Self-regulated self-excited brushless three-phase synchronous generator

For lightweight and compact implementation of a generation set, many attempts have been made by some researchers to develop a brushless self-excited synchronous generator without an ac exciter. A previous paper proposed a novel self-excitation scheme by which the second-space harmonic component of armature mmf is used for exciting the rotor field system. In this excitation scheme the effect of the series excitation characteristic, as well as a self-excited and brushless implementation without an ac exciter is automatically obtained. However, in the case of system configuration of the generator already reported, voltage regulation in the inductive load condition was very large. To remove this problem, this paper presents a new system configuration of the generator with a self-regulating feature that can compensate voltage regulation automatically. The new generator consists of a stator installing two three-phase windings, externally connected to a load and a capacitor bank, respectively, and a rotor with field and harmonic windings. In this paper the system configuration and theoretical concepts of the presented generator are described and detailed experimental investigations with a laboratory machine are also shown.     

Brushless self-excited three-phase synchronous generator without exciter

This paper describes principles together with analytic and experimental studies of an exciterless, brushless, and self-excited three-phase synchronous generator which was devised by authors. Since traditional brushless and dc self-excited three-phase synchronous generators without exciter did not have the self-exciting function by series characteristic component proportional to the load current inside the generator, they need auto-voltage regulating equipment or a transformer with three windings and condensers to obtain constant voltage characteristics. It also has the following problem in the case of two-pole traditional generator: oscillatory tension is generated at the shaft of the rotor caused by the magnetic force between magnetic poles of stator and rotor windings, and it causes mechanical vibration and noise. This paper proposes a new brushless and self-excited three-phase generator solving the aforementioned problems: the ratio of poles of the windings for providing power to load (armature and field windings) to the windings for supplying exciting power (stator and rotor exciting windings) is 1 to 5. Then oscillatory tension does not generate theoretically. Furthermore, a self-exciting three-phase generator using the 5th-harmonic component of armature reaction which makes series characteristic component proportional to the load current, currently is available. In this paper, the winding construction, the electric circuit, and the principle of the aforementioned generator are described, and the experimental results of the trial-produced generator show that the three-phase terminal voltage waveforms are almost sinusoidal and also balanced, and the voltage can be kept almost constant for the change of load. This generator has high reliability because of its simple construction.     

谐波励磁的混合励磁发电机比较与分析

为了解决现有一些混合励磁永磁电机的无刷化问题,将谐波励磁应用于混合励磁发电机中,提出两种谐波励磁的混合励磁发电机。分别介绍这两种谐波励磁的混合励磁发电机的结构及其工作原理,从谐波电动势产生的根源和途径、谐波绕组感应电动势的能力、运行效率、绕组用铜量,以及调节方便性等5个方面,针对这两种谐波励磁方式进行详细的比较和分析。分析结果表明,齿谐波励磁的混合励磁发电机具有较明显的优势。最后,研制了一台齿谐波励磁的混合励磁发电机并进行实验,实验结果表明,齿谐波励磁的混合励磁发电机具有较宽的气隙磁场调节能力和较高的运行效率。     

A new self-excitation scheme for three-phase synchronous generators

A new self-excitation scheme has been developed for three-phase synchronous generators. The generator that uses this scheme behaves as a flat-compound machine without automatic voltage regulators. The stator of the generator is provided with an armature winding that generates the fundamental and 2nd-harmonic mmfs. The rotor is equipped with a field winding and a harmonic winding. The harmonic winding is magnetically coupled to the 2nd-harmonic mmf produced by the armature winding. The current flows in the stator armature winding by way of a three-phase set of capacitors connected across its three-phase terminals and the ac voltage is induced in the rotor harmonic winding due to the armature 2nd-harmonic mmf. By connecting the harmonic winding to the field winding through a rectifier circuit, self-excitation of the generator is obtained. This excitation scheme is both self-excited and brushless, and no exciter is required. Additionally, voltage regulation due to load variation can be improved by connecting suitable capacitors. In this paper the operating principle and circuit configuration of the generator are explained and the experimental results using a 1-kVA prototype machine are shown. The generator characteristics are theoretically clarified by approximate analysis, and appropriateness of the theory and the usefulness of the proposed scheme are experimentally confirmed.     

