六相同步发电机的稳态电磁参数

从Park方程的基本原理出发,建立了六相同步发电机的基本方程,得到了六相同步发电机的d轴等值电路和q轴等值电路。等值电路中的综合互感抗体现了六相同步发电机2个Y之间的磁耦作用,由电枢反应电抗和综合漏互感抗2部分组成。通过对六相同步发电机单Y运行(另一Y开路)和双Y运行的分析,得出双Y运行同步电抗为2倍的单Y运行同步电抗与单Y自漏抗之差。以空载短路试验的实例,测试了六相同步发电机特性曲线,以及d轴同步电抗、自漏抗和短路比。从电磁理论分析和实际运行特性2方面,验证了六相同步发电机的稳态电磁参数。     

考虑磁饱和影响的同步发电机励磁电流计算

在考虑同步发电机磁路饱和效应的基础上,提出了发电机励磁电流计算的数学模型.该模型涉及发电机的空载特性曲线、保梯电抗和磁路磁链方程,计算过程比较简便、实用.对于不计饱和特性、直接采用饱和电抗以及采用定子漏抗替代保梯电抗的三种情况分别进行了励磁电流计算,以发电机V形曲线的形式比较了该模型与这三种情况下的计算结果差异,经多台发电机励磁电流的计算和实际测试,验证了该模型的有效性和实用性.     

考虑交叉饱和影响的永磁同步电机稳态参数有限元分析

针对永磁电机相关控制策略及性能计算均需要准确地得到电感和磁链等稳态参数,而它们又受交叉饱和效应影响严重,常规方法无法准确计算的问题,以有限元为工具,分析了计算永磁磁链和直轴、交轴电枢反应电感的不同方法。研究了交叉饱和效应对永磁电机的直轴、交轴电枢反应电感的影响,提出由于交叉饱和效应导致的直轴交轴存在互感,以及直轴上的永磁磁势产生交轴磁通的问题。采用冻结单元磁导率的方法,将非线性场线性化,计算得到了稳态参数随直轴、交轴电流变化的趋势。通过对比,使用计算得到的稳态参数仿真结果和实际测试结果,在空载与负载条件下的吻合很好,证明了使用冻结磁导率法计算参数是可靠的。     

内置式永磁同步电机电感参数的研究

分析了永磁体磁势和电枢磁势共同作用时内置式永磁同步电机的电感特性,基于交流静态法,提出了一种改进的测量内置式永磁同步电机定子自感和互感以及交直轴电感的方法。为了考虑饱和和交叉耦合效应对电感参数的影响,该方法首先根据所测电压和电流数据计算出不同转子位置和电流下的磁链,然后根据磁链计算出电机自感和互感以及交直轴电感参数,并应用该方法进行了实测研究。结果表明,实测结果与有限元分析结果吻合较好,验证了该方法的可行性和有效性。     

汽轮发电机计及双因素非线性影响的功角特性

为研究磁路饱和与磁场畸变双因素非线对汽轮发电机功角特性的影响,利用有限元方法获得发电机的有功和无功功角曲线,揭示计及双因素非线性的电抗随功角变化的规律,然后将分运行区间的饱和电抗用于功角特性解析法计算。研究结果表明,汽轮发电机计及双因素非线性后,极限功角小于90°,极限功率下降,无功功率减小;随着功角的增大,直轴电抗先增大后减小,交轴电抗变化不大,两者差值可达到14%;与直接用有限元方法计算的功角特性进行对比,用分运行区间电抗的计算结果非常吻合,而用空载特性修正的饱和电抗的计算结果相差较大。研究结果可为同步发电机静态稳定极限的确定和暂态稳定的判断提供参考。     

基于直观线性化模型的同步发电机电磁力矩解析

含阻尼绕组同步发电机电磁力矩系数的传统算式忽略直轴阻尼绕组与励磁绕组的互感,且不考虑自动励磁调节(AVR)的作用。为提高电磁力矩系数计算的准确性,细化关于AVR和阻尼绕组对机组稳定性影响的认识,基于计及阻尼绕组作用的c1-c12模型,采用微振荡法建立了计及AVR以及直轴阻尼绕组与励磁绕组互感的同步发电机电磁力矩系数表达式。基于这些表达式,按是否与AVR有关,将电磁力矩划分为固有分量和受控分量,对交、直轴阻尼绕组,励磁调节主通道等对机组同步能力特别是阻尼能力的影响以及低频振荡的机理进行了详细分析。分析表明,AVR总是削弱机组阻尼;在AVR作用下,交轴阻尼绕组的阻尼作用得到增强,而直轴阻尼绕组反而可能提供负阻尼;外部电抗和有功负载的增大导致固有阻尼能力下降;AVR削弱阻尼的强度不仅与其增益有关,而且随着固有阻尼能力的下降而增强。根据c1-c12模型与Phillips-Heffronk1-k6模型下阻尼力矩系数之差,给出了k1-k6模型等效阻尼系数算式。     

