JP2593514B2 - Exciter of variable speed induction machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an exciting device for a wound-type induction machine, and more particularly, to exciting a variable-speed induction machine when operating in parallel with an electric power system. It concerns the device.

(Prior Art) This is a power generation system that has been put to practical use because it can be composed of a variable speed prime mover such as a wind turbine, a water turbine, a pump turbine, a winding type induction generator, and a variable frequency excitation device. FIG. 5 shows a structural example of the variable speed power generation system. The winding induction generator (hereinafter referred to as induction generator) 1A and the prime mover 2A are directly connected to the shaft. The primary winding of the induction generator 1A is connected to the power system, and the secondary winding is the cycloconverter 3 and the transformer for the cycloconverter. It is connected to the electric power system via the switch 4. Further, a voltage vector detector 7A for detecting the magnitude V _A of the generator terminal voltage and the phase θ _A , and a phase for detecting a value (hereinafter referred to as a shaft rotation angle) θ _r obtained by converting the generator shaft rotation angle into an electrical angle. Detector 6
, _A power detector 9 for detecting a generator output PA, a current detector 8 for detecting a secondary current of the generator, and a control device 5B to constitute an excitation control device. Control apparatus 5B is generating control signals to the generator output P _A, determined by the operating generator terminal V _A are each target value P ^*, such that V ^* cycloconverter 3. FIG. 6 shows an example of the configuration of the control device 5B. In Figure 6, PID controller 501 is input to the difference between P ^* and P _A,
Outputs torque component current command ▲ I ^* _g ▼. The PID controller 502 receives the difference between V ^* and _VA , and outputs the excitation component current command ▲ I ^* _d
Output ▼. Vector detector 508 secondary current i _2, and outputs a secondary current phase reference ▲ theta ^* ₂ torque component current from ▼ I _g2 exciting component current I _d2. Also, PID controllers 504, 505
Respectively, input ▲ I ^* _g ▼ _-Ig2 , _Io + ▲ I ^* _d ▼ + _Id2, and output quadrature component command values VV ^* _g and VV ^* _d ▼ of the secondary voltage.
Where I _o is the exciting current. ▲ V ^* _{g for} two-phase / three-phase converter 509
▼, ▲ V ^* _d ▼, secondary current phase reference ▲ θ ^* ₂ ▼
amplitude Each phase is ▲ θ ^* ₂ ▼ -φ _v, Generates the three-phase balanced voltage commands ▲ V ^* _R2 ▼, ▲ V ^* _S2 ▼, ▲ V ^* _T2 ▼. However ^{_{▲ θ * 2 ▼ = θ A}} -θ r, φ v = tan -1 (▲ V
^* _d ▼ / ▲ V ^* _g ▼). In the cycloconverter, the fundamental component of the cycloconverter output voltage is ▲ V ^* _R2 ▼, ▲
The phase is controlled so that V ^* _S2 ▼ and ▲ V ^* _T2 ▼. Since the output voltage of the cycloconverter controlled by the control device 5B configured as described above is applied to the secondary winding of the induction generator 1A, the secondary voltage of the induction generator 1A and the frequency of the secondary current are ▲
θ ^* ₂ ▼ is differentiated. Therefore, the induction frequency of the internal induced voltage E _A of the generator 1A, as _E is represented by equation (1) becomes equal to the frequency _A of the primary voltage, induction generator
1A will operate in synchronization with the grid. The induction generator that operates in synchronization with the system by controlling the exciting current in this way is referred to as a variable speed machine and will be described below.

FIG. 7 is a vector diagram based on the system voltage _VL , where _A is a phase difference with the terminal voltage _L (hereinafter referred to as a phase difference angle) is δ _IA
And Reference numeral ₁ denotes a primary current vector diagram in which the torque component current (that is, the component current in phase with _A ) is _g1 , and the excitation component current is _d1 . The voltage drop of ₁ X _A is leakage impedance X _A, also _g1 X _A represents the voltage drop due to the torque component current. _A is an internal induced voltage vector. _g2 ,
_d2 is a vector obtained by converting the torque component current and the excitation component current of the secondary current to the primary side.

By the way, since the responses of the PID controllers 504, 505, 502 are fast, it can be generally considered that _Ig2 = I ^* _g ▼, _Id2 = I ^* _d ▼, and _VA = V ^* . The variable speed transmission output P _A from Figure 7 can be expressed by equation (2).

