KR100463330B1 - How to Evaluate Generator Performance Against Nonlinear Loads - Google Patents

Abstract

The output performance of the completed generator was evaluated by the temperature test by the equivalent reverse phase current without the nonlinear load test equipment. After the temperature saturation at the rated load and the rated speed of the generator, the generator was stopped and the surface temperature of the rotor field winding ( Measure T ₁ ) by resistance method, short-circuit the two phases of the generator, adjust the field winding so that the current of √3I ₂ flows to the stator at the rated speed, and stop the generator after the temperature saturation. Measure the field winding surface temperature (T ₂ ) by resistance method, short-circuit the three phases of the generator, adjust the field current to be the same as the field current value in the two-phase short circuit, stop the generator after temperature saturation open the electronic field winding surface temperature (T ₃₎ a process of measuring the resistance method, and, a rotor field winding surface temperature measured by each of the above process, by a predetermined method In terms of the temperature rise (T _eq) calculations, and then the generator design of the temperature rise predetermined value to meet if determining the installation site of the generator load conditions, including the step, sikimyeo is excluded the use of a non-linear load equipment reduce the manufacturing cost of the It is possible to accurately verify the performance of the generator, providing the reliability of the test, and meet the needs of consumers by shortening the performance evaluation test of the generator.

Description

How to Evaluate Generator Performance Against Nonlinear Loads

The present invention relates to a generator, and more particularly, to a method for evaluating the performance of a generator to evaluate the output performance test for a completed generator by a temperature test by an equivalent reverse phase current without a nonlinear load test facility such as a rectifier.

In general, as shown in FIG. 1, the generator is configured to rotate the rotor 1 consisting of the north pole and the south pole in an arbitrary direction by using a turbine or other physical kinetic energy. A change in magnetic flux occurs in the coils (a, a ') (b, b') (c, c ') that are maintained at predetermined intervals while maintaining the voids. do.

As described above, the generated voltage is transmitted to the load device as shown in FIGS. 2 and 3 to generate a harmonic current by the switching process of the SCR which converts the voltage of the AC component into the voltage of the DC component.

The harmonic current generated as described above generates a reverse rotating magnetic field in the synchronous generator to generate a counter electromotive force by flowing a current rotating in the reverse phase to the coil.

Therefore, the rotor field distorts the terminal voltage of the stator windings and increases the temperature of the windings due to the relationship between the stator and the rotating rotor, so that the generator G increases the stray load loss by the waveform distortion. Because the electronic surface causes eddy currents to increase the temperature of the rotor, the generator's specified output will not be obtained in a nonlinear load facility that uses the generator's voltage.

Therefore, in order to evaluate the performance of the temperature rise, vibration, noise, distortion of the output waveform, and the like, which are conventionally connected to equipment such as large-capacity multi-pulse rectifiers, large-capacity inverters, and computer equipments represented by semiconductors as communication loads, A nonlinear load facility, such as one equipment, was used, and performance evaluation tests were conducted by testing the actual load.

As described above, in order to measure the output performance of a generator for a nonlinear high frequency load, it is expensive because it analyzes the reverse phase current capacity and temperature rise of the generator through the generation of a real load with an expensive nonlinear load facility. There was a problem of raising the production cost.

Also, the harmonic current content rate due to harmonic loads depends on the rectification method (6 pulses, 12 pulses…) and the presence or absence of other electronic devices such as transformers. Since it is difficult to equip the load facility that can implement the condition, there was a problem that it is impossible to accurately verify the performance of the generator even if the actual load test.

The present invention has been made in view of the above-described general problems, and an object thereof is to provide an equivalent sequence current corresponding to a total harmonic current distortion (THCD) through a short circuit of a generator terminal. The temperature rise value of the generator is measured, and then the temperature rise regulation value of the generator design is satisfied.

The present invention for achieving the above object, the process of stopping the generator after the temperature saturation at the rated load and the rated rotation speed of the generator and then measuring the rotor field winding surface temperature (T ₁ ) by the resistance method;

In which the separation of the two-phase of the generator at the rated rotation speed, and then to the stator so that a current can flow in the _second √3I adjust the field winding and to stop the generator after the saturation temperature rotor field winding surface temperature (T ₂₎ to the resistance method Measuring process;

Short-circuit the three phases of the generator, adjust the field current to be equal to the field current value in the two-phase short circuit, stop the generator after temperature saturation, and measure the rotor field winding surface temperature (T ₃ ) by the resistance method; and ;

Calculating a temperature rise value (T _eq ) by calculating the rotor field winding surface temperature measured through each of the above processes by a predetermined method, and then determining whether the temperature rise regulation value at the time of generator design is satisfied. It is done.

