JPS59201635A - Method of starting 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] [Technical Field of the Invention] The present invention relates to a method for starting a power conversion device, such as a DC power transmission device or a frequency conversion device, which coordinates a forward converter and an inverse converter and operates from the beginning. . In particular, the present invention relates to a method for starting the power converter installed in a power plant that can reduce disturbances that occur when starting the power plant.

[Technical background of the invention]

FIG. 1 shows a DC two-terminal power transmission system diagram as an example of a power conversion device. In FIG. 1, AC power from a power plant 10 is sent to an AC-DC converter (hereinafter referred to as a forward converter) 30 via a transformer 20i, where it is converted into DC power. This DC power is transmitted via DC power transmission lines 50 and 51 after silt sol is removed by a DC reactor 40 . The transmitted DC power is again converted to AC power by a DC-AC converter (hereinafter referred to as an inverse converter) 31 via a DC reactor 41, and is then supplied to the AC system 11 via a transformer 21.

In the conventional device described above, the DC current d flowing through the DC lines 50 and 51 is determined by controlling the forward converter 30 with a constant current, and the DC voltage vd is determined by controlling the inverse converter 31 with constant voltage control or constant margin angle control. It was decided to do so. Such control characteristics are shown in FIG.

In FIG. 2, ■-1 and I-2 indicate the control characteristics of the forward converter blade, and I[-1 and I[-2 indicate the control characteristics of the inverse converter 31.
The control characteristics of each are shown. Although details will be described later, ■d represents a DC voltage setting value, Δ■dp represents a voltage margin, ■dp represents a DC current setting value, and ΔWorkdp represents a current margin. Such control characteristics are provided by the control device shown in FIG.

The control device shown in FIG. 3 controls both the forward converter (9) and the inverse converter 310, but when controlling the forward converter 30, the switch ω is opened and the inverse converter 31 is controlled. Closed in case. Therefore, when controlling the inverter 31, the adder 70 has a current margin (-ΔI
d, ) are added, the constant current control circuit (A
CR) 80 is 11 based on the command of (Dp - ΔDp)
Control is performed according to the characteristics shown in Fig. 2 fJ-2II. Therefore, when controlling the forward converter 30, the constant current control circuit (AC
R) The control characteristics of 80 (Fig. 2 l-2) are the inverse conversion circuit 31.
The current merge is thicker by 2161 than in the case of . On the other hand, the control characteristic (1) of the forward converter (equipment) is the characteristic when operating at the minimum value of the control angle determined by the characteristics of the forward converter blade.

The constant voltage control circuit (AVR) 81 performs control based on the difference between the DC voltage setting value ■dp from the adder 71 and the DC voltage Vd, but the forward converter blade determines the direction of the DC voltage ■d shown in FIG. Constant voltage control circuit (AVR) 81 to consider it as a negative value.
The control angle from is the maximum value determined by the constant voltage control circuit (AVR) 81. On the other hand, since the inverter 31 considers the direction of the DC voltage ■d shown in FIG. 1 to be a positive value,
The control angle is determined by the constant voltage control of the constant voltage control circuit (AVR) 81, and the control characteristic of (1)-1 in FIG. 2 is created.

The constant margin angle control circuit (AγR) 82 is a circuit that generates a control angle to ensure a constant margin angle γ to prevent commutation failure of the inverter 31 during normal operation. A control angle expressed by the following equation is calculated from the AC voltage Vao and the AC voltage Vao. That is, it is expressed as.

Constant current control circuit (ACR) 8Q, constant voltage control circuit (AVR) 81. and constant margin angle control circuit (AγR) 8
The control angle signal outputted from 2 is applied to the minimum value selection circuit 90, which selects the minimum control angle α. Therefore, the forward converter blade and the inverse converter 31 have this minimum control angle α? It will be turned around.

