JPS60141123A - Solar light generator plant - 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] This invention relates to a solar power generation device.

Figure 1 shows the basic circuit of a conventional solar power generation device. In the figure, ■ is a solar cell, 2 is a DC switch, 3 is a diode (flywheel diode), 4 is an I) G reactor, 5 to 10 are sirisks for separately excited inverter I,
11 is a rectifier transformer, 12 is a breaker for inverter I,
13 to I5 are the capacitances of cables and filters existing in the section from the excitation impedance of the rectifier transformer 11 to the AC circuit breaker 16; 17 is a generator operation control device;
A is a solar power generation device.

The AC circuit breaker 16 includes a switch and the like, and is not necessarily connected to one location, but is often connected in series or parallel in multiple stages. The capacitance 15 exists in both the solar power generation device A and the AC system.

At present, it is not common to connect a photovoltaic power generation system and an alternating current system using a separately excited inverter, so the negative effects of the former's independent operation have not become apparent.

That is, when the AC circuit breaker 16 is opened for some reason, the load of the solar power generation device A becomes the capacitance 13.
~15. Control device】7. A few of the Hakuraku style, C,
R, and a condition in which these back capacitances 13 to 15 are dominant may be established. At this time, the reactive power required by the passive inverter I can be supplied from the phase advance capacity of cables, filters, etc., so the inverter I can commutate and is disconnected from the AC system. The ship continued to roll off the coast, and the entire solar power generation system became an escape route, creating a dangerous situation.

In order to avoid this, it is necessary to send an off signal of the AC breaker 16 to the solar power generation device A side and open the DC switch 2 to cut off the energy source.

However, in an actual system, the AC circuit breaker 16 is often installed not only at one location but at many locations in series or parallel. Therefore, which AC system breaker 1
Even if the DC switch 6 is opened, the DC switch 2 must be opened, but such a configuration would make the system extremely complicated and expensive, making it extremely difficult to implement.

In view of the above problems, it is an object of the present invention to provide a photovoltaic power generation device that can be used more safely each time the power supply circuit is opened by detecting interruption of the AC system by an economical and economical means. .

An embodiment of the first invention will be explained based on FIGS. 2 to 4. In this embodiment, in a circuit similar to that shown in FIG. 1, a negative sequence voltage (or a negative sequence current is also possible) is detected in the AC side line rather than the passive inverter 1, more specifically, in the AC side line rather than the rectifier transformer 11. An IJ relay 8 is installed to
Switch 2 is opened, and then circuit breaker 1 for inverter I is opened.
A sequence is set up to open circuit 2.

The operation will be explained below. For convenience of explanation, in FIG. 3, Cyrisks 5 to 10 in FIG. 2 are shown]X.

Ty, Tz, "I"U, Ty, 'FW
, and the capacitance N13-15 is expressed as cu V , cv
Not expressed as W+ CWIJ.

When the AC system is cut off while operating in conjunction with the AC system, the solar power generation device enters independent operation with a phase-advanced load, but in this case, the AC side of the inverter 1 is connected to the reverse phase. A voltage appears.

During operation of inverter I, the zero point of the UV phase voltage (
t-to) is used as a synchronization signal, and from this synchronization point onward, cyrisk firing pulses are applied to each phase at fixed time intervals (control angle α) during one cycle. For the sake of simplicity, the load is assumed to be only the capacitance, and the commutation type angle is omitted, and the reason why the solar power generation device A operates independently and the principle behind the generation of the reverse phase component will be considered.

In FIG. 4, 1=1. Suppose that the AC side is cut off.

(1,1t =, t, ~ 'ro' The synchronization signal obtained at t = lo gives each phase a pulse with a predetermined control angle α, and the thyristor TX receives a commutation pulse at the thyristor TY. Until given (Cyrisk TX --r
The conduction continues until the commutation of Y) occurs. When the thyristors Tx and 'FW are in the conductive state, the V-phase voltage is no longer constrained by the AC system, so it is fixed at a value obtained by dividing the W-U phase voltage by the capacitances CUV and CVW. In other words, the V-phase voltage is E・, = (Cu v / (Cu v→-Cvw)]
X(EW-El) However, the phase voltages of U, V, and W phases are EU and E■, respectively.

Let it be JEW.

If Cu v =Cv w =Cwu-Co, EV-
(EwlEu)/2. We will proceed under these conditions below.

Now, since the U-W phase is conducting, the capacitance CUV,
Charging begins for the parallel capacitance of the series body of CVIII/ and the capacitance CWU, and the W-U phase voltage becomes (Cu v
+Cvw) 10 Cwu l 10 EWI gu+ UI Ew+, Eu+ is 1=1. These are the W-phase and U-phase voltages at . The voltage waveform plotted with the inductance DC・L of the DC circuit set to a sufficiently large value and i constant is shown in Figure 4 (
A), and the current waveforms of each phase are shown in FIG. 4(B).

