JP2000232736A - Linked distributed power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a distributed power generation system which can suppress linkage point voltage within a prescribed value, without the installation positions of power generating devices, peripheral loads and control time constants. SOLUTION: In power generating devices 7 and 9, power converters 15 convert the generated powers of power generating sources 13 into powers, which can be linked with a distribution system 1 and supply the powers to the distributed system 1. Control units 17 have functions of control over the power converters 15 and functions of communicating with the outside. The communication functions include functions which transmit the operation voltage information signals S1 to the outside, and further, functions which receive signals S2 supplied from the outside. A central unit 11 monitors the operation voltage information signals S1 which are transmitted from the control units 17 and calculates remote control signals, corresponding to the power generating devices 7 and 9 respectively based on the operation voltage information signals S1 and supplies the calculated remote control signals S2 to the power generating devices 7 and 9 respectively and controls their operations remotely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed power generation system using photovoltaic power generation or the like.

[0002]

2. Description of the Related Art In recent years, power generation devices represented by photovoltaic power generation have been spreading. Due to the development of legal systems and technical guidelines, reverse power flow from the power generator to the power system has been recognized.
It became possible to accommodate other loads in the power system.

[0003] Reverse power flow operation has the advantage that the surplus generated power of the power generator can be used effectively, but on the other hand, when the power generator starts reverse power flow operation, the voltage is locally localized around the interconnection point. As a result, there is a risk that the power supply system will deviate from the voltage supply management standard defined by the Electricity Business Law, and it is necessary for each power generation device to take measures for increasing the voltage. At present, the Electricity Business Act requires that the supply voltage at customer service
101V ± 6V for 0V system, 2 for 200V system
Since the voltage is set to be maintained in the range of 02V ± 20V, the voltage at the interconnection point must be maintained in this voltage range.

[0004] Since it is difficult to take measures against the above-mentioned local voltage rise by the upper substation equipment, a function for preventing the voltage rise at the interconnection point except for a very small capacity power generator is provided in the power generator. Each of them must be provided, and constant monitoring and control of output voltage fluctuations are required.

According to the distributed power system interconnection technical guideline (Japan Electric Association), as one of the conditions for the power generator to carry out the above reverse power flow, it is necessary to provide the power generator with measures against voltage fluctuation. It is clearly stated that there are reactive power control methods that adjust the power factor of the output current to inject a reactive power component (leading component),
An active power control method for suppressing the active component of the output power is recommended.

[0006]

2. Description of the Related Art Various problems that have not occurred in the past are expected to occur when power generation devices are widely used and power generation devices are installed at high density in a power distribution system. The voltage rise at various points in the distribution system due to the reverse power flow of the lower power generation device is one of the major problems.

[0007] The 15th Solar Power System Symposium (organized by the solar power generation society, sponsored by: June 2, 1998)
(July-June 4th: Venue: Invention Hall), the following specific problems were introduced.

When the power generators are installed at a high density, (1) When the voltage control measures are not taken for each of the power generators, the voltage easily exceeds the control standard due to the reverse power flow of several power generators. May be lost. (2) In the voltage rise suppression method based on reactive power injection or active power output limitation, which is a countermeasure on the power generator side against voltage rise, the location of the power generator (distance from pole transformer)
In addition, there is a possibility that inequality such as restriction of the active power output of a specific power generation device due to the control time constant of the power generation device and concentration of reactive power on the specific power generation device may occur.

[0009] The above-mentioned problem of the rise of the interconnection point voltage due to the reverse power flow is caused by the impedance of the distribution line. For example, two solar power generators having the same capacity can obtain the same level of solar radiation under the same solar radiation conditions. When connected in the same power distribution system, two power generators may have the same power generation capability, but a difference may occur in the amount of generated power depending on conditions such as the distance from the substation and the response speed of the power generator. That is.

In a conventional power generation system utilizing natural energy, such as a solar power generation system or a wind power generation system, the amount of generated power is extremely unstable. As a control method, a method of distributing the generated power of each power generation device to a load is effective. Japanese Patent Application Laid-Open No. Hei 9-135536 discloses a centralized control type power distribution system that takes such consideration into account. However, no consideration has been given to the technique of maintaining the voltage in the distribution system as described above.

From an economic point of view, although the installation costs of the above two power generators are almost the same, the power sales fee paid by the purchaser of the generated power does not include the generated power amount as described above. The difference between the two causes a difference, resulting in unfairness.

