Independent Electric Power Research Articles

Analysis of the System Impact upon Thyristor Controlled Series Capacitor Relocation Due to Changes in the Power System Environment

Owing to geographical and political influences, Korea has an independent electric power system and the highest density of electric power facilities in the world. Large-scale base power generation complexes are located in non-metropolitan coastal areas, while the most expensive combined cycle power plants are operating or under construction in the metropolitan areas, which have the largest electricity demand. It has become difficult to secure a site for power plants, and the existing power transmission network is insufficient because of the additional construction of generators in existing power generation complexes, the increase in capacity of facilities, and the rapid increase in new and renewable energy. In particular, the East Coast region has a problem of transient stability for this reason, which is being addressed in advance through power generation restrictions. In addition, TCSC (Thyristor Controlled Series Capacitor) is installed and operated to expand the capacity of existing power transmission lines and improve stability in the failures of nearby high-voltage lines until new transmission lines that take more than 10 years are installed to resolve power generation restrictions. However, after the construction of a new transmission line, the efficiency of the existing TCSC is degraded, and for efficient use, it is necessary to rearrange the installation location to utilize the optimal TCSC according to changes in the configuration of the nearby power system. Moreover, a detailed analysis is needed on whether the TCSC designed according to the existing grid configuration exhibits accurate control performance even after the relocation and whether it interferes with nearby generators. In addition to the dynamic performance based on real-time simulations, it is necessary to study the control performance and interaction for this power electronic equipment. This study verified the need to change controller parameters, the interaction effect with nearby generators for stable operation, and the system effect of TCSC relocation using the same replica controller as the actual field controller, as well as RTDS (Real Time Digital Simulation) simulating the entire power transmission system.

Hot-Wire Laser-Directed Energy Deposition: Process Characteristics and Benefits of Resistive Pre-Heating of the Feedstock Wire

This study investigates the influence of resistive pre-heating of the feedstock wire (here called hot-wire) on the stability of laser-directed energy deposition of Duplex stainless steel. Data acquired online during depositions as well as metallographic investigations revealed the process characteristic and its stability window. The online data, such as electrical signals in the pre-heating circuit and images captured from side-view of the process interaction zone gave insight on the metal transfer between the molten wire and the melt pool. The results show that the characteristics of the process, like laser-wire and wire-melt pool interaction, vary depending on the level of the wire pre-heating. In addition, application of two independent energy sources, laser beam and electrical power, allows fine-tuning of the heat input and increases penetration depth, with little influence on the height and width of the beads. This allows for better process stability as well as elimination of lack of fusion defects. Electrical signals measured in the hot-wire circuit indicate the process stability such that the resistive pre-heating can be used for in-process monitoring. The conclusion is that the resistive pre-heating gives additional means for controlling the stability and the heat input of the laser-directed energy deposition.

Energy Development and Energy Policy in Developing Countries in the Context of Globalization

The article is devoted to the problem of the development of independent electric power systems in elaborating countries under the conditions of growing power stuff deficit. Economic and electric-power policy that aids to active consumers’ and independent manufacturers’ formation at the world market of power manufacturing is the subject of the investigation. A separate section is devoted to the reviewing of the technologies of energy and the scientific potential of the countries, their ability to form the power agenda independently and rationally on the basis of their own stuff, technology and science resources.

Development of technology for a long-term monitoring and automatic data acquisition system

The Central Research Institute of Electric Power Industry conducted research to develop a long-term monitoring technology to clarify pore water pressure and water chemistry in drilled boreholes. An automatic data acquisition system for the long-term monitoring was also developed. The automatic data acquisition system has an independent electric power supply and data communication system. The electric power is supplied from solar and wind power. The data communication is secured through a satellite or 3G/4G line. A very low power consumption system can be readily installed by creating personal area networks between measuring devices using Zigbee digital radio. A demonstration of the system was conducted under harsh natural conditions for 18 months. It was confirmed that the system has sufficient reliability for actual operation.

