JPH03270664A - Ac excited synchronous generator, constitution thereof and variable speed generating facility - Google Patents

Abstract

PURPOSE:To suppress higher harmonic distortion and to obtain a high quality output voltage waveform by selecting the order (k) of higher harmonic field magnetomotive force of a stator slot so that a relation k2-knot equal to 1 is satisfied when the number of slot of rotor is k2. CONSTITUTION:Rotor slots 11 and stator slots 12 are arranged, respectively, in a rotor 7 and a stator 8 with same intervals. Higher harmonic voltage caused by the number of the rotor slot is suppressed by reducing the number of winding coefficient with respect to the spatial higher harmonic of the armature winding. When the number k2 of the stator slot per two poles and the order (k) of the higher harmonic of field magnetomotive force do not satisfy a relation ¦k2-k¦=1 and the winding coefficient of the armature winding with respect to ¦k2-k¦ order spatial higher harmonic is reduced, higher harmonic voltage caused by the number of stator slot and the higher harmonic components of field magnetomotive force can be suppressed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of configuring an AC-excited synchronous generator, and in particular, to a method for configuring an AC-excited synchronous generator, in particular, using the generator configured to improve the output voltage waveform. Regarding variable speed power generation equipment.

[Conventional technology]

In the variable speed power generation equipment shown in FIG. 1, the 8 field windings of the generator are excited with variable frequency alternating current, and the sum of the speed of the rotating magnetic field formed by the excitation and the rotational speed of the rotor is always constant, Induces an AC output voltage of constant frequency in the armature winding.

By adopting such a variable speed power generation system, for example, JP-A-57-113971, JP-A-62-1655,
As disclosed in Publication No. 81, it is possible to improve the frequency adjustment ability, stability, and overall power generation efficiency of the power system.

Incidentally, since the rotor of the generator used in the variable speed power generation system is excited by alternating current, the stator and rotor both have iron core slots arranged at equal intervals as shown in FIG. 2.

[Problem to be solved by the invention]

In the variable speed power generation equipment described in the above conventional technology, the AC excitation type synchronous generator is used as a generator. They did not even consider the mechanical structure that the machine should have.

That is, since the AC-excited synchronous generator has a rotor and a fixed child core slot structure, magnetic resistance pulsations occur due to these slots. Furthermore, there is a problem in that such magnetoresistive pulsations can cause output voltage distortion. Therefore, unless you use an AC-excited synchronous generator whose mechanical structure, such as the slot structure, number of slots, and winding configuration, has been carefully considered, the quality of the voltage waveform supplied by this type of variable-speed power generation equipment cannot be improved. It cannot be done. However, conventionally, in the output voltage waveform of an AC-excited synchronous generator used in variable-speed power generation equipment, little consideration has been given to harmonics generated by the mechanical structure of the AC-excited synchronous generator.

The present invention has been made in view of the above points, and provides an AC-excited synchronous generator with a mechanical structure capable of suppressing generated harmonics and supplying an output voltage waveform of good quality, and a variable speed generator using the same. The purpose is to provide power generation equipment.

[Means to solve the problem]

In the following, a method for suppressing specific harmonics that can be relatively large will be described.

In an AC-excited synchronous generator, as shown in the following example, spatial pulsation of magnetic resistance due to rotor slots, voltage harmonics caused by the fundamental wave of field magnetomotive force, and spatial pulsation of magnetic resistance due to stator slots. Voltage harmonics may occur due to magnetic pulsations and harmonics of certain field magnetomotive forces.

Voltage harmonics caused by the spatial pulsation of magnetic resistance due to rotor slots and the fundamental wave of field magnetomotive force, that is, when the number of rotor slots per two poles is 1, □±1st voltage voltage harmonics If the winding coefficient fw (k1, 1.) of the armature winding for the first harmonic is large, the harmonic component cannot be ignored. This is achieved by reducing the winding coefficient for the ±1st harmonic.

