Parallel Transmission Lines Research Articles

Influence of mutual coupling modelling on the effectiveness of a distance relaying algorithm applicable to long parallel transmission lines

Influence of mutual coupling modelling on the effectiveness of a distance relaying algorithm applicable to long parallel transmission lines

On the system of ensuring electrical safety of maintenance works performed on 35 – 750 kV power transmission lines being under induced voltage implemented in the Republic of Belarus

The article studies the matters of physics of interaction of parallel overhead power transmission lines. Cases are presented, where the maximum induced voltage values are expected on individual sections of closely approaching de-energized and energized power transmission lines. Possible scenarios are presented of direct contact with an unearthed conductor (wire) of OPL in the normal operation mode. Substantiation is presented of review of the list of the lines, which, when de-energized or earthed at terminal sections (in the switchgear of substations and power plants) have the values of induced voltage on the earthed conductors, as reduced to the maximum permissible continuous current of the affecting OPL, exceeding 25 V . Criteria are identified to classify OPL as being affected by induced voltage. The article considers organizational and technical procedures applied to provide safe maintenance works under induced voltage on de-energized overhead power lines (OPL) located within an area affected by energized OPL. Attention is given to the detailed description of types of earthing of OPL, line equipment, working section and workplaces used by State Production Association Belenergo. The mathematical apparatus used in the analytical calculations of the induced voltage values has been analyzed. The technical implementation of acceptable schemes of performing the repair and maintenance works on the earthing of de-energized OPL is considered. Performing geophysical ground survey by the method of vertical electrical sounding at places of mounting special low-resistance earthing electrodes is proposed and implemented. The methodology is developed and tested for measuring induced voltage values, which sets the order of induced voltage measurements on de-energized OPL running close to energized OPL with the voltage 110 kV, and higher. Comparative analysis is presented of results of analytical calculations and experimental research. Conclusions are made supporting the approach adopted and confirming the expediency of the system of ensuring electrical safety of maintenance works performed on 35–750 kV power transmission lines being under induced voltage implemented in the Republic of Belarus.

Analysis, Modeling, and Mitigation of Parasitic Resonances in Integrated Metallic Seal Rings

The cause of a measured −1.4-dB dip at 80 GHz in a silicon capacitor was investigated and determined to be the primary resonance of the integrated metal seal ring (SR) enclosing the component. Specifically, the proximity of a capacitor electrode to the SR was found to activate two parasitic, parallel, and open-circuited coplanar strip transmission lines (TLs), each having their ${\lambda /2}$ resonance at this frequency. This model was confirmed with 3-D finite-element method electromagnetic simulations and measurements of modified SRs. Building on the proposed TL interpretation of the problem, an ultra-broadband equivalent circuit model was developed for such capacitors, successfully replicating the measured SR resonance. Then, the fundamental resonance frequency and related quality factor of various-sized integrated metal SRs were accurately predicted. Finally, potential solutions to damp or cancel such parasitic resonances were investigated. Although cutting the SR at selected locations to disable the parasitic lines was experimentally proven to be successful, damping the parasitic signal with highly doped silicon is found to be the best option in terms of effectiveness and practical implementation. Novel solutions, analogous to the use of radio frequency terminations, were also tested. This paper, to the best of our knowledge, is the first extensive characterization of parasitic resonance afflicting electronics enclosed by an integrated metal SR. The analysis, equivalent circuit model, and solutions reported here can be directly applied to arrays of components or circuits, and are scalable to any device size and operating frequency.

A novel single-ended fault location scheme for parallel transmission lines using k-nearest neighbor algorithm

This paper proposes k-nearest neighbour (k-NN)-based method for fault location estimation of all types of fault in parallel lines using one-terminal measurement. Discrete Fourier Transform (DFT) is used for pre-processing the signals and then the standard deviation of one cycle of pre-fault and one cycle of post-fault samples are used as inputs to k-NN algorithm. The results obtained under various fault conditions demonstrate the high accuracy of the proposed scheme to estimate the fault location. The accuracy of the k-NN-based fault location scheme is not affected by alteration in fault type including inter-circuit faults, fault location, fault inception angle, fault resistance, and pre-fault load angle.

