In order to enable medium-voltage applications at an operation voltage of 5-kV level, a novel 7.2-kV/60-A Austin SuperMOS SiC power switch is developed. Static and dynamic performances are ...characterized at various voltage and current levels. The device exhibits excellent dynamic performance with a high dV/dt up to 122 V/ns during the turn-off. The output charge of the Austin SuperMOS is also measured to enable accurate dynamic loss estimation. A unique automatic gate turn-on mechanism is identified, which facilitates a substantial reduction of the third quadrant conduction loss during the deadtime in converter operations. A high-voltage isolated power supply with low coupling capacitance and an optically triggered intelligent gate driver circuit with protection functions are integrated into the medium-voltage power switch, enabling safe and reliable medium-voltage operations of the Austin SuperMOS.
This paper deals with the problem of the optimal selection of capacitor banks in electrical AC distribution systems for minimizing the costs of energy losses during a year of operation through a ...discrete version of the vortex search algorithm (DVSA). This algorithm works with a hypersphere with a variable radius defined by an exponential function where a Gaussian distribution is used to generate a set of candidate solutions uniformly distributed around the center of this hypersphere. This center corresponds to the best solution obtained at the iteration t, which is initialized at the center of the solution space at the iterative search beginning. The main advantage of combining the exponential function with the Gaussian distribution is the correct balance between the exploration and exploitation of the solution space, which allows reaching the global optimal solution of the optimization problem with a low standard deviation, i.e., guaranteeing repeatability at each simulation. Two classical distribution networks composed of 33 and 69 nodes were used to validate the proposed DVSA algorithm. They demonstrated that the DVSA improves numerical reports found in specialized literature regarding the optimal selection and location of fixed-step capacitor banks with a low computational burden. All the simulations were carried out in MATLAB software.
Electrical equipment will experience a rise in temperature during normal operation. During a development process, prototypes and laboratory tests will be required to make sure the temperature rises ...are within acceptable limits as defined by standards. The aim of having a tool to predict the temperature rise, is to reduce the number of prototypes and test loops needed in the laboratory during a development period. Advanced simulation tools such as CFD can give valuable results, however, they require expertise user and extensive compute and manpower allocation. This paper presents a practical design approach developed for providing a first, quick and rough estimate of the temperature rise of the most critical parts in an air insulated switchgear. The main idea behind the method is to first use the method described in IEC 60890 to estimate the temperature rise of the gas inside the switchgear. Then, simplified heat transfer calculations are used to estimate the over-temperature of critical parts relative to the surrounding gas. The accuracy of the temperature estimates will depend on how well the power input is known, especially the contact resistances. Further, it may be challenging to predict the influence of large metallic construction elements that may function as heat sinks.
This article proposes a control and modulation strategy for medium-voltage (MV) drives that exhibits excellent steady-state and transient behavior. Specifically, optimized pulse patterns (OPPs) and ...direct model predictive control are employed so that the associated advantages of both, such as minimum stator current total demand distortion (TDD) and fast transients, respectively, are fully exploited. To do so, the current reference trajectory tracking and modulation problems are addressed in a coordinated manner in the form of a constrained optimization problem that utilizes the knowledge of the stator current evolution-as described by its gradient-within the prediction horizon. Solving this problem yields the optimal real-time modification of the offline-computed OPP, which guarantees that very low-and close to its theoretical minimum value-stator current TDD is produced at steady state, and very short settling times during transients. To highlight the effectiveness of the proposed strategy, a variable speed drive system consisting of a three-level neutral point clamped inverter and an MV induction machine serves as a case study.
Considering single-phase to ground (SPG) faults accounting for more than 80% of all faults, neutral ineffectively grounded mode (NIGM) is the most promising choice for medium voltage (MV) islanded ...microgrids (MGs) to enhance operation reliability. But due to the weak fault current and flexible network topology of islanded MGs, it is difficult to detect SPG fault lines. To solve this issue, this paper firstly analyzes the SPG fault characteristics of the MV islanded MGs with different NIGMs and network topologies. It is found that the looped MGs have a virtual terminal, i.e., the point where zero-sequence current (ZSC) is zero. And the feature differences between fault and non-fault lines are revealed. Based on that, an SPG fault line identification method is proposed. The main criterion is constructed based on the skewness signs of high frequency zero-sequence voltage (ZSV) and ZSC. Additionally, the fundamental amplitude of the difference between the actual ZSC received from another terminal and the ZSC calculated from local ZSV and ZSC is used to formulate an auxiliary criterion. Finally, the effectiveness of the proposed method is validated in a 10kV islanded MG model considering different NIGMs, different fault conditions, arc grounding faults, and the influences of the line parameter, operating point and measurement noises.