In addition, the present invention is characterized in that in each process, the rotor field winding surface temperature is increased by supply of an equivalent reverse phase current.

Hereinafter, a preferred embodiment of the present invention will be described in detail.

The harmonic current generated by the nonlinear high frequency load can be calculated as the equivalent reversed phase current (I _2eq ) .The content of each order depends on the rectification method and the component of the site load. Calculate by reference.

The order and theoretical content of each harmonic current generated by harmonic load are shown in Table 1 below.

Table 1

Basis of Reference Electric Cooperative Research Vol. 46, No. 2 (A.C.E Report No.15.1979) IEEE 519-1981 Guide For Harmonic Control And Reactive Compensation Of Static Power Conveters. Rectification method (Pulse) 6 12 24 6 12 18 24 Harmonic Current Content (%) Harmonic order 5 17.5 2.0 2.0 17.5 2.6 2.6 2.6 7 11.0 1.5 1.5 11.0 1.6 1.6 1.6 11 4.5 4.5 1.0 4.5 4.5 0.7 0.7 13 3.0 3.0 0.75 2.9 2.9 0.4 0.4 17 1.5 0.2 0.2 1.5 0.2 1.5 0.2 19 1.25 0.15 0.15 1.0 1.0 1.0 0.1 23 0.75 0.75 0.75 0.9 0.9 0.1 0.9 25 0.75 0.75 0.75 0.8 0.8 0.1 0.8

Since the magnitude of the harmonic current is inversely proportional to the order, it is sufficient to consider up to the 25th order to calculate the equivalent reverse phase current through the generator output terminal short circuit, and the equivalent reverse phase current (I _2eq ) of each harmonic current is expressed by Equation 1 below. Calculated by

Equivalent Reverse Phase Current (I

In addition, since the equivalent reverse phase current to be actually _{charged by the} generator should consider the ratio of the harmonic load capacity to the rated capacity of the generator, the final equivalent reverse phase current (I _g2eq ) of the generator is _{expressed by} Equation 2 below. For reference, when selecting a generator, the reverse phase current capacity of the generator should be considered.

Generator equivalent reverse current (% I

Where P is the harmonic load capacity (KVA), PG is the generator rated capacity (KVA),

% I _g2eq : Equivalent reverse phase current value (%) to generator rated capacity,% I _2eq : Harmonic current of nonlinear load converted to equivalent reverse phase current (%).

In the terminal of the three-phase synchronous generator, the current calculation at each terminal by the symmetrical coordinate method is as follows.

The basic formula of a three-phase synchronous generator using the current calculation symmetry coordinate method at the generator terminals is as follows.

I ₀ : image current, I ₁ : normal current, I ₂ : reverse phase current, V ₀ : image voltage, V ₁ : normal voltage, V ₂ : reverse phase voltage, Z ₀ : image impedance, Z ₁ : normal impedance, Z ₂ : Reversed phase impedance, E ₁ : Supposed voltage, V ₀ = -Z ₀ I ₀ , V ₁ = E ₁ -Z ₁ I ₁ , V ₂ = -Z ₂ I ₂ .

The temperature rises most by nonlinear harmonic currents are the field windings of the generator rotor. Therefore, the temperature rise test is performed by measuring the surface temperature of the field windings.

The temperature rise test is carried out under rated load and through a two-phase short circuit in which the stator windings have a reverse phase current of the same magnitude as the normal current and a three-phase short circuit where only the steady current flows.

First, the temperature rise test at the rated load is performed by the temperature rise test at the rated load and rated rpm of the generator. After the temperature saturation, the generator is stopped and the surface of the rotor windings (T ₁ ) is measured using the resistance method. Measure

In addition, in the case of the temperature rise test through the two-phase short circuit of the generator terminal, the calculation of the generator terminal voltage and current is carried out as follows using the above-described generator formula.

When the two-phase short circuit of the three-phase synchronous generator, that is, the b-phase and the c-phase, is shorted, a reverse phase current of the same magnitude as the normal current is generated in the stator winding as follows.