Single-Switch-Based High-Power Bipolar Pulse Generator With Inverted U-Shaped Parallel-Plate Transmission Line

This paper presents a single spark-gap switch (SGS)-based high-power bipolar pulse generator (BPG) for many applications, such as high-power electromagnetic (HPEM) effect tests. Here, we propose an inverted U-shaped parallel transmission line structure to implement the single-SGS-based BPG. Unlike the previously reported BPGs based on synchronized operation of two SGSs, the proposed BPG does not require simultaneous or synchronized closure of the two switches. Detailed dimension parameters obtained by electromagnetic simulation. The proposed BPG was manufactured and tested for validation. The experimental results demonstrated that the BPG produced a bipolar pulse with a peak-to-peak amplitude of 44.9 kV and a pulsewidth of 2.27 ns, where the SGS was filled with nitrogen gas of 16 atm and the turn-ON voltage was 56 kV. For applications of HPEM effect tests, we discuss methodologies to control the amplitude and pulsewidth of generated bipolar pulses in the proposed BPG.

Algorithm for Fault Location and Classification on Parallel Transmission Line using Wavelet based on Clarke's Transformation

Algorithm for Fault Location and Classification on Parallel Transmission Line using Wavelet based on Clarke's Transformation

A New DC-Offset Removal Method for Distance-Relaying Application Using Intrinsic Time-Scale Decomposition

This paper presents a new adaptive method based on the intrinsic time-scale decomposition (ITD) tool for suppressing the decaying dc component effect on phasor estimation. The ITD decomposes a non-stationary fault signal into a proper rotation component (PRC) and a monotonic trend signal. The PRC is the fundamental frequency component, which is used by the discrete Fourier transform (DFT) to estimate the phasor, and the monotonic trend signal is the decaying dc component. The combination of the ITD and the DFT is a simple accurate method for phasor estimation that is applicable to protection schemes with the minimum sampling rate and also to the off-nominal power system frequency. Three types of data, i.e., mathematical, simulated, and real field fault, are examined to assess the performance of the proposed method. The obtained results confirm that the proposed method not only improves the distance relay operation, but it is not also affected by the change in the fault inception angle, fault type, fault location, power system frequency, and network topology. Furthermore, the method works both with a series compensated transmission line and a parallel transmission line.

A hybrid method for fault location estimation in a fixed series compensated lines

This paper proposes a fault distance estimation scheme for fixed series capacitor compensated parallel transmission lines using discrete wavelet transform and decision tree regression. The purpose of the data mining based scheme is to avoid the complicated equation based methods that have been suggested by researchers to overcome the drawbacks of conventional fault location scheme. Although decision tree has inherent advantage over other methods like artificial neural network and support vector machines to work with large data sets, it has not been used in fault location estimation in series compensated (SC) transmission line so far. Decision tree is chosen to locate the faults because of its ability to work with large data set and high accuracy in associating the fault pattern to the fault distance using regression analysis. The discrete wavelet transform processed signals makes the decision process of decision tree regression easy by providing appropriate features. The proposed method is evaluated with variation of fault location, fault type, pre-fault load angle, location of series capacitor, degree of series compensation, fault inception angle, line parameters, inter-circuit faults and fault resistance. The test result of decision tree regression based location estimation scheme ensures that, it can estimate the fault distance accurately.

A broadband and low cross polarization antenna with a balun of microstrip line coupling to slot line.

In this paper, a wide-band low cross polarization antenna with a structure of microstrip line coupling to slot line as the balun is proposed. The radiation part of the antenna is fed by two pairs of parallel transmission line via a transition from a slot line which is coupled by a microstrip line. Because it is fed by parallel transmission lines, which is balanced-fed structure, the antenna can achieve an improved low cross-polarization performance. The height of the antenna is 0.146λ0 (λ0 is the wavelength of lowest frequency). The prototype antenna demonstrates a measured impedance bandwidth of 93.5% (2.7–7.44 GHz), a 3-dB-gain bandwidth of 77% (2.7–6.1 GHz), and a maximum gain of 10.5 dBi at 4.5 GHz.