P _A = E _A · V _A sin / X _A = V _A · I _g1 = V ^* ▲ I ^* _g ▼ …… (2) The PID controller 501 sets ▲ I ^* _g ▼ such that P _A = P ^*. ▲ I ^* _g ▼ and ▲ I ^* _d ▼ at the time of settling are P _A = P ^* , V _A
= Realizing V ^* said to become a quadrature component command value of the secondary current for obtaining the primary current I _1. The output of the variable speed machine is controlled by V ^* , 機 I ^* _d ▼, II as shown in equation (2).
^* It is determined by _g ▼ and controlled without depending on the rotation angle θ _r and the terminal voltage phase difference angle θ _A.
It can be said that fluctuations and loss of power transmission caused by output changes do not exist in the variable speed machine. In other words, it can be said that the variable speed machine can perform constant output operation without being affected by the system state.

(Problems to be Solved by the Invention) The fact that a variable speed machine can perform a constant output operation without being affected by the system state means that, in other words, even if an adjacent synchronous machine is shaking, the shaking is controlled. It has no effect. It is an object of the present invention to provide an exciting device for a variable speed machine that improves the stability of an adjacent synchronous machine by fluctuating the output of an adjacent variable speed machine by focusing on this point.

(Means for Solving the Problems) An exciting current is controlled based on a current command based on a phase of a system voltage which has almost no phase fluctuation even when an adjacent synchronous machine is fluctuating or a phase equivalent thereto.

(Operation) When the synchronous machine and the variable-speed machine are connected to the system via a common transmission line, if the accident is recovered in a state where the phase difference angle of the synchronous machine is increased due to a transmission line accident, a known operation is performed. As described above, the phase difference angle and output of the synchronous machine fluctuate, and as a result, the phase difference angle of the voltage on the power station side (hereinafter referred to as a power transmission end) of the transmission line also fluctuates. If the variable speed machine is current controlled in a phase that is not affected by this,
Since the output current of the variable speed machine has a constant phase difference angle with the system voltage, when the power transmission end voltage phase difference angle fluctuates, the phase difference between the power transmission end voltage and the variable speed machine output current also fluctuates. When the phase difference angle of the internal induced voltage of the synchronous machine increases, the synchronous machine output increases, the phase difference angle of the transmitting end voltage also increases, the phase difference between the transmitting end voltage and the output current of the variable speed machine increases, and the output of the variable speed machine decreases. . Thus, when the phase difference angle of the synchronous machine fluctuates, the output change of the variable speed machine is opposite to the output change of the synchronous machine. That is, the variable speed machine operates so as to absorb the output fluctuation of the synchronous machine.

(Example) FIG. 1 shows a configuration example of the present invention. FIG. 1 is different from FIG. 5 in that a phase detector 14 installed on the system side of the transmission line (hereinafter referred to as a power receiving end) and detecting a system voltage phase θ _L , a transmitter 15 installed on the power receiving end, A receiver 16 installed at the power plant has been added. Further, the difference is that the voltage detector 7 is used instead of the voltage vector detector 7A, and the configuration of the control device 5 is partially changed. The configuration of the control device 5 is shown in FIG. The adder / subtracter 515 is provided with a system voltage phase signal θ _L and a shaft rotation angle θ.
_The secondary current phase reference _{** 2} ▼ is obtained from _r .

Vector detector 508 detects the secondary current phase reference from the secondary current signal i ₂ ▲ θ ^* ₂ ▼ phase with a 90 ° delay current component I _a2, I _b2. PID controllers 501 and 502 are respectively P ^* −P _A , V ^*
Is input to -V _A, the command value of the ^{_{I a2, I b2 ▲ I *}} a ▼, ▲ I
^* Output _b ▼. PID controllers 504 and 505 and a two-phase / three-phase converter 509 are the same as those in FIG. In addition, PID controller
504,505,502 are adjusted to respond fast, but PID
Controller 501 because of the need to achieve cooperation with the output control of the prime mover 2A, delay from P ^* P _A is adjusted to the response of the order of 1 to 2 seconds.

Since the PID controllers 504, 505, 502 respond at high speed, V _{A
^{= V *, I a2 = ▲}} I * a ▼, I b2 = ▲ * b ▼, also the secondary current phase reference ▲ theta ^* ₂ ▼ a when viewed from the primary side ^{_{▲ θ * 2 ▼ + θ r}} = θ L becomes Since the phase of the system voltage coincides with the system voltage of the primary current, if the current components delayed by 90 ° are I _a1 and I _a2 , respectively, I _a1 = I _a2 and I _b1 = I _b2 . However, the excitation current _Io is ignored for simplicity.

