JP3319640B2 - Active power and reactive power control device in AC system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for controlling active power and reactive power in an AC system.

[0002]

2. Description of the Related Art AC power distribution networks are huge networks,
The feeder is considered a distributed constant circuit. The longer the feeder line, the larger the impedance drop and the larger the phase lag of the current, so that the transmittable power decreases. Therefore, a current source is provided in parallel with the existing AC system to change the magnitude and phase of the injected current, while a voltage source is provided in series with the AC system to change the magnitude and phase of the applied voltage and sent by the AC system. Active power and reactive power controllers are used to increase power in response to load requirements.

Hereinafter, such a conventional control device is shown in FIG.
Will be described. FIG. 14 schematically shows a general power distribution network. The voltage at the transmitting end is E ₁ , the phase is θ ₁ , and is transmitted to the transformer Tr via a feeder having an impedance X, and the consumers U ₁ ,
Power is distributed to U ₂ , U ₃ , U ₄ , and U ₅ . Assuming that the voltage and the phase in the transformer Tr are E ₂ and θ ₂ , respectively, the power P transmitted in the power distribution network is transmitted in a direction from the advanced phase to the delayed phase, and is expressed by the following equation. Here, δ is a phase difference angle. P = (E ₁ · E ₂ / X) sin δ, δ = θ ₁ −θ ₂ In such an AC system, some or all of the consumers require very large power or large delay reactive power. Then, the voltage drop due to the feeder line increases. In the above equation, E ₂ becomes smaller and θ ₂ is further delayed.
The phase difference angle δ increases to maintain transmission power. However, in order to secure stable power supply, the phase difference angle δ cannot be more than 90 °. Rather, 90
It is necessary to operate with a margin of °, and in that sense there is a limit to the transmitted power.

[0004] In addition to steady voltage drops, load fluctuations can sometimes be a problem. When some customers take a fluctuating load, the impedance drop of the transmission line also fluctuates, and in addition to the fleet itself with the fluctuating load, other consumers sharing the transformer Tr receive a voltage at the receiving end. Fluctuates. This appears as flickering of the lighting equipment called flicker, and also causes various capacitors to generate heat. Several methods have been put into practical use and studied to solve such problems.

FIG. 15 shows one method already used in an actual system, in which a compensator is provided in parallel with an AC system. The compensator is composed of an anti-parallel circuit of a capacitor C, a reactor L connected in parallel with the capacitor C, and thyristors S ₁ and S ₂ . The C, when there is no parallel circuit of L, and the delayed reactive power Q ₂ to which take the customer increases, the voltage variation increases larger voltage drop due to the impedance of the feeder is. Here, when connected to the feeder line to capacitor C, reactive power Q4 goes invalid power, the impedance X ₁ can be reduced voltage drop due proceeds system when is not a component constant load becomes lighter As a whole, the power is consumed, which is not preferable in terms of voltage stabilization.

Therefore, a reactor L is inserted in parallel with the capacitor C, and the current of the reactor L is supplied to the thyristors S ₁ , S ₂
And the reactive power is adjusted while compensating for the impedance drop so that the reactive power of the entire system does not advance. When the load taken by the customer involves the fluctuation of the reactive power, the impedance drop also fluctuates and causes flicker. However, the current of the reactor L can be controlled so as to absorb the fluctuation component. in this way,
C in AC system, or absorbed by L connects the parallel circuit delay to take the reactive power Q ₃ taken by the parallel circuit or cancel the reactive power Q _2, the reactive power Q ₃ the variation of the lagging reactive power Q ₂ Thus, the transmission power when the load becomes large is maintained.

FIG. 16 shows a capacitor C ₁ , connected in series with a feeder circuit to compensate for the impedance drop of the feeder line.
In this method, C ₂ and C ₃ are added. The capacitors in order to change the phase advance amount is divided, are antiparallel circuit of a thyristor in parallel to each capacitor as can the unwanted capacitor detach S _p1, S _p2, S _p3 is connected . When it is not necessary to insert a capacitor, the antiparallel circuits _Sp1 , _Sp2 , and _Sp3 of the thyristor are all _supplied with gate signals and utilized. If you want to maximize the capacity of the capacitor making use of only C ₁ example, the capacitor C ₂ to give a gate signal to the anti-parallel circuit S _p2, S _p3 thyristor, C
₃ is short-circuited. The idea is the same as that of FIG. 15 or to compensate or cancel the delayed reactive power Q6 due to the impedance X ₂ of the feeder line by the capacitor C _1, C _2, leading reactive power due to _{C 3 Q 7, Q 8,} Q 9 .

[0008]

In the conventional method shown in FIGS. 15 and 16, the thyristor is actually controlled, and one control is performed in one cycle of the AC system regardless of the detection method.
It is basically to make corrections several times. Then, even if an attempt is made to compensate for harmonics, it is not possible to compensate for a change that is faster than one cycle of AC. In effect, the effect can be expected only for the low-frequency fluctuation component. In the circuit shown in FIG. 15, when an ON signal is input to the thyristors S ₁ and S ₂ , the current is determined by the voltage and the size of the reactor L at that time, so that the current waveform still includes harmonics. Figure
In circuit 16, a capacitor C ₁ for fast,
When C ₂ and C ₃ are turned on, they must be changed stepwise, and the amount of reactive power Q ₇ , Q ₈ and Q ₉ can only be changed stepwise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its object is to provide a reactive power compensator capable of responding quickly to fluctuations faster than the frequency of an AC system, and to continuously transmit reactive power from a leading region to a lag region. Active power in AC systems that can be changed, generate voltage and current as close as possible to sinusoidal waves as much as possible, and can supply stable power no matter how the load condition changes by combining parallel compensation and series compensation. And a reactive power control device.