考虑磁场饱和效应的电励磁同步电机矢量控制

电励磁同步电机矢量控制系统中电压模型磁链观测器受初始定子磁链值以及电压和电流测量值的影响,采用电流模型对其进行修正可提高磁链观测器的精度。随着负载电流的增大,电机的磁路会进入饱和状态,传统线性电流模型磁链观测器误差较大,通过引入d轴饱和指数可准确描述磁场饱和状态下电机定子磁链随电流的变化规律。同步电机矢量控制实验验证了电压-电流混合磁链观测器的准确性以及饱和磁场控制的有效性。     

Determination of Synchronous Reactance and No‐Load Saturation Curve of Synchronous Machines by dc Test Considering Magnetic Saturation Effect

dc Tests can accurately determine the unsaturated synchronous machine‐equivalent circuit constants by a simple standstill test. This paper presents two improved dc tests that account for the magnetic saturation of the stator iron core by the main flux. These tests are tentatively named Step Response Test (I) and Step Response Test (II). The former can predict the incremental d‐axis synchronous reactance by performing a Fourier transform of the voltage and current measured when a small step voltage is applied to the two armature terminals as a field current flows. The latter can determine the incremental d‐ and q‐axes synchronous reactances by the same Fourier transform of the voltage and current measured when a small step voltage is applied to the two armature terminals as an armature current flows. In addition, this paper introduces a new method to calculate not only the static d‐ and q‐axes synchronous reactances but also the no‐load saturation and short‐circuit characteristic curves. This new method does not require the results from any additional tests including the rotational driving tests and dimensional information, which can only be obtained from the manufacturer. To demonstrate the validity of the proposed method, results of an experiment using 10‐kVA laminated synchronous machines with damper winding are presented.     

Effects of Synchronous Machine Saturation,Circuit Parameters,and Control Systems on Transient Stability

The effects of synchronous machine iron saturation, circuit parameters, and control systems on the power system transient stability phenomena are presented in this paper. Effect of saturation is considered to be very important on the power system steady-state and transient performances when it is required to calculate the power system stability characteristics accurately. For solid round rotor body synchronous machines, saturation effects are significant in both d- and q-axis, and because of this nonlinearity, the d- and q-axis magnetizing reactances are depressed to a considerable degree from their unsaturated values under both steady-state and transient operations. The system stability performance is also greatly influenced by the machine control system and damper circuit parameter variations.     

基于串联制动电阻的生物质能同步发电机组低电压穿越研究

对用于生物质能发电(BPP)的并网同步机组(SG),其低电压穿越(LVRT)不便沿用大型SG紧急控制措施。采用串联制动电阻(SBR)实现BPP中SG的LVRT,采用计及励磁系统动态控制的等面积定则,提出了SBR阻值解析算法。基于SG及励磁系统,量化SBR功率,将其引入SG加速面积中,建立了SG加速和减速面积表达式。结合机械功率和切入功角,利用等面积定则,推导出满足LVRT准则SBR最小阻值的解析算法。改变系统参数,分析其对SBR最小阻值的影响,以选择新安装BPP电厂参数。动态仿真结果验证了基于解析算法选取SBR阻值的正确性。可以发现SG惯性或励磁电压上限越大,q轴同步电抗、d轴暂态电抗或变压器电抗越小,机械功率或切入功角越小,所需的SBR阻值越小。对SBR阻值影响从大到小依次排序为d轴暂态电抗、惯性时间常数、q轴同步电抗、变压器电抗、励磁电压上限值。     

永磁同步电动机参数测量与功率角计算方法

为测量和分析永磁同步电动机的直、交轴电抗参数,对其空载实验和负载实验进行了分析讨论。介绍了一种结合空载实验的简化负载实验,提出了功率角计算方法,得到了直、交轴电抗值。对其使用条件进行了阐述,并进行了实验和参数误差分析。     

考虑磁路饱和的IPMSM电感辨识算法及变参数MTPA控制策略

内置式永磁同步电机(IPMSM)d、q轴电感会随着磁路饱和程度的不同而发生改变,这会降低最大转矩电流比(MTPA)控制的有效性。考虑到定子电流引起的磁路饱和及交叉饱和效应的影响,提出了相应的d、q轴电感辨识算法和变参数MTPA控制策略。采用基于旋转高频电压注入的d、q轴电感辨识算法可在其他电机参数未知的前提下得到不同负载条件下的d、q轴电感;变参数MTPA控制策略能够充分利用标幺值化处理的优势,在转矩-最优电流控制表不变的基础上,只需根据实际d、q轴电感更新电流基值和转矩基值便可克服电感变化带来的不利影响,并实现一定转矩条件下的最佳MTPA控制。最后在电机控制实验平台上通过实验对提出的电感辨识算法和变参数MTPA控制策略的可行性和有效性进行了验证。     