I _a = 0, I _b = -Ic, and I ₁ = E ₁ / (Z ₁ + Z ₂ ) = -I ₂ .

In addition, the magnitude of the current value of each output terminal, i.e., each phase, is calculated as follows.

I ₀ = 1/3 (I _a + I _b + I _c ), I ₁ = 1/3 (I _a + aI _b + a ² I _c ), I ₂ = 1/3 (I _a + a ² I _b + aI _c ).

I ₁ | = | I ₂ | = I _b / √3 = I _c / √3.

Therefore, the current calculation formula of the three-phase synchronous generator in the two-phase short circuit is | I ₁ | = | I ₂ | = I _b / √3 = I _c / √3. Adjust the field current (I _f ) so that a current of √3I ₂ flows through the stator at the rotational speed.

After the temperature saturation, the generator is stopped and the field winding temperature (T ₂ ) of the rotor is measured by the resistance method.

In the case of the temperature rise test through the three-phase short circuit of the generator terminal, the calculation of the generator terminal voltage and current is carried out as follows using the above-described generator formula.

If a three-phase short circuit occurs in the generator terminal, the generator terminal voltage is zero, and only normal current flows as follows.

I ₁ = E ₁ / Z ₁ and I ₂ = I ₀ = 0.

Therefore, short-circuit the three phases, and then adjust the field current to be equal to the value of the field current (I _f ) at the time of the two-phase short circuit to perform a temperature rise test at the rated speed of the generator.

After temperature saturation, the generator is stopped and the surface temperature (T ₃ ) of the rotor's field winding is measured by the resistance method.

In the above, the difference between the saturated temperature value after the two phases are short-circuited and the saturated temperature value after the three phases are short-circuited becomes a temperature value raised by the reverse phase current component.

In addition, in the temperature rise test through the two-phase short circuit, the field current is adjusted so that the equivalent reverse phase current resistance value of the generator designed by referring to the field survey and the theoretical value can flow. Adjust the field current value in the same way as the temperature rise test.

Evaluating the temperature rise test by the equivalent reversal current from the field winding surface temperature value of the rotor measured by the resistance method after the temperature rise test at the rated load and the temperature rise test in the two-phase and three-phase short circuits as described above. Equation 3 below.

T

Then, it is determined whether the evaluated temperature rise value T _eq satisfies the temperature rise regulation value at the time of generator design.

As described above, the present invention executes the performance test and evaluation of the produced generator by the temperature test method of the equivalent reverse load through the short circuit of the generator output terminal without the test of the actual load, thus eliminating the use of load equipment and reducing the production cost. It provides the reliability of the test by accurately verifying the generator's performance regardless of the installation site load condition of the generator, and satisfies the needs of consumers by shortening the performance evaluation test of the generator.

1 is a cross-sectional view of a typical three-phase generator configuration,

2 is a schematic circuit diagram of a process of using a generated voltage in a nonlinear load device.

3 is a waveform diagram illustrating a process of converting an AC voltage generated in FIG. 2 into DC by a nonlinear load device.

Claims (3)

A generator comprising the steps of: stopping a generator after saturating a temperature at a rated load and a rated rotational speed of the generator and measuring the rotor field winding surface temperature (T ₁ ) by a resistance method; In which the separation of the two-phase of the generator at the rated rotation speed, and then to the stator so that a current can flow in the _second √3I adjust the field winding and to stop the generator after the saturation temperature rotor field winding surface temperature (T ₂₎ to the resistance method Measuring process; Short-circuit the three phases of the generator, adjust the field current to be equal to the field current value in the two-phase short circuit, stop the generator after temperature saturation, and measure the rotor field winding surface temperature (T ₃ ) by the resistance method; and ; Calculating a temperature rise value (T _eq ) by calculating the rotor field winding surface temperature measured through each of the above processes by a predetermined method, and then determining whether the temperature rise regulation value at the time of generator design is satisfied. Generator performance evaluation method for nonlinear loads. The method according to claim 1, wherein in each of the above processes, the rotor field winding surface temperature is increased by supply of an equivalent reverse phase current. The method of claim 1, wherein the calculation of the temperature rise value T _eq from the rotor field winding surface temperature is performed as in Equation 4 below. T Here, T ₁ is the rotor field winding surface temperature at rated load, T ₂ is the rotor field winding surface temperature at the two-phase short circuit, and T ₃ is the rotor field winding surface temperature at the three-phase short circuit.