As the applications of Magnetohydrodynamic (MHD) energy conversion, research and development for high-efficiency and low emission electric power generation system, MHD accelerations and/or MHD thrusters, and flow control around hypersonic and re-entry vehicles are introduced. For closed cycle MHD power generation, high-efficiency MHD single system is the most hopeful system and space power system using mixed inert gas (MIG) working medium is proposed. For open cycle MHD, high-efficiency coal fired MHD system with CO2 recovery has been proposed. As inverse process of MHD power generation, MHD accelerators/thrusters are expected as the next generation propulsion system. Heat flux reduction to protect re-entry vehicles is expected by an MHD process for safety return from space missions.
Advanced energy storage systems have been widely applied to industries and are being installed at large buildings and factories to realize efficient energy usage. This paper presents a control method of load frequency control and distribution network control (loss reduction control) using a part of customers' owned battery capacity. When 10% of total battery capacity of 100MW in the network of 30GW generator capacities is used for load frequency control, a total of 1500MW generation units for load frequency control, at maximum, can be stopped without deterioration of power quality. In addition, when batteries are used for loss reduction of distribution network, 2% of loss on a summer day can be reduced. To realize both effects in maximum, the novel integrated control algorithm is proposed and its economical effect is evaluated by numerical simulations.
In this paper, we assume 2 models for securing reserve capacity. One is “Commitment-based Security Model” and the other is “Reserve Market-based Security Model”. In Commitment-based security model, ISO commits procurement of reserve energy to a particular generation company. Meanwhile, in Reserve market-based security model, ISO procures reserve energy through reserve market. The main object of this research is to investigate which model will be preferable for the viewpoint of consumer's cost. To compare these models, two things are considered in this paper. One is bidding behavior of agents which bids to energy market and reserve market. To consider this, Q-Learning of multi-agent model is used. Also, the Unit Commitment (UC) is considered to calculate generation cost. This is to calculate the cost for securing reserve power more precisely.
There are many commercial power system analysis packages available on the market. Although most of these tools are typically computationally efficient, they do not provide the flexibility and ability to simulate generic models of generators or networks. This is cumbersome for research and development purposes. The development of power system models of appropriate fidelity is a key aspect of power system simulation processes. The models must allow all relevant multi-disciplinary modeling criteria, e.g. model structure and data handling, to be computed efficiently, easily, and with sufficient accuracy. This paper presents how the adoption of recent technology on object-oriented physical systems modeling can be implemented with an integrated power system analysis package MidFielder. Used in combination with MidFielder, this can provide the completeness of power system analysis package for industrial, educational and research purposes. In order to realize the proposed interface system, this paper also discusses about methods to manage a large set of power system data by using database technology and means of graphical user interface (GUI).
This paper discusses reverse power flow from a home co-generation system (H-CGS) in terms of energy conservation and influence on electric power systems. Data of actual electricity and hot-water demand observed in a family including 2 adults and 2 children for a year was used as a case study for a typical installation. When the reverse power flow is allowed with the exception during mid-night, considering the influence on electric power system, the reduction in annual primary energy consumption can be increased by about 40% relative to that in the operation without reverse power. The reverse power flow is large during the daytime in winter-season, because the power output of H-CGS is large for meeting large hot-water demand. Even if the reverse power is allowed throughout a day, the primary energy conservation is almost same with that in part time reverse power operation, while the reverse power during mid-night is as large as that during daytime. Finally, the economic value of reverse power flow as a measure for reducing CO2 emission was evaluated. The result shows the economic value of reverse power flow in PR operation corresponds to 23,000 yen/t-C.
This paper discusses an eigenvalue estimation method suitable for wide-area and real-time stability monitoring of large power systems. Eigenvalues corresponding to electromechanical dynamics can be obtained from system matrix identified based on synchronized measurements of rotor angles and rotor speeds of generators and load fluctuations. One problem to actualize the eigenvalue estimation is high equipment cost of measuring enormous number of load fluctuations. In the paper, in order to solve the problem, we propose a new concept of pseudo load model which is assumed to express dynamical characteristics of loads. By introducing the load model, the composite dynamics of power systems and loads is identified from the synchronized measurements of only machines. Even if the load fluctuations do not have white noise characteristics, the eigenvalues can be obtained based on the composite dynamics identification. In the paper, the effectiveness of the pseudo load model in eigenvalue estimations is confirmed by simulation studies using 3-machine power system model.