FIG. 8 is a drawing of a vector diagram in a state where the same V ^* and P ^* are set as in the drawing of FIG. Since P ^* and V ^* are the same, _A of FIG. 8, _A, δ _A ,, ₁ is the same phase ₁ is the same as the Fig. 7 the system voltage vector _L
The difference is that it is decomposed into I _a1 and I _b2 with a delay of 90 °. At a FIG. 8, the phase difference angle φ of _{^{1 tan -1 (▲ I * b}} ▼ / ▲ I * a
▼) and is variable speed transmission output P _A is expressed by equation (3).

P _A = E _A V _A sin / X _A = V _A I ₁ cos (δ _A -φ) …………… (3) For simplicity, assuming that there is no branch from the variable speed machine to the transmitting end, the magnitude of the voltage at the transmitting end is V _s, the exactly the same (4) to represent the variable transmission output (3) using the phase difference angle [delta] _s.

P _A = V _S I ₁ cos (δ _S −φ) (4) From the equation (4), the variable speed machine output P _A is the phase difference angle θ _{s of the} voltage at the transmission end.
For a change, P _A and reverse of the change that is θ _s is to increase / decrease is said to decrease / increase.

The variable speed machine output P _A and synchronous machine output P _B are impedance _Xe
If the power is transmitted to the system by the transmission line, the power transmission line power P _L is expressed by the equation (5), where the power transmission terminal voltage is V _s , the phase difference angle is δ _s , and the power receiving terminal voltage is _VL. .

P _L = V _S V _L sin δ _S / X _E (5) If the fluctuation of the transmission end voltage caused by the fluctuation of the output P _B of the synchronous machine after the transmission line accident is approximated to the fluctuation of the voltage constant phase difference angle difference δ _s , P _a, the ratio of the variation amount of the P _L is, -dP _a / dδ _S and dP _L / d? _S
Is the ratio of By the way, from equations (4) and (5), _{(6), dP A / dδ} S, the dP _L / d? _S determined as (7). P _A = 0.85P _U as an example, the load power factor 0.85 P _L = 1.7P _U variable speed motor, as phase difference angle 70 ° of the sending end voltage (6),
(7) to estimate the equation when _{tan (δ S -φ) ≒ 0.62} , dP A / d
_{δ S = 0.53, cotδ S =} 0.3, dP L / dδ S = 0.72 , and the
The fluctuation ratio of P _A and P _L is 0.53: 0.72.

Variation of P _L when P _B is the fluctuation of ± 0.1P _U is ± 0.058P _U, variation of phase angle [delta] _S is + 6 °, the -5 °. This is the case of variable speed motor is a constant-output operation P _L varies ± 0.1P _U, variation + 20 ° of the phase angle [delta] _S, If it is a large place where the contribution to the stability of the synchronous machine as compared to -8 ° I can say.

The calculated operating condition is not always possible with the synchronous machine alone, but it is an operating point that is possible because it is operating in parallel with the variable speed machine. Condition.

FIG. 3 shows another embodiment of the present invention. In FIG. 3, the system voltage phase θ _L is not directly detected, and the control device 5A is used based on the terminal voltage phase θ _A detected by the terminal voltage vector detector 7A.
Is detected indirectly in the equation ₍₁ ). In FIG. 4, the subtractor 52 is used.
At 1, the difference Δ between the terminal voltage phase θ _A and the output θ _L of the phase generator 524
is calculated by the PI controller 522, the correction frequency _c is calculated by the PI controller 522, the sum of the reference frequencies _o and _c is calculated by the adder 523, and the phase generator 524 generates a phase signal of θ _L = 2πt based on the calculated value. The integration time constant of PI controller 522 is
The value is set to a value sufficiently larger than the period of the system fluctuation, and the proportional gain is determined so that θ _L follows θ _A stably, but can be stabilized at a small value of about 0.04.

With such a configuration, &thgr; _L follows the frequency and phase &thgr; _A of the terminal voltage at a following speed determined by the integration time constant of the PI controller 522. Note that the following speed is adjusted to a small value that cannot follow the system fluctuation. Since the average value of the system voltage frequency is controlled to be substantially constant, in a normal operation state in which the terminal voltage frequency is equal to the system voltage frequency, the average value of the terminal voltage frequency is substantially constant,
θ _L follows the frequency and phase θ _A of the terminal voltage, respectively. Therefore, the operation state of this embodiment is also operating state that is shown in the vector diagram of Figure 7 in a conventional manner under normal operating conditions is is shown in FIG. 8 _{θ L = θ A, V L} , the relationship I ₁ Are the same.

Even if the frequency phase of the terminal voltage suddenly changes due to a system fault, etc., θ _L does not follow, so that the primary current I ₁ is controlled with a constant phase difference with respect to the system voltage. 8, which is the same as the embodiment shown in FIGS. As described above, the embodiment shown in FIGS. 3 and 4 operates in the same manner as the embodiment shown in FIGS. 1 and 2.
It can be seen that a similar effect can be obtained.