Thermodynamic analysis of a novel sodium hydroxide-water solution absorption refrigeration, heating and power system for low-temperature heat sources

A novel sodium hydroxide-water solution absorption refrigeration, heating and organic Rankine cycle power system is proposed for low-temperature heat source utilization. The sodium hydroxide-water solution absorption refrigeration is employed as top cycle which directly absorbs heat from low-temperature heat source. While R218 organic Rankine cycle and heating subsystem are adopted to produce power and heating as designed in bottom cycles. Under the considered condition, model results indicate that refrigeration, heating and electricity efficiency are 0.8244, 0.4019 and 0.03437 with the capacity of 945.2, 460.8 and 39.41 kW, respectively. Energy and exergy efficiency of refrigeration, heating and electricity are also theoretically analyzed with various condensation temperature, evaporation temperature, turbine inlet pressure, split ratio and mass fraction of rich sodium hydroxide solution. Sensitivity of parameters to system performance is also analyzed and results indicate that energy and exergy efficiency are remarkably influenced by operating parameters. A comparison between the proposed system and three independent electrical refrigeration, heating and power systems shows that the proposed system has superior performance and the maximum primary energy saving ratio can reach approximately 0.4889. In conclusion, with the multi-productions of refrigeration, heating and electricity, the proposed polygeneration system provides a more rational and effective energy utilization from a single low temperature heat source at suitable level.

Characteristics of a fish aggregating device with ocean energy harvester

Fishes are easy to be gathered around fish aggregating devices (FADs), which is an environment-friendly artificial ocean infrastructure. This study has proposed and developed a new type of FAD with a current turbine to generate an independent electric power for navigational and environmental sensors, especially at archipelago areas with fishery and aquaculture. A mooring type of FAD with a horizontal axis turbine (HAT) or a vertical axis turbine (VAT) was designed to avoid an unexpected collision with fishes. The characteristics of fluid force on FAD were investigated by numerical and theoretical works assuming steady state in time and the motions of FAD were also examined by experimental works. The proposed FAD can achieve 15% reduction for averaged snap load and 30% for maximum one. The amplitudes of surge, sway and heave motions excited by vortex-induced vibration (VIV) in wave-current conditions can be reduced up to 50%. The current flow around FAD and designed turbine was computed by CFD to estimate hydrodynamic force and vortex field. The numerical results in the fluid force are in overall agreement with the experimental and theoretical ones. Moreover, generated electric power by the optimized turbine was estimated at a typical archipelago area in Indonesia. The first model of FAD without turbine was built up and has been installed in real ocean field.

Reliability-based design optimization of passive poison injection system (PPIS) for advanced heavy water reactor

In nuclear power plants (NPPs), the use of passive safety systems such as accumulators, condensers, evaporative heat exchangers, and gravity driven cooling systems provide enhanced safety and reliability. In addition, they eliminate the huge costs associated with the installation, maintenance and operation of active safety systems that require multiple pumps with independent and redundant electric power supplies. As a result, passive safety systems are preferred in advanced reactor concepts. In current NPPs, safety systems which are not participating in day–day operation, are kept isolated, require a signal to open the valve. It is proposed to replace these valves by passive components and devices such as self-acting (passive) valves, rupture disks, etc. Some of these innovative passive valves, which do not require external power, have been recently designed, developed and tested at rated conditions. These valves are proposed to be used in several passive safety systems of indigenous advanced heavy water reactor (AHWR). One crucial and important passive safety system which has been designed for AHWR is passive poison injection system (PPIS). Since it is passive, it not only provides higher reliability, but also ensures safe shutdown of the reactor in case of insider threats or malevolent acts leading to disabling and failure of wired shutdown systems of the reactor. Since the passive systems developed are meant for nuclear reactor applications, they must be reliable enough for its desired operation under all reactor operating conditions. As these systems are indigenously designed with no prior plant operating experience, assessment of reliability of passive systems is an important task for ensuring extensive use in nuclear power plants. In view of this, it is necessary to define a roadmap for estimation of reliability of passive systems to be used in AHWR. As a case study, the reliability assessment has been carried out for passive poison injection system of AHWR. Two failure modes of PPIS namely, (1) probability of failure on demand and (2) probability of spurious actuation of system are considered. Analysis has been carried out for evaluating the demand failure probability and spurious injection probability for five proposed schemes for design comparison. An experimental facility along with prototype of passive valve named as poison injection passive valve (PIPV) has been successfully developed for demonstration of PPIS of AHWR. Based on the F-distribution, testing scheme for valve was suggested: minimum of 9088 cycles, if no failures are observed or 14,360 cycles, if one failure is observed to ensure the target unavailability of 3.3E−4 with 95% confidence. This paper briefly describes about the passive shutdown system, i.e., PPIS and its reliability assessment along with the probable configurations of active and passive valves under development for AHWR.