In a power generation device such as a photovoltaic power generation device, electric power is extracted from scarce natural energy. Therefore, in order to effectively use the power as a main energy source, a large number of power generation devices need to be installed in a large area. Without widespread dissemination, it cannot truly contribute to the energy problem due to economic inequality.

A fundamental solution to the above problem is:
It may be possible to increase distribution lines or further expand the range of supply voltage management standards stipulated by the Electricity Business Act.
To achieve this, a huge investment is required, and it is difficult to immediately take countermeasures for the entire power system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a distributed power generation system in which even when a plurality of power generators are operated in an interconnected manner, the voltage at the interconnection point can be kept within a management standard and safe operation can be continued. It is.

Another object of the present invention is to prevent the unfairness of the power generation amount of each power generation device due to the installation location and the peripheral load from occurring, and to achieve a distributed operation that allows for smooth operation and management of the system. It is to provide a type power generation system.

Still another object of the present invention is to provide a distributed power generation system that does not cause unfairness in the amount of power generated by each power generation device even if there is a difference in control time constant between the power generation devices.

[0017]

In order to solve the above-mentioned problems, a power generation system according to the present invention includes a plurality of power generation devices and a central device. Each of the power generation device is provided to a power consumer, a power conversion device,
And a control unit, which are distributed and connected to the same power distribution system. The power converter converts power generated by a power source such as a solar cell into power operable to be connected to the power distribution system and supplies the power to the power distribution system. The control unit has a function of controlling the power conversion device and a communication function of communicating with the outside, and the communication function directs at least information of an operating voltage output from the power generation device to the outside. Send
Includes the function of receiving signals supplied from outside.

[0018] The central unit monitors at least the operating voltage information transmitted from the control unit by the communication function of the control unit, and monitors the power generation device based on the operating voltage information. A remote control signal corresponding to each is calculated, and the calculated remote control signal is given to each of the power generating devices to remotely control the operation of the power generating device.

As described above, in the power generation system and the power distribution system according to the present invention, in each of the power generation devices, the power generated by the power generation source is converted into power operable to be connected to the power distribution system and supplied to the power distribution system. Therefore, in the power consumer, power can be supplied from the power distribution system and the power generation device owned by the user to the power equipment used by the user. Further, when the power generation capacity of the power generation device becomes excessive with respect to the power consumption of the power equipment used by the power generation device, the surplus power can be supplied to the power distribution system to obtain an economic benefit by selling the power.

When surplus power is supplied to the power distribution system, a reverse power flow occurs, and as described above, various problems may occur as described above.

As means for solving this problem, in the power generation system according to the present invention, the control unit has a communication function for communicating with the outside in addition to a function for controlling the power conversion device. The communication function transmits information on the operating voltage of the power generator to the outside,
Includes the function of receiving signals supplied from outside.

On the other hand, a central device is provided in addition to the above configuration of the power generator. The central device monitors the operation voltage transmitted from the control unit provided in the power generation device, and calculates a remote control signal corresponding to each of the power generation devices based on the information of the operation voltage, and the calculation is performed. The remote control signal is supplied to each of the power generation devices to remotely control the operation thereof.

According to this configuration, the central device can monitor the operating voltage of each power generating device while giving a remote control signal to each power generating device, so that the operation of each power generating device can be collectively controlled from a remote place. With this centralized control, the burden of voltage fluctuation countermeasures is prevented from being concentrated on a specific power generation device, and the interconnection point voltage (operating voltage) is within the management standards even when a plurality of power generation devices are connected and operated. And safe driving can be continued.

In addition, since the entire power generation device is used as a measure against voltage fluctuations, the power generation amount of each power generation device is prevented from being unfair due to the installation location, peripheral load and control time constant, and the system is smoothly operated and managed. It can be performed.

The present invention further discloses a specific control method of the operating voltage, a control unit included in the power generation device, and a specific configuration of the central device.

[0026]

FIG. 1 is a block diagram of a power distribution system having a distributed power generation system according to the present invention. The power distribution system includes at least one power distribution system 1 and a power generation system according to the present invention. The power distribution system 1 is electrically coupled to a power transmission system 5 via, for example, a pole transformer 3 or the like. The distribution system 1 may be a single-phase AC,
It may be three-phase alternating current.

