• Journal of Electrical Engineering and Technology
• /
• v.6 no.2
• /
• pp.161-166
• /
• 2011

This paper proposes an algorithm for determining critical generator lists using accelerating power and synchronizing power coefficient (SPC), and critical generator group (CGG) from CGG candidates, which is a combination of critical generators. The accurate determination of CGG provides a more accurate energy margin while providing system operator with information of possible unstable generator group. Classical transient energy function (TEF) method selects the critical generators with big corrected kinetic energy of each generator at the moment of fault removal. However, the generator with small acceleration after fault, that is, the generator with small corrected kinetic energy, is also likely to belong to CGG if the generator has small synchronizing power. The proposed algorithm has been verified to be effective compared with the classical TEF method. We utilized the power system of Korean Electric Power Corporation(KEPCO) as a test system.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.6
• /
• pp.306-314
• /
• 2005

In this paper, a new approach that is based on EEAC & only with network solutions for CS&S in the transient stability assessment is developed. The proposed CS&S algorithm in conjunction with EEAC to include the capability of performing on-line TSA without TDS is used to calculate the critical clearing time for stability index. In this algorithm, all generators are represented by classical models and all loads are represented by constant impedance load models. The accelerating & synchronizing power coefficient as an index is determined at its disturbance through solving network equation directly. As mentioned above, a new index for generator is generally used to determine the critical generators group. The generator rotor angle is fixed for non-critical generators group, but has equal angle increments for critical generators group. Finally, the critical clearing time is calculated from the power-angle relationship of equivalent OMIB system. The proposed CS&S algorithm currently being implemented is applied to the KEPCO system. The CS&S result was remarkably similar to TSAT program and SIME. Therefore, it was found to be suitable for a fast & highly efficient CS&S algorithm in TSA. The time of CS&S for the 139 contingencies using proposed CS&S algorithm takes less than 3 seconds on Pentium 4, 3GHz Desktop.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.8 no.2 s.21
• /
• pp.58-66
• /
• 2005

This paper presents miniaturized setback generators based on the conversion of mechanical energy into electrical energy for military applications, especially power supply for electronic fuzes. In order to minimize the volume of setback generators, a ring-shaped magnet enclosing a coil assembly is adopted. A mechanical safety system, shear plate, is used as a release mechanism of the setback generators to prevent the generators from operating accidentally. The setback generators are intended not to ignite an electrical detonator but to charge a capacitor which is capable of driving electronic circuit of fuze. We design the setback generators using the simulation results of an electromagnetic analysis tool, $Maxwell^{(R)}$ 2D. In experimental study, we perform safety tests of the shear plate and firing tests of the fabricated setback generators. The present setback generators show that the voltage of 14.2V is charged at the capacitor of $30{\mu}F$ within the charging time of 0.68msec and the critical acceleration for safety is 5,000G, thus verifying that the setback generators with a ring-shaped permanent magnet can be applicable to the power supply of small-caliber electronic fuze.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.11
• /
• pp.1897-1904
• /
• 2008

In this paper, the method for effective stability analysis of Jeju power system in 2011 is proposed. The stability analysis of Jeju power system was carried out by using proposed method In case of Jeju power system with wind turbine generators or without wind turbine generators, including CSC HVDC or VSC HVDC. The steady-state stability is validated by SCR and ESCR, PV curve, QV curve. And the transient stability is analyzed by CCT(Critical Clearing Time). VSC HVDC has more advantages than CSV HVDC on the stability. Also, Jeju power system without wind turbine generators has more advantages than Jeju power system with Wind Turbine Generators on the stability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.5
• /
• pp.2388-2392
• /
• 2013

Wind generation systems are very different in nature from conventional generation systems. Therefore it is necessary to research dynamic characteristics of wind generation systems connected to a power system. The stability analysis of wind turbine generator is an important issue in the operation of the power system. The result of angular stability of the power system that consists of only synchronous generators is different from that of the power system including wind turbine generators. This is due to the fact that generators connected to wind turbines are generally induction generators. The angular stability assessing synchronization of generators is determined by its corresponding critical clearing time(CCT). Wind turbine models for the analysis of power system are varied and difficult to use, but now these are standardized into four types. In this paper, the analysis of the CCT of the power system connected to wind farm considering the location and capacity is performed by using DFIG(Doubly-Fed induction Generator) wind turbine built-in type3 model in PSS/E-32.

