savings in switching energy compared with the conventional switching scheme and the Vcm-based switching scheme, and the simulated differential-nonlinearity (DNL) and integrated-nonlinearity (INL) are 0.160 and 0.156LSB, respectively. The proposed switching scheme is verified in a 1.2-V 10-bit 16 MS/s SAR ADC in 65 nm CMOS technology. At maximum sampling rate, the proposed SAR ADC achieves an effective number of bits (ENOB) of 9.50 and a power consumption of 103.5μW, leading to a Figure of Merit of 8.93 fJ/Conversion-step.

A porous elastomer with a cavity array for three-dimensional plantar force sensing

Human gait is an important indicator for diagnosis of various movement-related disorders. Three-dimensional (3D) plantar force monitoring enables real-time recording of contact forces in both the normal and tangential directions in each step, providing useful clues for identification of irregular gait patterns or gait-related health issues. Most flexible sensors for gait monitoring focus on contact forces in the normal direction, being limited to detect forces in the tangential direction. Herein we have developed a porous elastomer with a cavity array (PECA) to measure 3D contact forces for gait analysis. The sensor consists of two fabric electrodes and a dielectric layer of porous Ecoflex elastomer containing a 5 × 5 cavity array, forming four parallel-plate capacitor units in a soft construction. Therefore, a 3D force in any arbitrary direction generates four unique capacitive electrical signals. Importantly, the PECA includes a well-designed combination of micrometer-scale pores and millimeter-sized cavities, dramatically improving the detection sensitivity and linear elasticity range. We have demonstrated high sensitivities of 0.41 N−1 and 0.23 N−1 in the normal and tangential directions, respectively. The flexible PECA-based sensors have been tested to sensitively distinguish various standing postures and different stride lengths for gait analysis, promising reliable translation into areas such as healthcare monitoring, sports training, and rehabilitation engineering.

A hybrid SAR ADC with input range extension

—This paper proposes a differential 10-bit 1 MS/s successive approximation register (SAR) analog to digital converter (ADC) with input range (IR) extension. Employing 512 capacitor units and a reference voltage VREF, it attains a ±1.875VREF input range and a resolution of 10.91 bits. The hybrid SAR ADC decomposes the capacitive digital-to-analog converter (CDAC) into an incremental CDAC and a binary-weighted CDAC. For input signals larger than 0.75 VREF, the incremental CDAC is used to reduce the net sampling charge by biasing its capacitor bottom plates on proper reference voltage to implement input range extension. Furthermore, the increment CDAC contributes to enhancing linearity. The input frequency limitation is theoretically analyzed in the paper. This design is implemented with a 180-nm CMOS technology and achieves a 10.47 effective number of bits (ENOB). It consumes 26.8 μW at 1 MS/s with a 1.8-V supply and occupies an area of 0.0118 mm2.

Optimization Design of Temperature Field Distribution for AC High Voltage Parallel Capacitors

Abstract With the change in the overall harmonic working background of the system, the harmonic current spectrum borne by high-voltage AC shunt capacitors becomes increasingly complex, particularly with a gradual increase in high-frequency harmonic content. The wide frequency band, large value range, and long duration of harmonic current lead to increased heating of the capacitor. In this paper, a thermal field physical model is established for an AC parallel filter capacitor based on the skin effect, and trends are analysed in the current distribution of the capacitor plate under the skin effect. Furthermore, based on this established model, it is analysed how harmonic order and capacitor placement mode affect temperature field distribution within the capacitor, and it is concluded that these factors impact temperature rise release. This research lays a theoretical foundation for designing capacitor unit structures.

A new technique for improving performance of conventional CRLH resonators using IDC/UISs with enhanced harmonic suppression in balanced dual-band BPFs

Abstract The design of balanced filters based on composite right/left hand (CRLH) structure is well developed. Among those, few designs exist which although they provide some good responses, suffer from narrow stopbands and interdependent passbands. This paper proposes a new technique for improving the characteristics of dual-band balanced bandpass filters (B-BPFs) based on planar CRLH. Using unequal inductive stubs (UISs) attached to the interdigital capacitor (IDC) unit cell, we were able to achieve outstanding harmonic suppression and passband controllability. This structure offers higher degrees of freedom compared to conventional designs and provides better control over the filter specifications. Mathematical modeling, analysis, simulation, fabrication, and performance measurement of the proposed technique in a dual-band B-BPF are also provided. Our work resulted in an independent and controllable dual-band B-BPF with ultra-wide upper differential-mode (DM) stopband of 5.9f 1 and common-mode (CM) suppression of 40.4 and 32.6 dB for the first and second bands, respectively.