Hidden High Voltage Safety Risks for Parallel High Voltage Transmission Lines

High voltage (HV) infrastructures market is growing due to the corresponding growth in industries and population. To ensure continuous and reliable electrical power supply, existing substation and transmission lines are being upgraded to accommodate the additional load requirements. These upgrades involve up-rating the existing transmission lines or the installation of new lines. To save on easement cost and reduce the environmental impacts, transmission lines are occupied the same easement or path. This parallel option introduces the risk of induced voltage which could reach an unsafe condition and jeopardize the safety of works and people. This paper analysis and highlight the hidden risk associated with two parallel transmission lines that connected the same high voltage substation. The theoretical study which is supported by the case study shows the high risk potential tempering with the OHEW on the isolated circuit while the other one is still energized

Analysis of the three-dimensional hybrid electric fields and the related electrostatic induction effects of 800 kV DC and 500 kV AC parallel transmission lines considering environmental factors

With the great development of ultra high voltage (UHV) transmission technology, there exist some 800kV DC and 500kV AC parallel transmission lines sharing the right of way in China. Due to hybrid electric field induced by 800kV DC and 500kV AC parallel transmission lines, the electromagnetic environment of the parallel lines will become more complex compared to that of either individual line. Furthermore, environmental factors such as relative air humidity, relative air density and wire surface equivalent roughness coefficient will influence hybrid electric field along the long transmission line from west to east China. This paper first establishes the equivalent model of transmission lines, human body and rain drop. Afterwards, the three dimensional electric field and ion flow field below the 800kV DC and 500kV AC parallel transmission lines are calculated by combining the 3-D modified CSM (charge simulation method) and the Deutsch hypothesis respectively. Next, different hybrid electric field distributions are obtained with different environmental factors. Finally, related electrostatic induction effects on human body under the parallel transmission lines are also analyzed. It is concluded that the induced currents on the surface of the human body are within the range of limited values specified by INCIRP with different environmental factors.

Method for measuring the electric field strength under UHV/EHV AC/DC parallel transmission lines

In the measurement of hybrid electric field strength such as electric field under UHV/EHV AC/DC parallel transmission lines, simultaneous measurement of direct current component and ac electric field components is a key problem to be solved. In this paper, an improved method for AC/DC hybrid field strength measuring device (rotary voltmeter) is proposed, and a type of Bernoulli curve stator is designed. After using the new structure, when the rotor is rotating, the stator area exposed to the electric field changes sinusoidally. The mathematical expression of the change of the area is derived from the principle of mathematics, based on this, the spectral characteristics of the output of the measuring equipment under the AC and DC hybrid electric fields are studied. In addition, the corresponding relationship between the AC/DC electric field and the spectrum of the result of the measurement is established. This paper presents a method of measuring the ground electric field of AC/DC parallel transmission lines considering both AC/DC components. A calibration experiment is carried out in DC electric field, which verifies the accuracy and effectiveness of the method.

Calculation of the ground hybrid electric field of ±800kV EHV DC and 750kV UHV AC parallel transmission lines

Based on the method of time-domain upwind difference algorithm, the ground hybrid electric field is calculated. The typical tower is selected from the ±800kV Hami- Zhengzhou DC transmission project and the 750kV Tianshui-Baoji double-loop transmission line project. In the paper, the minimum height above ground is determined when the individual AC and DC lines meet the electric field limits, respectively. Then the article analyzes the AC and DC parallel spacing and the width of the corridor, using the weighted method to determine the control values of hybrid electric field.

Appropriate selection of shunt compensation reactor in parallel transmission lines: A case study

Shunt reactors are widely deployed as effective compensation means against the capacitive behavior of high voltage transmission lines. Subsequent to load rejection or light load conditions, a resonance phenomenon is highly potent due to remarkable capacitive feature of these lines. Reactor failure, threatening the interior insulation of high voltage equipment connected to the line, and early aging of insulations are some of the main concerns regarding resonance voltages. To study the phenomenon, different cases including complete disconnection of the transmission line, single and double pole operation of breakers, and short circuit faults on the de-energized line are simulated with two different knee points of reactor saturation. A sensitivity analysis is also conducted considering the soil resistivity and corona phenomenon. Different solutions such as neutral reactors and resistors, complete transposition of the circuits, capacitor bank and replacing the ground disconnector switches with breakers are examined in the worst case to limit the resonance overvoltage. In contrast to previous contributions, it is shown that when the shunt compensation reactor is not appropriately determined, none of the solution methods alone can resolve the resonance phenomenon. Hence, an exact and carefully-selected compensation level is of great significance.

