High Voltage Power Research Articles

The three-level inverter topologies analysis for application by electric centrifugal pump units

In the article, the schemes for providing AC power with frequency conversion for the induction submersible electric drive of oil production units are analyzed. The electric submersible drive is widely used and has stringent efficiency requirements, so this research is relevant. The centrifugal pump units are composed of a low-voltage power source, a frequency converter, a step-up transformer, a cable line, an electric drive and a centrifugal pump. This article discusses options for replacing the step-up transformer and two-level voltage / frequency converter with a three-level flying capacitor converter (FCC) or a three-level clamping diode converter (NPC). The expected states of the power high voltage IGBT modules are described. The waveforms of the inverter output voltage and the submersible induction motor stator voltage in different circuits are shown. A voltage levels analysis for each module is done, the electric drive starting time change is estimated, the total harmonic distortions (THD) are calculated, and a 1.1% THD reduction by applying the NPC circuit is shown. The harmonic current spectrum for each circuit is presented.

Optimal Placement and Sizing of Wind Turbine Generators and Superconducting Magnetic Energy Storages in a Distribution System

High penetration of intermittent wind-turbine generation (WTG) into electric distribution system along with large variations of load demand introduce many problems to the system such as high power losses, voltage sag, and low voltage stability. To mitigate such problems, the distribution system is supported by superconducting magnetic energy storages (SMESs). This paper is aimed at determining the optimal placement and sizing of WTGs and SMESs in a distribution system using a proposed multi-objective-function based optimization method. The method is a hybrid one being based on an efficient algorithm called Equilibrium Optimizer (EO) along with loss sensitivity factor (LSF). The weighted-sum multi-objective function (IMO) is formulated for simultaneous minimization of energy-loss and voltage-deviation as well as enhancement of voltage-stability as indices characterizing the distribution system performance. The weight factors are no longer assumed or left open to the preferences of the decision maker. They are computed while optimizing the indices of the IMO in order to determine the optimal placement and sizing of WTGs and SMESs. The proposed method for optimal placement and sizing of WTGs and SMESs is tested and validated on the standard IEEE 33-bus distribution system with time-varying voltage-dependent load models including residential, industrial, commercial, and mixed loads as well as variable wind-speed. The results obtained using EO algorithm are compared with those obtained by particle swarm optimization (PSO) and genetic algorithm (GA) to validate the effectiveness of EO. The numerical results and simulations imply that the combination of WTGs and SMESs can successfully achieve minimization of energy-loss and voltage-deviation as well as enhancement of voltage-stability, and thereby significantly improve the performance of distribution system.

Arm current reversal‐based modular multilevel DC‐DC converter

Nowadays, most of the converters used in high-power high-voltage (HV) applications are the conventional modular multilevel converters (MMC). However, in the case of DC-DC conversion, an imbalance of the capacitor voltages occurs and the conventional MMC fails to operate correctly. This paper introduces an arm current reversal-based modular multilevel DC-DC converter, which successfully provides balance among the capacitor voltages while operating in DC-DC conversion. The proposed configuration is used in medium voltage DC grids to feed DC loads or to interconnect between two DC grids of different voltage levels. The proposed converter is a two-stage DC-DC modular converter, which consists of a single-phase half-bridge MMC with half-bridge submodules (HBMMC) followed by a single-phase H-bridge MMC with half-bridge submodules (SMs). The operational concept of the proposed converter is based on reversing the arm current direction and reversing the output terminals with the help of the H-bridge MMC stage, which ensures the same direction of the voltage at the load terminals. The proposed converter provides a high conversion ratio, bidirectional power flow, simple architecture, and a simple control scheme. Detailed illustrations, analysis, and design of the proposed converter are presented. Besides, MATLAB-based and Opal RT-based simulation results and experimental results are presented to validate the proposed configuration claims.

Crosstalk Suppression in Monolithic GaN Devices Based on Inverted E-Field Decoupling

A novel structure of inverted electric-field decoupling (IED) to suppress the lateral crosstalk in monolithic gallium nitride (GaN) devices is proposed in this article. The IED structure features a Schottky metal in the trench between high-voltage power and low-voltage logic GaN devices, which is lined with nitride passivation and electrically connected with an on-chip integrated negative voltage supply ( ${V} _{-}$ ). The IED structure forms the inverted electric fields ( ${e}$ -fields) against the power device exerted ones, which can reduce the local ${e}$ -fields at logic devices, decouple the monolithic devices, and suppress the lateral crosstalk. The calibrated TCAD simulation has been carried out for 100- and 650-V rating monolithic GaN devices with IED structure. During the blocking state of power device, the crosstalk current can be suppressed to negligible percentages over the current of power device by ${V} _{-} V, while in switching operations, both the crosstalk current and gate voltage in the logic device can be effectively suppressed. Possible false turn-on can be eliminated when ${V} _{-} V for 100-V rating and ${V} _{-} V for 650-V rating. The IED structure demonstrates high feasibility with a large process window. The proposed IED structure is promising for solving the crosstalk problems in high-frequency and highly integrated monolithic GaN devices and integrated circuits (ICs) for power conversion applications.