The power generation system includes a plurality of power generation devices 7 and 9
And a central device 11. The number of generators 7, 9
Although two are shown in the figure, the number is arbitrary. Each of the power generators 7 and 9 is installed in a power consumer, and includes a power source 13, a power converter 15, and a controller 17.
And are distributed and connected to the same power distribution system 1. The power generators 7 and 9 are connected to the distribution system 1 at service points (pillars) X1 and X2 via service lines 19 and 20 having line impedances Z1 and Z3, respectively. In addition, power equipment 21 of each power consumer is connected to the service lines 19 and 20.

The power conversion device 15 converts the power generated by the power generation source 13 into power operable to be connected to the power distribution system 1 and supplies the power to the power distribution system 1. The power source 13 is a solar cell, wind power, or the like. The power converter 15 is a DC-AC converter that converts the power supplied from the power source 13 into an alternating current by a switching operation. This type of power converter 15
Since the technology for converting the power generated by the power generation source 13 into power operable to be connected to the distribution system 1 is already known, the details thereof are omitted.

The control section 17 has a function of controlling the power conversion device 15 and a communication function of communicating with the outside. The communication function includes a function of transmitting operation voltage information output from the power generators 7 and 9 to the outside and receiving a signal supplied from the outside. Although not shown, a sensor for detecting an operating voltage, a sensor for detecting an output current or an input current of the power converter 15 and the like are provided, and a signal obtained by the sensor is supplied to the control unit 17. .

Except that the control unit 17 has a communication function of communicating with the outside, the basic operation of the power generators 7 and 9 and
The control policy is already known in Japanese Patent Application Laid-Open No. Hei 8-123561, a distributed power system interconnection technical guideline (Japan Electric Association), and the like.

The central unit 11 monitors the operating voltage transmitted from the control unit 17 by the communication function of the control unit 17 and controls each of the power generators 7 and 9 based on the operating voltage information. A corresponding remote control signal is calculated, and the calculated remote control signal is given to each of the power generators 7 and 9 to remotely control the operation thereof.

The central unit 11 and the power generators 7 and 9 are connected by signal transmission lines 23 and 25. The signal transmission lines 23 and 25 may be different communication lines or the same communication line. As the communication means, an existing circuit network such as a telephone line or power gable may be used, or a dedicated line may be provided. The invention is not limited to wired communication, and wireless communication may be used. In this embodiment, the signal transmission lines 23 and 25 are shown for clarity of explanation. The signals flowing through the signal transmission lines 23 and 25 may be analog signals or digital signals.

As described above, in each of the power generation devices 7 and 9, the power conversion device 15 converts the power generated by the power generation source 13 into power operable for interconnection with the power distribution system 1 and supplies the power to the power distribution system 1. Since the power is supplied, the power consumer can supply power from the power distribution system 1 and the power generation devices 7 and 9 owned by the user to the power equipment 21 used by the user. Further, when the power generation capacity of the power generation devices 7 and 9 becomes excessive with respect to the power consumption of the power equipment 21 used by the power generation devices 9 and 9, the surplus power is supplied to the distribution system 1 to obtain an economic benefit by selling power. be able to.

When surplus power is supplied to the distribution system 1,
A reverse power flow occurs, and as described above, the individual power generators 7,
If the voltage management measures are not taken for the power supply 9, the voltage may easily exceed the control standard due to the reverse power flow of the power generators 7 and 9. When the output is restricted, the active power output of a specific power generator 7, 9 is limited by the installation location of the power generator 7, 9 or the control time constant of the power generator 7, 9, As described above, there is a possibility that inequality may occur such as a concentration of reactive power in a specific power generation device in the vehicle.

As means for solving this problem, in the illustrated power generation system, the control unit 17 for controlling the power conversion device 15 has a communication function for communicating with the outside in addition to a function for controlling the power conversion device 15. . The communication function transmits operating voltage information output from the power generators 7 and 9 to the outside,
Includes the function of receiving signals supplied from outside.

On the other hand, a central device 11 is provided in addition to the above configuration of the power generation devices 7 and 9. The central device 11 includes the control unit 1
7 and monitors at least the operating voltage transmitted from the control unit 17 and calculates a remote control signal corresponding to each of the power generators 7 and 9 based on the operating voltage information S1. Then, the calculated remote control signal S2 is given to each of the power generators 7 and 9 to remotely control the operation thereof.