In the forward converter blade, the control characteristics shown in Fig. 2 l-1 and I-2 are obtained, and in the inverse converter 31, the control characteristics shown in ■-1 and ll-2 are obtained, and the DC power transmission system in Fig. 1 is It is operated at point A on Figure 2.

In summary, the forward converter blade is controlled by the control angle determined by the constant current control circuit 80, and the three inverse converters are controlled by the control angle determined by the constant current control circuit 81 or the constant margin angle control circuit 82. will be controlled by.

[Problems with background technology]

Under the above control, power from the power plant 1o is transferred to the AC system 1 via the forward converter (9) and the inverse converter 31.
When transmitting DC power to 1, there were the following problems.

That is, when the forward converter blade and the inverse converter 31 were operated by the conventional control device (FIG. 3), it was not possible to transmit power below the rated power of 10. The reason for this is that when operating the forward converter blade and the reverse converter 31, the DC current setting value ■dwo is normally set at 10 to prevent the DC current ■d from intermittent.
% or less. As a result, for example, if the power plant lo is a nuclear power plant, the nuclear power plant needs to maintain a low power state for a while for initial load operation at the time of startup, so the power plant lo is Even if you try to start it, the power will be 10% by DC power transmission.
- or more, the frequency of the AC side voltage of the forward converter 3o decreases, making it impossible to operate the generator in the power plant. In severe cases, the reactor may be forced to shut down.

[Purpose of the invention]

Therefore, the present invention solves the above-mentioned conventional problems by enabling the power converter to start up while coordinating between the power plant and the power converter when power is transmitted by the power converter. The purpose is to provide a possible startup method.

[Summary of the invention]

In order to achieve the above object, the operating method according to the present invention causes the forward converter to perform constant voltage control at startup, and causes the reverse converter to use a temporarily set DC current setting value different from the DC current setting value. Constant current control is performed, and the DC voltage setting value of the constant voltage control on the forward converter side is corrected by the frequency of the AC system on the forward converter side, and the value on the DC current membrane is set to the temporary DC current setting value. , the forward converter performs constant current control, the inverse converter performs constant voltage control, and the DC current setting value of the constant current control on the forward converter side is set to the frequency of the AC system on the forward converter side. It is characterized by the fact that the system is operated with proper correction.

[Embodiments of the invention]

The present invention will be described below based on illustrated embodiments.

FIGS. 4, 5, and 6 show a control device (FIG. 4) and a control characteristic diagram (FIG. 5) for carrying out the starting method according to the present invention.
Figure 6) is shown. In FIG. 4, the same or overlapping parts as those in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

Configuration of Control Device The control device according to the present invention requires a control device for controlling the forward converter 3o and a control device for controlling the inverse converter 3; 9) is shown in FIG. 4, and the one shown in FIG. 3 is used for the inverter 31.

In FIG. 4, this control device is roughly divided into a current control system and a voltage control system. First, the current control system will be explained.

The preset DC current setting value 1dp is corrected by the current correction signal in the adder 72. That is, the frequency signal F from the power plant 10 side is applied to the current setting value correction circuit (AF
C) 100, current set value correction circuit (AFC)
100 outputs the current correction signal as a positive signal to the adder 72 via the switch 63. The switch 63 is controlled by a maximum value selection circuit 130, which will be described later. Corrected current setting value Id,. is input to the maximum value selection circuit 130.

On the other hand, this maximum value selection circuit is given a temporary DC current setting value used at startup by the generator 110.

dpst As a result, the maximum value selection circuit 130
The larger value of t is output to the adder 70 as the pseudo current setting value "dpi".