On the other hand, voltage harmonics are caused by spatial pulsation of magnetic resistance due to stator slots and harmonics of specific field magnetomotive force. When the wave order is k, the next voltage harmonic in the range of about 2-1 to 2+1 is Ikz-
It becomes large when kl becomes a small value and the winding coefficient fw (k, -0) of the armature winding for 1-2-1 spatial harmonics becomes a non-negligible value. Therefore, the voltage harmonic order k From 2-1 to 2-1, to suppress voltage harmonics in the range of about +1, select 2 for the number of stator slots per 2 poles so that 2-k does not become l in 1,
This can be realized by reducing the winding coefficient of the armature winding for the first harmonic to lk, -.

[Effect]

Voltage harmonics caused by the number of rotor slots can be suppressed by reducing the winding coefficient of the armature winding for spatial harmonics.

On the other hand, the difference lk, -kl between the number of stator slots per two poles, 2, and the specific field magnetomotive force order is not 1, and
By reducing the winding coefficient of the armature winding with respect to the first spatial harmonic, voltage harmonics caused by the number of stator slots and field supermagnetic force harmonic components can be reduced.

A voltage waveform supplied from a variable-speed power generation facility using an AC-excited synchronous generator that takes such matters into consideration will have good quality and less distortion.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of variable speed power generation equipment for explaining one embodiment of the present invention, and is illustrated assuming wind power generation equipment in particular. The variable speed power generation equipment uses an AC excitation type synchronous generator 1 as a generator, and a variable frequency AC converter 3 is connected to the field side terminal 2 of the generator 1. As shown in FIG. 4, the AC-excited synchronous generator 1 used here consists of a rotor 7 and a stator 8, both of which have rotor slots 11. stator slots 12, each having a field winding 9. An armature winding 10 is provided. Furthermore, as shown in FIG. 2, rotor slots 11. The stator slots 12 each have a cross-sectional configuration such that they are arranged at equal intervals between the rotor 7 and the stator 8, and the speed of the rotating magnetic field formed by the field winding 9 and the rotor 7 that is displaced by the windmill 5 are The frequency of the voltage induced in the armature winding 10 is always kept constant by controlling the rotational speed of the armature winding 10 to be constant regardless of the frequency supplied by the AC excitation device f3. Therefore, a voltage of a constant frequency is outputted to the power system 6 from the armature side terminal 4 in FIG.

In the following, we will discuss the harmonic generation mechanism resulting from the mechanical structure such as the winding configuration and the number of slots of the AC-excited synchronous generator.

The field winding of an AC-excited synchronous generator takes the form of a so-called distributed winding in which the field winding is distributed and wound in slots at spatially different positions. Therefore, taking harmonics into consideration, the spatial distribution of field current j(xtt) is expressed as j(xyt)=Σ alsink(x-(L16j
) (1) where X is fixed to the stator coordinate system and the two poles correspond to 2π. ω. is the angular frequency corresponding to the synchronous speed, and ak is the amplitude of the second-order current distribution. From this current distribution, the magnetomotive force distribution A T (
x v t ) becomes AT(xtt)=/ j (x, t)·dx.

Next, considering spatial changes in magnetic resistance due to the rotor and stator slots, the spatial distribution of permeance P(x, t), which is the reciprocal of the aI low resistance distribution, is assumed as follows.

P (x, t) = P, −P, ・cosk, (x
-(110t)-P, 11cosk, x (
3) In equation (3), 1 and 2 are the number of rotor slots and stator slots per two poles, respectively, and Po, Pl and P2 are the smooth permeance, the pulsating permeance amplitude due to the rotor slots, and This is the permeance amplitude of the pulsation caused by the stator slots.

The first term is a component that does not vary both temporally and spatially,
The second term is a component that varies temporally and spatially as an effect of the rotor slots, and the third term is a component that varies only spatially as an effect of the stator slots. Since the magnetic flux density can be calculated as the product of magnetomotive force and permeance, the magnetic flux density distribution B(x, t
, ) becomes as follows.

