Electronic Frequency Converter Research Articles

Interconnection Control of Electronic Frequency Converters to Prevent Overvoltage Caused by Three-Phase Unbalanced Power

Interconnection Control of Electronic Frequency Converters to Prevent Overvoltage Caused by Three-Phase Unbalanced Power

Study on Interconnecting Operation Control of Electronic Frequency Converters for Shinkansen Realizing the Replacement of Rotary Frequency Changers

Study on Interconnecting Operation Control of Electronic Frequency Converters for Shinkansen Realizing the Replacement of Rotary Frequency Changers

High-Pressure Positive-Displacement Hydraulic Pumps in Concrete Sample Testing Machines

This article discusses a way to solve the problem of operational quality control of concrete in the construction of critical structures with the use of small-sized testing machines. To reduce the testing machines size, it is proposed to use a high-pressure hydraulic drive. As a promising way to control the machine, the practical experience is described of using a pump with a constant displacement, the drive of which uses an electronic frequency converter.

О современных решениях машинно-электронных генерирующих систем для малой энергетики и подвижных объектов

It is often believed that wind energy today is not always a profitable (in business terms) electricity generating technology. There is no doubt, however, that this environmentally clean technology with an inexhaustible resource implies its widespread use not only in the near future, but also nowadays under the appropriate conditions. In the final analysis, the interests of national security play a decisive role here, and, hence, the priority in solving the problem of power supply availability and the country’s security through the development of small-scale power generation (including, above all, the development of wind and hydropower industries) remains to be decided at the state level. Higher reliability of autonomous power supply (APS) and the renewable nature of energy resources used by it are the factors determining the fundamental difference between the APS for geographically dispersed consumers that are located far away from centralized power lines. The first design-and-organizational objective, which should be addressed in a particular country, is to compile a map of the distribution of wind and hydropower resources, based on which the advisability of using this technology should be analyzed. The second objective is to use the most rational technical solutions for wind (hydro) electrical installations. The article considers the structures of alternative versions of installations that are presented only by a comprehensive electrical package in the form of a combined machine-and-electronic generating system of the «variable speed-constant frequency» type. Synchronous and asynchronous machines are considered as converters of mechanical energy into electrical energy. The second version implies the use of induction machines with a squirrel-cage rotor and with a phase rotor. The mechanical energy converters operate jointly with an electronic frequency converter, which can be embodied as two series-connected four-quadrant converters. The article presents a brief comparative analysis of five wind turbine structures operating autonomously and in parallel with the grid. The results of computer simulation of the most rational options are presented. The aim of the study is to give an idea to the developers about the modern solutions for constructing comprehensive electrical packages for wind power systems and to simplify the procedure of selecting the most rational solution.

Frequency-adjustable electric drive for energy saving and optimization of technological processes in electrical complexes

The relevance of the study lies in the search for energy-saving technologies. So, at present, the most common type of electric drive in industry is asynchronous, most of which are unregulated. Replacing an unregulated electric drive with an adjustable one in various units can significantly reduce energy consumption, increase the life of the mechanical part of the drive and improve the quality of the adjustable process parameter. The replacement consists in installing an electronic frequency converter between the network and the motor of the device. This device changes the rotational speed of the motor rotor by changing the frequency and amplitude of the supply voltage. The most common are frequency converters with an intermediate DC link. Such devices are built on electronic keys, which are made on IGBT (Insulated Gate Bipolar Transistor) transistors. Using the NI Multisim14 software, a model was created to determine power savings during the implementation of VFD.The paper gives the rationale for the introduction of a frequency-controlled electric drive (VFD) to optimize technological processes in electrical complexes and systems, in particular, a complete analysis of the energy efficiency of VFD application in pumped water supply systems is presented as an example. The calculation of its economic efficiency for a particular installation is also given.

Optimal Joint Energy and Secondary Regulation Reserve Hourly Scheduling of Variable Speed Pumped Storage Hydropower Plants

This paper presents a mixed integer linear programming model for the hourly energy and secondary regulation reserve scheduling of a price-taker and closed-loop variable speed pumped-storage hydropower plant, considering the energy losses due to the use of electronic frequency converters. The plant participates in the day-ahead energy market and in the secondary regulation service of the Iberian electric power system. The model is utilised to compare the income of the plant with and without considering the variable speed technology, with synchronous or asynchronous machines, with and without bypassing the frequency converter in generating mode, and with and without perfect information of the electric power system data. Numerical testing results demonstrate that the operation with the variable speed technology could help notably to enlarge the income of the power plant and that the secondary regulation reserve market might be the main source of revenue for the power plant.