According to this configuration, the central device 11
While monitoring the operating voltage of each of the power generators 7 and 9, a remote control signal S2 is given to each of the power generators 7 and 9 so that
9 can be collectively controlled remotely. Therefore, it is possible to avoid concentration of the load of the voltage fluctuation countermeasures on a specific power generator among the power generators 7 and 9, and even when the plurality of power generators 7 and 9 are connected to each other, the connection point voltage ( Operating voltage) within the control standards, and safe operation can be continued.

In addition, since the power generators 7 and 9 as a whole take measures against voltage fluctuations, the power generation amount of each of the power generators 7 and 9 should not be unfair due to the installation location, peripheral load or control time constant. , The system can be smoothly operated and managed.

The remote control signal S2 can include an active power adjustment signal for adjusting the output active power of the power generators 7, 9 and a driving power factor adjustment signal for adjusting the driving power factor of the power generators 7, 9. . In this case, in adjusting the operating voltage to be within a predetermined set value, reactive power is injected by a remote command from the central unit 11 to adjust the operating power factor, and then the output of the power generators 7 and 9 is adjusted. A two-stage remote control that regulates (limits) the active power can be employed.

The control unit 17 performs remote control by the central device 11 and, based on information on the operating voltage detected by itself,
It is preferable to have a function capable of controlling the power conversion device 15 by itself. According to this configuration, when an abnormality occurs in the communication system, the power conversion device 15 can be controlled by itself without waiting for the remote control signal S2 from the central device 11.

Next, referring to FIGS.
A specific example of the control unit 17 and the central device included in 9 will be described. FIG. 2 is a block diagram showing an example of the power generation devices 7 and 9 used in the power generation system shown in FIG. In the figure, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

The illustrated control unit 17 includes a communication unit 51,
Remote control unit 53, output control unit 55, communication monitoring unit 57
, A switching unit 59, a voltage fluctuation prevention unit 61, a logic determination unit 63, and a protection unit 67. Each of these units is configured as an electric circuit, but does not need to be independent as hardware, and can be realized as a one-chip or plural-chip digital signal processing device or an analog signal processing device. . In this case, it is appropriate that each unit is considered as a signal processing step rather than as a circuit device. Circuit breaker 67 for AC output line
Is inserted.

Of the components included in the control unit 17,
Output control unit 55, voltage fluctuation prevention unit 61, logic judgment unit 6
3, the protection unit 65 and the circuit breaker 67 are described in the 1995 Solar and Wind Energy Lecture Paper No. It is already known as 13 mag. The feature of the present invention is that a communication unit 51, a remote control unit 53, a communication monitoring unit 57, and a switching unit 59
And so on.

The communication unit 51 transmits information S1 of the operating voltage in the power generators 7 and 9 to the central unit 11 through the communication line 23.
And has a function of receiving the signal S2 supplied from the central device 11. The operating voltage information S1 includes its own output active power Pn, operating power factor θn, and interconnection point voltage Vn (n =
1, 2, ...). The remote control signal S2 supplied from the central device 11 includes a driving power factor signal Sθ,
The active power output rate signal S (ξ), the stop signal φ, and the like are included.

The remote control unit 53 controls the power conversion unit so that the output active power and the output reactive power instructed by the central unit 11 are controlled by the remote control signal S2 (θ, ξ, φ) supplied from the central unit 11. 15 is controlled.

The control unit 17 performs remote control by the central device 11 and, based on information on the operating voltage detected by itself,
It is preferable to have a function capable of controlling the power conversion device 15 by itself. According to this configuration, when an abnormality occurs in the communication system, the power conversion device 15 can be controlled by itself without waiting for the remote control signal S2 from the central device 11.

In response to such a configuration, the control unit 17
Includes a switching unit 59. The switching unit 59 switches between self-power control and remote control. Switching section 59
When the movable contact 71 is switched to the fixed contact 73 and connected to the remote control unit 53, remote control is performed. When the movable contact 71 is switched to the fixed contact 75 and is connected to the voltage fluctuation preventing unit 61, self-control is performed. Although the illustrated switching unit 59 is displayed as a contact switch, it is employed only to make the switching operation visually understandable. Needless to say, it can be realized as a contactless circuit.

The communication monitoring unit 57 is provided as a means for automatically performing the switching control described above. The communication monitoring unit 57 monitors the communication operation of the communication unit 51, and when it is determined that the communication operation is normal, connects the movable contact 71 of the switching unit 59 to the fixed contact 73 and switches to the remote control side. . When it is determined that the communication operation of the communication unit 51 is abnormal, the movable contact 71 of the switching unit 59 is connected to the fixed contact 75 and switched to the remote control side.