[0010]

In order to achieve the above object, the invention according to claim 1 comprises a first power converter capable of controlling a current at an appropriate position of an AC feeder, A voltage controllable second power converter is provided which is electrically insulated from the power converter. The first power converter has a function of converting AC to DC and is provided in parallel with the feeder line. Installed, and controls the effective and ineffective components of the input current of the converter so that the voltage at the installation point maintains the set voltage, the second power converter has a function of converting DC to AC, and Insert the output in series with the incoming wire through the transformer,
The voltage in the same phase as the feeder voltage and the 90 ° phase with the feeder current so that the voltage at the installation point maintains the set voltage
An active power and reactive power control device in an AC system characterized by generating a shifted voltage and compensating for a voltage drop due to feeder line impedance.

[0011] a second aspect of the present invention, an appropriate position of the AC-out wire through a first power converter capable current control, the alternating current with a frequency higher than the AC of the first wire when the power converter A second power converter that can control the output voltage is connected to the first power converter, and the first power converter has a function of converting feed line AC to high-frequency AC, and is installed in parallel with the feed line. The second power converter has a function of converting high-frequency AC to AC of the feeder line by controlling the effective and ineffective components of the input current of the converter so that the voltage at the installation point maintains the set voltage. And, the output is inserted in series with the feeder line through a transformer, and the voltage at the installation point is 90% with respect to the line current when the voltage is in phase with the feeder line voltage so as to maintain the set voltage.
An active power / reactive power control device in an AC system characterized by generating a voltage out of phase and compensating for a voltage drop due to feeder line impedance.

According to a third aspect of the present invention, in the active power and reactive power control device in the AC system according to the first aspect, a DC circuit of the first power converter and a DC circuit of the second power converter are provided. It is electrically connected, and the input current control of the first power converter and the output voltage control of the second power converter are used together to compensate for a voltage drop due to the impedance of the feeder.

[0013]

According to a fourth aspect of the present invention, there is provided the active power and reactive power control device in the AC system according to the third aspect , wherein the capacitor installed in a circuit connecting the first power converter and the second power converter. The input current of the first power converter is controlled so that the voltage is kept constant.

[0015]

According to a fifth aspect of the present invention, there is provided the active power and reactive power control device in the AC system according to the second aspect, wherein the capacitor installed in a circuit connecting the first power converter and the second power converter. as the voltage is kept constant, and controlling the circulating current of the first power converter.

[0017] According to a sixth aspect of the invention, the active and reactive power control device in an alternating current system according to claim 2, of the first power converter of the high-frequency side and the high-frequency side of the second power converter Another high frequency power supply is connected to the coupling line, and the input current control of the first power converter and the output voltage control of the second power converter are used together to compensate for the voltage drop due to the impedance of the feeder. Features.

[0018] claimed invention seventh aspect, claim 2 in active and reactive power control device in an alternating current system, wherein said first high-frequency side of the power converter second
The high-frequency side of the power converter is electrically insulated, and the input current control of the first power converter and the output voltage control of the second power converter are used together to compensate for the voltage drop due to the impedance of the feeder. It is characterized by doing.

[0019]

According to the present invention, a current controllable converter is inserted in parallel to a feeder line, and the output of the voltage controllable converter is inserted in series into a feeder circuit via a transformer and transported through the feeder line. Control power. The former supplies a reactive current that cancels out the reactive power of the feeder while maintaining the DC voltage or high-frequency voltage of the converter constant, and compensates for the voltage drop between the transmission end and the connection point of the controller. In the latter case, the active voltage source is inserted at the connection point of the control device and strengthened, and the power transmission end and the power reception end are substantially separated from each other so that even if the load on the customer is bad, there is no problem. The power can be supplied.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG.
2 is an equivalent circuit diagram of the circuit of FIG. As shown in FIG.
In an AC feeding system, VS is a transmitting end voltage, VR is a receiving end voltage, and both are connected by a feeder having an impedance X. The feeder midpoint (voltage V _M) established the active and reactive power control apparatus of the present embodiment is used as a compensation device for minimizing the feeding circuit losses. That is, a converter CONV1 capable of supplying the current Iq via the transformer Tr1 is connected in parallel to the feeder. DC output side of the converter CONV1 are connected capacitor C ₁₁ is the DC voltage V _d1 is controlled to be constant. On the other hand, the secondary winding of the transformer Tr2 is connected in series to the feeder line, and the primary winding thereof is connected to the converter CON.
V2 and operates as a voltage source for supplying an AC voltage Vpq to the feeder. The converter CONV1 is controlled by a control circuit CONT1.
The DC circuit of V2 is connected to a DC constant voltage source Vdc,
It is controlled by the control circuit CONT2. Further, the DC voltage source V _dc, the variable voltage rectifier CONV3 a reactor L _12, consists capacitor C _12, a DC voltage is V _d2.

In the present embodiment, the active power and reactive power control devices of the present invention are installed at the midpoint of the feeder, but the impedance X is omitted in the figure. Also,
It is clear that there is no practical problem if it is installed at a place other than the intermediate point.

FIG. 2 shows an equivalent circuit of the circuit shown in FIG.
That is, the power control device according to the present embodiment uses the converter CON that can supply the current _Iq to the intermediate position of the feeder line.
The V1 in parallel, connected in series to the feeder line voltage source CONV2 that can supply an AC voltage V _pq, a compensation device for minimizing feeding circuit losses.

By the way, when the electric power demanded by the consumer is gradually increased, the voltage drop due to the feeder line impedance is increased and the voltage at the receiving end is gradually decreased unless a compensator is installed. To prevent this, the delay current component of the load must be canceled by the lead current component of the compensator. Assuming that the combined current of both ideally cancels out and only the current in phase with the voltage remains, this means that only the resistance drop of the feeder wire substantially remains, and the impedance drop is extremely small .
Even if the current cannot be completely cancelled, if a compensating device is used to take the leading current, the impedance drop between the transmitting end and the intermediate point can be reduced.