Next, the voltage control system will be described. The preset DC voltage setting value Vdp is corrected by an adder 73 using a voltage correction signal. That is, the frequency signal F from the power plant 10 side is given to the voltage setting value correction circuit (AFV) 101, and this voltage setting value correction circuit (AFV) 101 sends the voltage correction signal as a positive signal to the adder 73 by switching the switch. Output via 64. The switch 64, like the switch 63, is controlled by the maximum value selection circuit 130. Further, a bias signal from the bias signal generator 120 is applied to the adder 73 via a switch 65 as a negative signal. This bias signal is a signal for biasing the DC voltage setting value VdpR on the concave side of the forward converter so that the voltage on the forward converter side is not higher than the voltage on the inverse converter 31 by p. Switch 65 is controlled by maximum value selection circuit 130. In this way, the adder 73 outputs the pseudo DC voltage setting value Vdpx, and the adder 73 outputs the pseudo DC voltage setting value Vdpx.
Sent to 1.

The circuit configuration after the adders 70 and 71 is almost the same as that in Fig. 3, but in the circuit of Fig. 4, the pseudo DC voltage setting value ■dp1 (corresponding to the DC voltage setting value ■d in Fig. 3) is used. The difference is that is added as a positive value. Further, the DC current setting value ■d in FIG.

Operation of Control Device Next, the operation of the above-mentioned control device will be explained. As mentioned earlier, using the control device shown in FIG. 4 for the forward converter (9),
It is assumed that the control device shown in FIG. 3 is used for the inverter 31. However, the pseudo DC current setting value d and □ in FIG. 4 are used as the DC current setting value d in FIG. 3.

First, the power plant 10 is started, and the forward conversion doubling and inverse converter 31 is also started. At this startup, switch 6
3 is open, and switches 64 and 65 are closed.

Furthermore, since the DC current setting value ■d from the power plant 10 is smaller than the temporary DC current setting value "dpsTT," the pseudo DC current setting value "dpi" from the maximum value selection circuit 130 is the temporary DC current setting value "dpsTT". dps'l'T. on the other hand,
Pseudo DC voltage setting value Vdp
1 output)...(1)

FIG. 5 shows the control characteristics of the forward transform doubling and inverse transformer 3 in the above startup state. That is, the constant current control circuit (ACR in FIG. 4) 80 determines the DC current Id'f: based on the provisional DC current setting value dpsTT, thereby producing the characteristic 2-2 in FIG. In addition, the constant voltage control circuit (Fig. 4 AVR) 81
Since the result of subtraction between the pseudo DC voltage setting value Vdpl and the DC voltage Vd that can be measured in the adder 71 is input,
yields the property of i. The characteristics of the inverse converter 31 are as shown in (1)-1 and n-2 in FIG. 5 as in FIG. 3. Between the DC power transmission systems, the operational operating points of 51 are the three points shown in FIG. Characteristics (constant current characteristics) are determined by -2.

Here, since the pseudo DC voltage setting value of the forward converter I is expressed by the equation (1), the voltage setting value correction circuit (AF
V) By the action of 101, the AC system of the forward converter 30]
If the frequency F of 1 increases, the DC voltage ■d increases, and the power transmitted through the DC power transmission system increases. Furthermore, if the frequency F decreases, the DC voltage Vd decreases, and the power transmitted through the DC power transmission system decreases. Therefore, the output power of the power plant 10 shown in FIG. 1 can be successfully absorbed by the DC transmission system, the frequency of the AC system on the forward converter blade side can be kept constant, and the power plant 10 can be started without disturbance.

The temporary DC current setting value dpsTT is set to a value at which the DC current Id determined by the constant current characteristic of the inverter 31 (FIG. 5, ll-2) is not interrupted, and the 64 The signal vdpbias is set so that the pseudo DC voltage setting value vdp1 determined by equation (1) does not exceed the DC voltage setting value Vdp of the inverter 31.

Depending on the activation state of the DC power transmission device described above, the power plant 10
When the DC current setting value Id, which is sent to the forward converter side from Output signal engineer d.