A High ENOB 14-Bit ADC without Calibration

This paper presents an implementation of a 14-bit 2.5 MS/s differential Successive-Approximation-Register (SAR) analog-to-digital converter (ADC) to be used for sensing multiple analog input signals. A differential binary-weighted with split capacitance charge-redistribution capacitive digital-to-analog converter (CDAC) utilizing the conventional switching technique is designed, without using any calibration mechanism for fast power-on operation. The CDAC capacitor unit has been optimized for improved linearity without calibration technique. The SAR ADC has a differential input range 3.6 Vpp, with a SNDR of 80.45 dB, ENOB of 13.07, SFDR of 87.16 dB and dissipates an average power of 0.8 mW, while operating at 2.5 V/1 V for analog/digital power supply. The INL and DNL is +0.22/−0.34 LSB and +0.42/−0.3 LSB, respectively. A prototype ADC has been fabricated in a conventional CMOS 65 nm technology process.

Arrangement for reliable power supply to emergency commercial customers with techno-economic performance improvement of PV enhanced distribution systems

Accelerating engagement of distributed energy resources unleashed the dependency on traditional electric power generation. To reduce the craving for traditional power dependency and unplanned outages the power distribution sectors are gradually adopting cleaner and reliable electrification. However, the unscheduled and unorganized engagement of stochastic generation from renewable energy sources (RES) makes the distribution system operation more vulnerable. For reliable and continuous power supply with RES, scheduled operation of BSSs and power capacitor (CAP) units can be integrated to provide emergency power supply support to consumers. In this paper, the supply of continuous and reliable power to commercial and emergency customers has been investigated subject to complete reliability (CR). The benefit-to-cost ratio (BCR) has been maximized to give reliable power to consumers by the minimum investment cost by utility, which can benefit both electric customers and power distribution operators in a single platform. The maximization of BCR has been evaluated by optimal S-CDS of the BSSs and S-S of CAP units’ operation through the PSO technique in the considered 28-bus active distribution network in different seasons. The techno-economic benefit of integrating only BSSs and BSSs with CAP units in the prospective locations has been analyzed. The improvement in battery life and decrease in SAENS, SADPL, and SADD have been obtained, which shows the efficacy of the proposed work.

A Bidirectional Single Capacitor Unit Based Hybrid T-Type Converter Topology With Sensor-Less Voltage Balancing Capabilities

A Bidirectional Single Capacitor Unit Based Hybrid T-Type Converter Topology With Sensor-Less Voltage Balancing Capabilities

Distributed generator and capacitor‐embedded reconfiguration in three‐phase unbalanced distribution systems using teaching learning‐based optimization

AbstractIn the transmission and distribution networks, both active and reactive power play significant roles. While active power does the beneficial work, reactive power maintains the voltage that necessitates management from a system reliability perspective. The voltage variation from the nominal range may result in unintentional operation and early component failure. To maximize the amount of real power that can be transported over the power‐transmitting media, the system must also control reactive power flow. In a three‐phase unbalanced distribution system reinforced with distributed generator units (DGUs) and shunt capacitor units (SCUs), this paper suggests a teaching learning‐based optimization (TLBO) approach to be applied to combinatorial problems for simultaneous reduction of real power loss and net reactive power flow, enhance voltage stability index (VSI) and minimize aggregated voltage deviation index. A multiobjective formulation based on TLBO has been implemented to choose the ideal sizes and placements of DGUs and SCUs in large distribution networks. The case studies have been carried out on an IEEE 33‐bus standard system and a large 123‐bus unbalanced system. The analysis of the IEEE 33‐ and 123‐bus test systems reveals the economic efficiency of the suggested TLBO algorithm. Notably, by applying DG and capacitor simultaneously in the 33‐bus system, a significant reduction of 59.35%, 55.05%, and 50.76% (phases a, b, and c), and for the 123‐bus system, a significant reduction of 43.65%, 19%, and 48.65% (phases a, b, and c) in total active power losses have been achieved. The results suggest that the proposed method renders significant improvement in voltage stability and reduces power losses concerning the base case for both test systems.