New fault location scheme for three-terminal untransposed parallel transmission lines

This paper proposes a new fault location scheme in the phase-domain for three-terminal untransposed double-circuit transmission lines utilizing synchronized voltage and current measurements obtained by GPS technique. The proposed scheme is derived taking into consideration the distributed line model and the mutual couplings effect between the parallel lines to obtain accurate results. The proposed scheme is derived based on the transmission line theory and Taylor series expansion of the distributed line model parameters. All fault types including normal shunt faults, evolving faults, and cross-country faults can be discriminated from each other and the fault location can be obtained for all fault types. The evolving faults include earth faults occurring at the same location in two phases of one circuit or two phases of different circuits at different fault inception time. While cross-country faults include earth faults occurring at different locations in two phases of one circuit or two phases of different circuits at same or different fault inception time. The proposed scheme is tested under different fault locations, different fault resistances, different fault inception angles, and all fault types including cross-country and evolving faults. Also, the effect of different sampling rate, measurement and synchronization errors, earth resistivity variations, and transmission line parameters errors on the proposed scheme is considered. Simulations studies conducted by MATLAB software demonstrate that the maximum estimation error in fault location does not exceed 3.06%.

Dual-Band Design Theory for Dual Transmission-Line Transformer

In this letter, a novel dual-band (DB) design theory for dual transmission-line (TL) transformer is introduced, and it only consists of two parallel TLs with different physical lengths. Design equations for these two characteristic impedances and their physical lengths are derived in closed form. Through mathematical analysis, two different DB design expressions are newly summarized and proved under the condition of even and odd physical length ratios, respectively. It is proven that the proposed topology could realize around eight times lower impedance transformation ratio than that in conventional works. For verification purposes, two 5– $50~\Omega $ transformers with different frequency ratios have been simulated, fabricated, and measured. Measured and simulation results are matched very well.

Accurate Formula to Determine Resonant Frequency of Double Sided Printed Dipole Antenna

ABSTRACTTwo arms of double-sided printed dipole antenna (DSPDA) are printed on opposite faces of a dielectric material. The antenna is fed by the printed version of two-wire parallel transmission line. This configuration has the advantages of high impedance bandwidth and low cross polarization. The width of each dipole arm is generally kept below 0.05λ0 to achieve high cross polar discrimination. However, it is observed that, in case of DSPDA the resonating length is different from that of the conventional half-wave dipole antenna. In this paper, we have proposed a semi-empirical but accurate formula to predict the resonant frequency for a given length of DSPDA. A prototype antenna is fabricated using the proposed formula which is validated against experimental results. Measured resonant frequency of the fabricated DSPDA matches closely with the theoretical one.

New travelling‐wave‐based protection algorithm for parallel transmission lines during inter‐circuit faults

An ultra-high-speed, accurate and reliable algorithm is proposed in this study for the identification and faulted phases selection of inter-circuit faults. For this purpose, modal components of current samples just before they arrive to the relay location are extracted. Teager energy operator is used here for the extraction of current travelling waves (TWs). The amplitude of the TWs in different modal components and their ratios in similar modal components are used for the inter-circuit fault identification and finding the faulted phases. Test signals are simulated in PSCAD/EMTDC software and the algorithm is implemented in MATLAB. Results show that the proposed algorithm is a really ultra-high-speed algorithm which can be reliably used for the identification and classification of the inter-circuit faults.

Research on Safety Protection for Live Working on 1000kV AC Transmission Line with AC and DC Multi-circuit Transmission Lines

In recent years, in order to save line corridors and reduce the scope of demolition, some new transmission modes for high voltage AC and DC power transmission line are proposed. According to the characteristics of the parallel transmission line, this paper studies the distribution characteristics of the electric field intensity of multi circuit parallel transmission lines and the single circuit transmission line. Comparing and analysing the simulation results of the electric field strength, the safety measures for live working of 1000kV AC transmission line with multi circuit parallel transmission lines is put forward. That is the electric field protective equipment and measures used in the live line work of the 1000kV UHV AC single circuit line can meet the requirements of the live operation of the 1000kV UHV AC double circuit line.

Microwave Voltage-Controlled Oscillator With Harmonic-Suppressed Stepped-Impedance-Resonator Filter

This brief proposes a new low-phase-noise microwave voltage-controlled oscillator (VCO) with a harmonic-suppressed stepped-impedance-resonator (SIR) filter. Since the filter is synthesized by multiple resonators, it can provide a high-quality factor to improve the phase-noise performance. In addition, the harmonic-suppressed property of the filter adopted in this brief can alleviate the noise contributed from the oscillation harmonics. By applying the two techniques mentioned, the proposed VCO is designed at 2.4 GHz with a three-pole Butterworth filter, which is synthesized by the parallel transmission-line SIRs to reduce the circuit size. The proposed VCO using a three-pole filter has a measured phase noise of −147 dBc/Hz at 1-MHz offset frequency with a corresponding figure-of-merit of −203.18 dBc/Hz.