B (x, t) = P (x, t) ・A T (x
, t) 2 to 2 to 2 to k (4) The magnetic flux Φ(1) linked to the armature winding is the half of each spatial harmonic of the magnetic flux density B(x, t) derived from equation (4). If we consider that it is a definite integral of the space over the waves.

k 2 k (5) In equation 9(5), 2 is a proportionality constant, and f and i are n
The winding coefficient appearing in the equation 0, which is the winding coefficient of the armature winding for the next spatial harmonic, is the fundamental wave of the spatially distributed magnetic flux, or the magnetic flux of each spatial harmonic interlinks with the winding. This is a coefficient indicating the ratio. In other words, when the 5-winding coefficient f vs is l, all the harmonic magnetic fluxes between n spaces interlink with the windings, and the 1-winding coefficient f
When te is O, the n-space harmonic magnetic flux does not interlink with the winding at all (References: For example, Takeshi Anayama, Fundamentals of Energy Conversion Engineering, Maruzen, 1972)9 Furthermore, equation (5) By time-differentiating, the armature voltage can be calculated as shown in the following equation.

(6) In equation (6), the first term is a voltage harmonic generated due to the air harmonic component in the field magnetomotive force, and is determined by the field magnetomotive force harmonic component and the smooth permeance.

In particular, =1 is the fundamental wave component of the output voltage.

The second and third terms are voltage harmonics generated due to permeance pulsations due to the rotor slots. Section 4, Section 5
The terms are voltage harmonics generated due to permeance pulsations due to stator slots and specific field magnetomotive force harmonics.

Here, a method for suppressing harmonics that may become relatively large will be described below.

Especially when k is 1 in the second and third terms of equation (6),
In other words, when It disappears.

On the other hand, in the fourth term of equation (6), the amplitude of the k-th time harmonic voltage is as follows, where lk, -kl are small values, and k, -
The winding coefficient fw(
When k, -0 becomes a value that cannot be ignored.

In particular, in the range of 2-1 to 2+1, the time harmonic order k in equation (8) becomes 1, so that the harmonic component cannot be ignored.
When the number of stator slots per two poles is 2, which satisfies the condition that 2-kl is 1.

Armature winding winding coefficient f for 1 to 2-kl spatial harmonics
w(k2-0 is the winding coefficient fur for the fundamental wave.

Since the winding coefficient fwL for the fundamental wave cannot normally be made small, the harmonic component may become large.

As described above, unless the number of rotor slots 11, the number of stator slots 12, and the winding coefficient of armature winding 10 in FIG. 2 are appropriately selected, the various harmonics described above will occur. .

Now, when the number of rotor slots 11 is a multiple of 6 for the two poles of rotor 7, the absolute value of the amplitude a of the current distribution shown in equation (2) above is as follows. .

At this time, in the first term of equation (6) above, when the order of the field magnetomotive force is 1, that is, the amplitude of the output voltage fundamental wave and the above (
7) In the equation, the ratio of the amplitude of the first voltage harmonic is P z f v fhiill −・(
10) Po 2・f,1 becomes. Now, as a limit case in the above equation (3), when the pulsation permeance due to the rotor slot is maximum, such as p2=o, puniP, equation (10) becomes 1 "゛"" (11) 2・f v
l, and the distortion rate of the output voltage at armature side terminal 4 is n
When it should be less than or equal to (p, u,), at least (11)
Since the equation must be less than or equal to n, the winding coefficient f・Ikx± of the armature winding for the k1±1st spatial harmonic is
1) is f w n1*t)≦2・n−f, 1 (
12) must be satisfied.

On the other hand, when the order of the field magnetomotive force in the first term of equation (6) is 1, that is, when the amplitude of the output voltage fundamental wave and the above (8)
The ratio of the next voltage harmonic amplitude to Eq. Now, the above (3
), when the pulsating permeance due to the stator slots is maximum, such as p, = o, p2 = po, the equation (13) becomes, and the distortion rate of the output voltage at the armature side terminal 4 is n.
When it should be less than or equal to (p, u,), at least (14)
Since the formula must be less than or equal to n, the winding coefficient fw(k2-
0 is f W fkz-kl≦2 ・n ・Ikz-kl ・
The relationship k-f-1 (15) must be satisfied.

lk here.

