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DC community and residential microgrids are recognized as effective means for electrification of remote areas as a result of monumental efforts in many parts of the world — most significantly in India — but also through similar efforts in Nepal, Cameroon, New Guinea and Nigeria. So far modular approaches have been developed that enable construction of scalable microgrids based on PV and battery storage...
Normally, fault resistances come out with errors in the fault calculation algorithm on conventional Mho distance protection scheme which might force the relay to under-reach/over-reach based on the network conditions. With a constrained shape, Mho Directional distance elements can provide more resistive coverage while discriminating between forward and reverse faults. In this work, the recurring effect...
Partial discharge (PD) in power transformer degrades the dielectric insulation and results in insulation failure and breakdown after a long period. In fact, a partial discharge detector can gather signals from two or more PD sources which increase the difficulty on pattern recognition and insulation state assessment. How to separate multiple PD signals is meaningful to subsequent data processing....
In order to improve the robustness of fault diagnosis method based on model in the modular multilevel converter, an improved predictive model of the circulating current is established. A correction method is proposed to compensate for the uncertainties of the parameters and the measurement errors, and the disturbances are eliminated by using multi-step prediction method. The fault detection method...
To improve the reliability of modular multilevel converter (MMC), the fault submodules must be isolated rapidly. In this paper, a new fast fault diagnosis method is proposed containing two steps: fault detecting and fault locating. Fault detection step finds failures by improved predictive model which detects the fault by comparing the difference between the predictive value and the measured one of...
The microgrid concept was proposed as a way to facilitate the integration of distributed renewable energy resources. However, due to the use of distributed energy resources (DERs) microgrids face new protection challenges that need resolved. One of those challenges is that traditional protection methods, such as overcurrent protection, cannot be used mainly because of low fault currents, bi-directionality...
It is difficult to locate the single-phase-earth fault in neutral ineffectively grounded systems, because the fault current is weak. Aimed at this problem, this paper proposes a new fault section location method based on the relative entropy degree. The proposed method computes the relative entropy degree of every feeder section, and then determines the state of the sections. For the faulty section,...
A method for fault location based on correlative characteristic values (CCVs) in resonant grounded system is presented. In this method, zero-sequence current signals of two different data windows are extracted for each feeder terminal unit (FTU) after a single-phase-to-ground fault occurs. Then, their correlation coefficient which is called CCV of each FTU is calculated. Furthermore, CCVs of all FTUs...
This paper presents a novel method for locating two faults, instead of a single fault, in three-terminal transmission lines. It is assumed two faults occur in two different sections of a three-terminal transmission line and the faults may occur simultaneously or one after another before the first fault is cleared. It is also assumed types of faults are unknown and no measurement equipment is available...
When fault occurs in hybrid transmission line, the complicated refraction and reflection effects may happen during the propagation of fault traveling wave, this can lead to the decrease of fault ranging accuracy. To increase the fault ranging accuracy, the traveling wave propagation characteristics of overhead line — submarine cable hybrid line are analyzed, and a double terminal traveling wave ranging...
Discharge location is an important issue and technical guarantee for AC withstand voltage test which is the key test in the handover test of extra-high voltage (UHV) equipment. In order to ensure the smoothly processing of the equipment defect inspection as well as the elimination of hidden fault, the discharge location technique in AC withstand voltage test of 1100kV Gas insulated metal-enclosed...
Modern electric power systems are witnessing deployment of an increasing number of distributed renewable energy resources. Reliability of grid infrastructure plays a key role in increased use of renewable energies. Fault management is a key function in reducing outage time and increasing system reliability. In the past, various fault location methods have been proposed for electric power distribution...
DC-DC converters face an exponential growth in the context of the ever-increasing use of DC grids, namely at the home and business levels. In this domain, efficiency and reliability are of major concern. Solutions already available in the literature concerning fault-tolerant DC-DC converters do not consider the application of such converters in household environments and their constraints. To solve...
This paper presents the design, analysis, and experimental validation of a fault detection and identification (FDI) scheme for dc-dc power electronic converters. The FDI scheme includes two new classes of fault filters: (1) a linear-switched fault detection (FD) filter and (2) a bank of linear-switched fault identification (FI) filters. Both the FD filter and the bank of FI filters have a structure...
It is costly to have a conventional three phase electricity supply system to service sparsely-populated rural areas. As a solution, the single wire earth return (SWER) network is widely used which has only one overhead conductor delivering power and the ground is used for the return path. This paper presents an on-line monitoring system, currently under development, to provide real-time power quality...
With the expansion of the grid scale, fault location for transmission lines put forward higher requirements. In this paper, the fault current as the research object, according to the singularity of the fault current, the iterative SVD decomposition method is adopted to reduce the noise of the fault current traveling wave, and the singular points of the fault current are detected by the dichotomy recursive...
It has a complicated and variable feature of fault transient traveling wave in cable and overhead line hybrid transmission line. Theoretical analysis and simulation method have been used to study the propagation characteristics of fault transient traveling wave in cable and overhead line hybrid line. The principle of single line traveling wave method for hybrid line is expounded and the influence...
The design of improved fault location system and its experimental test system is presented in this paper. The fault location system is based on traveling waves and contains several innovative algorithms, considering the main influential factors such as the uncertainty of wave speed and the accuracy of transmission line length. Besides, the design of experimental system for testing the location precision...
Because the fault characteristics are not obvious and the detection is difficult, the high impedance fault is always the difficulty of the distribution network fault identification. According to the actual situation of power grid, the current signal at each measurement point in the line is selected to be a measured one, and the corresponding complex sequence current and zero sequence current are obtained...
Sol-gel composite can be useful for high temperature ultrasonic transducer applications and PbTiO3/Pb(Zr, Ti)O3 sol-gel composite is promising piezoelectric material because 100μm thick PT/PZT poled by positive DC corona discharge at high temperatures showed highest sensitivity among other sol-gel composites between room temperature and 400°C. However, high temperature poling process including cooling...
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