水轮发电机瞬态和超瞬态电抗的数值计算

本文用有限无法求解了大型水轮发电机内的二维正弦涡流场，提出了励磁绕组和阻尼绕组端部漏抗的归算方法，并以清江电站３０１千瓦水轮发电机为例，计算了瞬态和超瞬态电抗的饱和值。     

水轮发电机瞬态和超瞬态电抗的数值计算

本文用有限元法求解了大型水轮发电机内的二维正弦涡流场，提出了励磁绕组和阻尼绕组端部漏抗的归算方法，并以清江电站３０万千瓦水轮发电机为例，计算了瞬态和超瞬态电抗的饱和值。     

汽轮发电机的三阶模型和超-超瞬态电抗

用多个回路来模拟实心转子、槽楔和阻尼回路中的涡流,导出汽轮发电机三阶模型的运算电机和超一超瞬态电抗;并从电磁场数值计算所得的频率特性,确定三阶模型的各个电抗和时间常数;为三阶模型的工程应用和更精确地预计和计算汽轮发电机的瞬态和异步运行等动态问题打下基础。     

水轮发电机瞬态电抗的数值计算

用直轴运算电抗的频率特性和二维正弦电磁场的有限元解法,求得了水轮发电机的直轴瞬态电抗。为计及励磁绕组的端部漏磁,用归算法把端部漏磁导并入了直线部分。为保证励磁绕组每匝的感应电流相等,对励磁绕组施加了串联约束。最后通过实例计算,比较了施加与不加串联约束对瞬态电抗值的影响。     

不对称阻尼绕组凸极同步电机瞬态及超瞬态参数的分析与计算

现代凸极同步电机转子阻尼绕组结构设计比较灵活，除通常对称等节距阻尼绕组外，还有对称不等节距绕组和不对称、但以二极电机为周期循环的阻尼绕组。该文以不对称、但以二极电机为周期循环的阻尼绕组的同步电机模型作为研究对象，对阻尼绕组按实际的网形电路选取回路，从派克方程出发，获得该模型的磁链方程和电压方程，经由dqo变换及一些技巧性处理，导出运算电抗xo(s)和xq(s)，然后经参数辩识，确定电机的直、交轴瞬态电抗和超瞬态电抗以及相应的时间常数。该文方法不但适用于不对称、但以二极电机为周期循环的阻尼绕组，也适用于等节距和不等节距的对称阻尼绕组。该文提供的是计算凸极同步电机暂态参数的一种新方法。     

西门子隐极同步发电机电抗计算的探究

利用几何定理对定子和转子圆导线绕组槽形进行处理,计算出在额定电流和短路饱和时中小型三相隐极同步发电机的定子、转子和阻尼绕组的槽（槽部、槽顶、槽口、齿顶）漏抗、端部漏抗、定子绕组谐波和斜槽漏抗、阻尼绕组谐波漏抗、励磁绕组对阻尼绕组的漏抗,与西门子（Siemens）公司提供的该发电机电抗参数的计算机计算结果完全一致。     

突然短路试验测定水轮发电机的饱和电抗值

三相突然短路试验是测定水轮发电机瞬态参数的常规试验方法,但在水电站现场,在额定电压下进行试验存在一定安全风险,难以直接测定饱和电抗值。有关研究表明,可以采用不同电压下测定的电抗非饱和值,推算饱和电抗值。本文对一水轮发电机,开展了在多个空载电压下的三相突然短路现场试验,根据直接测定的不同电压下的多个非饱和电抗值,采用线性最小二乘法外推得出了水轮发电机直轴瞬态电抗和超瞬态电抗的饱和值。试验结果表明,计算得到的饱和电抗值与设计值偏差在10%以内,满足相关容差要求。该方法在水电站现场测定水轮发电机直轴瞬态和超瞬态电抗饱和值方面具有可行性,能够满足工程上的测试需要,值得行业借鉴。     