基于背靠背三电平电压变换器的直驱式风力发电系统

直驱式风力发电系统由2个背靠背二极管中点钳位型三电平电压变换器构成,机侧变换器采用间接转矩向量控制,通过调节永磁同步发电机的转速,实现风能最大跟踪;网侧变换器采用电网电压定向的向量控制,实现d、q轴电流解耦控制,使d轴电流控制有功功率,q轴电流控制无功功率。针对直驱式风力发电系统中能量流向以及二极管中点钳位型三电平的特点,提出了一种只需检测上、下电容电压,首发向量全部为负短向量,利用冗余电压向量控制中点电压平衡的方法。为提高该系统抗电网电压波动能力,采用软件锁相环,实现电网电压的同步。仿真结果表明,该控制策略实现了最大风能跟踪和功率因数为1的逆变。     

Determination of d and q reactances of permanent-magnet synchronousmotors without measurements of the rotor position

The interest in permanent-magnet synchronous motors (PMSMs) is increasing in a wide area of applications. Since most PMSMs will operate without a shaft sensor in the future, valuable information for experimental determination of machine parameters will be lost. In this paper, therefore, a method is presented where the induced EMF and the d-axis reactance are determined in a no-load test and the q-axis reactance is determined in a load test. The load angle δ is determined from the load test by means of a new analytical method. In this way, no separate measurement of the load angle is required. The method is especially suitable for line-start PMSMs which normally operate with negative d-axis current and, therefore, are not saturated in the d-axis flux paths. Moreover, the method is very simple to carry out for any laboratory technician, since the only tests that have to be made are standard tests which are made on standard induction motors on a regular basis     

REPRESENTATION OF SATURATED SALIENT-POLE SYNCHRONOUS MACHINE BY A SINGLE MAGNETIZATION CURVE

ABSTRACT

The paper describes a new method of representing saturated salient-pole synchronous machine by a simple method. The essence of the model is to represent the machine, along any intermediate axis, by a single magnetisation characteristic. This approach is useful when an accurate assessment of the flux level is required. Therefore, the model expresses the magnetising or the synchronous reactance as a function of the angle between the resultant m.m.f., rather than the flux, and the d-axis. Moreover,the model is simple and can be easily defined provided that the d- and q-axis characteristics are known. Thus, the model is of value in power-systems studies.     

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。     

龙滩水电站计算机监控系统结构及特点

龙滩水电站是中国目前第二大在建水电站，根据电站在电网中的地位，考虑到电站设备控制的复杂程度以及庞大的系统规模，在严格遵循“全开放、分布式”理念的基础上，应用开出重漏保护装置、独立测温单元、并联冗余不间断电源等自动控制新技术和新设备，使其成为充分满足电站各方面实用化要求的成熟可靠的监控系统。     

Modeling and Simulation of a PMSG-based Marine Current Turbine System under Faulty Rectifier Conditions

This paper deals with the modeling and simulation of a permanent magnet synchronous generator (PMSG)-based marine current turbine (MCT) under faulty rectifier conditions. The modeling of the generator is established in the synchronous rotating d-q reference frame. The control of the speed, the d-axis current, and the q-axis current are achieved using proportional integral (PI) correctors. The faulty mode deals with the study of single and multiple open-switch damages appearing in the pulse width modulation (PWM) power rectifier. Simulations are carried out to highlight the proposed PMSG-based MCT performance in both cases using MATLAB/Simulink environment.     

汽轮发电机饱和同步电抗的波动

本文以６００ＭＷ汽轮机电机为例,用有限元法计算了不同瞬时的饱和同步电抗,阐明了受饱和影响时同步电抗的波动情况。     

带反电势负载的三相发电机整流系统直流脉动分析

目前应用广泛的交流发电机整流系统向负载供电时，通常在直流侧带反电动势和RC滤波器以改善直流输出电压的谐波特性。该文基于d-q坐标系下同步发电机的基本磁链和电压方程，经过合理的简化处理，建立了三相交流发电机整流系统的等效电路模型，把交流电机看作带内部阻抗的正弦电压源。利用整流器开关函数导出了直流输出电压的数学模型，引入直流电压脉动系数的定义来描述输出电压的特性。通过实验研究分析了带RC滤波器和反电动势负载时输出电压的谐波及脉动系数，与计算结果对比验证了文中方法的正确性。