(Between 21t = 1'O' and L2, at t = 'ro', the Zyristor 1'Y receives an I trigger and due to the charge stored in the capacitance CUV, cUv-Pu-
A current flows through the circuit Tx→1'Y-Pv→CUV, and the Zyrister Tx becomes a reverse current, turning off the Zyrister '1'x. Namely, Zyrista TV.

Due to the conduction of 1゛w, charging begins in the parallel capacitance of the series body of the capacitances CUV and CWU and the capacitance Ji Cv w.

The U-phase voltage EU is 1/2 of the difference between EW and E,/.

f31 t = L From 2 onwards, Cytastar Tw, "rY, Tu...
Commutation progresses in the order of..., and the voltage of the non-conducting phase appears as a divided voltage of the voltage between the other two phases.

Next, fluctuations in commutation pulse timing will be explained.

At the time of t=1"1]', the voltage between the U and V phases becomes zero, and the synchronization signal is converted. After a time period corresponding to the control angle α has elapsed from this point, each phase is Commutation control is performed on the Zyristor using a new control angle α.

L=L2. At t3, it operates according to the synchronization signal determined by L=tQ, and as a result, the Xyrister rW,'
The conduction time between FV and thyristors 'l'Y and Tz is different from the conduction time between other thyristors.

If the above operation is followed, the voltages of each phase become unbalanced and contain negative phase voltages. The relay 18 detects this negative phase voltage, and the detection signal opens the DC switch 2, and then the circuit breaker 12.

As mentioned above, the case where the solar power generation device is operated independently is when the loss is small compared to the phase-advanced reactive load, and the current in the DC side reactor 4 circulates between the phase-advanced load and the phase-advanced reactive load. Most of the current is reactive current.

That is, the load impedance of the solar cell 1 increases isometrically, and the output decreases.

Next, an embodiment of the second invention will be described based on FIG. In this embodiment, a relay 19 for detecting the second harmonic component is provided in the DC side line rather than the separately excited inverter and inverter in a circuit similar to that shown in FIG. 1, and the operation of this relay 19 is A sequence is set up in which the DC switch 2 is opened based on this, and the breaker 12 for the inverter I is then opened.

In the actual circuit, DC-L is finite and the circulating current with the phase-advanced load becomes an unbalanced current because the voltage is an unbalanced voltage, and the content rate of the second harmonic on the DC side of the inverter I is To increase. Therefore, the purpose can be achieved even if the content or content rate of the second harmonic is detected on the DC side.

Note that if a capacitor with a particularly large capacity is connected to the AC side in addition to a filter or cable, the line voltage will rise, the voltage in the control circuit will be insufficient, and control will become uncontrollable, causing the inverter I to stop. Therefore, there is no need to take the above measures.

In addition, in the actual circuit, there are excitation inductance and leakage inductance of the rectifier transformer 11, and losses in the control power source on the AC side from the inverter 1, and the voltage and current waveforms are the sawtooth waveforms shown in Figure 4 (A). The waveform does not become the rectangular wave shown in FIG.

As described above, the solar power generation device of the first invention includes a solar cell, a passive inverter that connects the solar cell to an AC system, and a negative phase voltage on the AC side line from the inverter. Alternatively, it is provided with means for detecting a negative phase current and means for opening the power supply circuit based on the detection.

Moreover, the second invention provides a means for detecting a second harmonic component on the DC side line rather than the inverter, instead of detecting the negative phase voltage (current), and opens the power supply circuit by this detection. It is composed of These first. Both of the second inventions have the following effects.

Of course, in the case where there are a large number of AC circuit breakers, if any of the circuit breakers is opened, the detection means described above can detect this and automatically open the power circuit of the solar power generation device. I can do it.

In other words, there is the effect that safety and circuit protection can be achieved satisfactorily while taking simple and economical measures.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram of a conventional example, Fig. 2 is an electric circuit diagram of an embodiment of the first invention, Fig. 3 is a circuit diagram of its main part, and Fig. 4 (A) and (B). are voltage waveform diagram, current waveform diagram,
FIG. 5 is an electric circuit diagram of an embodiment of the second invention, and FIG. 6 is a diagram of actually measured voltage and current waveforms. 1...Solar cell, 2...DC switch, 18...Negative phase voltage (current) detection relay, 19...2nd harmonic component detection relay, ■...Separately excited type in-hark

Claims (1)

[Claims] (11) A solar cell, a separately excited inverter that connects the solar cell to an AC system, a means for detecting a negative sequence voltage or a negative sequence current on a line on the AC side of the inverter, and a method for detecting the negative sequence voltage or current (2) A solar cell, a separately excited inverter that connects the solar cell to the AC system, and a second harmonic on the line on the DC side of the inverter. A solar power generation device comprising means for detecting a component and means for opening a power supply circuit based on the detection.