FIG. 3 is a block diagram showing an example of the central unit 11. The illustrated central device 11 includes a receiving unit 31,
Transmission unit 33, setting input unit 35, maximum value detection unit 37
, A determination unit 39, a remote control signal calculation unit 41, and a stop signal generation unit 43. Each part of the central device 11
Although it is configured as an electric circuit, it does not need to be independent as hardware and can be realized as a one-chip or plural-chip digital signal processing device or an analog signal processing device. In this case, it is appropriate that each unit is considered as a signal processing step rather than as a circuit device. When implemented as a digital signal processing device, typically a CPU is used.

The receiving section 31 receives the operating voltage information S1 transmitted from the power generators 7, 9. The transmission unit 33 transmits a remote control signal S2 to the power generators 7, 9.

The transmission unit 33 transmits three types of signals to each of the power generators 7 and 9. The first signal is a signal representing the driving power factor angle θ (hereinafter, referred to as driving power factor signal Sθ), and is a signal for designating the driving power factor for the power generators 7 and 9.
The driving power factor signal Sθ may be a signal having a value corresponding to the power factor angle θ or a signal converted to a power factor (cos θ).

The second signal is a signal indicating the ratio (ξ) of the active power actually output by the power generators 7 and 9 to the power that can be output by the power generators 7 and 9 at a certain timing during operation. (Hereinafter referred to as an active power output rate signal ξ) and is used to limit the output active power of the power generators 7 and 9. For example, 100% output when ξ = 1.0, ξ = 0.0
In this case, by determining in advance the correspondence with the 0% output, the active power outputs of the plurality of power generators 7 and 9 can be simultaneously controlled at a constant rate.

A third signal is a stop signal Sφ, which can stop one or a plurality of specific power generators 7 and 9. The above three signals Sθ, S (ξ) and Sφ take a form such as an analog signal system or a digital signal system, and can be processed and output in a form suitable for communication means at the time of transmission.

The setting input unit 35 is a means for inputting the number of power generators 7 and 9 (two in the illustrated case) within the monitoring range of the central unit 11 and power distribution system information including the AC operating voltage range. It is. The power distribution system information is input to the setting input unit 35 using, for example, a keyboard or a mouse.
Is input to

The maximum value detection section 37 detects the maximum one of the AC operating voltages of the power generators 7 and 9 within the monitoring range. The AC operation voltage is determined at the interconnection points Y1 and Y2 (see FIG. 1).
Voltage. The determination unit 39 determines whether the detected maximum value is within a set range.

When the detected maximum value is higher than the set value, the remote control signal calculation section 41 adjusts the remote control signal S2 for each of the power generators 7 and 9. The remote control signal calculation unit 41 adjusts the driving power factor signal Sθ and the active power output rate signal S (ξ) among the three signals Sθ, S (ξ) and Sφ included in the remote control signal S2, and 33.

The stop signal generation unit 43 determines whether the maximum value deviates from the set range of the AC operation voltage even though the remote control signal calculation unit 41 adjusts the remote control signal within a predetermined range. A stop signal Sφ for stopping a specific power generator among the power generators 7 and 9 is generated. The stop signal φ may be used as a signal for stopping one or a plurality of specific power generation devices 7 and 9 when an overvoltage occurs.

As a control method of the power generation devices 7 and 9 by the central device 11, a remote control signal S2 is transmitted to the plurality of power generation devices 7 and
9 at the same time, and in a plurality of power generators 7, 9,
A method in which the output active power limitation and the operating power factor adjustment are performed simultaneously can be adopted. In this case, the remote control signal calculation unit 41 keeps the active power output rate signal ξ (output active power) constant when the maximum value of the AC operating voltage of the plurality of power generators 7 and 9 is out of the set range. While maintaining this, the driving power factor signal Sθ (driving power factor) is adjusted.