This paper deals with experimental investigation on a novel fault location method using air-gap flux distributions of a synchronous generator connected to a power system. Air-gap fluxes are the sum of field fluxes and armature reaction fluxes. Changes in armature current and field current at fault contribute directly to the armature reaction fluxes and field fluxes, then resultant air-gap fluxes. Therefore, air-gap fluxes can be utilized to locate fault. Wavelet analysis is applied to induced voltages of search coils which are wound around a stator tooth top for measurement of air-gap flux. It is shown that fault type and location are estimated from the change of search coil voltages measured during fault.
Undesirable operation of zone 3 impedance relay (mho relays) is a possible factor for causing cascading failure as seen in several previous large scale blackouts, where power flow redistribution and power swing caused by outage or switching operations satisfy the condition for the relay operation. So far, the condition itself has not fully been investigated, and therefore, there has been little attempt to avoid the relay operation by means of direct power flow control. This paper analyzes the condition for zone 3 relay operation from the viewpoint of its sensitivity to power flow. An operating margin for security is defined for each relay to carry out effective monitoring. It is newly pointed out that undesirable operation can be effectively avoided by reactive power controls as well as real power controls. The method to compute the operation margin is also given through the analysis of the optimal Var location to control the operation margin. Effectiveness of the proposed method is demonstrated using the IEEE test systems.
A high efficiency cogeneration system (CGS) is proposed for utilizing high temperature exhaust gas (HTEG) from a gas engine (GE). In the proposed system, for making use of heat energy of HTEG, H2O turbine (HTb) is incorporated and steam produced by utilizing HTEG is used as working fluid of HTb. HTb exhaust gas is also utilized for increasing power output and for satisfying heat demand in the proposed system. Both of the thermodynamic characteristics of the proposed system and a gas engine CGS (GE-CGS) constructed by using the original GE are estimated. Energy saving characteristics and CO2 reduction effects of the proposed CGS and the GE-CGS are also investigated. It was estimated that the net generated power of the proposed CGS has been increasd 25.5% and net power generation efficiency 6.7%, compared with the the original GE-CGS. It was also shown that the proposed CGS could save 27.0% of energy comsumption and reduce 1137 t-CO2/y, 1.41 times larger than those of GE-CGS, when a case syudy was set and investigated. Improvements of performance by increasing turbine inlet temperature were also investigated.
We have performed fault current limiting test using YBCO thin film and investigated reason of the destruction during current limiting. Destruction phenomena of the film are two patterns. One occurred immediately after current limiting and the other one occurred during current limiting. In a phenomena of destruction, quench propagation velocity almost doesn't change as against increases of energy consumption per unit time, energy consumption per unit area increases as energy consumption per unit time increases. Therefore, local part of the film reaches dissolution temperature and arc occurres. As a result, it is considered that the performance of the film is improved by decreasing energy consumption per unit time. Thus, we connected parallel capacitor to the film for limiting energy consumption per unit time. Consequently, the performance of the film in current limiting will be improved.
An etching fuse is used for semiconductor protection, and is expected to have higher current breaking performance in smaller size. This paper describes test results of etching fuses having three kinds of element patterns to improve current breaking performance. The first kind concerned the additional plating on the current conducting (heat radiation) part of the element, while the thickness of plating at current breaking part remained as it was. Test results showed that this pattern made the element resistance lower compared with no additional plating element, and thus the improvement of current rating up to approximately 30% could be achieved. The second kind concerned the increase in the number of parallel current breaking points (P) of fuse element. Experiments revealed that the cut-off currents and the I2t values decreased with the number of P. The third concerned the prolongation of breaking part and the increase of the number of series breaking points (S). Test results exhibited that the increase of S was slightly effective in current breaking performance rather than the extension of breaking part. Current breaking characteristics of these element patterns are useful in improving the etching fuse performance for semiconductor protection use.
In Japan, lightning damage to FRP blades of wind turbine generators has been increasing in parallel with the recent increase in the installation of wind turbine generators. Therefore, we established a test method, while clarifying the destructive climate of lightning, and examined a method of preventing destruction. A high-voltage test clearly showed that lightning easily penetrates FRP that is not processed to be conductive. Moreover, after developing a test method, an examination with a large current successfully reproduced blade damage, and revealed the failure mechanism, which explains breakdowns of actual machines. If lightning penetrates a FRP blade, the air temperature inside the blade rises. As a result, pressure increases and the blade is damaged. Moreover, the breakdown of positive polarity (winter) lightning can be examined with a large current that is generated by a short circuit generator.