西门子隐极电机电抗和时间常数及突然短路电流

用额定电流时的主电抗和额定电压（突然短路饱和）时的电枢、励磁和阻尼绕组漏电抗、阻尼绕组谐波漏抗、励磁绕组对直轴阻尼绕组的漏抗,计算出隐极同步电机的超瞬变和瞬变电抗、时间常数以及突然短路电枢和励磁电流,与西门子（Siemens）公司提供的发电机超瞬变和瞬变电抗参数、时间常数、突然短路电流的计算机计算结果完全一致。     

具有不同转子匝数的新型双馈风力发电机低电压穿越能力的瞬态性能分析

分析了转子绕组匝数可变的双馈风力发电机在电网电压跌落时的瞬态性能。该电机通过转子绕组的匝数变化,来抑制转子电流上升,实现低电压穿越。本文建立了基于Matlab/Simulink的仿真模型,分别对全电压跌落和部分电压跌落两种情况下的低电压穿越能力进行分析,并讨论匝数变化的参数n取值对于瞬态性能的影响。分析得出了不同电压跌落情况下,绕组匝数对电机性能影响均有所不同。最后,本文给出了7.5kW样机的测试结果,验证了该新型结构双馈风力发电机能够有效实现低电压穿越。     

大型同步发电机超瞬变电抗现场测试与分析

短路是发电机最常见的运行故障,其中又以三相对称短路产生的危害最大,而计算三相短路电流就必须知道发电机交轴和直轴的超瞬变电抗.某大型水电站为了防止机组电网波动、提高机组运行中过载能力,采用转子任意位置外施电压法测试发电机超瞬变电抗.由试验结果可知,采用阻尼环内连接方式的水轮发电机在不同工况下的交直轴超瞬变电抗测试值有较大的差异,与交轴阻尼作用相对较弱的理论相吻合.     

A method of predicting transient constants of synchronous machines

It is difficult to determine the subtransient (transient) reactance and subtransient (transient) short-circuit time constants of medium and large synchronous machines by the sudden three-phase short-circuit test because large-capacity equipment is required. This paper describes a new method of measuring these constants by means of a simple test using a small dc power supply. The key points of this method are as follows. (1) A dc voltage is applied to the armature winding (two terminals with the third one open) of a stationary synchronous machine through a resistance. When the two terminals are closed, the winding is short-circuited and the current in the armature winding decays. The whole process of decaying current is recorded. (2) The value of the transient phenomena of the winding calculated from circuit equations (armature, field winding and damper winding circuits) is compared with actual data, and the unknown equivalent circuit constants are identified by the least squares method. (3) Transient phenomena of the sudden three-phase short-circuit are calculated by the two-reaction theory using identified constants, and, hence, these constants are calculated. The transient constants of synchronous machines obtained by the new method agree closely with the observed values.     

3/3相双绕组发电机系统的等效电路模型

整流桥的存在使3／3相双绕组发电机系统成为非线性系统，发电机始终处于非对称运行状态，为了对此进行解析分析，将3／3相双绕组发电机的d,q轴变量分解为低频分量和高频分量分别加以处理，忽略转子回路电阻对高频电流和阻尼绕组对低频分量的作用，在d,q轴超瞬变电抗近似相等的条件下，分别建立了3／3相双绕组发电机系统从整流绕组侧和交流绕组观察的等效电路模型，给出了模型中等效发电机的Park程，稳态运行矢量图及相应稳态量的计算方法，该模型可用于系统稳态和似稳态过程的分析计算。     

Determination of equivalent circuit constants of synchronous machines from the extended Dalton‐Cameron method

This paper presents a method of determining the equivalent circuit constants which accord with the physical construction of synchronous machines, using the dc decay testing method with the rotor in arbitrary position (proposed by the authors and called the extended Dalton–Cameron method). The conventional Dalton–Cameron method calculates the direct‐ and quadrature‐axis subtransient reactance from a standstill response test in any arbitrary rotor position using a single‐phase power supply. The extended Dalton–Cameron method determines the direct‐ and quadrature‐axis operational impedances for each slip from a standstill response test using a small‐capacity dc power supply. The direct‐ and quadrature‐axis operational impedance loci thus obtained synchronous machine constants (subtransient, transient, and synchronous reactances) are used to estimate the direct‐ and quadrature‐axis equivalent circuit constants which accord with the physical construction of synchronous machines. As an example, equivalent circuit constants are determined for a 10‐kW laminated salient‐pole‐type synchronous machine with damper winding. The validity of the equivalent circuit constants is confirmed by comparing the calculated resistance and leakage reactance of the field winding determined from the operational impedance when the terminals are short‐circuited, to those when the terminals are connected to an external resistance. © 2001 Scripta Technica, Electr Eng Jpn, 138(1): 56–67, 2002     