If kl is 1, f s f k2 - k) = f m 1
(16), and since equation (15) cannot hold, Ikz −kl≠1 (17)
The number of stator slots per two poles that satisfies the condition is 2.
It is necessary to do so.

By using the AC-excited synchronous generator configured as described above, it is possible to obtain a variable speed power generation facility with reduced distortion in the output voltage.

Next, the process of determining a mechanical configuration with less harmonics for the AC-excited synchronous generator 2 in the variable speed power generation equipment shown in FIG. 1 will be described.

In this type of rotating electric machine, the number 1 winding coefficient of the core slot, the harmonic order of the magnetomotive force, etc. are not determined independently, but are mutually related.

In other words, in order to realize a mechanical configuration with fewer harmonics,
For example, there is a method of performing several trial calculations to satisfy the conditions such as the winding coefficient and the number of slots mentioned above, and searching for suitable conditions.

Figure 3 shows an example of the process of searching for conditions that reduce voltage waveform distortion. In other words, the number of rotor slots and the winding method of the field winding are determined at 101° and 102 in the figure, and then the winding coefficient of the armature winding for each spatial harmonic suppresses the harmonics included in the output terminal voltage. The number of stator slots and the winding method of the armature winding are changed as shown in 103 to 106 in the figure until the optimum value is reached. The procedure involves determining the method of winding a wire.The following is an example of the process.

Now, it is assumed that the distortion rate of the voltage waveform defined by the standard is within 3%, and the configuration of the stator and rotor that satisfies this is determined. Furthermore, assuming an AC-excited synchronous generator with about 20 poles, the number of rotor slots per two poles is 1, and the coil pitch and pole pitch as the field winding form are as shown in Table 1. Decide as follows.

Table 1 At this time, the amplitude a of the normal magnetic field current distribution shown in equation (1) above is obtained as follows.

π 0 For this specification, the voltage harmonic order shown in equation (7) above is 24±1st. Therefore, the winding coefficients of the armature winding in question are the 23rd and 25th orders, and these are the 3rd order.
The values will be as shown in the table.

As can be seen from the equation (18) in Table 3, when the number of rotor slots per two poles is a multiple of 6 as in this example, the order of the field magnetomotive force is as small as the fundamental wave. 6m±1 (m=
1.2.3...) Water harmonic components exist.

Next, determine the configuration of the stator. First, consider the number of stator slots per two poles as 2, and the coil pitch and pole pitch as the armature winding configuration as shown in Table 2.

Looking at Table 2, it can be said that the winding coefficients for the 23rd and 25th orders have values comparable to those of the fundamental wave, and that the voltage harmonics shown in equation (7) above may become large.

Here, the pulsating permeance vibration due to the rotor slots viewed from the stator side is assumed as follows.

P1=0.1・P, (19
) Using this permeance vibration 111P1, calculate the 23rd and 25th harmonics corresponding to the voltage harmonics in equation (7) above, and normalize them with the fundamental wave voltage calculated from equation (6) above to obtain the fourth harmonic. The values shown in the table are obtained.

Table 4 Table 6 From this, the stator configuration considered in Table 2 does not satisfy the voltage distortion rate standard. Next, consider that the number of stator slots per two poles is 2, and the coil pitch and pole pitch as the armature winding configuration are as shown in Table 5.

Table 5 Using these values and the permeance of formula (10),
Table 7 shows the results of calculating the 23rd and 25th voltage harmonics.

Table 7 Also for this specification, the voltage harmonic order shown in equation (7) above is 24±1st as before. That is, the winding coefficients of the armature winding in question are 23rd and 25th orders, and these have values as shown in Table 6.

Looking at the table, the harmonics are reduced. Such a reduction effect is obtained by having a small winding coefficient of the armature winding for the 23rd and 25th spatial harmonics, that is, the 1st ± 1st spatial harmonics in equation (7) above.

On the other hand, try calculating the harmonics in equation (8) above. The orders in question here are the 17th and 19th orders, assuming that the difference between the number of stator slots per two poles is 2 and the field supermagnetic force harmonic order is within ±1. Here, the permeance amplitude P2 due to the stator slots seen from the stator side is P, = 0.8・p, (20
), and since 1 is 1 for both the 17th and 19th orders, the winding coefficient is the winding coefficient for the fundamental wave, and the 17th and 19th voltage harmonics calculated by equation (8) are is as shown in Table 8.