, close the switch 63, and close the switch 64.
, 65 opens. Therefore, the control characteristics as a DC power transmission device are transferred to those shown in FIG. That is, forward converter I
The pseudo DC current setting value "dpl" is d, □=I d
p + (output of AFC100)...(2
), and the constant current control circuit 80 produces a constant current characteristic of I-2 in FIG. The pseudo DC voltage setting values d and □ become the DC voltage setting value dpR, which produces the constant voltage characteristic of I-1 in Fig. 6. Also, the DC current setting value dp of the inverter 3 in Fig. 3 uses the same pseudo current setting value d, □ for forward conversion doubling, so the constant current characteristic n-2 in Figure 6 only follows the pseudo current setting value dp□, and the other characteristics are the same as the 5th There is no difference from the figure.On the other hand, the DC voltage setting value for forward conversion doubling ■d
Since pR is set higher than the DC voltage setting value vd of the inverter 31, the operating operating points in this state are six points.

Here, the pseudo DC current setting value "dpi" for forward conversion doubling is (
2) As can be seen from the equation, the DC current setting value Idp sent from the power plant 10 is adjusted by the current setting value correction circuit (AFC).
Since the correction is based on the output from 1.00, the transmitted power of the DC transmission system is adjusted to keep the frequency of the power station 10 on the blade side of the forward converter constant, and the power transmitted to the AC system on the concave side of the forward converter is adjusted. This means that the connected power plant 10 can be started up without any disturbance.

Thus, while the power generated by the power plant 10 is low, the fifth
After operating the DC transmission system with the control characteristics shown in the figure, power plant 1
The DC current in the Potash DC transmission system has a large amount of power generated.■
Since operation will be performed with the characteristics shown in Fig. 6 after d can flow beyond the intermittent limit of 31 between the forward and reverse converters, it is necessary to coordinate startup between the power plant 10 and the DC power transmission device. As a result, power plant 1 was activated by starting the DC transmission system.
0 can be suppressed from being disturbed.

〔Effect of the invention〕

As described above, according to the present invention, at the time of startup, all forward converters are controlled at a constant voltage, and the inverse converter is controlled at a constant current using a provisional DC current setting value different from the DC current setting value, The DC voltage setting value of constant voltage control on the forward converter side is corrected by the frequency of the forward current system on the forward Y converter side, and if the DC current setting value exceeds the temporary DC current setting value, The Oboro converter controls constant current, and the inverse converter controls constant voltage,
By correcting the DC current setting value of the constant current control on the forward converter side by the frequency of the AC system on the forward converter side, it is possible to reduce disturbances between the forward converter and the power plant when transmitting power via the power converter. It is possible to perform less cooperative activation.

[Brief explanation of the drawing]

Figure 1 is a diagram of the DC transmission system, Figure 2 is a control characteristic diagram of each component of the DC transmission system, Figure 3 is a block diagram of the control device for the inverter, and Figure 4 is the starting method of the present invention. 5 and 6 are characteristic diagrams showing control characteristics according to the present invention. 10...Power plant Jl...AC system (9)...Forward converter 31...Inverse converter gloss...DC transmission line 80...Constant current control circuit 81...Constant voltage control Circuit 82... Constant voltage control circuit 90... Minimum value selection circuit 100... Current set value correction circuit (AFC) 101...
- Voltage set value correction circuit (AFV) 110...Temporary DC voltage set value generator 130...Maximum value selection circuit. Applicant's agent Kiyoshi Inomata (

Claims (1)

[Claims] In a method of operating a power converter equipped with a forward converter and an inverse converter operated in coordination, the forward converter is caused to perform constant voltage control and the inverse converter is set to direct current at startup. Constant current control is performed using a temporarily set DC current setting value that is different from the current value, and the DC voltage setting value for constant voltage control on the forward converter side is corrected by the frequency of the AC system on the forward converter side. , If the DC current setting value exceeds the temporary DC current setting value, the forward converter is caused to perform constant current control, the inverse converter is made to perform constant voltage control, and the DC current of constant current control on the forward converter side is A method for starting a power converter, characterized in that the current setting value is corrected according to the frequency of an AC system on the forward converter side and the power converter is operated.