Modeling of electromagnetic influences of multi-wire traction networks for pipelines

In this work, digital models for determining the electromagnetic influences of multi-wire traction networks on pipelines are developed. When developing models, an approach based on multiphase behaviour simulation of electric power systems was used. This approach adequately addresses all the influencing factors, which include modules and phases of currents flowing through the overhead contact wire suspension, 6–10–25 kV power transmission lines laid on the supports of the overhead line, and lines of rails. In addition, it is possible to take into account similar parameters for stresses at the nodal points of a multi-wire system. Among the key factors are the railway clearance when laying pipes parallel to the railway track, railway clearance trajectory in the presence of non-parallel sections, and the electrical characteristics of the soil along the clearance route. The research results demonstrated that a 25 kV electromagnetically unbalanced traction network exerts significant influence on a pipeline running in parallel. It was shown that the maximum induced voltages at specific points along the pipe fall within the range of 300–700 V, which significantly exceeds the permissible level of 60 V. It was revealed that currents exceeding 20 A flowing through the pipe can have an adverse effect on anticorrosive protection devices. To mitigate electromagnetic impacts on the pipeline, the following measures are recommended: reducing the length of pipeline and railway clearance sections, increasing the gap between the traction network and the pipe, and installing an additional grounding source. The pipe can be connected to the supplementary grounding source through filters tuned to a frequency of 50 Hz, which involve capacitor units to prevent malfunctions during the operation of pipeline protection devices. Thus, the developed digital models allow the induced voltages generated by multi-wire traction networks and the currents flowing through the pipes to be adequately determined. These models offer an informed choice of measures that ensure the safety of pipeline maintenance.

A Compact Metamaterial Dual-band Branch-line Coupler for 5G Applications

This study introduces a compact branch-line coupler (BLC) based on metamaterial (MTM) technology that can operate in sub-6 GHz 5G frequency bands. Conventional vertical and horizontal sections of the BLC were replaced with T-shaped TLs and interdigital capacitor (IDC) unit cells incorporated into the BLC sections to improve their performance and reduce their dimensions. The BLC is designed on a Rogers RT5880 substrate material, and it operates at dual frequencies of 0.7 GHz and 3.5 GHz. The design was simulated using CST Microwave Studio software and achieved enhanced frequency band ratio.

A Multilevel Switched Capacitor Inverter with Reduced Components and Self-Balance

This paper presents a novel 13-level switched capacitor multilevel inverter, which uses less devices to achieve six-fold voltage gain. The proposed topology structure consists of twelve transistors, two diodes, and three capacitors. It is worth mentioning that characteristics as having five complementary switch pairs and self-balanced electric capacity voltages are conducive to simplifying the control strategy. Moreover, the above components constitute the switched capacitor unit and L-type unit. The inverter can acquire more voltage levels and a higher voltage gain by using multiple L-type units with fewer elements. Furthermore, the cost function is employed to comprehensively appraise the performance of the proposed inverter. The comparison with other existing 13-level inverters shows that the proposed multilevel inverter can effectively decrease the value of the cost function. Finally, the simulation and experimental results are presented to demonstrate the feasibility and effectiveness of the 13-level inverter.

Reduction of Voltage Fluctuations in Electrical Networks Supplying Motors with a Rapidly Changing Load by Installing Longitudinal Compensation Batteries

The article deals with the reduction of voltage fluctuations in electrical networks of industrial enterprises with the help of longitudinal compensation batteries. The purpose of the article is to develop a method for calculating the optimal parameters of the longitudinal compensation installation, which makes it possible to perform calculations using numerical characteristics of the range of changes in the voltage and flicker dose. To achieve this goal, it is necessary to solve the following tasks: to develop a method for selecting the parameters of reducing voltage fluctuations, taking into account the random nature of the change in the parameters of network modes; using the proposed method, to develop a calculation method that allows choosing optimal parameters of capacitor units. The most significant result is the experimental and theoretical confirmation that the proposed method for selecting the parameters of longitudinal compensation batteries, taking into account the random nature of the change in the flicker dose, makes it possible to effectively apply longitudinal compensation to reduce voltage fluctuations in electrical networks of industrial enterprises with a rapidly changing load. The significance of the results is proved by the fact that the proposed method makes it possible to select a longitudinal compensation installation to limit voltage fluctuations at the design stage, thereby ensuring the quality of electric energy in networks with consumers having a rapidly changing load. The resulting calculation method is planned to be used in distribution electrical networks when performing technical measures to ensure the quality of electrical energy.