角接三相异步发电机单相带载稳态分析

给出三角形接法三相自激异步发电机为单相负载供电时系统的连接方式,通过对系统中独立节点电量关系的推导,将发电机基值频率下的正序和负序等值电路通过简单的阻抗元件连接,构成合成等值电路。根据Kirchhoff定律,以合成等值电路中回路阻抗模值为零作为系统稳态运行的条件和分析计算的基础。采用优化方法计算了不同电容组合下系统的负载电压,求取了负载电压一定时电机所需并联的电容组合,并根据不同稳压电容组合下系统的负序电流所占比重求得最佳平衡状态下的稳压电容值。计算值与实验值相互吻合,验证了该分析方法的有效性和准确性。     

谐波励磁同步发电机空载谐波磁场分析

说明了利用ANSYS有限元分析软件的电磁分析功能对谐波励磁同步发电机空载谐波磁场进行分析,通过对谐波励磁同步发电机的电磁场进行计算,得出了样机的矢量磁位Az、磁力线分布图和磁密分布图。然后对电磁场的计算结果进行后处理,得出了谐波励磁同步发电机的旋转磁场波形、谐波绕组电压波形和谐波绕组空载特性曲线。最后用在谐波励磁同步发电机上的实验结果与计算结果的比较说明了方法的正确性,可为谐波励磁同步发电机的设计提供理论依据。     

Analysis of brushless three-phase synchronous generator without exciter

Recently, a demand for small-capacity generators has been increasing as electric sources in small ships and automobiles or as portable electric sources driven by engines. It is desired that the structure of small-capacity generators be simple and robust, and that the generators be highly reliable, easily maintained and controlled. This paper describes an analysis of the original brushless synchronous generator without exciter. The output voltage can be adjusted in the wide range by controlling the stator dc current. To analyze the characteristics of this generator, the finite element method is applied. It is found that the results of theoretical analysis agree well with the experimental results.     

弱电网下基于谐波状态空间模型的光储-虚拟同步发电机稳定性分析与优化控制研究

虚拟同步发电机(virtual synchronous generator, VSG)技术因提供阻尼和惯量而被广泛用于新能源并网逆变器。光储并入弱电网易发生频率耦合等问题,因而VSG并网稳定性分析变得更加复杂。针对光储并入弱电网系统,考虑频率耦合,在dq域中建立基于谐波状态空间(harmonic state space, HSS)理论的多时间尺度虚拟同步发电机模型。采用归一化参数灵敏度分析法,揭示功率环、电压环和低通滤波中虚拟惯量J、虚拟阻尼Dp、下垂系数Ku、比例系数kpu和截止频率ωc等关键控制参数根轨迹的特性和电网强度对系统稳定性的影响。并通过调整优化控制参数,提高系统稳定性。最后在Matlab/Simulink仿真平台验证谐波状态空间模型精确度和关键参数根轨迹特性。     

同步发电机可拓励磁控制器

为了克服传统励磁控制方法的缺点,依据可拓学理论,设计了同步发电机励磁控制器.控制器以参考电压与发电机机端电压的偏差及其微分作为特征量,根据电力系统的实际情况确定特征量的经典域和可拓域,经过关联度计算、测度模式识别,确定所采用的控制策略.应用MATLAB/Simulink软件建立了基于同步发电机三阶非线性数学描述的单机无穷大电力系统仿真模型,可拓控制器用MATLAB之S函数编程实现.与常规PID励磁控制器的仿真比较结果,验证了可拓励磁控制器对于改善电力系统小扰动稳定性和大扰动稳定性的有效性.     

大型发电厂发电机同期回路及检查试验方法分析

介绍了目前大型发电厂发电机同期回路的设计情况,分析了大型发电厂发电机同期回路可能存在的问题,提出了对发电机同期回路及自动准同期装置进行全面检查试验的方法,使发电机同期并网时能更安全、可靠。     

同步发电机励磁与STATCOM非线性协调控制

提出同步发电机励磁与静止同步补偿器(Static Synchronous Compensator,STATCOM)非线性协调控制方案。在研究同步发电机励磁与静止同步补偿器协调控制问题的基础上,以系统重要物理量建立多目标控制方程,并运用目标全息反馈法进行非线性协调控制设计。所提出的非线性控制方案充分考虑了同步发电机端电压、有功功率和角速度以及STATCOM接入点电压,并确保它们在非线性反馈中得到惩罚与控制,从而具有良好的动、静态性能。最后,建立系统仿真模型,进一步验证所提出方法的有效性。     

小功率发电机励磁系统的恒功率因数控制

针对单台并网运行的小功率同步发电机恒功率因数控制问题,采用励磁电流和功率因数双闭环PID控制方法,并网前调节励磁电流使机端电压满足并网条件,并网后调节励磁使功率因数恒定形成恒功率因数控制。以TMS320F2812型DSP为核心器件,充分发挥了它运算速度快,外设功能强大的优点,设计出一种简单、实用励磁调节器,并通过了仿真试验和实验室调试。实验证明系统具有投励准确,投励过程震荡小,功率因数稳定性高的特点。     

