JPS583537A - Power converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power conversion device that controls the amount of power flow between two different power systems.

Japan's power system can be broadly divided into the 40Hz system in Japan and the 30Hz system in eastern Japan.

As a device for connecting one electric power system and controlling the amount of power between the systems, there is a rotary wave number exchanger using an induction machine or the like, or a stationary frequency converter using a mercury rectifier. recently.

Static frequency converters using semiconductor-controlled rectifiers such as thyristors in place of mercury rectifiers have been put into practical use.

Furthermore, even within the Sj□Hz system, there are various power systems managed by several power companies, with varying voltage ratings and equipment capacities. In order to control the amount of power, a power converter that converts from alternating current to direct current to alternating current is used. In particular, a device with a long DC power line is known as a power converter for direct current power transmission. Fig. 1 is a schematic diagram showing the configuration of a conventional power converter. ! ;Connect the OHz thread system and 40Hz system.

This shows a case where the amount of power flow between the two systems is controlled.

In the figure, BU81 is the 3-phase power line of the SO Hz power system, and BUS2 is the 3-phase power line of the 40Hz power system.

TRI and TR2 are power transformers, and 881m and 882 are AC/DC power converters consisting of thyristor bridge circuits.

Lo is a DC reactor, CAP 1e CAP2 is a phase advancing capacitor that also serves as a harmonic filter, FJVCI e
BVC2 is a reactive power compensator.

The reactive power compensator 8VC1 is composed of a power transformer R5゜thyristor rectifier circuit 88) and a DC reactor L1, and the reactive power control circuit QRs makes the reactive power Q1 at the receiving end equal to the command value QI C=0). The zero reactive power compensator 5VC2 in which the current ILL flowing through the DC reactor L1 is controlled is similarly configured,
The reactive power Q at the receiving end is controlled by the reactive power control circuit AQR2.
2 is equal to the command value Q2 (=(7)).
2 is controlled 0 First, the electric line BUSl of the 30Hz system
to 4 (for example, when sending power to a 7Hz system or power line BU82.

The operation of this device will be explained.

A current detector c'r, 1 and voltage detectors FT, t- are installed at the receiving end of the power line BUS1 to detect the instantaneous values of voltage and current of the three phases. This is input to the primary active reactive power calculation circuit PQCI, and the active power P1 and reactive power Qst are
demand. Similarly, a current detector c'r, 2 and a voltage detector p'r, 2 are installed at the power receiving end from the electric line BU82, and together with an active reactive power calculation circuit PQC2, active power P2 and reactive power Qtt Detection◇The active power P1 is detected as positive in the direction in which the person is coming, and the active power P2 is detected as positive in the direction in which the person leaves. Further, as for reactive power Q1sQz, delayed reactive power is detected as positive, and advanced reactive power is detected as negative.

When transmitting electric line NUBtic power from the electric line BU81, the AC/DC power converter 881 operates as a forward converter, and the AC/DC power converter 81i1z operates as an inverse converter.

The power command value p>o is set by the power flow rate setting device VRP.
is given. Seamit circuit 8H is the power command value P">
When it is O, the output signal "/" is generated.

Connect the switch swl to the t- side, and connect the switch sW2 to the b side. That is, the forward converter S81 has a power flow rate P
The output voltage v1 is controlled so that =(Pl+P2)/- is equal to the command value P, and the output voltage v2 of the inverter s+s2 generates a constant DC voltage v! controlled by sea urchins.

CTo is a DC current detector that detects the current Iot flowing through the it flow IJ handle LO. The power control circuit APR is the average value (P1+Pz) of the power detection values P1 and P2 at both receiving ends.
The DC current fat is controlled so that / is equal to the command IIP.

Further, oPHl and PHZ are used to control the output voltage v2 of the constant voltage control circuit Avaa inverter 882 to a constant value v4k, respectively, and PHZ are the phase control circuits of the AC/DC power converters 881 and 882. If the output voltages of the devices S81 and 882 are taken in the direction of the arrow in the figure, V1 = kysV, 1sootα1 v2 = -h, # vsl! - Becomes hat α2. However, kv is a conversion constant, and vll # v12 are AC/DC power converters 881s? and the AC side input voltage of 8S2. The firing control angle α1 of the forward converter 8810 is controlled in the range of 00 to qo0, and the firing control angle α2 of the inverse converter sSt is 900.
O firing control angle α2 set in the range of ~tro0=/1
At 0°, the AC side input power factor of the inverter 882 is l, but since it is necessary to shift the firing timing t by the commutation advance angle r to perform natural commutation, the 1 firing control angle α2 =
tto0−r, and V2= −kv”Vs2・Law (
Generates an output voltage of 1to0-7>.

