JPH01291636A - Distributed power source linking system - Google Patents

Abstract

PURPOSE:To reduce the cost by connecting a load between a DC/AC converting means and a linking means and connecting lead-in wires for respective consumers between them. CONSTITUTION:A link unit 30 comprises a linking switchgear 31, a protective unit 32 for detecting a fault at the side A of a power system or the side C and separating solar cells 20 from the power system A, a transformer 33 and a filter 34 for bypassing higher harmonics. A lead-in wire 35 is connected to point C between a DC/AC converter 21 and the linking unit 30, and power is fed from the power system A through the linking unit 30 to respective homes 19. Harmonics produced in the DC/AC converter 21 flow to a load 22, and only a little bit thereof passes through the linking unit 30, and thereby it is not required for the DC/AC converter 21 to produce a clean sinusoidal wave. Consequently, only simple DC/AC conversion control is required and no augmentation of the filter 34 in the linking unit 30 is required. Furthermore, the cost can be reduced remarkably because only one linking unit 30 is required.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an electric power system having at least one AC power source using a rotating machine consisting of a power generation means such as thermal power generation, and an electric power system installed at a consumer etc. The present invention relates to a grid interconnection system for distributed power sources that is suitable for interconnecting distributed power sources consisting of power generation means such as solar power generation that are interconnected to a power grid.

(Prior Art) In recent years, technological development of power sources using power generation means such as solar power generation and fuel cell power generation has been progressing.

For example, solar power generation is difficult to handle because its output is easily affected by the weather and cannot be generated at night.Furthermore, systems that use fuel cells as a power source have shutdown periods for inspections, so these solar power When using power generation means such as power generation and fuel cell power generation as a power source, there is a problem that it is difficult to stably supply power to household loads etc. when used alone. power generation,
At least one alternating current power source (hereinafter referred to as main power source) using a rotating machine consisting of a power generation means such as internal combustion power generation is connected to a power system that has power generation means such as solar power generation and fuel cell power generation as a distributed power source. Efforts are being made to ensure a stable power supply.

By the way, conventionally, for interconnection, as shown in Fig. 3, orthogonal conversion means 2 (usually pulse (converted to alternating current by width modulation) and power system 3
Protective devices necessary for interconnection with 4. Switch 5. An inverter device 7 is exclusively used which is integrated with a interconnection means 6 consisting of a filter F etc. that prevents harmonics generated by the transformer H2 orthogonal conversion means 2 from flowing into the power grid. In addition, 8
is a high-voltage distribution line, T is a pole transformer, and R is each household Sl~
A drop-in line for supplying power to Sn, 9 is a household load.

(Problem to be solved by the invention) However, in the conventional inverter device, since the orthogonal conversion means 2 and the interconnection means 6 are integrated, one interconnection means is required for one distributed power source. Moreover, in the interconnection means 6, most of the harmonics generated from the orthogonal transformation means 2 must be removed by the filter F, so the filter F must be strengthened, which causes problems such as increased cost. However, this invention was made in view of these problems, and its purpose is to provide a grid interconnection method for distributed power sources that is inexpensive and capable of supporting multiple distributed power sources with a single interconnection means. The goal is to provide a comprehensive system.

(Means for Solving the Problem) In order to achieve the above object, the present invention provides a distributed power source consisting of a power system having at least one AC power source using a rotating machine and power generation means such as solar cells and fuel cell power generation. and an orthogonal conversion means for converting the DC voltage output from the distributed power source into an AC voltage and applying the AC voltage to the load. A grid interconnection system, in which the load is connected between the orthogonal conversion means and the grid interconnection means, and a drop-in line for supplying power from the power grid to each consumer is connected from between them to each 7a main house. It is connected to

(Function) The load is connected between the orthogonal conversion means and the interconnection means, and a drop-in line for supplying power from the power system to each consumer is connected from there between to each consumer. , it is possible to support multiple distributed power sources with a single interconnection means.

(Example) Hereinafter, an example of a grid interconnection system for distributed power sources according to the present invention will be described based on the drawings.

In FIG. 1, reference numeral 11 denotes an AC power source using a rotating machine consisting of power generation means such as thermal power generation, nuclear power generation, internal combustion power generation, etc., and hereinafter, this is referred to as the main power source 11.

The voltage of the power generated by the main power source 11 is stepped down to 6 KV by a distribution substation 12, branched through a desired number of distribution lines 13, and distributed from the distribution substation 12.

Branch power to each distribution line 13 is transmitted through a circuit breaker 14 and a distribution line 15.
The power is supplied to pole transformers 16 installed at various locations through the power supply. The power supplied to the pole transformer 16 has a voltage of 1
The voltage is stepped down to 00V and supplied to each household (19<S major household).