Non-conventional Cascade Multilevel Inverter with Lower Number of Switches by Using Multilevel PWM

The multilevel inverter is attracting the specialist in medium and high voltage applications, among its types, the cascade H bridge Multi-Level Inverter (MLI), commonly used for high power and high voltage applications. The main advantage of the conventional cascade (MLI) is generated a large number of output voltage levels but it demands a large number of components that produce complexity in the control circuit, and high cost. Along these lines, this paper presents a brief about the non-conventional cascade multilevel topologies that can produce a high number of output voltage levels with the least components. The non-conventional cascade (MLI) in this paper was built to reduce the number of switches, simplify the circuit configuration, uncomplicated control, and minimize the system cost. Besides, it reduces THD and increases efficiency. Two topologies of non-conventional cascade MLI three phase, the Nine level and Seventeen level are presented. The PWM technique is used to control the switches. The simulation results show a better performance for both topologies. THD, the power loss and the efficiency of the two topologies are calculated and drawn to the different values of the Modulation index (ma).

A REVIEW OF STUDY AND ANALYSIS OF PARTIAL DISCHARGE FOR DIFFERENT INSULATION MATERIALS WITH CAPACITANCE VALUE

In the high voltage (HV) electrical power system, a variety of solid, liquid and gaseous materials are used for insulation purposes to protect incipient faults within the HV power equipment. Among these, solid insulation is widely used for high voltage equipment in high voltage power systems. Most insulation materials are not perfect in all respects and always contain some impurities. In high voltage (HV) electrical equipment, the quality of the insulation plays a very important role. Continued growth in the power system has provided the opportunity to protect equipment for healthy operation throughout its useful life.

Pareto Frontier of the Arm Energy Ripple and the Conduction Losses of a Modular Multilevel Converter

Modular multilevel converters can achieve high power quality and voltage ratings, becoming a good alternative for high-voltage direct-current applications. However, the circulating current and capacitor voltage ripple remain significant drawbacks, mainly due to the impact on efficiency and power density. In this work, a stationary operation of a modular multilevel converter is optimized by calculating the Pareto frontier of the arm energy ripple and the conduction losses for different operating conditions. From the set of optimal solutions, the best trade-off between energy ripple and power losses can be chosen depending on the application requirements. Therefore, an optimal operating point regarding capacitor voltage ripple and circulating current was found, optimizing efficiency and allowing a reduction of capacitance, hence size and cost. The theoretical analysis and results are validated experimentally on a prototype test-bench.

Non-Isolated n-Stage High Step-up DC-DC Converter for Low Voltage DC Source Integration

The dc-dc converters with high step-up DC-voltage gain play a vital role in integrating low voltage DC sources. Though several converter topologies are reported in the recent past, attempts have been made to reduce the components, especially the switching devices, passive elements, converter losses, etc., of the converter. A novel DC-DC converter topology, viz., single switched impedance network (SSIN)-based converter with n-stage is proposed in this paper. The operation of the SSIN based converter in continuous and discontinuous conduction modes are discussed. The effect of parasitic elements on DC-voltage gain and efficiency of the SSIN is carried out. The small-signal model of the SSIN converter is derived. The performance of the SSIN converter is compared with the similar converter topologies. The 500 W prototypes of the SSIN with n = 1 and n = 2 are fabricated, and the experimental results are presented in this paper. To improve the converter performance, SiC-based semiconductor devices are used. The SSIN converter with two-stage has low switch loss at 500 W load, improved efficiency during high power and high output voltage operation, the switch stress of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> /2, etc.

Risk assessment of a solar attack according to ISO 31000 standard

Energy supply remains the greatest challenge for many of Eastern European countries and their economy. In post-soviet and ex-Yugoslavian countries, till today there exists a system where some of the power plants rely on high voltage (HV) and medium voltage (MV) power grids in the process of distribution of electric energy (EE) to final consumers. This makes them vulnerable to solar storms due to HV power transformers which are especially sensitive to geomagnetic induced current (GIC). The acquisition of electrical power infrastructure could put the electrical infrastructure out of service from a couple of months to a year or more. Loss of income, for ordinary families, is a primary hazard of a long power outage. Business continuity of industry and other critical infrastructures (CI) is important in this scenario, but it is a significant challenge for small businesses and enterprises as well. This paper introduces ISO 31000 standard to such scenarios with the primary goal of achieving resilience of companies against such disaster as a new method of vial response to avoid scope of similar hazards.

