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.     

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.     

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.     

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。     

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。     

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。     

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。     

混合磁极式的混合励磁永磁同步发电机仿真

为了研究混合磁极式的混合励磁永磁同步发电机转子上既有永磁体、又有励磁绕组的运行性能,建立了混合磁极式的混合励磁永磁同步发电机的基本方程;根据该电机的转子结构及定子绕组的实际连接方式和空间分布情况,分析了模型中电感参数及永磁体在其他回路中产生的磁链的特点,并给出其表达式;采用有限元法计算各参数表达式中的系数,能准确考虑磁极形状及永磁体的作用,利用数值方法对该电机的性能进行仿真.在1台混合磁极式的混合励磁永磁同步发电机样机上进行了实验,仿真结果和实验结果吻合较好,验证了仿真模型的正确性和参数计算的准确性.     

阻尼绕组对凸极同步发电机空载电势波形的影响

采用二维瞬态涡流场有限元法,对装有阻尼绕组的凸极同步发电机的空载电势波形进行了计算,分析了阻尼绕组节距对空载电势波形的影响。结果表明,阻尼绕组可以削弱定子齿谐波分量,而对与阻尼绕组节距有关的谐波分量则有加强作用。     

同步发电机整流系统的分析方法和研究领域

同步发电机整流系统的广泛应用以及其多类型的系统结构和运行方式 ,形成了一个以该系统为对象的研究领域 ,本文对该系统的分析方法和研究所涉及的领域进行了综合性的讨论 ,归纳总结出分析该系统的主要分析方法和研究领域。     

同步发电机暂态分析中模型的合理选择

同步电机模型对电力系统稳定分析具有重要的影响。分析了同步电机三相短路的物理过程 ,推导了 5种形式的发电机模型 ,并指出两者间的联系。通过算例验证 ,在电力系统进行计算时应该根据实际要求 ,合理选择发电机的模型 ,否则各种模型计算的结果会有一定的差别。     

发电机励磁回路负端接地原因分析

通过对某电厂机组运行过程中转子一点接地保护报警报文的分析,对发电机转子接地保护试验和励磁回路的绝缘检查,找出了二次电缆绝缘受损是造成励磁回路负极接地的原因,经绝缘修复处理,消除了机组运行安全隐患。     

Transient performance of a single-phase self-regulated self-excited induction generator using a three-phase machine

This paper presents the transient behavior of a three-phase star connected self-excited induction generator (SEIG) using three capacitors connected in series and parallel with a single-phase load. The voltage regulation of this generator is very small due to the effect of three capacitors. The dynamic model of the above generator has been developed based on stationary reference frame d–q-axes theory incorporating the effect of cross-saturation. The steady-state model of the scheme has also been developed. The simulated results of both the transient analysis for the different dynamic conditions, such as initiation of self-excitation, load perturbation and short-circuit and the steady-state analysis are compared with the experimental results. Both the simulated and experimental results are in close agreement with each other.     

Basic characteristics of a self-excited induction generator under secondary excitation at constant voltage

A self-excited wound-rotor induction generator excited with a capacitor can be used as an independent source for small-capacity wind power generator. With constant excitation capacitance, the secondary-circuit power of the induction generator is returned to the primary circuit through a converter, an inverter and a transformer; the power is controlled at the inverter so that the generator voltage is always maintained constant in spite of the changes of generator speed and load. The basic characteristics of the generator under the above conditions are analyzed. The fundamental waves of both the main circuit and the feedback circuit are determined. Using these results, the equations for various portions of the generator are derived, the performance characteristics of the generator are then analyzed and compared with experimental results.     

长定子直线同步电动机轨道空间处的电枢反应电抗和谐波漏抗

介绍了长定子直线同步电动机轨道空间处定子磁场的特点,提出了轨道空间处电枢反应电抗和谐波漏抗的计算方法,并以磁悬浮列车Transrapid-08为例,验证了该法的正确性。