Next, even if the operating power factor signal Sθ (operating power factor) is adjusted within a predetermined range, the maximum value of the AC operating voltages of the plurality of power generators 7 and 9 is out of the set range. Adjusts the active power output rate signal S (ξ) to limit the output active power, and controls the AC operation voltages of the plurality of power generators 7 and 9 so that the maximum value falls within a set range. In this case, in the plurality of power generators 7 and 9, the driving power factor θ controlled by the driving power factor signal Sθ is the same as each other, and the ratio of the limit of the output active power by the active power output ratio signal と is equal to the same ratio. It is preferable to control so that

Next, a collective centralized control system according to the present invention,
The conventional individual control method will be described in more detail with reference to data. FIG. 4 shows an operation waveform diagram obtained by the conventional individual control system, and FIG. 5 shows an operation waveform diagram obtained by the collective centralized control system according to the present invention. In obtaining the operation waveform diagrams of FIGS. 4 and 5, in the power distribution system of FIG. 1, the power generators 7 and 9 were connected to the low-voltage power distribution system 1 at intervals of about 100 m. When the power generation source 13 is performing a power generation operation in a normal solar radiation state, both the power generation devices 7 and 9 can output 2.0 kW. For simplicity of explanation, the load in each customer is assumed to be zero, and the power generators 7, 9
Has a reactive power control recommended by the grid connection guidelines and a connection point voltage fluctuation adjustment function by limiting the active power output, and the connection point voltage at the time of reverse power flow is 107.0 V, respectively.
The following description will be made on the assumption that the vehicle is set to operate.

First, the operation of the conventional individual control system and its problems will be described with reference to the operation waveform diagram of FIG. The conventional individual control method refers to the control unit 17 included in the power generators 7 and 9 without the central device 11 in FIG.
Are power generation systems that perform independent control operations.

As shown in FIG. 4, two power generators 7, 9
Start operating simultaneously, the distribution system impedance Z
D1, ZD2 and drop-in impedance Z1, Z2
Therefore, the voltages V1 and V1 at the respective interconnection points Y1 and Y2
2 rises. The voltage V1 at the interconnection point P1 of the power generator 7 is 1
06.9V is within the legal range stipulated by the Electricity Business Act, so it continues to operate without any problem.
The power generation device 9 installed at a distance from the
2 is 109.2 V, which may deviate from the legal range (period A).

Therefore, the power generator 9 performs an operation of first injecting reactive power to lower the voltage V2 of the interconnection point Y2 by a predetermined operation control algorithm (period B). As a result, in the power generation device 9, the voltage V2 at the interconnection point Y2 decreases due to the injected reactive power.

As in the last stage of the period B, even when the power generator 9 operates at a power factor of 85%, which is the limit of reactive power injection, the voltage V2 at the interconnection point Y2 of the power generator 9 remains within the set range. Does not fit.

Therefore, the power generator 9 is provided as the following means.
An operation of limiting the output active power component and reducing the voltage V2 at the interconnection point Y2 is performed (period C). As at the end of the period C, when the power generation device 9 suppresses the output active power to approximately 18.5%, the interconnection point voltage has decreased to the set voltage of 107.0 V. It ends and reaches a steady state as in period D.

While the power generation device 9 performs the above-described control operation, the power generation device 7 belonging to the customer R1 can continue to output 100% output of 2.0 kW with almost no control operation. it can. If the conditions of the solar radiation, the supply voltage from the upper substation, and the peripheral load are constant, the operation state as in the period D is continued, and the power generation device 9 has the same power generation capability of 2.0 kW as the power generation device 7. While the output is 18.5%
You must continue to operate with restrictions. This gives the consumer R2 a great sense of unfairness.

Next, the operation of the power generation system according to the present invention will be described with reference to FIG. First, immediately after the operation is started, the impedance Z of the distribution system 1 and the service line 19 is set.
Because of 1, Z2, the voltage V2 at the interconnection point Y2 of the power generation device 9 becomes 109.2V that deviates from the set voltage of 107.0V (period A).

The output active power of the power generators 7 and 9 (P1 =
2.0 kW), driving power factor (cos θ1 = cos θ2 =
1.0), the information of the voltage V1 at the interconnection point Y1 = 106.9 V and the information of the voltage V2 at the interconnection point Y2 = 109.2 V are transmitted to the central unit 11 by the communication unit 51 provided in each of the power generation devices 7 and 9. The data is transmitted and received by the receiving unit 31 of the central device 11.

In the central device 11, the maximum value detector 37 selects the maximum voltage V1, V2 of the interconnection points Y1, Y2. In this embodiment, the voltage V2 at the interconnection point Y2 is selected as the maximum value.