Research of Motor Soft Start by High Voltage Motor Drive Inverter

The over-current phenomenon of direct starting of high voltage and high power motor is serious bad for the safety of motor. We are usually using motor soft start method when we need to start a motor. There are some motor soft start methods, they can somehow reduce the starting over-current, but they are still having some defects except motor drive inverter. Motor drive inverter can not only realize the purpose of energy saving, but also is an ideal soft start device. We can see a lot of papers about control method research of motor drive inverter, but no paper research on motor soft start by motor drive inverter [1]. This paper focuses on research of motor soft start by motor drive inverter. The optimal frequency range of soft start is obtained through theoretical analysis. The simulation results verify the correctness and feasibility of the theoretical analysis.

Analysis, identification and design of robust control techniques for ultra-lift Luo DC-DC converter powered by fuel cell

In recent years the development of alternative energy source is getting more importance because of high quality characteristics in power generation system with low cost. The proliferation of DC-DC converter is widely used for high power and low voltage applications. In such cases, the ultra-lift Luo converter is the suitable one compared to voltage lift VL Luo-converter and super-lift (SL) Luo-converters because of their limitations in voltage transfer gain and more voltage ripples. This paper proposes the proportional integral (PI) and fuzzy logic (FL) controllers for the fast and efficient operation of ultra-lift (UL) Luo-converter. An air breathing fuel cell (ABFC) stack is developed and which is taken as an input power source to the ultra-lift Luo-converter. This paper will give focus on design, mathematical analysis and operation of fuel cell powered DC-DC converter is incorporated with PI and FL controllers which are simulated using MATLAB/Simulink software. Furthermore, simulation results of ABFC are also presented to review the effects of temperature from 30°C-70°C in fuel cell voltage. The dynamic response of PI and FL controllers are sifted for line as well as load voltage regulations and the simulation results are presented using MATLAB/Simulink.

Partial Power Conversion and High Voltage Ride-Through Scheme for a PV-Battery Based Multiport Multi-Bus Power Router

With the development of renewable energy technology, distributed power supply mode with multi energy and multi-directional power flow including utility grid, renewable energy and energy storage unit has gradually become a research hotspot. An AC/DC hybrid multi-port power routing (MPPR) system which based on partial power conversion (PPC) of dual DC buses is proposed in this paper. The photovoltaic (PV) port, the battery port and two DC voltage buses form a power router. PV maximum power point tracking (MPPT) and high-voltage ride through (HVRT) of the grid-tied inverter are implemented by the same auxiliary port voltage modulation. The PPC based PV conversion features that only the power determined by voltage difference between PV panel and the series connected DC bus is dealt with, which significantly reduces the loss compared to the full power conversion (FPC) for PV. The detailed control schemes of all converters and energy transmit are given. The simulation and experimental results verify the effectiveness of the proposed scheme.

Digital models of advanced high-voltage traction power supply systems

Digital models of advanced high-voltage traction power supply systems

Research on Zero Value Detection Technology of Porcelain Insulator

High-voltage insulators are one of the devices widely used in power systems, and their pros and cons are directly related to the safe and stable operation of the power system. The large-tonnage UHV insulator AC withstand voltage detection method is restricted by conditions at the engineering site, and the detection efficiency is low and difficult to implement. The research on the method of detecting UHV zero-value insulators using high-voltage pulses and the development of portable detection devices are of great significance. This article has completed the portable insulator detection device using a miniaturized high-voltage pulse test power supply. The developed portable UHV zero-value insulator detection device can effectively judge zero-value, low-value and high-value UHV insulators, and adapt to large quantities of UHV insulators. Requirements for efficient testing.

A Power Supply for a Gas-Discharge Laser Based on a Lithium–Polymer Battery

The results of experimental studies are presented and the experience of operating the power supply of a continuous gas laser, which is based on a lithium–polymer storage battery without an intermediate voltage converter, is analyzed. The long-term (more than 4-year) operation of a high-voltage battery power supply as a component of a laser system with an open-circuit voltage of 7.76 kV, a load voltage of 6.1 kV, a load current of up to 250 A, a power higher than 1.5 MVA, and a stored energy of 550 MJ is demonstrated. The response time of the switch for disconnecting the load in the case of breakdowns in the discharge chamber did not exceed 120 μs. The results of measurements of the internal resistance of the batteries and its changes during operation are presented.