FIG. 3 shows a control circuit which embodies this.
That is, in FIG. 3, the voltage drop between the transmitting end and the intermediate point is detected by a deviation between the command value _VM0 ^* (average value of three phases) of the intermediate point voltage and the average value _VM0 of the measured voltages. Further, in order to perform stable current control between the wire and the converter CONV1 can the voltage across the DC voltage V _d1 i.e. capacitor C ₁₁ must have established. Thus, FIG. 3 has two voltage control loops, V _d1 and V _M0 ,
The magnitude and phase of the input voltage of the converter CONV1 are controlled in order to control the advance current _Iq (the line currents I _R , I _S , I _T ) while controlling the two voltages stably.

A configuration for realizing the operation will be further described. The deviation between the DC voltage command value V _d1 ^* and the actual voltage V _d1 is multiplied by K ₁ by a proportional amplifier. Since this deviation needs to be compensated for by the active power, the multipliers M ₁ , M ₂ ,
In M _3, unit sine wave [Phi _R voltage midpoint, [Phi _S,
Multiply with Φ _T. The outputs of the multipliers M ₁ , M ₂ and M ₃ are the input current commands of the converter for reducing the DC voltage deviation to zero. On the other hand, the deviation between the command value V _M0 ^* (average value of the three phases) of the midpoint voltage and the average value V _M0 of the measured voltage is caused by the delay current component of the feeder line, and the component is canceled. When such a leading current component is supplied, the voltage drop of the feeder line is compensated.

Therefore, the deviation between the command value V _M0 ^* of the midpoint voltage and the average value V _M0 of the measured voltage is multiplied by K ₂ by the proportional amplifier, and the output is multiplied by the unit sine in multipliers M ₄ , M ₅ and M ₆ . The signals Φ _R , Φ _S , and Φ _T are multiplied by a signal advanced by 90 °. The differential operation element indicated by the symbol D advances the phase by 90 ° by differentiating the unit sine waves Φ _R , Φ _S , and Φ _T. The output of the multipliers M ₄ , M ₅ , M ₆ refers to the current command to be taken in the converter to compensate for the voltage drop in the feeder line. Multipliers M ₁ , M ₂ ,
Output a multiplier M ₄ of M _3, M _5, the output of the M ₆ are summed in adders _{A 1, A 2, A 3} , the line current to be taken by the converter CONV1 command ^{_{I R *, I S *,}} I _T
^* Is made. After that, the comparators C ₃ , C ₄ , and C ₅ compare the current with the actual current for each phase, and perform PWM modulation through the amplifiers K ₃ , K ₄ , and K ₅ , and perform R, R A voltage command is given to the S and T phases. The converter CONV2 is a so-called reverse converter for converting DC into AC, which generates an AC voltage _Vpq and inserts it in series into a feeder line to produce the same effect. As shown in FIG.

[0027] In FIG. 4, (the average value of the three-phase) V _M0 ^* wear voltage command value of the electric wire, V _M0 denotes a voltage value of the average of the feeder line measured. The two voltages are compared by the comparator C _10, is K ₁₁ times by the amplifier multiplier M _11, M _12, M ₁₃
And are multiplied by the unit sine waves Φ _R , Φ _S , and Φ _T respectively. The outputs of the multipliers M ₁₁ , M ₁₂ , and M ₁₃ mean voltage command values that are in phase with the so-called electric wires, meaning that the voltage drop of the feed wires is supplied from the converter CONV2, in other words, from another power source.

On the other hand, since the voltage drop of the feeder line is caused by the inductance of the feeder line, the voltage drop can be compensated by inserting a capacitive voltage into the feeder line. For this purpose, the line currents I _R , I _S , and I _T are detected, and the respective phases are set to 90 °.
° Generates advanced signal to create another voltage command value.

Next, the R phase will be described as a representative. The phase (ωt−θ) of the current IR is advanced by 90 ° (π / 2
+ Becomes .omega.t-theta) of the phase, multiplying the proportional coefficient K _R. The sum output of the multiplier M ₁₁ in the adder A _11, making the voltage command value V ^* _pq (R). As is clear from the above description, the voltage command value V ^* _pq (R) is a command value including a component for supplying a voltage component having the same phase as that of the feeder from another power source and a component for supplying a capacitive voltage to the feeder. is there. The ratio of the two components is determined by changing the magnitude of the proportionality coefficient K _R. Then
V ^* _pq (R) is the measured value of the voltage in the comparator C ₁₁ V
It is compared with _pq (R), through a voltage controlled amplifier K ₁₂ so they match, making voltage command INV inverter R-phase (R) by performing the PWM modulation. The S-phase and the T-phase are redundant and will not be described.
Make (T). Since the DC voltage source _Vdc is a well-known variable voltage rectifier and filter, it is not necessary to particularly explain.

Although the configuration of the present invention has been described based on the embodiment, the present invention provides a first converter capable of controlling the magnitude and phase of the input current and the magnitude and phase of the output voltage. By using a controllable second converter together, the voltage drop of the feeder line is compensated, and the active power of the feeder line is controlled to enable large power transfer.