Optimal Selection and Arrangement of Cables for Compact Overhead Transmission Lines of 138/230 kV

The use of compact overhead transmission lines are promising alternatives for high voltage transmission in urban areas. The cost of right of way acquisition for new projects is prohibitive in some cases. So, the use of existent right of way as a corridor of large amount of energy is interesting in the environment point of view and is very economic. This paper presents a new methodology developed for optimizing the project of compact overhead transmission lines with multiple circuits. This methodology comprises the selection of both bare wire conductors and earth-wires, its spatial arrangement, the topology of the tower for circuits under voltages of 138kV and 230kV. In this work, two independent electrical power for each voltage level are considered. The problem is formulated as a constrained many objective optimization, which is solved using evolutionary optimization techniques. To aid the decision maker in the choice of the non-dominated solution at the end of the optimization process, a decision making procedure is proposed. The result point out to structures with narrow right of way and high efficiency when compared to conventional transmission line.

Intelligent vehicle electrical power supply system with central coordinated protection

The current research of vehicle electrical power supply system mainly focuses on electric vehicles (EV) and hybrid electric vehicles (HEV). The vehicle electrical power supply system used in traditional fuel vehicles is rather simple and imperfect; electrical/electronic devices (EEDs) applied in vehicles are usually directly connected with the vehicle’s battery. With increasing numbers of EEDs being applied in traditional fuel vehicles, vehicle electrical power supply systems should be optimized and improved so that they can work more safely and more effectively. In this paper, a new vehicle electrical power supply system for traditional fuel vehicles, which accounts for all electrical/electronic devices and complex work conditions, is proposed based on a smart electrical/electronic device (SEED) system. Working as an independent intelligent electrical power supply network, the proposed system is isolated from the electrical control module and communication network, and access to the vehicle system is made through a bus interface. This results in a clean controller power supply with no electromagnetic interference. A new practical battery state of charge (SoC) estimation method is also proposed to achieve more accurate SoC estimation for lead-acid batteries in traditional fuel vehicles so that the intelligent power system can monitor the status of the battery for an over-current state in each power channel. Optimized protection methods are also used to ensure power supply safety. Experiments and tests on a traditional fuel vehicle are performed, and the results reveal that the battery SoC is calculated quickly and sufficiently accurately for battery over-discharge protection. Over-current protection is achieved, and the entire vehicle’s power utilization is optimized. For traditional fuel vehicles, the proposed vehicle electrical power supply system is comprehensive and has a unified system architecture, enhancing system reliability and security.

Hardware Implementation of Voltage Control for Self Excited Induction Generator Used in Small Power Generation

With the development of controlled converter circuits and the rapid growth of independent electric power station, the self-excited induction generator (SEIG) is increasingly being used for different small power generation systems. This paper investigates the analysis and implementation of a control scheme for maintaining a single phase load RMS voltage and frequency constant, fed by self-excited induction generator under variable speed and load. The proposed control is useful for isolated small power applications such as uncontrolled small hydro turbine or wind turbine. Experimental results confirm good performance and the effectiveness of the proposed control.

Design and development of innovative passive valves for Nuclear Power Plant applications

