JPS6367413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for starting an AC/DC converter in an AC/DC converter that is connected to a grid or directly connected to a nuclear power plant or the like.

Figure 1 shows a configuration diagram of bipolar single-line DC power transmission directly connected to nuclear power generation. It is connected to an AC bus 5 via a transformer 4 . The AC bus 5 is connected to forward converters 8 and 9 via conversion transformers 6 and 7, and the converters 8 and 9 convert AC power obtained by nuclear power generation into DC power, and convert the AC power obtained by nuclear power generation into DC power. The converted DC power is further converted into AC power by inverters 10 and 11 and supplied to the load. 12,1
3, 14, and 15 are smooth reactors, 16, 17 are main lines, and 18 is a neutral line. For convenience of explanation,
Forward converter 8, main line 16, inverse converter 10, neutral line 1
The pole composed of 8 is called the P ₁ pole, and the other poles are called the P ₂ pole.

Generally, when starting a converter, it is usually started at the minimum operating power value in order to minimize the influence on the grid. FIG. 2 shows one example. Second
In the figure, the DC at startup is 10% of the rated value. If the DC current is too small, the current will be intermittent, which is unfavorable for the thyristor elements that make up the converter.
It is about 10%. Also, time T ₁ in FIG. 2,
That is, the time it takes for the transmitted power to rise to 10% of the rated power is usually 200ms to 300ms. On the other hand, in nuclear power generation, when the rated load is taken from a no-load state, it is done slowly over a long period of time. An example is shown in FIG. That is, at the beginning of startup, the generator output G ₁ is a few percent of the rated value, the time of T ₁ is several tens of seconds, the time from T ₁ to T ₂ is about 10 minutes, and the generator output G ₁ is a few percent of the rated value. G ₂
(usually 10% of the rating), i.e. T ₂
The time from T ₃ to T 3 is about one day, and the time from T ₄ to T ₅ , which is the time to start up the generator output from G ₂ to the rated output, is about 1 hour.

As explained above, one of the advantages of DC interconnection such as DC power transmission is high-speed power flow control, but this advantage is reversed in a system configuration directly connected to nuclear power generation as shown in Figure 1. This is a drawback, since the control between the two cannot be coordinated at all during startup, so a new startup method is required.

Therefore, an object of the present invention has been made to meet such demands, and is to provide a DC interconnection equipment, that is, a converter startup method that allows coordination between nuclear power generation and DC interconnection. It is in.

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

Normally, in a system configuration as shown in Fig. 1, each converter 8, 9,
The control circuits including the start/stop control circuits 10 and 11 are independent, and the _P1 pole and _P2 pole can each be operated independently. Accordingly, according to the conventional starting scheme, the P ₁ -pole converter 8 is started as a forward converter and the converter 10 is started as an inverse converter. On the other hand, the P2 _- pole converter 9 can be activated as an inverse converter, and the converter 11 can be activated as a forward converter using the conventional activation method, and there is no difficulty at all. At this time, the operating power value of _P1 pole and _P2 pole should be the same value.

Next, we will discuss the effect.

As mentioned above, if the operating power values of P ₁ pole and P ₂ pole are set to the same value and P ₁ pole converter 8 and P ₂ pole converter 11 are started as forward converters at almost the same time, (therefore, , P _1- pole transducer 10 and P _2- pole transducer 11
will be activated as an inverse transformer. ) The load seen from the nuclear power side becomes zero. That is, when the converter is started using the above-mentioned starting method, the initial load of nuclear power generation becomes zero. If the converter is started in this way and the power transmitted by the converter is increased according to the generated power value on the nuclear power side after a predetermined time,
It is possible to operate in coordination with the nuclear power side. Fourth
The figure is a time chart based on one embodiment of the present invention, and the operation of the present invention will be explained in further detail using this time chart.