FIG. 5 is a circuit diagram of another embodiment of the present invention. In the embodiment shown in FIG. 1, a first converter CONV1 which is installed in parallel with a feeder line and performs current control, and a second converter inserted in series with the feeder line and controls a voltage applied to a feeder circuit are: Each had a separate DC power supply. That is, the DC power of the first converter CONV1 is
A voltage V _d1 charged in the second converter of the DC power supply is a constant voltage source V consisting of a variable voltage rectifier and filter
_{At dc} , the voltage is V _d2 . Converter CONV1 and CONV
The DC circuit 2 is electrically insulated, but this DC circuit is connected in the present embodiment shown in FIG. That is, if V _d1 = V _d2 = V _d , the constant voltage source V _{dc including the} variable voltage rectifier and the filter becomes unnecessary. The control circuit CONT is comprised of CONT1 and CON in FIG.
T2 can be integrated and applied as it is. Namely, converter CONV1 controls the input current I _q, while maintaining the voltage V _d of the capacitor C to a constant, the converter CONV2 3-phase output voltage V _pq is a V _d as a DC voltage source
Control.

FIG. 6 shows a first embodiment applied to the embodiment of FIG.
It is a control circuit block diagram of a power converter . As already described with reference to FIG. 3, as the power required by the consumer gradually increases, the voltage drop due to the feeder line impedance increases, and the voltage at the power receiving end gradually decreases. Therefore, if a leading current is taken by the compensator, the impedance drop between the transmitting end and the intermediate point can be reduced.

FIG. 6 shows a control circuit which embodies this.
In FIG. 6, the voltage drop between the power transmitting end and the intermediate point is detected by the deviation between the command value _VM0 ^* (average value of three phases) of the intermediate point voltage and the average value _VM0 of the measured voltages. Further, in order to perform stable current control between the wire and the converter CONV1 can the voltage across the DC voltage V _d1 i.e. capacitor C ₁₁ must have established. In this embodiment,
It has two voltage control loops of V _d1 and V _M0 and stably controls the two voltages to control the advance current I _q (the line current is I
_R , I _S , I _T )
The magnitude and phase of the input voltage of V1 are controlled.

Next, the operation of this embodiment will be described. The deviation between the DC voltage command value V _d1 ^* and the actual voltage V _d1 is multiplied by K ₁ by a proportional amplifier. Since this deviation needs to be compensated for by the active power, in the multipliers M ₁ , M ₂ and M ₃ ,
Multiply by the unit sine waves Φ _R , Φ _S , Φ _T of the voltage at the intermediate point. The outputs of the multipliers M ₁ , M ₂ and M ₃ are the input current commands of the converter for reducing the DC voltage deviation to zero. On the other hand, the deviation between the command value V _M0 ^* (average value of the three phases) of the midpoint voltage and the average value V _M0 of the measured voltage is caused by the delay current component of the feeder line, and the component is canceled. When such a leading current component is supplied, the voltage drop of the feeder line is compensated.

Therefore, the deviation between the command value V _M0 ^* of the midpoint voltage and the average value V _M0 of the measured voltage is multiplied by K ₂ by a proportional amplifier, and the output is multiplied by the unit sine in multipliers M ₄ , M ₅ and M ₆ . The signals Φ _R , Φ _S , and Φ _T are multiplied by a signal advanced by 90 °. The integration operation element indicated by the symbol I advances the phase by 90 ° by integrating the unit sine waves Φ _R , Φ _S , and Φ _T. The output of the multipliers M ₄ , M ₅ , M ₆ refers to the current command to be taken in the converter to compensate for the voltage drop in the feeder line. Multipliers M ₁ , M ₂ ,
Output a multiplier M ₄ of M _3, M _5, the output of the M ₆ are summed in adders _{A 1, A 2, A 3} , the line current to be taken by the converter CONV1 command ^{_{I R *, I S *,}} I _T
^* Is made. Thereafter, the comparators C ₃ , C ₄ , and C ₅ compare the current with the actual current for each phase, and perform PWM modulation through the amplifiers K ₃ , K ₄ , and K ₅ , and perform R, R A voltage command is given to the S and T phases. The converter CONV2 is a so-called reverse converter for converting direct current to alternating current. The converter CONV2 generates an AC voltage _Vpq , which is inserted in series into a feeder line to produce a similar effect. As shown in FIG.

In FIG. 7, V _M0 ^* indicates a feed command voltage value (average value of three phases), and V _M0 indicates a measured average _feed wire voltage value. The two voltages are compared by the comparator C _10,
Is K ₁₁ times given to the multiplier M _11, M _12, M ₁₃ by the amplifier, the unit sine wave [Phi _R respectively, [Phi _S, is multiplied with [Phi _T. The outputs of the multipliers M ₁₁ , M ₁₂ , and M ₁₃ mean voltage command values that are in phase with the so-called electric wires, meaning that the voltage drop of the feed wires is supplied from the converter CONV2, in other words, from another power source. On the other hand, since the voltage drop of the feeder line is caused by the inductance of the feeder line, the voltage drop is compensated by inserting a capacitive voltage into the feeder line. For this purpose, the line currents I _R , I _S , and I _T are detected, and signals whose phases are advanced by 90 ° are generated to generate another voltage command value.

Here, the R phase will be described as a representative.
The phase (ωt−θ) of the current IR is delayed by 90 ° (ωt−
θ−π / 2) and multiply by the proportional coefficient K _R. The sum output of the multiplier M ₁₁ in the adder A _11, making the voltage command value V ^* _pq (R). Then, the voltage command value V ^* _pq (R) is a command value including a component for supplying a voltage component having the same phase as that of the feeder from another power source and a component for supplying a capacitive voltage to the feeder. The ratio of the two components is determined by changing the magnitude of the proportionality coefficient K _R. Then, V ^* _pq (R) is compared with the measured values V _pq of the voltage in the comparator C ₁₁ (R),
Through a voltage control amplifier K ₁₂ so they match, P
Performs WM modulation and outputs voltage command INV for inverter R-phase
Make (R). The S-phase and the T-phase are redundant and will not be described, but the voltage command values INV (S) and INV (T) of the inverter are generated by the same configuration as that of the R-phase. Since the DC voltage source _Vdc is a well-known variable voltage rectifier and filter, it is not necessary to particularly explain.