Multilevel converter topologies for open-end stator winding medium-voltage (MV) induction motor drives have been researched from the last two decades. In this paper, a dual n-level modular multilevel ...converter (MMC) topology has been proposed for open-end stator winding MV induction motor drives. The control requirements of the proposed system are low device switching frequency, minimal harmonic distortion of machine stator currents, elimination of common-mode voltages in machine stator windings, and maintaining floating capacitor voltages around their nominal value. Based on these requirements, an emerging modulation technique for MV induction motor drives known as synchronous optimal pulsewidth modulation has been developed for the proposed dual nL-MMC topology. The laboratory measurements from a dual three-level MMC fed 1.5-kW open-end stator winding induction motor drive demonstrate the performance of proposed technique.
INTRODUCTION: The field of mechanical engineering technology is an emerging technical field with many research directions, and there are many directions of intersection with other disciplines, among ...which the field of mechanical engineering has outstanding research advantages. With the continuous development of mechanical engineering technology, the research direction of mechanical engineering applied to the field of mechanical engineering is also continuously enriched and developed. Mechanical engineering research focuses on realizing the monitoring and control of the dynamic performance of mechanical systems, as well as realizing the integration of design and system control. OBJECTIVES: In order to improve the disassembly efficiency, reduce the disassembly cost and disassembly energy consumption, it is optimized using social engineering methods to achieve better results and reduce the disassembly cost and energy consumption. METHODS: Aiming at the drive and anti-skid control strategy of four-wheel hub motor, it was simulated using improved social engineering algorithms, and based on this, three road recognition algorithms were selected for low, medium, and high adhesion road verification. RESULTS: Through the study of automobile anti-skid control system, the basic structure of automobile anti-skid control system is summarized and some solution measures are proposed. A new type of drive anti-skid control system is proposed for the problems of high vibration and noise of automobile brake. The drive anti-slip control system is characterized by simple structure, easy maintenance, simple control and reliable operation, and high operation efficiency. CONCLUSION: This study shows that the system not only has excellent drive anti-slip effect, but also has good control performance. In addition, this drive anti-slip system is able to ensure the safe and reliable operation of mechanical brakes in various harsh environments. This new drive anti-slip control system is a new type of drive device that can be widely used for driving force on various mechanical brakes and drive wheels, and the study of this device is of great significance.
The business of distribution system operators is rapidly evolving as the distribution grid is hosting more distributed energy resources. Technology for monitoring, control, and protecting the grid is ...progressively pervading the lower segment of the network. These changes require a performing communication infrastructure to enable data exchange among the control centers of the grid. The 7th Framework Program European Project INTEGRIS proposes a hybrid infrastructure-based on broadband power line (BPL), Wi-Fi, and fiber optics (FO)-to enable services for grid management. This mix of technologies provides a balanced tradeoff between investments and benefits, meeting most of the requirements of the smart grid. This paper investigates the technologies that could be adopted and describes the experimental assessment performed in an operational environment in Italy. Using this installation, transfer time, time synchronization accuracy, dependability, and throughput are evaluated and analyzed over a long-term campaign. Results show that the FO is the best communication media, able to provide a two-way latency of 3 ms (95 percentile), whereas BPL has a two-way latency of 57 ms (95 percentile -4 hops). Those results confirm that a careful selection of the technologies is required to satisfy requirements of smart grid.
Sulfur hexafluoride (SF6) is a manmade gas widely used as an insulating gas in high voltage applications and the power industry. In 1937, GE introduced SF6 as an insulation gas in the electric ...industry; since then, SF6 has become ubiquitous in medium-voltage (MV) and high-voltage (HV) equipment. Among its key attributes are its intrinsic non-toxic, non-corrosive, and non-flammable nature, in addition to its superior stability over a wide operating window, good thermal conductivity, high dielectric strength, and excellent arc quenching capabilities. These properties make it particularly amenable as an insulating and arc-quenching gas in electrical equipment and as a result, over 90% of gas-insulated switchgear globally uses SF6 as the insulating gas. Despite its widespread use in the power industry, the largest contribution to SF6 emissions is the high energy density community.
Hollow cathodes are efficient plasma sources and have been used in a wide variety of applications including electric propulsion, surface processing and plasma-material interaction studies. Recently ...General Electric in collaboration with Princeton PPPL have been working on a hollow cathode based medium voltage circuit breaker that can enable point to point meshed grid using DC current transmission necessary for integrating renewable energy sources, such as wind and solar.
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