Analysis of an Abnormal Secondary Voltage Accident of Capacitive Voltage Transformer

Capacitive Voltage Transformer (CVT) is an important measurement and protection equipment in power system, which has the characteristics of high electrical strength, large insulation margin and reliable operation. During the operation of CVT, its upper and lower capacitors, compensation reactors, lightning rods and other components often have faults. The faults of CVT can be found in time by judging the secondary voltage value. In this paper, an abnormal secondary voltage fault of CVT is introduced. Combined with test and disassembly analysis, it is determined that the fault is caused by breakdown of capacitor unit. Through fault simulation, this paper studies the typical CVT faults and the change law of secondary voltage, and puts forward the threshold of the secondary voltage abnormal alarm of CVT, providing important reference for CVT online monitoring.

A nine‐level T‐type inverter (9L‐TTI) with voltage boost capability

AbstractThis paper introduces a 9L T‐type boost inverter (9L‐TTI) based multilevel topology, which generates a nine‐level output voltage in the boost mode. This topology uses 12 switching elements alongside less voltage stress and one switched capacitor unit. This is the significant advantage of the mentioned topology. Following the discussion of the advantages of the provided design, a comparative study is conducted. This results in a reduction in device counts, cost‐effectiveness, and voltage stress on the devices. For switching scheme, fundamental switching frequency‐based modulation is incorporated by having nearest level control (NLC) technique. For proper validation of this work, it is also demonstrated through test results. Here the results are demonstrated at different load conditions, which include resistive and inductive loads. Further, it is demonstrated at different modulation indices and total harmonic distortion (THD) of converter voltage and current for RL‐load, is validated from the power quality improvement point.

Power management algorithm for standalone operated renewable distribution generator with hybrid energy backup in microgrid

<p>In a micro grid system during standalone condition the system may not be stable and might not compensate the required load. Especially for renewable source integrated micro grid system grid disconnected condition is more critical as the renewable sources are unpredictable. The renewable distribution generator needs backup module for support to the loads during standalone condition. In this paper complete distribution network with multiple renewable sources which include PV plant, wind plant and fuel cell source is modeled with power management algorithm (PMA) in only photovoltaic (PV) plant. PMA controls the hybrid backup modules supporting the PV DG. The hybrid backup modules considered for the support are battery unit and super capacitor (SC) unit. The battery and SC units charge or discharge as per the PMA controller with respect to power generated by the PV source. The charge and discharge of these units are dependent on PV power, state of charge (SOC) of battery and SOC of SC. These three sources compensate the critical load connected in the micro grid. A comparative analysis is carried out with and without backup modules and PMA during grid islanding condition on the proposed distribution network. All graphical and parametric comparisons are done using MATLAB/ Simulink software with time domain plots generated by PowerGUI tool.</p>

Optimum estimation of series capacitors for enhancing distribution system performance via an improved hybrid optimization algorithm

AbstractAs the load on distribution networks grows, system operators and planners are constantly challenged with the issue of voltage regulation or enhancing the quality of supply to customers at the load end of lengthy distribution lines. This paper presents the optimum determination of series capacitor units in a distribution system to maximize energy‐saving and enhance voltage levels. Interestingly, series capacitors can enhance the capability of transmission lines, reduce line losses, enhance the performance of buses with large induction motor loads and reduce voltage flicker. At the same time, the limitations of series compensation are taken into consideration while calculating its optimum values. To achieve the planning objective and optimal load flow objective, two strategies: The Improved Grey Wolf Optimization method (I‐GWO) and Tabu Search (TS), are hybridized to get the benefit of their advantages. The I‐GWO has a movement strategy called dimension learning‐based hunting for enhancing the balance between global and local search and maintaining diversity. The proposed (I‐GWO‐TS) algorithm can solve mixed‐integer programming to achieve the planning and the optimal load flow objectives. The proposed method can be applied to a real Egyptian distribution system that is heavily loaded, with poor voltage regulation, and also has high‐power losses. The obtained results demonstrate the capability of the proposed approach to determine optimal series capacitors’ location and sizing for maximization of energy saving. Further, the proposed method improves the network performance regarding the voltage profile and power losses, although the limitations of including series compensation were considered in the distribution system.