If the commutation advance angle r is constant, the output voltage v2 will also be a constant DC voltage.

The DC current 1o is the voltage V applied to the DC reactor LQ.
O output sense pressure v controlled by changing 1-Vtt
2 is controlled constant, so Vl = kv@vsl
・(2) Control is performed by changing α1. Direct current!
When it is desired to increase O, the ignition control angle α1 is controlled so that Vl>Vz, and when it is desired to decrease the DC current 1o, the ignition control angle α1 is controlled so that Vl<Vz. Near the steady point, if the resistance of the DC reactor L is ignored, the relationship Vl'q Vz holds true.

From gull α1--gut α2, it becomes αl'i/.

Figure 1 (a) e (b) shows electric line B of the 30Hz system.
Figure 0 is a voltage and current vector diagram for the l phase on the AC input side of each AC/DC power converter when power is being sent from USl to the power line BU82 of the 40Hz system (the resistance is the voltage and current vector diagram of the l phase of the AC input side of each AC/DC power converter
Figure 1 (b) is a voltage and current vector diagram of the converter 882.

Direct current! Considering the steady state m at 0, the relationship between V1+V2 and αL'QI holds true. Forward converter 811
The input current 11.1 of the inverter 882 lags the voltage Vll by a phase α1, and its magnitude is l,,1=l(・Io.In addition, the input current 11.2 of the inverter 882 is delayed by the voltage Vll. It lags behind Mal by a phase angle α2 g'' llI0-7, and its magnitude is llI2 ``k'' IO.

■. Yo1. ! cyo2 is the current flowing into the phase advance capacitors CAPI and CAP2, and 8.5 and IIIK are the lag currents flowing into the reactive power compensators 5vcl and 5vc2, respectively.

Input terminal III□ is valid! 2, and invalid summer, divided into □ Ipl = IIIL ” 608α1 = keIosCO
BαIIql "' fall "self α1= @Io@
Self α1 becomes. Delay current x, l+ Iss! The lagging current so that l is equal to the leading current xeapl! If you control 8m5.

Since the current IAC1 entering from the electric line 11US1 is only the effective component Ip1, operation can be performed in a state where the fundamental wave power factor is always l.

Similarly, input terminal! 1.2 is effective! p2 and invalid Iq
If you divide it into 2.

Ip2 = 11112・(2) α2=k”I(111
001α21qt Tomi512・Self αt=j1mXom
Self α2 and Nashi, Iq2 + l1llll = Ica
If the delay current kms is controlled so that it becomes p2,
Incoming current from electric line Bυ82! Mc2 is the effective part■p
becomes equal to 2. Effective part ■p2 is 1 for voltage V, □
Since the phase is shifted by 100, the fundamental wave power factor is I, which indicates that the power is returning in the direction of the electric line BU82. If the set value P of the power flow rate is increased, the DC current Io
In order to increase t, the ignition control angle α1 is changed transiently, but when the DC current approaches I′o corresponding to P=(Pi+P2)/k, it settles down to αIM/.

At this time, the invalid part on the input side is x,',=+c・I6・8
111α1 and na') -l5s5 = Ieapllq
If E t-reduced, ■mu C1” Ipl = k
・It becomes I6・gull α1, and only the power flow amount can be increased. Phase advance capacitors CAPI and CAP2
The currents ICl1pl and ICap2 are.

All you have to do is prepare an amount that is commensurate with the maximum power flow.

When the set value P of the power flow rate is set to a negative value, the switch 8Wx is connected to the b side, and the switch 8W2 is connected to the a side, and this time the electric line BU82 to I10 of the j□Hz system is connected.
Power is now sent to the electric line RUB1 of the Hm system. At this time, S81 is used as an inverse converter to perform constant output voltage control, and ss2 is used as a forward converter to perform DC current control.

This conventional power converter has the following drawbacks: In order to change the power flow rate, the DC current Io is
is increased or decreased, but as the change occurs, the reactive component I on the input side of the converter 8B and ss2 increases or decreases.
q1e IQZ is changed, and the current l1ss e of the reactive power compensators 5VC1 and 5vc2 is changed according to the change.
It is necessary to control IIIK.