同步发电机电磁暂态过程的实用方程

本文根据派克方程导出一组描述同步发电机电磁暂态过程的实用过程。这组方程计及转子转速变化对发电机电势的影响。用这组方程分析计算电力系统电磁暂态过程和机电暂态过程可以提高计算精度。     

FAST ACCURATE TRANSIENT STABILITY SIMULATIONS

ABSTRACT

The paper describes a Simultaneous Implicit (SI) approach for transient stability simulations based on an iterative technique using traingularised admittance matrix [1]. The reduced saliency of generator in the subtransient state is taken advantage of to speed up the algorithm. Accordingly, generator differential equations, except rotor swing, contain voltage proportional to fluxes in the main field, dampers and a hypothetical winding representing deep flowing eddy currents, as state variables. The simulation results are validated by comparison with two independent methods viz. Runge-Kutta simulation for a simplified system and a method based on modelling damper windings using conventional induction motor theory[2].     

同时带交流和整流负载的三相同步发电机系统的等效电路模型

同时带交流和整流负载的三相同步发电机系统是一个非线性系统 ,为了对此进行解析分析 ,将其中的三相同步发电机的d、q轴变量分解为低频分量和高频分量分别加以处理 ,忽略转子回路对高频电流的电阻和阻尼绕组对低频分量的作用 ,在d、q轴超瞬变电抗近似相等的条件下 ,分别建立了该系统的从整流负载侧和交流负载侧观察的等效电路模型。给出了模型中等效发电机的Park方程、稳态运行矢量图及相应稳态量的计算方法。该模型可用于系统稳态和似稳态过程的分析计算     

Verification of effect of damper windings on the transient condition of synchronous generator

This paper describes the results of an experimental investigation on the effects of the damper winding of a four‐pole synchronous generator at a synchronous generator transient. It is known from simulations that the damper winding acts effectively under synchronous generator transient conditions. However, experimental proof has not been obtained yet. Thus, experiments on damper effects were conducted using a laboratory‐scale power system. The damper winding of the tested generator consisted of five damper bars for each pole; the number of working damper bars could be changed manually. The damper currents at each bar were measured by a Rogowski coil. FFT analysis was applied to both the damper currents and armature currents under different operating conditions. The relationships between damper currents in the rotor and armature currents in the stator were made clearer than before. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(2): 33–42, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21278     

A calculation method of field current of synchronous machines at sudden short‐circuit

The mutual leakage reactance between D‐axis damper and field windings is ignored in conventional D‐axis equivalent circuits. It has been pointed out, however, that the calculated value of the field current differs considerably from the measured value if this reactance is not taken into account. This is due to the difficulty of determining the physically correct damper winding impedance value. A method of determining the equivalent circuit constants using the mutual leakage reactance has been reported previously, where the D‐axis damper winding time constant is measured from the upper and lower envelopes of field current at sudden three‐phase short‐circuit. Yet there are machines for which the upper and lower envelopes of field current are not readily established, and in this case the method is unsatisfactory. The authors describe a method to accurately identify the equivalent circuit constants taking into account the mutual leakage reactance, using a standstill test with a small‐capacity DC power supply (DC decay testing method). The field current at sudden short‐circuit can be simulated accurately using these equivalent circuit constants. The validity of the proposed method is demonstrated by implementation results on two salient‐pole synchronous machines at the same specifications (one with damper winding, the other without). Furthermore, the dependent relation between the armature leakage reactance and mutual leakage reactance, as well as its influence on the calculation of field transient currents, are made clear. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(3): 61–70, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20113