The recent Fukushima accident has resulted in an increased need for passive safety systems in upcoming advanced reactors. In order to enhance the global contribution and acceptability of nuclear energy, proven evidence is required to show that it is not only green but also safe, in case of extreme natural events. To achieve and establish this fact, we need to design, demonstrate and incorporate reliable ‘passive safety systems’ in our advanced reactor designs.In Nuclear Power Plants (NPPs), the use of passive safety systems such as accumulators, condensing and evaporative heat exchangers and gravity driven cooling systems provide enhanced safety and reliability. In addition, they eliminate the huge costs associated with the installation, maintenance and operation of active safety systems that require multiple pumps with independent and redundant electric power supplies. As a result, passive safety systems are preferred for numerous advanced reactor concepts. In current NPPs, passive safety systems which are not participating in day to day operation, are kept isolated, and require a signal and external energy source to open the valve. It is proposed to replace these valves by passive components and devices such as self-acting valves, rupture disks, etc.Some of these innovative passive valves, which do not require external power, have been recently designed, developed and tested at rated conditions. These valves are proposed to be used for various passive safety systems of an upcoming Nuclear Power Plant being designed by India. For example, the Hot Shutdown Passive Valves (HSPV), developed for the decay heat removal system keep the main heat transport system under hot conditions by passively sensing and controlling the system pressure. Another crucial and important valve which has been successfully developed is the Poison Injection Passive Valve (PIPV) for the Passive Poison Injection System. It not only provides higher reliability, but also ensures safe shutdown of the reactor in case of insider threats or malevolent acts in disabling active shutdown system of the reactor.Recently, an innovative valve called the Accumulator Isolation Passive Valve (AIPV) has been developed for the Emergency Core Cooling System (ECCS), which is engineered to mitigate the consequences of Loss of Coolant Accident (LOCA). During normal operation of the reactor, the pressurized accumulators (55bar) are kept isolated from the reactor core (70bar) by means of AIPVs. In case of a LOCA, these passive valves open when the main heat transport system pressure falls to a desired value. For prolonged cooling of the core, these passive valves regulate the discharge in a desired manner. These are non-standard, high pressure and high temperature valves, which are unavailable commercially and hence have to be indigenously designed and developed.This paper primarily deals with the design, development and testing of Accumulator Isolation Passive Valves (AIPV) proposed to be used in the ECCS. A 25NB size AIPV has been designed and successfully tested at Integral Test Loop (ITL) under simulated reactor conditions. It is a self-acting, ANSI 600 rating valve, which requires no external energy (i.e., neither air nor electrical power). It not only provides passive isolation but also passively controls high pressure liquid discharge through it. The design concept of the valve, functional performance, in situ valve testing methodology and the test results at simulated conditions are discussed.

大規模災害時におけるDTN技術を用いた複合的な船陸間災害情報共有ネットワークの提案と評価－可搬型DTN基地局による検討－

By the Great East Japan Earthquake in 2011, some base stations of telephones and cellphones suffered serious damages, so that afflicted people had difficulty communicating with each other. Since ships are equipped with some communication devices including satellite together with an independent electric power, they have a capability to help people to obtain and share important information immediately after a disaster. Therefore, a system for sharing information between disaster victims and supporters and preventing the second accident is required for ships. Previously, there are some literature on WiFi networks between ship and shore. However, nothing on how to construct information sharing networks between a ship and a disaster-stricken area. The purpose of this paper is to propose and evaluate hybrid information sharing networks between ship and shore by using DTN technology for large-scale disasters. We constructed and evaluated those using portable DTN base stations and DTN tablet stations between Ishinomaki port and Ishinomaki port office, Ishinomaki port office and Hiyoriyama park. Those systems were suggested effective to facilitate information sharing between a ship and a disaster stricken area.

New Battery Balancing Circuit using Magnetic Flux Sharing

To increase the capacity of secondary cells, an appropriate serial composition of the battery modules is essential. The unbalance that may occur due to the series connection in such a serial composition is the main cause for declines in the efficiency and performance of batteries. Various studies have been conducted on the use of a passive or active topology to eliminate the unbalance from the series circuit of battery modules. Most topologies consist of a complex structure in which the Battery Management System (BMS) detects the voltage of each module and establishes the voltage balancing in the independent electrical power converters installed on each module by comparing the module voltage. This study proposes a new magnetic flux sharing type DC/DC converter topology in order to remove voltage unbalances from batteries. The proposed topology is characterized by a design in which all of the DC/DC convertor outputs connected to the modules converge into a single transformer. In this structure, by taking a form in which all of the battery balancing type converters share magnetic flux through a single harmonic wave transformer, all of the converter voltages automatically converge to the same voltage. This paper attempts to analyze the dynamic properties of the proposed circuit by using a Programmable Synthesizer Interface Module (PSIM), which is useful for power electronics analysis, while also attempting to demonstrate the validity of the proposed circuit through experimental results.

A NEW METHOD FOR CALCULATING TRANSIENT ELECTROMAGNETIC RESPONSES OF AC/DC POWER SYSTEM WITH EXTERNAL ELECTROMAGNETIC PULSE INTERFERENCE

In this paper, a new method for calculating transient electromagnetic responses of AC/DC power system with external electromagnetic pulse interference is proposed. An input-output model of three-phase bridge rectifler is presented for the transient calculation. In order to study the efiect of the external electromagnetic pulse on the system, the fleld-to-line coupling model is introduced, and flnite-difierence time-domain method is adopted. Thus, the modeling method utilizes the analysis methods of the electric circuits and electromagnetic flelds synthetically to deal with the coupled fleld-circuit problems. The model and algorithm are validated by comparing the calculation results with the experiment ones. Finally, the efiects of some circuit parameters on transient responses are discussed. The method proposed in this paper lays the foundation for further researches on the transient electromagnetic performance of independent electrical power systems containing power electronics.