The selected maximum value V is given to the judgment section 39. The determination unit 39 determines whether or not the maximum value V falls within a set range. In the case of the embodiment, the set voltage upper limit is set to 107.0 V, and in the period A, the maximum value V2 = 109.2 V exceeds the set voltage upper limit 107.0 V. Part 41
Is transmitted to

The remote control signal calculation section 41 enters control for reducing the voltage V2 at the interconnection point Y2 by injecting reactive power and drooping active power (period B). The control method of the reactive power and the active power may be the same as the control method for the countermeasures against the voltage fluctuation, which is conventionally performed in the individual power generators 7 and 9. First, while maintaining the active power output rate １．０ at 1.0 (100%), a driving power factor angle θ for adjusting the reactive power is calculated, and a driving power factor signal Sθ is generated. Then, the transmitting unit 33
From the driving power factor signal Sθ and the active power output rate signal S
(Ξ) is transmitted.

In the power generators 7 and 9, the driving power factor signal Sθ received via the communication section 51 and the active power output signal S
(Ξ) is reflected in its own output current control. Information on the operating voltage as a result is transmitted to the central device 11, and the central device 11 continues to monitor the voltages V1, V2 at the interconnection points Y1, Y2.

In the central unit 11, the driving power factor signal Sθ received via the communication section 51 and the active power output rate signal S
In (ξ), first, the voltages V1 and V1 at the interconnection points Y1 and Y2 are set.
Until the maximum value of 2 falls within the set range, the power factor angle θ is increased based on the driving power factor signal Sθ, and reactive power is injected into the entire power generators 7 and 9 (period B).

Next, even if the power factor angle θ is changed within a predetermined range, if the maximum values of the voltages V1 and V2 at the interconnection points Y1 and Y2 do not converge on the set range, the central device 11 sets the following. As a countermeasure against this, the limitation of the output active power is started. Specifically, when the power factor angle θ reaches the upper limit in the central device 11, the voltage control based on the power factor angle θ is stopped, and the active power output rate signal S
The subtraction of the active power output rate に よ る by (ξ) is started. As a result of the subtraction of the active power output rate ξ, the overall output of the power generators 7 and 9 is limited at a fixed rate, and the measures for suppressing the voltage rise are continued (period C). Subtraction of active power output rate は
1, until the maximum values of the voltages V1, V2 of Y2 fall within the set range (upper limit: 107.0 V), and reach a steady state (period D).

As described above, the central unit 11 monitors the voltages V1 and V2 of the interconnection points Y1 and Y2 of the power generators 7 and 9 dispersedly connected to the same power distribution system 1, and Since the outputs of the power generators 9 and 9 are controlled at the same time, more effective countermeasures can be taken for voltage fluctuations, and even when the output active powers of the power generators 7 and 9 are limited, they are simultaneously limited at the same overall rate. Fair power generation is possible without being affected by the installation locations of 7, 9.

The present invention is not affected by the installation location of the power generators 7 and 9 and is not affected by the variation of the time constant of the control unit 17 of the power generators 7 and 9 and enables fair power generation. It is. Next, this point will be described.

FIG. 6 is a diagram showing another power distribution system. In the figure, the same components as those shown in FIG. 1 are denoted by the same reference numerals. In FIG. 6, the power generators 7 and 9 are arranged close to each other via the same service line 19, and the connection point voltages V1 and V2 of the two have the same value. It is assumed that a power source 13 composed of a solar cell or the like having a power generation capacity is attached. Each of the two power generation devices 7 and 9 has a function of preventing a voltage rise by controlling the reactive power and the active power. The set voltage upper limit value at the connection point Y1 is 107.
0V. In the power generation device 9, the control time constants of the reactive power and the active power in the control unit 17 are set to be higher than the control time constant of the power generation device 7.

FIG. 6 shows a power generation system according to the present invention. For convenience of explanation, a case where a conventional individual control system having no central device 11 will be described first. FIG. 7 is an operation waveform diagram in the case of the individual control method.

In the case of the conventional individual control system, the power generator 7
9 starts power generation at the same time, the voltage V1 at the interconnection point Y1,
V2 rises at the same time as shown in FIG. In FIG. 7A, in the period A, the voltages V1 and V2 at the interconnection point Y1 of the power generators 7 and 9 are 108.1V, which exceeds the set voltage upper limit value of 107.0V.

Therefore, in the next period B, reactive power is first injected into both power generators 7 and 9 to start measures to suppress voltage rise. However, since the control time constant of the reactive power injection in the control unit 17 is set to be faster than the control time constant of the power generator 7, the power generator 9 is more reactive than the power generator 7. Progresses.