Table 8 Table 9 For this specification as well, the voltage harmonic order shown in equation (7) above is 24±1st as before. That is, the winding coefficients of the armature winding in question are 23rd and 25th orders, and these have values as shown in Table 10.

As a result of calculating the voltage distortion rate using the 17th, 19th, 23rd, and 25th harmonics shown in Table 10, the distortion rate is 3.25%, which is not within 3%.
Think like a table.

Using these values and the permeance of equation (10),
The results of calculating the 23rd and 25th voltage harmonics are shown in the 11th
Shown in the table.

Table 11 Looking at the table, the harmonics are reduced.

On the other hand, try calculating the harmonics in equation (8) above. The order in question here is the number of stator slots per 2 poles k
If the difference between t and the harmonic order of the field magnetomotive force is within the range of ±1, then k will be the 17th order. Here, the permeance amplitude P1 due to the stator slot as seen from the stator side is calculated as before (1
Considering equation 1) 6 Also, since 1 plus 1 is 0.2, the winding coefficient becomes the winding coefficient for the 0.2nd harmonic, and its value is 0.0155. Using these (8)
The 17th voltage harmonic calculated by the formula is 0.19%, and the voltage distortion rate is 0.39%.

Here, by not setting the number of stator slots per two poles as a multiple of 2ti-6, the winding coefficient of the armature winding is smaller than the fundamental wave in the 17th voltage harmonic calculated by the above equation (8). It can be seen that the harmonic component is reduced because it does not become a value.

As described above, according to this embodiment, the output voltage harmonics of the AC-excited synchronous generator are as follows: The number of rotor slots per two poles is □, the number of stator slots is 2, and the air harmonics are adjusted according to the field magnetomotive force. When a wave component exists, the winding coefficient of the armature winding with respect to the interharmonics between +/-1 is small, and the voltage-time harmonic order k is in the range from 2-1 to +1. , 1 is 1 in ±
If the winding coefficient of the armature winding with respect to the first interharmonic is small in lk2±, the voltage with few harmonics becomes 1
A variable speed power generation facility is obtained which supplies an output voltage of good quality.

Although this embodiment has been described assuming a variable speed power generation device using wind power as an energy source, other variable speed power generation equipment such as hydraulic power generation equipment can also supply a high quality output voltage.

〔Effect of the invention〕

As described above, according to the present invention, harmonics in the output terminal voltage are reduced, and by using an AC-excited synchronous generator that provides a voltage waveform of high quality, a variable speed motor that provides a voltage waveform with few harmonics is used. You can get a power generator.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a variable speed power generation facility using an AC excitation type synchronous generator, and Fig. 2 is a partial cross-sectional view of the AC excitation type synchronous generator used in the variable speed power generation equipment of Fig. 1. FIG. 3 is a diagram showing a procedure for determining the configuration of an AC-excited synchronous generator, and FIG. 4 is an overview diagram of the AC-excited synchronous generator.

Claims (1)