ОСОБЕННОСТИ ОРГАНИЗАЦИИ МАЛОСЕРИЙНОГО ПРОИЗВОДСТВА ЖЕЛЕЗОБЕТОННЫХ ИЗДЕЛИЙ С ИСПОЛЬЗОВАНИЕМ ИХ ЭЛЕКТРОТЕПЛОВОЙ ОБРАБОТКИ ТОКАМИ ПОВЫШЕННОЙ ЧАСТОТЫ

The organization of the technological process of manufacturing concrete products with the use of electrothermal treatment with high-frequency currents at both large and small industrial enterprises is considered. This technology is also useful for winter concreting and field concrete work. The technology is based on the use of a centralized high-frequency power supply, made using high-power transistor voltage converters, for simultaneous processing of several products. A pilot plant for the implementation of such a technology and the results of an experiment with its use are presented. The plant capacity was estimated based on the developed work schedule. Using the example of manufacturing foundation blocks of the FBS 12.4.6 type, it is shown that the actual schedule of work on the manufacture of products using electrothermal treatment with high-frequency currents leads to the fact that the power consumed from the supply network has a relatively small value (13.2 kW), which almost any enterprise can afford.

Design and implementation of flyback converter as high voltage power supply for nanofibers production

Electrospinning is widely used method to produce nanofibers from the polymer solutions. Nanofibers are produced by loading polymer solutions into the syringe pump and applying a high voltage supply in the order of 5 kV–50 kV between the tip of needle and grounded collector. This paper presents the fabrication of low power high voltage power supply (HVPS) using flyback converter. It also demonstrates the mathematical modeling and simulation of flyback based low power HVPS. Mathematical modeling of flyback converter suggests that the output voltage depends on duty ratio, switching frequency and input supply voltage. Simulations are performed to visualise the behaviour of flyback based HVPS. From simulation results, a constant ripple free DC voltage of 5 kV is achieved. Flyback Converter is fabricated using 555 timer and TL494 IC as PWM generator. From 555 timer IC based HVPS, approximately 2 kV is achieved. High voltage of 5 kV is achieved using TL494 IC which varies non-linearly with increase in frequency for duty ratio above 40%. This work will be helpful to researchers for designing ripple free HVPS by appropriately selecting duty ratio and frequency.

Najczęściej występujące uszkodzenia fundamentów słupów linii elektroenergetycznych najwyższych napięć i sposoby ich napraw

W pracy omówiono zagadnienia związane z trwałością fundamentów słupów linii elektroenergetycznych najwyższych napięć (NN) oraz przedstawiono sposoby ich renowacji. W części badawczej przeprowadzono diagnostykę wybranych fundamentów słupów linii NN (400 kV) Wielopole–Noszowice. W trakcie wizji lokalnej ustalono, że istnieją odpryski i niewielkie ubytki powierzchniowe betonu, a w niektórych przypadkach ubytki otuliny zbrojenia bez widocznych wżerów. Na podstawie stopnia uszkodzeń określono zakres napraw niekonstrukcyjnych oraz zabezpieczeń antykorozyjnych, przedstawiając kolejne etapy ich realizacji.

A High Efficiency Linear Power Supply with Pure Sine Wave for High Voltage Test

The input part of the high-voltage test power supply is usually composed of switching devices; however, the pulse-type periodic interference caused by the switching devices makes the monitoring of the test power supply partial discharge more difficult. Therefore, this paper proposes a high-efficiency and distortion-free linear power supply based on piecewise-linearization with all N-type transistor. Under the same DC input, multiple power transistors are connected to different taps of the same transformer. By controlling the period of linear conduction of each power transistor in turn, we ensure that the power transistor works on the linear side (biased towards saturation) to reduce its conduction voltage drop and the output realizes sinusoidal piecewise linearization, so that the converter can greatly improve the system efficiency. After that, from the perspective of the lowest sum of the transistor loss, an optimization method for the design of the multi-winding transformer ratio at each stage is proposed. Finally, a power supply prototype based on four-piece linear converter with an output voltage of 220 V was built. The experimental efficiency reaches 87.03%, and, additionally, if the linear amplification is divided into more sections, the efficiency can be further improved.

Research on VRM in RF PA System Based on Enhancement Mode GaN HEMT

As a key part of the RF PA system, VRM (Voltage-Regulate-Modulator), whose main role is to offer pulse voltage for RF power transistor, is often slighted. As a result, VRM has been a restraining factor now. In order to realize the needs of high speed and high frequency, a new method based on enhancement mode GaN HEMT of designing VRM is proposed in this paper. By using this method, the rise time and fall time of VRM could be as about 10ns with the peak voltage 75V and the peak current 150A, which is quite suitable for driving high voltage and high power GaN-based RF power transistor.