As mentioned before, the capacity of this reactive power compensator BYC1, 8VC2 is the maximum value of DC current Io (rr, x)
If it is.

Ias5 = Il'apl −Iql= k@ (1
0(max) −10) ”Self αIImmII= Ic
ap2-Iq2 =k・('o(mx)-I6) * aimα2, which gives 5 phase angle αt''/*phase angle α2: llI0-7
Considering the relationship, the DC current Io is O~! . (,8)
Considering that it changes between.

l5s3 ”lm5x”f k 1o(maw)
sin r is required.

As mentioned above, l is the commutation advance angle required to naturally commutate the thyristor of the power converter, and is related to the inductance on the power supply side and the turn-off time of the thyristor. In particular, the former value is quite large in order to prepare for short-circuiting of the converter arm. Therefore, the commutation advance angle r is 300~+o0
Even if the commutation lead angle 7 = 300, which is usually the value of Blur. , j, reactive power compensator 5vcl
and 5vc2 capacity is power converter 881$P and 8B
The value of H becomes the capacitance of 2. Therefore, there is a drawback that the device is expensive and complicated. The present invention has been made in view of the above points, and does not use a reactive power compensator that was conventionally required.

It is an object of the present invention to provide a power conversion device that can maintain the fundamental wave power factor at the power receiving end at t/ and can freely control the amount of power flow between a different power systems.

FIG. 3 is a block diagram showing the configuration of an embodiment of the power conversion device of the present invention.

In the drawings, the same reference numerals represent the same or corresponding parts.

CT is a three-phase AC current detector, PT is an AC voltage detector, PQC is an active reactive power calculation circuit, 01 to C5 are comparators -Ai, A2 is an adder, H4CB), H, (
8) is the control compensation circuit - KG #Kl is the operational amplifier 〇Hereafter, the electric line BU8. A case will be explained taking as an example a case where power is sent from the electric power line BUS2 to the electric line BUS2. In other words.

SS1 is operating as a forward converter and '887 is operating as an inverse converter.

First, direct current! 0 is controlled as follows.

The DC current !0 is detected by the DC current detector c'r (, and compared with the DC current command value !0 by the comparator C2.The deviation '1=Io-rot is amplified by the operational amplifier Ko and one-phase control is performed. Input to circuits PH and PH2. Phase control circuits PH1 and PH2 convert voltages proportional to the human power #5 and a6 38 S 1 and 8S
It is controlled so that it is generated from 2.

Therefore, (command value) Io>(detected value) I of DC current.

In the case of , the deviation is 82〉O, and Q-"6"'Q'KO
enters the phase control circuits PH1 and PH2.

The output voltage v1 of the converter 8gl is in the direction of the arrow in FIG.

Further, as for the output voltage v2 of the converter ss2, a voltage proportional to the deviation ε2 is generated in the opposite direction to the arrow in FIG.

Therefore, the voltage applied to the DC reactor L is Ml
-v2>o, and the DC current Iot is increased.

Conversely, when the direct current (command value) Io < (detected value) IO, the deviation becomes 12 × O, and the output voltage V1-V2
<Q, and the DC current Iot- is decreased.

As a result, the DC current becomes l0=Io and settles down.

At this time, if the resistance of the DC reactor L is sufficiently small, Vl&-IV2.

Figures (a) and (b) are this one! FIG. 4 is a diagram of voltage and current vectors for seven phases at the power receiving end of the example (device shown in FIG. 3).

Figure M (a) is a vector diagram of the power receiving end of the converter 881.

Figure 3 (b) is a vector diagram of the power receiving end of converter SSZ.Next, while referring to Figure 3 and Figures (a) and (b) The operation of power control will be explained.

3-phase AC current detector CT, ) and 3-phase AC voltage detector P
T, detects the instantaneous values of the voltage and current at the receiving end of the converter 88i. This is the active reactive power calculation circuit PQ
C, and calculate active power P and reactive power Qt. The active power P takes a positive value in the direction of power flow from the electric line BU81 to the electric line BU82.

In addition, the reactive power Q assumes that delayed reactive power is positive.

The comparator C1 compares the reactive power Q with its command value Qt, and its output deviation #l=Q-Q is integrated by the next control compensation circuit H, (S). Control compensation circuit H
One of the output signals of p(8) is inputted to the phase control circuit PH1 via the adder M1'fr, and the other is inputted to the inverting amplifier and the phase control circuit PH2 via the adder M2. Ru.

Therefore, the input 85 of the one-phase control circuit PH, and the input a6 of the phase control circuit PH2 can be expressed as follows.