虚拟同步机并网运行下电网谐波抑制和故障穿越策略

针对电网发生对称故障瞬间传统阻抗重塑型谐波电流抑制方法严重加剧虚拟同步发电机(virtual synchronous generator, VSG)故障电流的问题,介绍了传统阻抗重塑型谐波电流抑制方法的原理。基于电网不对称故障下VSG谐波阻抗模型,揭示了传统阻抗重塑型谐波抑制方法加剧VSG故障电流的机理。在此基础上,提出一种VSG谐波电流与故障电流协同抑制方法。通过引入虚拟电感重塑电网故障点至VSG的等效阻抗,实现了VSG并网运行下电网谐波和故障电流的协同抑制,有利于改善电网电能质量并提高VSG的故障穿越能力。最后,通过仿真验证所提控制策略的正确性和有效性。     

采用协同控制理论的同步发电机非线性励磁控制

提出了一种基于协同控制理论的非线性励磁控制器。首先依据同步发电机励磁控制的基本要求和特点,选择机端电压、有功功率和转子角速度三个变量的偏差的线性组合构成流形,以保证有效控制机端电压和抑制系统功率振荡。然后以同步发电机非线性模型为对象,推导出了非线性协同励磁控制器（Synergetic excitation controller,SEC）的控制律,并根据电力系统的运行特性,探讨了控制器参数的选取原则。最后,单机无穷大系统仿真结果表明,无论在大扰动还是在小扰动下,所提非线性协同励磁控制器比常规的AVR+PSS方式下的励磁控制器都能更快更精确地调节机端电压,还能够有效地抑制系统的功率振荡。     

稀土永磁同步发电机分析计算

从径向激磁结构的稀土永磁同步发电机的特点出发，分析研究了其磁路和电枢反应计算方法，并运用矢量图进行设计求解。样机实测结果表明，本文所提出了的分析设计方法收到了良好的效果。     

A brushless three-phase synchronous motor using the armature winding as both load and DC excitation winding

This paper presents a new brushless three-phase synchronous motor which has no exciter. The technique applied to the motor provides an effective way for conventional brushless synchronous motors to simplify the system configuration. The stator of the motor is equipped with a double-star connected armature winding which has two neutral points. The rotor is a cylindrical one, which is equipped with a two-phase field winding. The field winding is connected with shaft-mounted rectifiers. A dc voltage is applied to the two neutral points of the armature winding to obtain the rotor excitation when the motor is operated at synchronous speed. At that time. the armature winding acts as a stator dc exciting winding while also acting as a load winding. In this paper the principle and characteristics of the motor are described. and the experimental results are shown. It is confirmed that with a 2-kW experimental machine, the proposed motor has good performance. For example, by adjusting the stator dc current, this motor power factor can easily be controlled within a wide range.     

新型无刷自励恒压输出三相同步发电机的研究

介绍一种新型无刷自励三相同步发电机。发电机的励磁电流是由电枢反应磁场的空间二次谐波所产生,无刷结构、自励磁,并且无需自动电压调节器,能在负荷变动情况下保持恒压输出。同时给出了1kW同步发电机的实验特性。     

同步发电机静止励磁装置的故障分析与处理

励磁系统是同步发电机的重要配套装备,良好的励磁系统对改善电力系统运行有着重要的意义。根据同步发电机静止励磁装置的运行状况及其特点,详细分析了该装置在运行过程中可能出现的故障、判别方法,以及所采取的相应处理措施。     

航空同步发电机波梯电抗分析及求取方法

航空同步发电机用零功率因数负载特性和空载特性所测得的波梯电抗数值比正常值大,致使在电机分析和计算中无法使用。为了解决航空电机的实用参数精确测试问题,分析了航空电机的结构特点,解释了出现这一现象的主要原因是由于励磁绕组漏磁增大。并给出一种利用励磁磁路饱和系数修正过饱和磁路励磁电抗的求取方法。用本方法对一台航空同步发电机的测试数据进行了计算,求得的结果比较合理。     

双定子混合励磁同步发电机电磁设计分析及实验研究

针对风力发电用永磁同步电机具有转速随机性较强导致端电压不稳定的特点,设计了一种双定子混合励磁同步发电机,并给出其电磁设计方法.利用三维有限元方法分析励磁电流变化时的电机空载磁场分布,并计算绕组磁链、感应电动势及电感等参数.研制了一台8极27槽样机,测试了发电机内外定子相电动势波形及空载特性.实验结果验证了理论分析的正确性,此电机结构合理,可有效提高电机功率密度,通过调节励磁电流,可稳定电机端电压,适用于风力发电等变速发电场合.