A PARAMETRIC STUDY AND PERFORMANCE EVALUATION OF DC ELECTROMAGNETIC PUMPS WITH BEMC-1 CODE

Electromagnetic pumps are used to control liquid metal fluid flow in cooling loops. The principle of operation of an electromagnetic pump is based on Lorentz’s force. This is obtained by interaction of the magnetic field and the electrical current, imposed and adjusted by independent external electric power sources. In this work are presented the continuous current electromagnetic pumps, their basic equations and the BEMC-1 code, developed for design and performance evaluation of a DC electromagnetic pump. The main objective of this paper is a parametric study for magnetic induction, static pressure, fluid flow and performance evaluation of the pump. The theoretical results are compared with the experimental data to get adjust factors to be used in the BEMC-1 code. In this way the BEMC-1 code can be validated and used in the evaluations and projects of DC electromagnetic pumps.

A Simulation-based Spectral Technique for Power Quality and EMC Design of an Independent Power System

A novel simulation-based spectral technique for power quality and electromagnetic compatibility (EMC) design of an independent electrical power system (EPS) has been proposed. Power filter optimization problem has been formulated to provide full solution of the electric power quality and conducted EMI problems in the EPS. The spectral technique has been implemented within a CAD tool. An example of power quality and EMC design has been provided for an independent EPS where an AC power source generates a power, which is comparable to the consumed power, and an additional power filter is calculated for an electronic product including a switch-mode power supply. Current and voltage spectra calculations have been verified with a block-oriented simulation program Simulink. Numerical experiments revealed a number of important features of the proposed spectral technique.

Investigation of a model HTSC transformer with amorphous alloy cores

There are presented the main principles of development of HTSC transformer intended for the individual tests and for investigation within the electrodynamic model of a power network and within the independent electric power installation. The model single-phase transformer incorporates two concentric HTSC windings and circular cores of amorphous alloy and anisotropic steel tapes. It was tested in LN 2 medium and permits to evaluate the developed technological processes. Experimental investigations showed amorphous alloys display relatively low level of losses in the magnetic core as compared to anisotropic steel. The combination of epoxy impregnated fiber glass tapes and liquid nitrogen showed acceptable electrical properties of electrical insulation of HTSC windings. The critical current of the windings was close to the critical current of short samples of Bi-2223 tape.

インターネット型自律分散電力システム(エネルギー・ネットワークシステム,<メカライフ特集>エネルギー)

インターネット型自律分散電力システム(エネルギー・ネットワークシステム,<メカライフ特集>エネルギー)

A linear programming methodology for the optimization of electric power-generation schemes

A mathematical model, based upon the application of a linear-integer programming algorithm, is presented for the optimum selection of independent electric power generation schemes in industrial power systems, taking into account reliability considerations. The problem is formulated as a mathematical programming problem, considering investment costs, fuel costs, operation and maintenance costs, power balance, maximum and minimum limits on the generated power of the units, as well as reliability considerations such as the unavailability of the generation scheme. These considerations include assumptions taken and simplifications performed in order to obtain an accurate enough linear model. The problem is solved using a conventional branch and bound algorithm for linear-integer programming, yielding to the optimum number of units, as well as the correspondent size and type. Results are presented for the application of the proposed methodology to a real case of an industrial power system. The technique is proved as a valuable tool for the planning engineer.

A Linear Programming Methodology for the Optimization of Electric Power Generation Schemes

A mathematical model, based upon the application of a linear-integer programming algorithm, is presented for the optimum selection of independent electric power generation schemes in industrial power systems, taking into account reliability considerations. The problem is formulated as a mathematical programming problem, considering investment costs, fuel costs, operation and maintenance costs, power balance, maximum and minimum limits on the generated power of the units, as well as reliability considerations such as the unavailability of the generation scheme. These considerations include assumptions taken and simplifications performed in order to obtain an accurate enough linear model. The problem is solved using a conventional branch and bound algorithm for linear-integer programming, yielding to the optimum number of units, as well as the correspondent size and type. Results are presented for the application of the proposed methodology to a real case of an industrial power system. The technique is proved as a valuable tool for the planning engineer.