• Journal of the Korean Solar Energy Society
• /
• v.23 no.3
• /
• pp.29-35
• /
• 2003

Generator for wind power can be either synchronous or asynchronous (induction) types. Induction and synchronous generators behave in a different way when subjected to severe faults. Induction generators does not have an angle stability limit and short circuit in the neighborhood of an Induction generator causes the demagnetization of the machine when the fault is cleared, the voltage raises slowly, while the grid contributes with reactive power to the generator and the magnetic flux recovers. On the other hand in the synchronous generators the recovery of the voltage is immediate, since the excitation of the rotor angle comes from an independent circuit. This paper shows the result of the transient state analysis in the network connected to wind generation system Several case studies have been conducted to determine the effect of the clearing time of a fault on the network stability. It has been found that the critical clearing time can be as low as 61ms in the case of induction generator compared to 370ms in the case of synchronous generator.

• KEPCO Journal on Electric Power and Energy
• /
• v.5 no.3
• /
• pp.229-233
• /
• 2019

Large-scale High Temperature Superconducting (HTS) wind power generators suffer from high electromagnetic force and high torque due to their high current density and low rotational speed. Therefore, the torque and Lorentz force of HTS wind power generators should be carefully investigated. In this paper, we proposed a Performance Evaluation System (PES) to physically test the structural stability of HTS coils with high torque before fabricating the generator. The PES is composed of the part of a pole-pair of the HTS generator for estimating the characteristic of the HTS coil. The 10 MW HTS generator and PES were analyzed using a 3D finite element method software. The performance of the HTS coil was evaluated by comparing the magnetic field distributions, the output power, and torque values of the 10 MW HTS generator and the PES. The magnetic flux densities, output power, and torque values of the HTS coils in the PES were the same as a pole-pair of the 10 MW HTS generator. Therefore, the PES-based evaluation method proposed in this paper can be used to estimate the critical characteristics of the HTS generator under high magnetic field and high torque before manufacturing the HTS wind turbines. These results will be used effectively to research and manufacture large-scale HTS wind turbine generators.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.4B no.4
• /
• pp.157-169
• /
• 2004

Motor & generator operation at widely variable speeds is needed in various applications but hybrid and electric vehicle (HEV) stand out today, as quite a few companies are launching this year their mass production of HEVs. The quest for better starter-generators is far from ended, though. The present review paper unfolds a comparative critical evaluation of various starter-generators and their control for HEV. Induction, interior PM synchronous, transverse-flux PM synchronous, switched reluctance, together with claw-pole and biaxial excitation PM synchronous (BEGA) configurations with their control are all considered in system evaluations.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.593-595
• /
• 2003

The introduction of electricity industry provides generators incentives to recover the related cost through the market. Hence, the generator should sell his/her electricity at high market-clearing price with optimal operation of his/her power plant. The maintenance of power plant is the most critical factor in affecting generators' decision-making. This paper analyzes technique for establishing maintenance schedule reflecting recovery cost and considers differences in monthly load pattern in minimizing LOLP.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.32 no.2
• /
• pp.59-64
• /
• 1983

This paper deals with the transient energy method of transient stability analysis of multi-machine power system by improving the transfer conductance, the kinetic energy and the critical transient energy. The tranfer conductance is considered more correctly, the generators of system are seperated to two states (critical and the rest state)and the correction term of critical transient energy (to reference point) is added. This analysis is performed by digital computer simulation and the application of this method to two model systems has shown its superiority to other available methods.