Turbine-generator Shaft System Research Articles

Diagnosis and Treatment of Burst Vibration Fault of Large Steam Turbine Generator Shaft System

Aiming at the burst vibration fault of a supercritical 600 MW steam turbine generator unit during the on-load operation, the characteristics of sudden vibration faults of the rotor system were compared and analyzed. By analyzing the weight-loss vibration response coefficient and the variation characteristics of the vibration vector, parts falling off fault at the low-low coupling of the rotor system were diagnosed. After inspection, it was confirmed that the burst vibration fault of the rotor system was caused by the falling-off of the blast baffle of the low-low coupling bolt. After the blast baffle was restored by hoisting the installation technique, the vibration of the steam turbine generator unit was stable during start-up and grid connection.

발전기 비동기 투입에 의한 터빈-발전기 축계 고진동 해소 사례

This paper presents the diagnosis and cause analysis method for the abnormal vibration of turbine generator shaft system that occur as a result of out-of-phase synchronization of a generator of the power plant. In addition, it introduces the practical example of correcting the generator high vibration to the power generation industry. The torque applied to the shaft system because of the out-of-phase synchronization was calculated, and the change in shaft vibration with respect to applied torque was analysed using the vibration signal analysis. Lastly, various corrective actions are explained for the shaft vibration reduction during planned preventive maintenance. The vibration was finally stabilized by replacing the generator shrunk-on coupling.

高压直流输电系统中次同步振荡研究综述

由于高压直流输电(HVDC)技术有着损耗小、线路造价低等优点，在我国电力系统中被广泛采用。但HVDC与汽轮发电机组轴系相互作用可能产生次同步振荡(SSO)，影响系统的安全稳定运行。本文以直流输电系统对次同步振荡的影响和抑制方法为立足点，对高压直流输电系统中次同步振荡研究进行综述。首先，比较了几种常用的HVDC数学建模方法。然后，总结了换流器触发方式、控制模式及控制参数等对次同步振荡的影响，并介绍了多直流运行、串补或其他电气设备与HVDC联合运行时的系统的次同步振荡特性。接着指出在HVDC整流侧的定电流控制器里附加次同步阻尼控制是一种最常用的抑制SSO的策略，并比较了常见SSDC的设计方法。本文还介绍了新型直流输电VSC-HVDC以及风电加入系统后对次同步振荡的影响。最后，结合电力系统的发展要求对高压直流输电系统的次同步振荡研究方向做出展望。 HVDC has been applied widely in power systems because it has some merits such as low loss, low line cost and so on. However, interaction between HVDC converters and turbine generator shaft system may cause subsynchronous oscillation (SSO) which threats the safety and stability of power systems. This paper is intended to make a survey on SSO in HVDC by proceeding from the influence of HVDC on SSO and corresponding suppression strategy. The common methods of HVDC mathematical modeling are compared first. Secondly, the paper summarizes the effect of HVDC converter trigger modes, control modes and control parameters on SSO. The SSO characteristics of multiple HVDC and HVDC combined operation with series compensation or other electrical equipment is also introduced. Then the most common suppressing strategy that is installing a supplementary subsynchronous damping control (SSDC) in the constant current controller of rectifier is pointed out. And the design approaches of SSDC are compared. Besides, the influences of VSC-HVDC and HVDC system including wind power on SSO are presented. Finally, vistas of research are projected into the future.

A Stochastic Analysis of Turbine Generator Shaft Torsional Torque considering Power System Load Capacity

Abstract: When the electrical disturbance occurs such as network fault, the circuit breaker clearing and reclosing operation are followed in power system. The fault current will affect to generator stator current and generator air-gap torque. The turbine shafts will also fluctuate, because the turbine is connected with the generator stator through electromagnetic forces. If this transient torque of turbine generator shaft system continues, the crack may be initiated in turbine generator shaft system and the shaft system break down. In general, there are two analysis methods that deterministic analysis method and stochastic analysis method. In this paper, the stochastic analysis method, which is considered circuit breaker operation time, is used for transient torque of turbine generator shaft system analysis by using ElectroMagnetic Transient Program (EMTP). The load capacity in power system is also considered because it is one of the influence factors, which decide magnitude of transient torque of turbine generator shaft system. Furthermore, through this stochastic analysis result, we derive zone of vulnerability for turbine generator protection aspects.

터빈 블레이드 모델링을 통한 터빈 발전기 축 시스템의 기계적 토크 응답 분석

터빈 블레이드 모델링을 통한 터빈 발전기 축 시스템의 기계적 토크 응답 분석

터빈 발전기 축 시스템의 다중 질량체 모델링을 통한 비틀림 응답 구현

터빈 발전기 축 시스템의 다중 질량체 모델링을 통한 비틀림 응답 구현

Analysis on Torsional Stresses in Turbo-Generator Shafts due to Two-Phase Short-Circuit Fault

Taking a 660MW turbine generator shaft system as a target system, the torsional stresses responses are calculated under two-phase short-circuit fault by the finite element (FE) method which can obtain torsional stresses in local areas accurately. The results show that torsional stresses threaten the safety of shafts appear at the first several cycles of the vibration. And the amplitude of stress in weak cross sections located between the low pressure cylinder and the generator is much greater. In addition, the proportion of torsional stresses frequency components in different sections is distinct. The results are helpful to improve the safety management level of the unit.