FIG. 8 is a circuit diagram of a third embodiment of the present invention. As shown in the figure, V _s in the AC feeding circuit lines sending end voltage, the V _r denote the receiving end voltages. It is assumed that both are connected by a feeder having an impedance X, and the active power and reactive power control devices of the present invention are installed at an intermediate point of the feeder, but the impedance X is omitted in the figure. It is also clear that there is no practical problem if it is installed at a place other than the intermediate point. The feeder midpoint (voltage V _M) converter CC-1 capable of providing a current I _q via the transformer Tr1 is connected.
Transformer Tr3 is connected to the output side of converter CC-1, Tr4 is connected to its secondary winding, and
Converter CC-2 is connected to the secondary side of r4. Converter CC-2 operates as a voltage source that supplies AC voltage _Vpq in series to the _feeder circuit via transformer Tr2.

The converters CC-1 and CC-2 are cycloconverters capable of so-called circulating current control, and one phase thereof has a circuit configuration shown in a frame CC-R in FIG. That is, converter CC-1 has CC-1R having the configuration of CC-1, CC-1S and CC-1 (not shown).
T, and a converter CC-2 is a CC-2R (not shown),
It consists of CC-2S and CC-2T. Also, the transformer Tr
A capacitor C is connected to the connection point between 3 and Tr4. The terminal voltage of the capacitor C is the cycloconverter CC-1,
A reference voltage of CC-2 is provided. The frequency is set by an oscillator (not shown) to about one digit higher than the commercial frequency of the feeder, and the magnitude of the active power is controlled so that the capacitor voltage becomes constant. The reactive power (circulating current) of the cycloconverter is controlled to match the reference voltage. That is, converter CC-1 is a frequency converter cycloconverter for converting a commercial frequency to a high frequency, and converter CC-2 is a frequency converter for converting a high frequency to a high frequency.

The equivalent circuit of the circuit of FIG. 8 is the same as that of FIG. That is, the power control device of the present embodiment includes a voltage source CC-2 capable of supplying an AC voltage _Vpq in parallel with a converter CC-1 capable of supplying a current _Iq to an appropriate position of a feeder line. This is a compensator for minimizing feeder loss by connecting the feeder to the feeder wire in series.

FIG. 9 shows converters CC-1 and C
It is an equivalent circuit for one phase of a resonance circuit interposed in the middle of C-2. The circuit loss in this resonance circuit is compensated by supplying active power from the feeder. When the resonance frequency is controlled to match the frequency of the reference oscillator, the converter C
Control is performed so that the delayed reactive power of C-1 and CC-2 and the advanced reactive power of capacitor C are balanced. In other words,
Due to the parallel resonance of the inductance component corresponding to the delayed reactive power and the capacitor C, the voltage and frequency of the capacitor are kept constant.

[0042] That is, in FIG., V _c is the capacitor voltage, L _cc is cycloconverter CC-1, CC-2
C, which is an inductance equivalent to the reactive power due to the sum of the circulating currents, is a resonance capacitor installed in the middle of the transformer as described above. If there is no loss in this parallel resonance circuit, the following relationship is established.

[0043]

(Equation 1) An increase in the circulating current because V _c is constant means that L _cc is substantially smaller than in equation (1). Then, the resonance frequency f determined by the equation (2) moves in a direction to increase. However, since the circulating current attempts to return to the original magnitude, L _cc increases, and the resonance frequency also returns to the original value and calms down. Given the state of the circulating current is reduced to the contrary, moves to the L _cc is larger direction determined by the equation (1). As a result, the resonance frequency determined by the equation (2) decreases. Then, the circulating current is increased at the same as the background, L _cc resonance frequency smaller settles back to its original value. When the resonance frequency is controlled to be equal to the frequency of the reference oscillator in this way, the delay current caused by the circulating current and the leading reactive power caused by the capacitor are controlled to be balanced.

After the voltage of the capacitor is established, it is very easy to think later. Converter CC-2 is a circulating current type cycloconverter using transformer Tr4 as an input transformer and transformer Tr2 as an output transformer. As described above, the converter CC- 2 described in detail in the margin of FIG.
R (CC-2R, CC-2S, CC-
2T). The converter CC-1 is a circulating current type cycloconverter using the transformer Tr3 as an input and the transformer Tr1 as an output transformer. However, since power flows from the Tr1 side to the Tr3 side, the power is converted from the low frequency side to the high frequency side in the power regeneration mode for the cycloconverter.

The control of the converter is given by the control circuit CONT. The method of producing a gate signal to be given to the thyristor based on the reference voltage of the capacitor and the voltage command is the same as that of a general cycloconverter. The content of the control circuit CONT is roughly divided into a portion for controlling the converter CC-1 (FIG. 10) and a portion for controlling the converter CC-2 (FIG. 11).

As the power demanded by the consumer increases gradually without the control device as in the present invention, the voltage drop due to the feeder line impedance increases, and the voltage at the power receiving end decreases steadily. To prevent this, the delay current component of the load must be canceled by the lead current component of the compensator. Assuming that the combined current of both ideally cancels out and only the current in phase with the voltage remains, this means that only the resistance drop of the feeder wire substantially remains, and the impedance drop is extremely small . Even if the current cannot be completely cancelled, if a compensating device is used to take the leading current, the impedance drop between the transmitting end and the intermediate point can be reduced. FIG. 10 shows a control circuit that embodies this.