CONTRIBUCIÓN DE UNA CENTRAL REVERSIBLE CON BOMBEO A VELOCIDAD VARIABLE A LA REGULACIÓN FRECUENCIA-POTENCIA DE UN SISTEMA AISLADO

The development of renewable energies is growing in recent years, promoted by many governments in response to climate change. The main drawbacks of renewable energies, come from uncertainty and variability in the short term of wind and solar radiation. For many years, pumped storage power plants have become one of the most important means to cover the lack of regulation, characteristic of aforementioned renewable energies. In addition, pumped storage power plants can nowadays be operated with variable speed, thanks to last decades improvements in electronic frequency converters. Converters are usually limited by electrical magnitudes (voltages or currents) but in some cases hydraulic limits can be more restrictive, as in high head power plants. The main objective of this work is to study the influence of a pumped storage power plant with variable speed on an isolated system, and to analyze how the hydraulic limits of the reversible turbine in pumping mode reduces the power plant regulation capacity. For this purpose, a dynamic model of the power plant and the isolated system has been developed by means of Matlab/Simulink. Some simulations are carried out and it is indeed stated that hydraulic characteristics constrain the possibility of the pumped storage power plant, to offer load-frequency regulation in the secondary market. Keywords: Pumped storage power plant, variable speed, load-frequency control, hydraulic stability limit, long penstock, simulation model

Application of Electronic Frequency Converter to the Shinkansen Railyard Power Supply

Application of Electronic Frequency Converter to the Shinkansen Railyard Power Supply

Review of maturing multi-megawatt power electronic converter technologies and reliability modeling in the light of subsea applications

The increasing demand for establishing deep water enhanced oil recovery systems for subsea boosting, power generation, transmission from remote subsea marine current turbine farms, efficient power transmission and operation of subsea dredgers and mining machines requires subsea based power conversion, as the subsea pumps, compressors and turbines need to be operated at varying power and voltage levels. Even though techno-economic studies indicate the absolute need for locating the multi megawatt power electronic converters in subsea, the recorded failure-in-time data of multi megawatt capacity industrial standard power converters are not encouraging. Reliability is the key factor, as subsea breakdowns lead to huge production losses, and system retrieval for repair and maintenance is very costly and time consuming. This paper reviews the present technical maturity of a typical industry standard 6MW capacity 6.6kV 3-level voltage source inverter based power electronic frequency converter, and describes a reliability model in the light of their use in subsea environments. Reliability modeling is done for different possible configurations, with Mean Time Between Failure as the driver. The results presented can be directly used by the system designers to select a suitable configuration based on the Mean Time Between Failure requirements. The results obtained provide confidence that a suitably configured multi megawatt power converter, when used in an oil filled enclosure in a deep water environment, could have an MTBF of more than twenty years.

Electronic Frequency Converter Feeding Single-Phase Circuit and Controlling Feeder Voltage With Fixed Power Factor Method for Shinkansen

In the Tokaido Shinkansen, the instantaneous feeding power of substations has increased because of the high-density train schedule and the improved acceleration performance of the rolling stock. If the load power of feeding substations increases any further, it will not be possible to maintain the feeder voltage when the power converter supplies only reactive power. In consideration of such a situation in the frequency conversion section, an electronic frequency converter that controls the ac voltage using a fixed power factor method was developed. The superiority of the proposed control method is confirmed with electromagnetic transient program calculations and field test results. The electronic frequency converter has been in operation since February 2009 with good performance, showing the success of the system development described in this paper.

Electronic Frequency Converter Controls A. C. Voltage Using Fixed Power Factor Method

In Tokaido Shinkansen, the power of a feeding substation increases in a short time because the train schedule is of high density and the acceleration performance of the rolling stock has improved. If the load power of the feeding substation increases further, the feeder voltage cannot be maintained when the power converter supplies only the reactive power. Because such a case was assumed in the frequency conversion section, we developed the Electronic Frequency Converter controls the A. C. voltage using the fixed power factor method. The Electronic Frequency Converter is under construction in the Numazu frequency conversion substation. We describe the domination of A. C. voltage control using the fixed power factor method.

Turbomolecular pumps with hysteresis motor for nuclear physics accelerators

A conventional turbomolecular pump utilizes an electronic power supply or frequency converter that provides start-up power (frequency ramp), speed regulation and protection controls dedicated to an individual turbo-pump. Nuclear physics accelerators or other large installations will benefit from a new concept, that provides a turbomolecular pump with an autosynchronous hysteresis motor that does not require an individual power supply. We describe a solution which allows groups of turbomolecular pumps to be operated from a central power source that provides a stable voltage and frequency supply. The turbomolecular pumps can be connected directly into the power source, significantly lowering the initial purchase and installation costs for large users of turbomolecular pumps.

Electronic frequency converters for precision measurements

Electronic frequency converters for precision measurements

On the use of crystal controlled synchronous motors for the accurate measurement of time.

Making use of the quartz frequency standard of the Dominion Observatory crystal clock an electronic frequency converter has been constructed that transforms the 50,000 cycle output of the crystal to a frequency of 60 cycles. Suitable amplification makes possible sufficient power for operating several standard 60 cycle motors and these are being used to drive printing and drum chronographs and for the operation of other types of recorders.