In FIG. 4, the P ₁ and P ₂ pole converters are started at the same time using the above-mentioned startup method, with the operating power values of the P ₁ pole and P ₂ pole being set to the same value. Now, it is assumed that the operating power value of _P1 pole and _P2 pole in Fig. 4 is 10% of the rated value. As is clear from Figure 4, at the beginning of startup,
P _1- pole converter 8 is a forward converter with 10% of the rating
On the other hand, P _2- pole converter 9 receives 10% of the rated power as an inverse converter.
The load output of the AC bus 5 in FIG. 1, and thus of the nuclear power generation, becomes almost zero. Nuclear power in this state is bypassed via a bypass valve. In this situation, the nuclear power generation value is 20
When the temperature rises to about % (ta in Figure 4),
If the P _2- pole power flow is reversed and the P _2- pole converter 9 is reversed from reverse converter operation to forward converter operation, at the time when the power flow reversal is completed (tb in Figure 4), the transmitted power shall be 20%. Thereafter, the power transmitted by the converter may be increased in accordance with the nuclear power generation operating power command value.

FIG. 5 shows a time chart when fine-grained control is implemented. As explained in Fig. 3, on the nuclear power side, an initial load of several percent is within the allowable value, so paying attention to this point, converter 8 with P ₁ pole is changed to 15% of the rating, P ₂ poles, etc. converter 9
will start at, for example, 10% of the rated value. Then,
As shown in Fig. 5, the load output of the AC bus 5 is 5
%, and the machine is operated in this state for a predetermined period of time. After that, depending on the nuclear power output, only the power transmitted from the _P1 pole is increased, and the operation continues with the power received from the _P2 pole kept constant, until the nuclear power output reaches about 20% ( At _t3 ) in Fig. 5, the power transmitted from the _P1 pole is reduced to 10%, and at the same time, the power flow at the _P2 pole is reversed.

In this way, as shown in FIG. 5, the transmitted power will be approximately 20% at the time when the power flow reversal is completed (t ₄ in FIG. 5). After that, it is only necessary to increase the power transmitted to the _P1 pole and _P2 pole again according to the nuclear power generation output. Further, although the explanation so far has been limited to one bipolar line, it is clear that the above method can be applied to each line even in the case of multiple bipolar lines. or,
Depending on the single unit capacity of the nuclear power generator, the number of generators, the single unit capacity of the converter, and the number of converters, multiple converters on the power transmission end are activated as forward converters so that the values are within the allowable values of the generator. , the remaining transducers can also be activated as inverse transducers.

As explained above, according to the present invention, some of the plurality of converters on the transmission end side connected to a weak power system or directly connected to a generator are converted into forward converters,
By starting the remaining part as an inverter and operating it so that the total transmitted power is within the allowable value of the grid or generator output conditions, voltage fluctuations in the grid are suppressed.
Alternatively, it has the remarkable effect of being able to solve the problem of the initial load of the generator and the problem of intermittent current of the converter, and also being able to apply the conventional proven starting method.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a bipolar single-line DC power transmission facility, Figure 2 is a diagram showing the startup pattern of conventional conversion equipment, Figure 3 is a diagram showing the load startup pattern of nuclear power generation equipment output, 4 and 5 are diagrams showing time charts at the time of starting the converter based on the present invention. 1... Nuclear reactor, 2... Turbine, 3... Generator, 4... Step-up transformer, 5... AC bus, 6,
7... Conversion transformer, 8, 9, 10, 11... Converter, 12, 13, 14, 15... Smoothing reactor, 16, 17... Main line, 18... Neutral line.

Claims (1)

[Claims] 1. In a bipolar single-line AC/DC conversion system, when starting a converter, the converter on the power transmission end side of one pole is started up as a forward converter, and the converter on the power transmission end side of the other pole is activated as a forward converter. A method for starting an AC/DC converter, characterized in that the converter is started by an inverse converter, and the power transmitted at the time of start-up is set to a predetermined value or less. 2. In a bipolar multi-line AC/DC conversion system, when starting the converters, for each bipolar unit, start the converter on the power transmission end side of one pole using the forward converter, and start the converter on the power transmission end side of the other pole. A starting method for an AC/DC converter, characterized in that a converter is started by an inverse converter. 3. In a multi-pole, multi-line AC/DC conversion system, when starting up the converters, start up multiple converters on the power transmission end using the forward converter, and start the remaining converters on the power transmission end using the inverse converter. A starting method for an AC/DC converter characterized by starting.