85”8%+82”K.

#6″-#Tokiju #2・KO For the sake of explanation, if we consider the case where I□=lo, then O; O, and the relationship of deviation ``5=Qe '6=-axis is established, Output voltage ML = V2 0 conversion constant kV a AC side input voltage t Vm = Vs□ = V pass, then Vl = kv@V, @008α1oca
11V2=-, eV, @cosα20Cj60cε4
Therefore, the cosine value of the firing control angle α1 of the converter ssl is proportional to the deviation axis, and the cosine value of the firing control angle α2 of the exchanger BB2 is 0, which is proportional to the negative value of the deviation axis.
There is a relationship between the ignition control angle αIK of l and the ignition control angle Y of exchanger 8B2 as αz=/100-α1 @DC current! 0←
Io, and the deviation axis ~Q, the ignition control angle α
The relationship between t”ttoo and α has collapsed.

The DC current rot is increased or decreased between the output voltages v1 and v2.

As mentioned earlier, the output voltage is V I S V2 in a steady state. !3.1 has a magnitude kIo and is flowing behind the voltage Vll by an angle α1.Also, the input current I, 2 of the exchanger SS2 has a magnitude −IQ, a voltage v, and a two-way angle α2S. It flows with a delay of /100-α1.Current 11
11 into the effective part I1 and the invalid part I, l, I,
l == 1111 ' (X)Sαl=ni・IQ @
1X18αIIqi ” l1m1 '=αl= and @iQ@l1iflα1, the current! is effective!,
2 and the invalid part■, divided into 1 xp, == 11m2 @(Xllαz= @16@
axα2Xq2=■1.2118i+1αg=ni・Io
It becomes eslnα2. Phase control angle α2S/100-α1
Inserting the relationship Ip, = -1pl iq2 =;i91 0In addition, the above-mentioned delayed reactive current! , 1÷I, l is the leading reactive current x of the phase advancing capacitors CAPI and CAP2
c, p1. It is equally controlled by I6.

From this state, consider the case where the command value P of the power flow rate shown in Fig. 3 is increased ◇ , deviation 85 ㎡ P - P > 0], control compensation circuit Hp
(8) The output shaft increases. Therefore converters 881 and 8
The output voltage v1-■2 of 12 increases, and 1x11αl and Issaki αt also increase. Therefore, % xp1=-■, 2
increases, the effective power P increases, and finally P=
P”.

In the process of becoming active power p=p, converter SS1 and 8820 firing control angles α1 and α2 change, so
This also affects reactive power control at the receiving end.

That is, when 0f)lα1 and -(2)α2 become white, 8IJlα1 and own α2 decrease, and Iq1==keI□@mα1<Ieap IIq,
= k・! o@selfα2<I. It becomes xp2. Therefore, the reactive power Q at the power receiving end becomes a lead and a negative value is detected. Therefore, the deviation a1=Q-Q>O, and the DC current command value Iot, which is the output of the primary control compensation circuit H1(8), is increased. Direct current! The control of 0 is as mentioned before, summer ◎=
It is controlled so that it becomes Io. As a result, the invalid portion I...
> and Iqt increases, and finally the reactive power Q=Q=0
controlled so that

However, when the DC current IO increases, the effective component I1, = -I
, 2 also increases, and the active power P becomes larger than its command value P1. Therefore, this time it operates to decrease α1 and α2t, and the DC current IO also decreases slightly.

That is, when the command value Pt of the power flow rate is increased,
Output voltage Vlsv2 and DC current of power converter 881 and SS2! Active power control and reactive power control are performed simultaneously while 0 is changing, and finally active power P=P
, output voltage VI Q v such that reactive power Q=Q.
, , and DC current 1. The value of 0 is shown in Figures (a) and (b).
In the vector diagram, the power flow rate command *pt-
As a result, the input current of the exchanger SS1 changes from I□1 to ■1, and the input terminal of the exchanger 882 changes from I
From 02! , 42, and only the effective part is I,, =
-I,2 has increased to Im1=nee■;t.

When the active power command value P is decreased, the control is performed in the same way, and the DC current Io and output voltage VINv2 are finally such that the active component P=P and the reactive component Q=Qゝ=O◇ Reactive power Q at the receiving end as reactive power command value Q = 0
In other words, the input fundamental wave power factor has been controlled so that it becomes zero, that is, the input fundamental wave power factor becomes I, but it goes without saying that the same control can be performed even if it is set to Q''>0 or Q<0.