In FIG. 10, the voltage drop between the transmitting end and the intermediate point is detected by the deviation between the command value _VM0 ^* (average value of three phases) of the intermediate point voltage and the average value _VM0 of the measured voltages. You. Further, in order to perform stable current control between the wire and the converter CONV1 can shall be established capacitor voltage V _c is. Therefore, having two voltage control loop of V _c and V _M0, converters in order to control also the _{(I R, I S, I} T is the line current) leading current I _q while stably controlling the two voltage The magnitude and phase of the input voltage of CONV1 are controlled.

The configuration for realizing the operation will be further described. Deviation of the capacitor voltage instruction value V _c ^* and the actual voltage V _c is ₁ × K by amplifier K1. Since this deviation needs to be compensated for by the active power, the multipliers M ₁ , M
₂ , the unit sine wave Φ _R of the voltage at the midpoint in M ₃ ,
Multiply with Φ _S , Φ _T. The outputs of the multipliers M ₁ , M ₂ , M ₃ are the input current commands of the converter for making the deviation of the capacitor voltage zero. On the other hand, the command value V _M0 ^* (average value of three phases) of the midpoint voltage and the average value V _M0 of the measured voltage
Is caused by the delay current component of the feeder line, and if a leading current component that cancels the component is supplied, the voltage drop of the feeder line is compensated.

Therefore, the difference between V _M0 ^* and V _M0 is determined by the amplifier K2
It is _doubled K by a multiplier M ₄ and the output, M _5, M
_{6 at} 90 ° from the unit sine waves Φ _R , Φ _S , Φ _T
Multiplied with the advanced signal. The differential operation element indicated by the symbol D advances the phase by 90 ° by differentiating the unit sine waves Φ _R , Φ _S , Φ _T. Multiplier M ₄ ,
The output of M ₅ and M ₆ means a current command to be taken in the converter to compensate for the voltage drop of the feeder line. The outputs of the multipliers M ₁ , M ₂ , M _{3 and} the outputs of the multipliers M ₄ , M ₅ , M ₆ are added in adders A ₁ , A ₂ , A ₃ , respectively, and a line current command I to be taken by the converter CONV 1 is obtained. _R ^* , _IS ^* and _IT ^* are created. Thereafter, the comparators C ₃ , C ₄ , C ₄
Compared to the actual current in the ₅ provides a voltage command through amplifier K _3, K _4, K ₅ to the converter CC-1. Specifically, in each of the phase controllers PHC ₁ , PHC ₂ , and PHC ₃ , the voltage command is compared with the capacitor voltage command, that is, the output voltage _{Vosc of an} oscillator (not shown), and the converters CC-1R, CC-1S, Generate phase signals α ₁ , α ₂ , α ₃ for CC-1T.

Converter CC-2 is equivalent to converter CC-1.
A converter that performs the reverse conversion operation to generate an AC voltage _Vpq and inserts it in series into a feeder cable to produce the same effect. The details of the control circuit are shown in FIG. It is.

In FIG. 11, V _M0 ^* indicates the voltage command value of the feeder wire (average value of three phases), and V _M0 indicates the measured average feeder wire voltage value. The two voltages are compared by the comparator C _10,
Is K ₁₁ times given to the multiplier M _11, M _12, M ₁₃ by the amplifier, the unit sine wave [Phi _R respectively, [Phi _S, is multiplied with [Phi _T. The outputs of the multipliers M ₁₁ , M ₁₂ , and M ₁₃ mean voltage command values in phase with the feeder line, meaning that the voltage drop of the feeder line is supplied from the converter CC-2, in other words, from another power source. .

On the other hand, since the voltage drop of the feeder line is caused by the inductivity of the inductance of the feeder line, the voltage drop is compensated by inserting a capacitive voltage into the feeder line. For this purpose, the line currents I _R , I _S , I _T are detected, and their phases are set to 90 °.
° Generate an advanced signal to create another voltage command value. The R phase will be described as a representative. Current I _R of the phase (ωt-
θ) is advanced by 90 ° to have a phase of (π / 2 + ωt−θ), and is multiplied by the proportional coefficient K _R. Then, the adder A ₁₁ adds the output of the multiplier M ₁₁ to obtain the voltage command value V.
^* Make _pq (R). As is clear from the above description, the voltage command value V ^* _pq (R) is a command value including a component for supplying a voltage component having the same phase as that of the feeder from a separate power source and a component for supplying a capacitive voltage to the feeder. is there. The two component ratios are determined by changing the magnitude of the proportional coefficient K _R. Then, V ^* _pq (R) is compared with the measured values V _pq of the voltage in the comparator C ₁₁ (R),
Through a voltage control amplifier K ₁₂ so they match, the phase controller PHC ₄ its output voltage of the oscillator V
_osc and the phase signal α given to the converter CC-2R.
Make ₄ . Since the S-phase and the T-phase overlap, the description is omitted, but the converter C has the same configuration as the R-phase.
Generate phase signals α ₅ and α ₆ for C-2S and CC-2T.

The configuration of the present invention has been described based on the embodiments.
The present invention uses a first converter capable of controlling the magnitude and phase of an input current and a second converter capable of controlling the magnitude and phase of an output voltage to thereby provide a feeder voltage. It compensates for the drop and controls the active power and the reactive power of the feeder line to enable large power transport.

[0054] In the embodiment of FIG. 8 mentioned earlier, establishing a voltage V _c by a resonance phenomenon of the equivalent inductance L _cc and the capacitor C of the circulating current circuit and a capacitor C between the converter CC-1 and CC-2 I was letting it. The capacitor C is an input voltage for the cycloconverters CC-1 and CC-2. For example, a rotary machine such as a high-frequency generator may be used to inject energy by another driving source. Also, if there is a high-frequency transmission and distribution system, the terminals of the intermediate circuit can be connected to the system. It does not matter whether it is a stationary machine or a rotating machine as long as it has a high-frequency power supply.Also, the intermediate circuit is electrically insulated, a resonance capacitor is provided on the converter CC-1 side, and a high-frequency generator is provided on the CC-2 side. However, the same operation can be performed. Also in this case, the circuit for controlling the two converters can obtain the same compensation effect as described above with reference to FIGS.