In this embodiment, the power system A refers to the system from the main power source 11 to the interconnection point B. This power system A is
In this embodiment, as is clear from FIG. 1, there is only one main power source.

20 is a solar cell installed in each home 19 as a distributed power source; 21 is an orthogonal converter (orthogonal converter) that converts the output voltage output from the solar cell 20 into AC voltage; and 22 is an air conditioner that operates on AC voltage. ,'ri light.

This is a load on refrigerators, etc. 30 is the load 2 from the solar cell 20
When the power supplied to power system 2 is insufficient, power from power system A can be supplied to load 22, and harmonics generated in orthogonal converter 21 are prevented from flowing to power system A. This is a grid connection device (grid connection means) for grid connection, which includes a switch 31 for grid connection and a protection device 32 that detects a failure on the power system A side or a failure on the power system C side and disconnects the solar cell 20 from the power system A. , a transformer 33, and a filter 34 that bypasses the harmonics. 35 is a drop-in line connected to the 0 point between the orthogonal converter 21 and the interconnection device 30, and this is a drop-in line connected to the power grid A that has passed through the interconnection device 30.
This is to supply electricity to each household 19.

Here, if the lead-in line 35 connected to point 0 is for 10 houses, and the output of the solar cell 2o is 2KW and the power consumption of the load 22 is 2KW, then the power output from the solar cell 20 of each home 19 (2KW ) is consumed by the load 22, and the total power passing through the grid interconnection device 30 for 10 houses is zero (by the way, in the conventional system, the power passing through each interconnection device is 2KW, and the power passing through the grid interconnection device 30 for 10 houses is zero) The total amount is 20KW).

Furthermore, since the harmonics generated by the orthogonal converter 21 also flow to the load 22, very few harmonics pass through the interconnection device 30. Therefore, the output waveform of the orthogonal converter 21 needs to be a clean sine wave. Therefore, the IIJ control for orthogonal transformation may be simple.

That is, there is no need to use PWM (pulse width modulation) for the orthogonal converter as in the conventional case, and there is no need to strengthen the filter 34 of the interconnection device 30. I wanted to,
The cost of the orthogonal converter 21 and the interconnection device 30 can be reduced, and furthermore, since there is only one interconnection device 30,
The cost of a distributed power supply interconnection system can be significantly reduced.

FIG. 2 shows another embodiment, in which the transformer 33
This also serves as a pole-mounted transformer 16 to further reduce costs.

(Effects) As described above, the present invention provides interconnection for interconnecting a power system having at least one AC power source using a rotating machine and a distributed power source consisting of power generation means such as solar cells and fuel cell power generation. and orthogonal conversion means for converting a DC voltage output from the distributed power source into an AC voltage and applying the AC voltage to a load, the system comprising: is connected between the orthogonal conversion means and the interconnection means, and a drop-in line for supplying electric power from the power system to each consumer is connected from between to each consumer. One interconnection means is sufficient for a plurality of distributed power sources, and therefore costs can be reduced. In addition, since the power output from the distributed power source is supplied to the load and then passes through the interconnection means, the harmonic power passing through the interconnection means is reduced, so there is no need to strengthen the filter of the interconnection means. Moreover, the advantage is that the transformation control of the orthogonal transformation means can be simple.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the overall configuration of an embodiment of a distributed power grid interconnection system according to the present invention, Fig. 2 is a block diagram showing the overall configuration of another embodiment, and Fig. 3 is a conventional distributed power supply system. 1 is a schematic configuration diagram showing a grid interconnection system. 11... Main power supply (AC power supply) 12... Distribution substation 14... Circuit breaker 15... Distribution line 16... Pole transformer 20... Solar battery (distributed type m) 21 ... Orthogonal converter (orthogonal conversion means) 22 ... Load 30 ... Grid connection device (grid connection means) 35 ... Drop-in line applicant Shikoku Research Institute Co., Ltd.

Claims (1)

[Scope of Claims] Interconnection means for interconnecting a power system having at least one AC power source using a rotating machine and a distributed power source consisting of power generation means such as solar cells and fuel cell power generation, and said distributed power source. A grid connection system for distributed power sources, comprising orthogonal conversion means for converting a DC voltage output from a DC voltage into an AC voltage and applying the AC voltage to a load, the load being connected to the orthogonal conversion means. A system interconnection of a distributed power source, characterized in that it is connected to a system means, and a drop-in line for supplying power from the power system to each consumer is connected to each consumer from between. system.