FIG. S is a block diagram showing the configuration of another embodiment of the present invention.

5ek% is an adder, K2 a K> is an operational amplifier with coefficient H, t, o l + LO! is a DC reactor, and R is the resistance of the DC line. The other embodiment shown in Fig. S differs from the embodiment shown in Fig. 3 in that the resistance Rt of the DC line is taken into consideration. This is necessary in the case of a power conversion device for DC power transmission, when the distance of DC power transmission is long and the resistance R cannot be ignored.
Electric line BU8. Effective power P1 from and electric line] IU8g
A difference in the effective power PtK going out occurs.

Therefore, P-=(P>+Pt)/ko is detected and controlled. Considering the case where there is some difference in reactive power Q1 and east, Q = (Ql + Q2)/
As described above, according to the power converter of the present invention, conventionally,
The fundamental wave power factor at the receiving end from both systems can always be maintained at 7 without using the required reactive power compensation device, and there is an advantage that the amount of power flow between both systems can be freely controlled. . Therefore.

It is possible to obtain an economical and simple-configured system not only as a frequency converter but also as a power converter for DC power transmission.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional power conversion device, Ma diagram (a
), (b) are voltage and current vector diagrams at the receiving end for explaining the operation of FIG. 1, and FIG. 3 is a block diagram showing the configuration of an embodiment of the power conversion device of the present invention. Figures φ (a) and (b) are vector diagrams of voltage and current at the receiving end to explain the operation of the device shown in Figure 3, and Figure S is a block diagram showing the configuration of another embodiment of the present invention. It is. Electric line of power system of BU81...gt BU8g...
Electrical lines TR1, TRg of the first power system...power transformers ssl, ss2...power converters CAPl, CAP2...phase advance capacitor Lo +
Lol e "O7...DC reactor R...Resistance CT, CT, □, CT,...CTo,...Current detector PT@e"ml e p'r,2...Voltage detector PQC, PQC1, PQC2... Active reactive power calculation circuit H1(8), Hp(8)... Control compensation circuit C1* C2* C5... Comparator KO+ Kl + K2 + K5... Operational amplifier A
l+mu2... Adder PHI, PH2... Phase control circuit. sv, , SV2...Reactive power compensation alt (TR
,, TR, Hatrans, 885 + 884 is a thyristor rectifier circuit. Lt+L2 is a DC reactor, CTiCT2 is a current detector, VRQl, VRQ2 are reactive power setters)
System QR2... Reactive power control circuit VRP... Power flow setting device APR... Power control circuit VRV... Output voltage setting device AVR... Constant voltage control circuit SH... Limit circuit.・ Applicant's agent Kiyoshi Muta 1, Display of the case Showa Patent Application No. 101011 2, Name of the invention Power converter; (, Person making amendment Related to the case Patent applicant (307) Tokyo Shibaura Electric Co., Ltd. Company [Telephone Tokyo (211) 2321 Main Representative] Column 1 of "Claims" of the Akira edition, the AC side of the first AC/DC power converter is connected to the first power system and the second AC/DC power conversion is performed. In the power conversion device, the AC side of the converter is connected to a second power system, and the DC sides of the two AC/DC power converters are connected so that a DC current flows in a constant direction via a DC reactor. The value of the DC current and the value of the DC side voltage are changed to the reactive power on the AC side of the two power converters in accordance with changes in the value of active power exchanged between the first power system and the second power system. A power conversion device characterized in that the power is controlled so that the power is constant. 2. According to the deviation between the active power command value and the detected value exchanged between the first power system and the second power system. , the DC side voltage of the two power converters is controlled, and the value of the DC current is controlled according to a deviation between a command value and a detected value of reactive power. power converter.

Claims (1)

[Claims] 1. The AC side of the first AC/DC power converter is connected to the first power system, and the AC side of the first AC/DC power converter is connected to the first power system. DC 1ll of said AC/DC power converter
f: In a power conversion device connected so that a direct current flows in a fixed direction via a DC reactor, the first
control so that the value of the direct current and the reactive power on the alternating current side of one of the power converters are constant according to changes in the value of active power exchanged between the power system and the first power system. A power conversion device characterized by: c. Control the DC side voltage of one of the power converters according to the deviation between the active power command value and the detected value exchanged between the first power system and the wc power system, and control the reactive power 2. The power conversion device according to claim 1, wherein the value of the DC current is controlled according to a deviation between a command value and a detected value.