As already described with reference to the circuit diagram of FIG.
The control of the converter is given by the control circuit CONT, but the method of creating a gate signal to be given to the thyristor based on the reference voltage of the capacitor and the voltage command is the same as in a general cycloconverter. The content of the control circuit CONT is roughly divided into a portion for controlling the converter CC-1 and a portion for controlling the converter CC-2.
12 and 13 are circuit diagrams of another embodiment for controlling the converter CC-2.

In FIG. 12, the voltage drop between the transmitting end and the intermediate point is detected by a deviation between the command value _VM0 ^* (average value of three phases) of the intermediate point voltage and the average value _VM0 of the measured voltage. You. Further, in order to perform stable current control between the wire and the converter CONV1 can shall be established capacitor voltage V _c is. Therefore, having two voltage control loop of V _c and V _M0, converters in order to control also the _{(I R, I S, I} T is the line current) leading current I _q while stably controlling the two voltage The magnitude and phase of the input voltage of CONV1 are controlled.

The configuration for realizing the operation will be further described. Deviation of the capacitor voltage instruction value V _c ^* and the actual voltage V _c is ₁ × K by amplifier K1. Since this deviation needs to be compensated for by the active power, the multipliers M ₁ , M
₂ , the unit sine wave Φ _R of the voltage at the midpoint in M ₃ ,
Multiply with Φ _S , Φ _T. The outputs of the multipliers M ₁ , M ₂ , M ₃ are the input current commands of the converter for making the deviation of the capacitor voltage zero. On the other hand, the command value V _M0 ^* (average value of three phases) of the midpoint voltage and the average value V _M0 of the measured voltage
Is caused by the delay current component of the feeder line, and if a leading current component that cancels the component is supplied, the voltage drop of the feeder line is compensated.

Therefore, the difference between V _M0 ^* and V _M0 is determined by the amplifier K2
It is _doubled K by a multiplier M ₄ and the output, M _5, M
_{6 at} 90 ° from the unit sine waves Φ _R , Φ _S , Φ _T
Multiplied with the advanced signal. The integration operation element indicated by the symbol I advances the phase by 90 ° by integrating the unit sine waves Φ _R , Φ _S , and Φ _T. Multiplier M ₄ ,
The output of M ₅ and M ₆ means a current command to be taken in the converter to compensate for the voltage drop of the feeder line. The outputs of multipliers M ₁ , M ₂ , M _{3 and} the outputs of multipliers M ₄ , M ₅ , M ₆ are added in adders A ₁ , A ₂ , A ₃ , respectively, and the line current to be taken by converter CC-1 command I _R ^*,
I _S ^* and I _T ^* are created. Thereafter, the comparators C ₃ , C ₄ , and C ₅ compare the actual current with the actual current for each phase in the same manner as in a normal current control circuit, and send a voltage command to the converter CC-1 through the amplifiers K ₃ , K ₄ , and K _5. give. Specifically, in each of the phase controllers PHC ₁ , PHC ₂ , and PHC ₃ , the voltage command is compared with the capacitor voltage command, that is, the output voltage _{Vosc of an} oscillator (not shown), and the converters CC-1R, CC-1S, Generate phase signals α ₁ , α ₂ , α ₃ for CC-1T. The converter CC-2 is a converter that performs the reverse conversion operation of the converter CC-1, generates an AC voltage _Vpq , and inserts the AC voltage _Vpq in series into a feeder line to produce a similar effect. Details of the control circuit are shown in FIG.

In FIG. 13, V _M0 ^* indicates the voltage command value of the feeder wire (three-phase average value), and V _M0 indicates the measured average feeder voltage value. The two voltages are compared by the comparator C _10,
Is K ₁₁ times given to the multiplier M _11, M _12, M ₁₃ by the amplifier, the unit sine wave [Phi _R respectively, [Phi _S, is multiplied with [Phi _T. The outputs of the multipliers M ₁₁ , M ₁₂ , and M ₁₃ mean voltage command values in phase with the feeder line, meaning that the voltage drop of the feeder line is supplied from the converter CC-2, in other words, from another power source. .

On the other hand, since the voltage drop of the feeder line is caused by the inductance of the feeder line, the voltage drop can be compensated by inserting a capacitive voltage into the feeder line. For this purpose, the line currents I _R , I _S , I _T are detected, and their phases are set to 90 °.
° Generate a delayed signal and create another voltage command value. The R phase will be described as a representative. Current I _R of the phase (ωt-θ) becomes a phase of the delayed 90 ° (ωt-θ-π / 2), multiplied by proportional coefficient K _R. And adder A ₁₁
Summing the output of multiplier M ₁₁ in the voltage command value V
^* Make _pq (R). As is clear from the above description, the voltage command value V ^* _pq (R) is a command value including a component for supplying a voltage component having the same phase as that of the feeder from a separate power source and a component for supplying a capacitive voltage to the feeder. is there. The two component ratios are determined by changing the magnitude of the proportional coefficient K _R. Then, V ^* _pq (R) is compared with the measured values V _pq of the voltage in the comparator C ₁₁ (R),
Through a voltage control amplifier K ₁₂ so they match, the phase controller PHC ₄ its output voltage of the oscillator V
_osc and the phase signal α given to the converter CC-2R.
Make ₄ . Since the S-phase and the T-phase overlap, the description is omitted, but the converter C has the same configuration as the R-phase.
Generate phase signals α ₅ and α ₆ for C-2S and CC-2T.