As described above, the embodiment shown in FIGS. 3 and 4 is effective for improving the stability of an adjacent synchronous machine.
Further, there is an advantage that a system voltage phase detector and a transmitting / receiving device are not required. In addition, since θ _L shown in FIG. 4 does not follow the system frequency fluctuation caused by the supply-demand imbalance of the entire system during normal operation, the phase angle of the internal induced voltage does not change, and _A change in the phase difference angle δ _A −δ _S causes a change in the generator output. Increasing the high happens when [delta] _S is the system frequency, decreased [delta] _A - [delta _S is, since the generator output is reduced,
This output change contributes to system frequency control. This can be said to be another effect of the embodiment shown in FIGS.

Although the above description has been made in the case of the induction power generation system, the motor operation during the pumping operation in the pumped storage power plant
It goes without saying that the operation and effect are exactly the same, just by reversing the direction of the power and the phase of the current.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain an exciting device for a variable-speed induction machine that improves the stability of an adjacent synchronous machine by fluctuating the output of the variable-speed induction machine.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of a control device used in the embodiment of the present invention, FIG. 3 is a block diagram showing another embodiment of the present invention, FIG. FIG. 5 is a configuration diagram showing a part of a control device used in another embodiment of the present invention, FIG. 5 is a configuration diagram of a conventional system, FIG. 6 is a configuration diagram of a control device used in a conventional system, FIG. Is a vector diagram for explaining the conventional system, and FIG. 8 is a vector diagram for explaining the present invention. 1A Induction machine, 2A Rotating machine 3 Exciting device 4, Power transformer 5 Control device 6, Rotation angle detector 7, Voltage detector 8, Secondary current detection Unit 9 Active power detector, 14 Voltage phase detector 15 Transmitter, 16 Receiver

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadahiro Yanagisawa 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. (72) Inventor Toshinobu Yamamoto 1-Toshiba-cho, Fuchu-shi, Tokyo Inside

Claims (2)

(57) [Claims] An exciting device for an induction machine that operates at a variable speed by connecting a primary winding of a winding type induction machine to an electric power system and applying an AC excitation to a secondary winding determined by a rotor speed and a frequency of the electric power system. A variable voltage variable frequency power supply for supplying an exciting current to a secondary winding, a transformer for supplying power to the variable voltage variable frequency power supply from an AC power supply, and a primary side for detecting a voltage of a primary terminal of the induction machine. A terminal voltage detector, a secondary current detector that detects a secondary current, a rotation angle detector that is mechanically coupled to the rotor of the induction machine and detects the rotor rotation angle of the induction machine, Active power detector to input and output to, comprising a system voltage phase detection device consisting of a phase detector to detect the system voltage ahead of the transmission line, a transmitter and a receiver, of the primary-side terminal voltage detector The output, the output of the secondary current detector, the output of the rotation angle detector and the validity A control device that controls the variable voltage variable frequency power supply by inputting a primary terminal voltage command value and an active power command value determined by an output of a force detector and an output and operation of the system voltage phase detection device, The control device includes means for generating a secondary current phase reference from the system voltage phase signal and the rotation angle signal, and a delay of 0 ° and 90 ° from the secondary current and the secondary current reference to the secondary current reference. Means for detecting the current component or the phase difference between the secondary current and the secondary current reference and the magnitude of the secondary current, and a delay of 0 ° from the secondary current reference of the secondary current from the active power command value and the active power signal Means for generating a command value of the phase difference between the current component or the secondary current and the secondary current reference, and from the primary terminal voltage and the primary terminal voltage command value of 90 ° with respect to the secondary current reference of the secondary current. Means for generating a command value for the magnitude of the delay current component or secondary current A current component having a delay of 0 ° with respect to the secondary current reference of the secondary current or a phase difference between the secondary current and the secondary current reference and its command value, and a delay of 90 ° of the secondary current with respect to the secondary current reference. A means for controlling the variable voltage variable frequency device so that the magnitude of the current component or the secondary current and its command value respectively match, and the active power in the opposite direction to the output when the adjacent synchronous machine is oscillating. , And contributes to improving the stability of an adjacent synchronous machine. In the control device, instead of the system voltage detection device according to the first aspect, a calculation is performed based on the primary terminal voltage phase based on a frequency which is not affected by the frequency fluctuation of the transmission end, and a transmission line end is calculated. An exciter for a variable-speed induction machine, comprising: means for detecting a phase following the system voltage phase.