Output Current Of Generator Research Articles

Research on Grounding Fault of 12-phase Rectifier Generator in Parallel Operation

12-phase rectifier generators have been widely used in ship power systems, since they can provide high quality DC voltage. In view of the safety and reliability requirements of power supply during ship navigation, the DC side grounding faults of two paralleled 12-phase rectifier generators are studied through theoretical analysis and simulation analysis. First of all, the DC voltage expression of the 12-phase rectifier generator under normal condition is derived. Secondly, the zero sequence circuits of the DC side grounding fault are studied, the DC voltage is calculated by the phasor method, the DC output current of generator is analyzed by the zero sequence circuits. Finally, the correctness of the analysis method is verified by the simulation model.

Enhanced Performance of PMSG in WECS Using MPPT - Fuzzy Sliding Mode Control

The wind turbine is a tool used to convert wind energy into electrical energy. This research applies the maximum power point tracking (MPPT) algorithm combined with the fuzzy sliding mode control (FSMC) to produce maximum power in the wind turbine. Addition of fuzzy logic algorithm to sliding mode control to reduce the chattering phenomenon caused by the high switching frequency of the MOSFET in the boost converter. The permanent magnet synchronous generator (PMSG) type of generator with a capacity of 600 watts is used to convert the mechanical energy of the turbine into electrical energy. Tracing the maximum power value of the generator with the MPPT-FSMC algorithm in this study based on the value of the generator output voltage, generator output current, and converter output voltage obtained through simulations on MATLAB / SIMULINK. Comparison of wind turbine performance using MPPT-FSMC and without MPPT is shown as validation of improved wind turbine performance when using intelligent control algorithm.

A Novel Fault Current Control Scheme to Reduce Synchronous DG's Impact on Protection Coordination

Synchronous-machine DGs are well known to cause miscoordination of distribution system protections because of the generator's ability to contribute large fault currents to the fault. This paper proposes a field discharge circuit to limit the generator's fault current, thus leading to a synchronous-machine DG with little impact on distribution system protection. In this paper, the operation of a solid-state switch-based field discharge circuit is studied, and its effects on the generator's output current during the fault are investigated. It is shown that the proposed scheme removes the steady-state component of the fault current and accelerates the decay of the transient ac component of the current. The results demonstrate that the proposed field discharge circuit is sufficient to prevent miscoordination of the feeder protections when short time-delay and/or inverse-time overcurrent relays are involved in the protection scheme.

Using Only the DC Current Information to Detect Stator Turn Faults in Automotive Claw-Pole Generators

The stator turn-to-turn short circuit is an important type of fault in automotive claw-pole generators. In a typical vehicle electric power system, the built-in rectifier of the generator makes it difficult to access the ac current or voltage information, rendering conventional sequence-component-based fault-detection methods useless. To detect such fault using only the available sensor information, a dynamic model of the claw-pole generator with stator turn faults is derived in this paper to analyze how the fault would interact with the connected battery and the static full-bridge rectifier and how it would affect the generator's output voltage and current. It is found that, in the rectified generator output current, the harmonic at one-third of the rectifier ripple frequency is a robust signature of the stator turn fault. The performance of the stator turn-fault detector is demonstrated by extensive experimental results. Although the fault detector is originally proposed for claw-pole generators, it is also applicable to most polyphase ac generators with a dc-link rectifier.

Control method comparison of doubly fed wind generators connected to the grid by asymmetric transmission lines

A speed controller operating on a doubly-fed induction generator can be improved to compensate asymmetries on voltage waveforms feeding the machine's stator. This is particularly interesting for variable-speed wind power generators connected to an electrical network through weak transmission lines. Any asymmetry on the line causes the currents to be unbalanced, which will distort voltage waveforms at the beginning of the line, degrade the power quality injected into the network, lower the efficiency of energy transmission and increase the thermal losses in the generator. This paper presents the performance of three different compensation procedures based on the control of the waveform of a doubly fed generator's output current. A brief description of the model of the wind power system developed using reference frame theory is first introduced, followed by the description of the three different control techniques proposed to maintain balanced currents: a linear proportional and integral (PI) controller, a nonlinear fuzzy controller and a mixed scheme consisting of a fuzzy control adjusting PI parameters online. The performance of the three methods are then compared in terms of their efficiency in controlling the speed and compensating asymmetries. Simulations show that current asymmetries can be greatly decreased, by waveform control without sacrificing speed regulation.

5635768 Gas turbine engine driven auxillary electric power unit with turbine speed controlled in response to generator output current

5635768 Gas turbine engine driven auxillary electric power unit with turbine speed controlled in response to generator output current

Stable source of infrared radiation for photometer calibration

The emitted power is stabilized by keeping the LED temperature constant and by feeding it from a constant-current generator composed of field-effect transistor (FET) T1 (KP902A), operational amplifier M1 (140UD7), resistors R1 and R2, and zener-diode voltage stabilizer D2 (D818E). The generator output current is 80 mA, the stabilization error not exceeding 0.05% for • changes of ambient temperature.

Cable-fault location by impulse-current method

The paper presents a new approach to cable-fault location based on the use of high-voltage impulse generators. It is shown that, when an impulse generator is connected onto a faulty cable, the waveform of the generator output current can be used to determine the position of a fault. Several advantages are gained by the use of a linear coupler to provide the signal to the instrumentation, and it is shown that the signal also indicates whether or not an acoustic signal is being produced at the fault. The nonlinear characteristics of faults, which introduce errors and complications into most existing methods of fault location, are fully exploited with the new technique. Digital transient recorders are shown to have many advantages over the currently used methods of recording impulse waveforms. The information stored in the memory of a transient recorder can be easily transmitted to another location for interpretation by an experienced engineer. The more complex waveforms obtained on multibranched networks would be interpreted with the aid of a computer. It is suggested, that both the hardware and software being developed for cable-fault location purposes will also find application in the growing field of diagnostic testing.