[0061]

As described above, according to the present invention, a current controllable converter is inserted in parallel to a feeder line, and the output of the voltage controllable converter is inserted in series into a feeder circuit via a transformer. The former converter controls the power transmitted through the electric wire, so the former converter supplies a reactive current that cancels the reactive power of the feeder while maintaining the DC voltage or the high-frequency voltage constant. The latter converter compensates for the voltage drop between the connection point of the device and the latter converter is strengthened by inserting an active voltage source at the connection point of the control device, and substantially converts between the transmitting end and the receiving end. Then, even if the load on the customer is bad, the power can be supplied without any abnormality.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of the circuit of FIG.

FIG. 3 is a control circuit of the first power converter applied to FIG. 1;
Configuration diagram .

FIG. 4 is a control circuit of a second power converter applied to FIG . 1;
Configuration diagram .

FIG. 5 is a circuit diagram of a second embodiment of the present invention.

FIG. 6 is a control circuit of the first power converter applied to FIG . 5;
Configuration diagram .

FIG. 7 is a control circuit of the second power converter applied to FIG . 5;
Configuration diagram .

FIG. 8 is a circuit configuration diagram of a third embodiment of the present invention.

FIG. 9 shows converter CC-1 and converter CC- shown in FIG.
FIG. 3 is an equivalent circuit diagram of one phase of a resonance circuit interposed between the two .

FIG. 10 is a control circuit diagram of CC-1 in FIG. 8;

FIG. 11 is a control circuit diagram of CC-2 in FIG. 8;

FIG. 12 is another control circuit diagram of the CC-1 according to the third embodiment shown in FIG. 8;

FIG. 13 is another control circuit diagram of the CC-2 according to the third embodiment shown in FIG. 8;

FIG. 14 is a system diagram of a general AC system.

FIG. 15 is a circuit diagram of a conventional compensator.

FIG. 16 is another circuit diagram of a conventional compensator.

[Explanation of symbols]

V _S ... sending end voltage, V _R ... receiving end voltages, the voltage of V _M ... apparatus installation point ( "MO" is an average value, * is the command value, no mark means measurements), CC-1, CC- 2, CONV1, C
ONV2 ... converter, V _d ... constant voltage source, Tr1, Tr2,
Tr3, Tr4, Tr5 ... transformer, CONV3 ... variable voltage _{rectifier, C 01, C 02, C} ... Capacitor, L ₀₂ ... reactor, I _q ... compensation current, V _pq ... compensation voltage, CONT1
, CONT2, CONT ... control circuit, C _1, C _2, C
_{3, C 4, C 5,} C 10, C 11, C 12, C 13 ... comparator, A
_{1, A 2, A 3,} A 11, A 12, A 13 ... adder, M _1, M
₂ , M ₃ , M ₁₁ , M ₁₂ , M ₁₃ ... Multipliers, K ₁ , K ₂ , K
_{3, K 4, K 5,} K 11, K 12, K 13, K 14 ... proportional constant,
PHC1, PHC2, PHC3, PHC4, PHC5,
PHC6 ... Phase controller.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J 3/00-5/00

Claims (7)

(57) [Claims] 1. A power controllable first power converter and a voltage controllable second power converter electrically insulated from the first power converter at an appropriate position of an AC feeder. The first power converter has an AC to DC conversion function and is installed in parallel with the feeder line, and the input of the converter is maintained so that the voltage at the installation point maintains the set voltage. The second power converter has a function of converting direct current to alternating current, and controls the active component and the reactive component of the current, and inserts the output of the second power converter in series with the feeder line through the transformer, and Generates a voltage in phase with the feeder line voltage and a voltage 90 ° out of phase with the feeder line current so that the voltage maintains the set voltage, and compensates for the voltage drop due to feeder line impedance. Power and reactive power control device in AC system 2. An electric current controllable first power converter at an appropriate position of an AC feeder, and an output voltage connected to the first power converter via an AC having a higher frequency than the AC of the electric wire. A controllable second power converter is installed. The first power converter has a function of converting feed line AC to high-frequency AC, and is installed in parallel with the feed line, and the voltage at the installation point is Controls the effective and inactive components of the input current of the converter so as to maintain the set voltage, the second power converter has a function of converting high-frequency AC to feeder AC, and transforms its output. inserted in series with the wire has through the vessel, so that the voltage of the installation point to maintain the set voltage, the voltage of the phase of the feeder voltage feeding circuit of 90 ° phase shifted relative to the conductor current <br /> To compensate for the voltage drop due to feeder line impedance Active and reactive power control device in an alternating current system, wherein. 3. A DC circuit of said first power converter and a DC circuit of said second power converter are electrically connected to each other to control input current of said first power converter and said second power. 2. The active power and reactive power control device in an AC system according to claim 1, wherein the output voltage control of the converter is used together to compensate for a voltage drop due to the impedance of the feeder line. 4. As the voltage of the first power converter capacitance for the circuit connecting the second power converter is maintained constant, 請 for controlling the input current of the first power converter
The active power and reactive power control device in the AC system according to claim 3 . 5. As the voltage of the installed capacitor circuit connecting the first power converter and the second power converter is maintained constant, 請 for controlling the circulating current of the first power converter
3. The active power and reactive power control device in the AC system according to claim 2 . 6. A high-frequency side of the first power converter and a high-frequency side coupling line of the second power converter are connected to another high-frequency power supply to control input current of the first power converter. 3. The active power and reactive power control device in an AC system according to claim 2, wherein the output voltage control of the second power converter is used in combination to compensate for a voltage drop due to the impedance of the feeder line. Wherein said first electrically insulates the high-frequency side of the high-frequency side and the second power converter of the power converter, the first input current control and the second power of the power converter 3. The active power and reactive power control device for an AC system according to claim 2 , wherein the output voltage control of the converter is used together to compensate for a voltage drop due to the impedance of the feeder line.