ACTIVE CONTROL SIMULATION OF TORSIONAL VIBRATION FOR TURBINE-GENERATOR SHAFT SYSTEM BASED ON GLOBALLY OPTIMAL CONTROL ALGORITHMS OF QUADRATIC REGULATOR

Global optimal control algorithms of linear quadratic regulator is combined with torsional vibration theory of turbine- generator shaft system, and torsional vibration energy of shaft system and control energy are chosen as performance index of active control. The global optimal control theory with linear quadratic regulator is brought about to control the tortional vibration of the large turbine-generator shaft system. And space state equations on active control of torsional vibration of turbine-generator shaft system are constructed. A solution way on Algebraic Ricatti Equation is proposed to determine the feedback control input matrix. This method is to construct a Hamiltonian matrix and solve its eigenvalue. A simulation program on active control of torsional vibration for discrete system is compiled and simulation analysis on active control of torsional vibration is carried out in a shaft system of 200 MW turbine-generator to examine the active control effectiveness. The results of time domain analysis on active control of torsional vibration show that employing the global optimal control theory of linear quadratic regulator can effectively decrease torsional vibration and control torque input.

A Methodology for Predicting Torsional Fatigue Crack Initiation in Large Turbine-Generator Shafts

This document presents results of a three-year program in which an analytical method was developed to estimate the cumulative fatigue damage sustained by a turbine-generator shaft system during a torsional transient. The work was conduted at the Steam Turbine-Generator Engineering and Manufacturing Department of the General Electric Company undr the sponsorship of the Electric power Research Institute (Proect RP1531-1). The product of this program was a methodology that used the results of analysis and torsional fatigue tests on 25.4 mm diameter laboratory specimens to predict the fatigue life of large-diameter shafts subjected to torsional transients. These predicted results were verified with 127 mm diameter specimens subected to simulated torsional transient load history tests. To account for complicated deformation cycles, range pair cycle counting and linear damage summation techniques were used. Notch root deformation response was characterized with a form of Neuber's rule. The results of tests of 25.4 mm and 127 mm diameter specimens showed that the proposed methodology characterized the torsional cumulative fatigue damage within a factor of two of the measured damage under laboratory conditions.

Investigation of the Torsional Performance of Superconducting Generators with an Advanced Network-Torsion-Machine Program

To investigate the torsional performance of turbine generators with a superconducting rotor an advanced digital program was developed which simulates the very complex electromagnetic and electromechanical interaction of the multi-shell damper system of the rotor with both the electrical power system and the turbine generator shaft system [1, 2]. First results are presented, demonstrating the capability of the program and the basic behavior of the torsional turbine generator. shaft system. The latter is. displayed by comparing the torsional performance of a 850 MW turbine when coupled to both types of generators, a superconducting and a conventional generator. The comparison confirms that. the torsional impact on turbine shafts and the superconducting rotor due to electrical transients is an important aspect of superconducting generator design and that careful resonance analysis is required to avoid unduly high torsional stressing.

Investigation of Transient Stabilizing Control Effects on Turbine-Generator Shaft Torques

In this paper, the implementations of some specific transient stabilizing control means, exemplified by dynamic braking resistor, forced excitation and fast turbine valving, are investigated from the view-point of their potential effects on the torsional stresses in a turbine generator shaft system. For the purpose of this study, a state space digital simulation model of one machine infinite bus system is employed whereupon. the interactions between the transient stabilizing control schemes, electrical and mechanical subsystems are well represented. The results of the phenomenon under investigation are presented and some pertinent conclusion drawn. In addition, the relative effects of thecontrol means implementations on the turbine generator shaft torques are compared and their benefits from the standpoint of power system stability are discussed.

The Impact of Dynamic Braking on Shaft Torgues

Motivated by recent concern for the safe operation of turbine-generator shaft sections when subjected to various power system disturbances and switching operations, this paper examines the impact of dynamic braking on transient shaft torques. A study of this type is crucial in evaluating the undesirable effects, if any, of dynamic braking on the turbine-generator shaft system, if brake resistors are to be utilized for stability augmentation.

Shaft torques during out-of-phase synchronization

As a consequence of shaft failures in two units in a Consumers Power gas turbine installation, a computer study was Performed to determine the torques In the turbine-generator shaft system during out-of-phase synchronization. Prior to this study, the possible occurrence of excessive torques in the turbine-generator shaft system without damage to the stator windings due to large currents was questioned. If the gas turbine-generator unit is designed to sustain the stator currents and the instantaneous shaft torques resulting from a three phase short circuit at the machine terminals, then the results of this investigation revealed that during out-of-phase synchronization the design torques may be exceeded by 2 to 3 times without exceeding the amplitude of the short circuit stator currents. From this it seems reasonable to infer that shaft failure could occur during out-of-phase synchronization without damage to stator windings due to excessive currents.