A phase diagram approach to the detection and location of faulty capacitor units in A 115-kV capacitor bank based on unbalanced current arguments

The protection of traditional high voltage capacitor banks relies on an unbalance relay which operates when an internal fuse is blown. However, the unbalance relay cannot indicate cause or position of the fault. Thus, an operator wastes time and human resources investigating the fault issues. To address this issue, a method to locate the fault position in a capacitor bank is developed in this study. The study was simulated by using PSCAD software and modeled on the 115-kV system of the Electricity Generating Authority of Thailand (EGAT). Case studies involving faults with varied phases, side and branch connections, row connections, and inception angles were considered. Moreover, the magnitude and argument of the current phase and unbalanced current were analyzed to identify the fault location in a capacitor bank. The performance of the proposed method was verified via comparison with that of traditional methods and the results of laboratory experiments. In addition, various voltage systems were observed to verify the flexibility and accuracy of the proposed method. The results demonstrate that the proposed method was more efficient than traditional methods at locating the fault position in a capacitor bank.

Beamforming networks using the Nolen matrix for 5G applications

A design of a wideband low loss 3 × 3 Nolen matrix is presented at 3.5 GHz. The proposed Nolen matrix is designed with the implementation of three branch-line couplers and two phase shifters. The interdigital capacitor unit cell is implemented in both the coupler and phase shifter to reduce the size and improve the bandwidth. The proposed 3 × 3 Nolen matrix is simulated using computer simulation technology (CST) software and then fabricated on the FR4 substrate with . The 3 × 3 Nolen matrix performance is achieved with a fractional bandwidth of 49% and operates at 2.52–4.2 GHz. The coupling factor of the 3 × 3 Nolen matrix across outputs at 3.5 GHz is −6 ± 0.98 dB with phase differences of 3.37° at port 1, 125.6° at port 2, and −117.8° at port 3. Then, the proposed Nolen matrix is attached with three standard microstrip antennas to prove the property of a unique beam scanning. The measured results approve the concept of three different phases scanning at 0°, 45°, and −40° with a reflection coefficient below −10 dB. Compared to the conventional Nolen matrix, the 3 × 3 Nolen matrix with a modified coupler is achieved with a low loss characteristics with phase error up to 2.2° and a compact size of 0.82 λ × 0.75 λ. The proposed Nolen matrix is suitable to be used in future 5G antenna beamforming applications.

On-Line Monitoring of Shunt Capacitor Bank Based on Relay Protection Device

In modern power systems, the installation of a shunt capacitor bank is one of the cheapest and most widely used methods for improving the voltage profile. One shunt capacitor bank is composed of mass capacitor units and have ground, ungrounded, delta, wye connections that make configuration of capacitor banks is various. In the case of long-term operation, the failure of a single capacitor unit of a capacitor bank is likely to cause uneven voltage, which will lead to the breakdown and burning of the whole group, resulting in huge losses. The relay protection device can detect the simultaneous voltage and current of the capacitor. By utilizing these data from the relay, the abnormal state of the shunt capacitor banks at the initial stage of the fault can be found through monitoring the slight change in capacitance. Timely and early maintenance and repair would avoid capacitor bank faults and potentially greater economic losses. Capacitor banks have different connection modes. For ungrounded wye-connected capacitor banks with an unknown neutral point voltage, the capacitance parameters of each branch cannot be calculated. A parameter symmetry based on the calculation method for capacitor parameters is proposed. For long-term monitoring and observation of the capacitor capacitance value, the fault state and abnormal state of the capacitor are identified based on statistical methods. The simulation established by PSCAD verified that a relay protection device can realized an effective monitoring of the early abnormal state of the capacitor bank.