Experimental studies on power system stability of a superconducting generator with high response excitation

Nitta, T.; Okada, Takao; Shirai, Yoshihito; Kishida, Takuya; Ogawa, Yoshihiro; Hasegawa, Hiroshi; Takagi, Kunihiko; Matsumoto, H.

doi:10.1109/59.589760

Cited by 17 publications

(6 citation statements)

References 4 publications

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“…This type of SCG has a special characteristic, SMES effect (6) , which can contribute to improve power system stability. It needs to be considered in selection process of locations and specific parameters.…”

Section: Discussionmentioning

confidence: 99%

Installation Schemes of Superconducting Generators in Power Systems

Sae-Kok¹,

Yokoyama²

2007

IEEJ Trans. PE

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Superconducting generator (SCG) with superconducting field winding offers various advantages, such as high efficiency, smallsize light weight, and so forth. A prominent one is to improve system stability and voltage stability owing to decreased synchronous reactance compared with conventional generators. Installation of SCGs in the power systems becomes one of the topics that should be considered. It concerns how and where SCGs should be installed and parameters setting of machines and controllers. Many conventional generators in power systems have been operated for many years and they have been nearly about to be reinstalled; replacement of conventional generators by SCGs in power systems might be a possible idea for the locations. It should be noted that it is not practical to replace all conventional generators by SCGs from economic and technical viewpoints; it is, however, necessary to determine appropriate locations and parameters such as synchronous reactance X d of as small as possible number of SCGs. In addition, control parameters such as gain values of AVRs and speed governors should also be selected appropriately.A method for determining optimal locations and synchronous reactance X d of SCG with low response excitation for stability enhancement in multi-machine power system has been proposed in Ref.(1). Eigenvalue sensitivity based parameter optimization technique has been employed to determine optimally synchronous reactance X d and used a specific rule that any generator which has a final synchronous reactance X d less than a threshold value is considered to be the SCG installing location and the determined synchronous reactance is used as the synchronous reactance X d of the SCG. In addition, gains of AVRs and speed governors of generators are also determined by the same parameter optimization technique. However, the method is found to have two main flaws. The first one is at the specific rule that the synchronous reactance of any generator which is not replaced by SCG is set back to the original values; that causes this method not to guarantee that the determined locations are optimal. The second one is that transient open-circuit time constant, which is comparatively very large because of near zero resistance of field winding has not been considered in optimization process. Such method should be modified or improved to obtain more reliable and systematic algorithm.In this paper, new methods for determining optimal locations and parameters of SCGs under multiple load flow conditions in multimachine power system for the purpose of dynamic stability improvement are proposed. Two new methods for installation schemes of SCG with low response excitation are proposed. The method type 1 uses the observation of global inter-area mode and approximated eigenvalue sensitivity to determine installation indices used to determine the SCG location. Synchronous reactance X d (X q ) and transient open-circuit time constant T do are determined later by eigenvalue sensitivity based parameter optimization technique....

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Section: Discussionmentioning

confidence: 99%

Installation Schemes of Superconducting Generators in Power Systems

Sae-Kok¹,

Yokoyama²

2007

IEEJ Trans. PE

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“…It can enables very rapid change in field current and the magnetic flux due to the change of the field current can reach the armature winding quickly. The excitation power by the quick change of field current is large and has a rapid change enough to affect the conditions of power system in self-excited operation of the generator (2) . Since the field winding is made of superconducting wire and is connected to the generator terminal through AC-DC converter, the field winding coupling with the converter can be considered as superconducting magnetic energy storage (SMES); hence, the effect of the exciter coupling with the AC-DC converter is called "SMES effect".…”

Section: Inroductionmentioning

confidence: 99%

“…In single machine to infinite bus system, influence of SCG * Department of Electrical Engineering, The University of Tokyo 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 with high response excitation on power system stability and its control system have been experimentally studied (2) ; high response excitation control of SCG with high response excitation for stability of superconducting field winding has been conducted (3) . In multi-machine power system, calculation methods of the equilibrium state considering SMES effect of the power flow and dynamic simulation of multi-machine power system including SCG with high response excitation and control system design based on energy function for SCG have been proposed (4) .…”

