A new method,in which proper fundamental is added to the instruc- tion current so that the passive filter part is forced to bear the fundamental voltage,is proposed.

Based on the analysis of the vectors of the rectifier, a control scheme is proposed, in which the amplitudeand phase decoupling of AC fundamental voltage are controled separately.

The large-sized generator ought to install the ground fault protection based on the zero-sequence fundamental voltage (3U 0)with the setting value not less than 5 V.But in the field operations,The 6 kV station service electrical system took place single-phase-to-ground faults reaulted in the zero-sequence fundamental voltages of generator reaching to 13.2 V and 11.9 V respectively,and the stator ground protection maloperated.

Protection schemes based on the zero sequence fundamental voltage and the third harmonic voltage and the injection voltage are presented in this paper, and based on which, the factors which affects the protection schemes based on the zero sequence fundamental voltage and the relevant measures is presented.

Furthermore, in terms of the relationship among the fault location, zero-sequence fundamental voltage, fault phase voltage, winding capacitance to ground and grounding transient resistance, which is obtained by the injection 20 Hz voltage protection, the fault location is calculated.

Thus, Based on the analysis of the mathematical model of unipolar PWM output waveforms with Walsh function, this paper proposes a method to solve the switching angles quickly in the full range of variation of fundamental voltage.

With the positive sequence fundamental voltage components and its minus Hilbert transformation as elements,a PQ transformation matrix is constructed. The active power P and reactive power Q can be obtained through the PQ transformation of the stator currents.

The height of radiation-induced steps at rational multiples (1/m) of the fundamental voltage can be obtained from analytic conditions applied to the solution of the differential equation describing the equivalent circuit of the junction.

We construct the PQ transformation matrix with the positive sequence fundamental voltage components and their Hilbert transformation as elements.

The research ranges from fundamental voltage balancing techniques to control issues of a proposed active filter.

The switching frequency in the steady-state depends on the fundamental voltage content u1 of the switched waveform.

The output power factor is approximately 0.6 with a significant displacement angle between the fundamental voltage and current.

This paper uses the method of the double Fourier series to analyze in detail the spectrum of P.W.M.inverter using the double-edgesym- metrical triangular carrier wave and the sinusoidal wave under the asynchronous modulation condition, and it describes the regularities and characteristics of the spectrum, It also makes an analytic computation of the synchronous modulation condition as a particular example of the asynchronous modulation condition and provides the formula for calculating the fundamental voltage...

This paper uses the method of the double Fourier series to analyze in detail the spectrum of P.W.M.inverter using the double-edgesym- metrical triangular carrier wave and the sinusoidal wave under the asynchronous modulation condition, and it describes the regularities and characteristics of the spectrum, It also makes an analytic computation of the synchronous modulation condition as a particular example of the asynchronous modulation condition and provides the formula for calculating the fundamental voltage nonlinear change when inverter translates with the little chopping ratio, At last, it further studies the necessity and behaviour of an"in-phase modulation"as well.

A new simulative for the zero sequence voltahes of large turbo-generator with a stator ground fault is presented in this paper. The digital simulation can be used to obtain correct fundamental and third harmonic zero sequence voltages at the neutral and the terminal of the generator and flexiblely study the characteristics of various generator stator ground fault protection schemes.For the purpose of the simulation, eqiova;emt corciots based on the actual connection of coil-groups of the generators are built...

A new simulative for the zero sequence voltahes of large turbo-generator with a stator ground fault is presented in this paper. The digital simulation can be used to obtain correct fundamental and third harmonic zero sequence voltages at the neutral and the terminal of the generator and flexiblely study the characteristics of various generator stator ground fault protection schemes.For the purpose of the simulation, eqiova;emt corciots based on the actual connection of coil-groups of the generators are built according to the distribution of the fundamentsl voltage and the third harmonic potential. Most large generators have a 60 degree phase band of the fundamental frequensy, so a 180 degree phase band of the third harmonic frequency, and their nutrals are grounded through a high impedance.In this case, the turn-voltage phasors under one pole, such as N pole, can then be constructed as an upper half circular arc of 60 degree for the fundamental frequency and 180 degree for the third harmonic frequency, and thar under the neighboring pole, such as S pole, as a lower hslf circular arc.The distribution of the fundamental voltage and the third harmonic potential depends on combining these circular arcs according to the number of poles and the connection method of stator winding of a cirtain generator, when a ground fault occurs, fundamental voltage and the thirs harmonic potential, as well as the distributed capacitance between the winding and the ground, are divided into two parts by the ground fault point.Based on that, a new simulative model os built after correctly processing of phase relation.All details for the simulation have been discussed about various large turbo-generator in this paper.

In this paper,recursive least square algorithm was used to estimate the real part and imaginarg part of the complex amplitude of the fundamental voltage of the input signals that suf-fered noise pollution. The effective value of currents,voltages, active power and reactive power were calculated. the frequency and power factor were measured by using voltage phase anglechange. The accuracy of measurement was raised, the velocity of convergence was improved andcalculating quantity was decreased...

In this paper,recursive least square algorithm was used to estimate the real part and imaginarg part of the complex amplitude of the fundamental voltage of the input signals that suf-fered noise pollution. The effective value of currents,voltages, active power and reactive power were calculated. the frequency and power factor were measured by using voltage phase anglechange. The accuracy of measurement was raised, the velocity of convergence was improved andcalculating quantity was decreased by adaptive sampling.