[Claims] 1. A rotor that stores field windings in core slots arranged at equal intervals, and a stator that stores armature windings in core slots that are arranged at equal intervals, A method for configuring an AC excitation type synchronous generator, in which a field winding housed in the rotor is excited by a variable frequency AC excitation device to induce an AC output voltage of a constant frequency in the armature winding, wherein the AC excitation The number of rotor slots and the winding method of the field winding are determined based on the capacity of the synchronous generator and the rotational speed of the rotor. The number of stator slots and the winding method of the armature winding are varied and the number of stator slots and the winding method of the armature winding are changed so as to obtain the optimum value for suppressing waves. A method for configuring an AC-excited synchronous generator characterized by determining a line method. 2. It has a rotor that stores field windings in core slots arranged at equal intervals, and a stator that stores field windings in core slots that are arranged at equal intervals, and stores them in the rotor. A method for configuring an AC excitation type synchronous generator in which a field winding is excited by a variable frequency AC excitation device to induce a constant frequency AC output voltage in the armature winding, wherein the capacity of the AC excitation type synchronous generator is The number of rotor slots and the winding method of the field winding are determined based on the number of rotor slots and the rotational speed of the rotor. Next, in order to suppress harmonics contained in the voltage output from the armature terminals, A method for configuring an AC-excited synchronous generator, characterized in that the number of stator slots and the winding method of the armature winding are varied, and the optimal number of stator slots and the winding method of the armature winding are determined through repeated calculations. . 3. It has a rotor that stores field windings in core slots arranged at equal intervals, and a stator that stores field windings in core slots that are arranged at equal intervals, and stores them in the rotor. In an AC excitation type synchronous generator in which a field winding is excited by a variable frequency AC excitation device and an AC output voltage of a constant frequency is induced in the armature winding, the number of stator slots per two poles is a multiple of 6. An alternating current excitation type synchronous generator characterized by having a number of 4. It has a rotor that stores field windings in core slots arranged at equal intervals, and a stator that stores field windings in core slots that are arranged at equal intervals, and stores them in the rotor. In an AC excitation type synchronous generator in which a field winding is excited by a variable frequency AC excitation device and an AC output voltage of a constant frequency is induced in the armature winding, the number of rotor slots per two poles is a multiple of 6. An AC-excited synchronous generator characterized in that the number of stator slots per two poles is not a multiple of six. 5. It has a rotor that stores field windings in core slots arranged at equal intervals, and a stator that stores armature windings in core slots that are arranged at equal intervals, and stores them in the rotor. In a method for configuring an AC excitation type synchronous generator in which a field winding is excited by a variable frequency AC excitation device and an AC output voltage of a constant frequency is induced in the armature winding, the number of rotor slots per two poles is k_1, the winding coefficient of the armature winding for the fundamental wave is f_w_1, the winding coefficient of the armature winding for the k_1±1st spatial harmonic is f_w_(_
k__1_±_1_), and when the distortion rate in the output voltage of the AC-excited synchronous generator should be at least n (p.u.) or less, the armature winding winding coefficient f_w_( ＿k＿＿１＿±＿＿１＿）is at least f_w_(＿k＿＿１＿±＿１＿)≦2・n・f＿w＿
1. A method for configuring an AC-excited synchronous generator, characterized in that the configuration satisfies the relationship 1. 6. It has a rotor that stores field windings in core slots arranged at equal intervals, and a stator that stores armature windings in core slots that are arranged at equal intervals, and stores them in the rotor. A method for configuring an AC-excited synchronous generator in which a field winding is excited by a variable frequency AC excitation device to induce a constant-frequency AC output voltage in the armature winding, comprising: exciting the field winding; The relationship between the specific harmonic order k included in the field magnetomotive force generated by the field and the number of stator slots per two poles k_2 satisfies the condition |k_2-k| The winding coefficient is f_w_1, and the winding coefficient of the armature winding for the k_2-k spatial harmonic is f_w_(_k__2_-_k
), and when the distortion rate in the output voltage of the AC-excited synchronous generator should be at least n (p.u.) or less, k
_ Armature winding winding coefficient f for 2-k spatial harmonics
w_(＿k＿＿2＿−＿k＿) is f_w_(＿k＿＿2＿−＿k＿)≦2・n・k・|k
A method for configuring an AC-excited synchronous generator, characterized in that the configuration satisfies the relationship:_2−k|·f_w_1. 7. A conversion device that converts energy such as wind or water power into rotational force, an AC excitation type synchronous generator that converts the rotational force into electric power, and a variable power generator provided at the field side terminal of the AC excitation type synchronous generator. In variable speed power generation equipment, which consists of a frequency AC excitation device and supplies the output of the AC excitation type synchronous generator to the power grid, the rotor and stator have an iron core slot structure, and the rotor is adjusted according to the power generation capacity, etc. A variable speed power generation facility characterized in that it uses the alternating current excitation type synchronous generator having a stator structure that corresponds to the rotor and suppresses the generation of harmonics in the output voltage.