Section: Inroductionmentioning

confidence: 99%

Excitation Control System Design of High Response Excitation Type Superconducting Generator for Improving Power System Dynamics

2005

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MemberSuperconducting generator (SCG) with superconducting field winding has many advantages such as small size, light weight, high generation efficiency. A prominent advantage is to improve power system stability owing to lower synchronous reactance compared with the conventional generator. High response excitation type SCG has a rotor with thermal radiation shield without damping effect; it can enable very rapid change in field current and the magnetic flux due to the change of the field current can reach the armature winding quickly. The excitation power is large and has a rapid change enough to affect the conditions of power system in self-excited operation of the generator. This effect is equivalent to the effect of a superconducting magnetic energy storage (SMES), then so-called "SMES effect", and it is expected to contribuite to transient stabilty improvement. In this paper, excitation control system design for high response excitation type SCG in consideration of SMES effect is proposed for improving power system dynamics by employing eigenvalue sensitivity. The SMES effect is considered to couple with the power system as a nonlinear load. The control performance of the proposed excitation control system is examined in IEEJ East 10-machine and West 10-machine systems. It is made clear that the SMES effect of SCG is utilized effectively and results in both transient and dynamic stability improvement. However, the performance depends on the locations of SCGs and fault contingencies.Keywords: superconducting generator, high response excitation, excitation power, SMES, power system stabilizer, excitation system InroductionSuperconducting generator (SCG) with superconducting field winding offers various advantages, such as high efficiency, small size, light weight, and so forth. A prominent advantage is to improve power system stability owing to the lower synchronous reactance compared with the conventional generator (1) . High response excitation type SCG has a rotor with thermal radiation shield without damping effect for screening time-varying magnetic flux to enter the field winding part. It can enables very rapid change in field current and the magnetic flux due to the change of the field current can reach the armature winding quickly. The excitation power by the quick change of field current is large and has a rapid change enough to affect the conditions of power system in self-excited operation of the generator (2) . Since the field winding is made of superconducting wire and is connected to the generator terminal through AC-DC converter, the field winding coupling with the converter can be considered as superconducting magnetic energy storage (SMES); hence, the effect of the exciter coupling with the AC-DC converter is called "SMES effect". It is expected that high response excitation type SCG using appropriate excitation control system can improve power system dynamics by effectively utilizing the SMES effect.In single machine to infinite bus system, influence of SCG

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“…In the steady state operations, however, the large AVR gain reduces the power system stability margin. Therefore, PSS (Power System Stabilizer) is necessary and AVR function has dead-band to switch the gain from for small disturbances to for large disturbances [5].…”

Section: A Scg With High Response Excitation Control and Smes 1) Expmentioning

confidence: 99%

Experimental study on system stability evaluation in parallel running of a superconducting generator and a SMES

Shirai

Nitta

Yamada

2002

IEEE Trans. Appl. Supercond.

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Parallel running operation of 100 kVA Superconducting Generator (SCG) with high response excitation and 0.4 MJ SMES (Superconducting Magnet Energy Storage) was carried out. The exciter capacity of the high response excitation is rather large compared with that of conventional generators. The exciter controller, that is, AVR (Automatic Voltage Regulator) and PSS (Power System Stabilizer) are designed taking the exciter power change at the excitation into account to improve the system stability. The SMES can also improve the power system stability. The SMES can give the small active power modulation of sinusoidal wave to the system. The system responses due to the SMES power modulation were observed and analyzed in order to evaluate the designed control functions of AVR, PSS and SMES. Frequency characteristics of the designed control functions were obtained from on-line data of the system. The system stability of parallel running of the SCG and the SMES was evaluated by use of SMES power control.

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Experimental studies on power system stability of a superconducting generator with high response excitation

Cited by 17 publications

References 4 publications

Installation Schemes of Superconducting Generators in Power Systems

Installation Schemes of Superconducting Generators in Power Systems

Excitation Control System Design of High Response Excitation Type Superconducting Generator for Improving Power System Dynamics

Experimental study on system stability evaluation in parallel running of a superconducting generator and a SMES

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