The power generator 9 injects reactive power until it reaches 85% of the operating power factor limit as in the last period of the period B in FIG. 7A. In this way, the active power is suppressed. When the output active power of the power generation device 9 is limited by 20%, the interconnection point voltage V
Since I and V2 reach the set voltage value of 107.0 V, the power generators 7 and 9 end the measures for increasing the voltage and enter the steady operation state (period D).

During this time, the power generation device 7 also performs a countermeasure against a voltage rise due to the injection of reactive power.
take time. For this reason, the power generation device 9 responding at high speed
It is responsible for most of the reactive power injection and the suppression of voltage rise by limiting the output of the active power.
(See FIG. 7 (c)) and operating at an output of 2.5 kW (see FIG. 7 (b)), whereas the power generator 9 has a power factor of 85
% (See FIG. 7 (c)) and output of 2.0 kW (see FIG. 7 (b)).

As in the above two examples, in the conventional countermeasures against voltage fluctuations of the individual power generating devices 7 and 9, the amount of trading power paid and paid to the customers R1 and R2, who are the installers of the power generating devices 7 and 9, respectively. Have the same unit price (in the case where the contract contents with the electric power company are the same), there is a problem that unfairness is caused depending on each installer due to the control time constant of the power generators 7 and 9.

Further, the above-mentioned problems are caused before installation.
If the installer of the generator 9 had been informed, the installer of the generator 9 would have considered the installation of the generator 9 more carefully and, in some cases, the installation of the generator 9 You may not have done it. In other words, the conventional countermeasures against voltage fluctuations include the problem of unfair power generation power prices, which hinders the spread of distributed power generation systems.

Next, the operation of the power generation system according to the present invention shown in FIG. 6 will be described with reference to FIG. Interconnection point Y
7, the voltages V1 and V2 rise at the same time, as shown in FIG. In FIG. 8A, in the period A, the voltages V1 and V2 at the interconnection point Y1 of the power generators 7 and 9 are 108.1V, which exceeds the set voltage upper limit value of 107.0V.

Therefore, in the next period B, reactive power is first injected into both power generators 7 and 9 to start measures for suppressing voltage rise. Although the control time constant of the reactive power injection in the control unit 17 is set to be higher than the control time constant of the power generation device 7 in the power generation device 9, the power generation devices 7 and 9 7, 9 driving power factor θ
1 and θ2 have been transmitted, the central device 11 determines the force resulting from the difference in the control time constants based on the operating power factors θ1 and θ2 of the power generation devices 7 and 9 sent from the power generation devices 7 and 9. Driving power factor signal Sθ to avoid imbalance in rate control
Can be generated.

If the maximum values of voltages V1 and V2 at interconnection point Y1 do not converge on the set range even when power factor angle θ is changed within a predetermined range, central device 11 starts limiting output active power. As described above, the total output of the power generators 7 and 9 is limited at a constant rate by subtracting the active power output rate ξ, as described above.

By the control operation described above, the power generators 7, 9
Are the same output active power P1 = P2 = 2.4
7 kW, active power output rate ξ = 0.988 (see FIG. 8B) and the same operating power factor cos θ1 = cos θ2 = 0.
85 (see FIG. 8C). Therefore, fair power generation is possible without being affected by the control time constant of the power generation devices 7 and 9.

When the no-load voltage of the distribution system is originally high,
When the maximum value of the interconnection point voltage does not fall within the set range due to the two measures of the reactive power control and the output active power suppression, for example, when the power generation devices 7 and 9 are installed extremely far from each other. In the case where the output active power of the power generators 7 and 9 is extremely limited, the stop signals Sφ starting from the highest voltage among the power generators 7 and 9 whose interconnecting point voltage exceeds the legal range are individually set. Can also be sent to stop.

[0090]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a distributed power generation system in which even when a plurality of power generation devices are connected to each other, the connection point voltage is kept within a management standard and safe operation can be continued. (B) It is possible to provide a decentralized power generation system in which the power generation amount of each power generation device does not become unfair due to the installation location or peripheral load and the system is operated and managed smoothly. . (C) It is possible to provide a distributed power generation system that does not cause unfairness in the power generation amount of each power generation device even if there is a difference in the control time constant between the power generation devices.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power distribution system having a distributed power generation system according to the present invention.

FIG. 2 is a block diagram showing an example of a power generation device used in the power generation system shown in FIG.

FIG. 3 is a block diagram showing an example of a central device used in the distributed power generation system according to the present invention.

FIG. 4 is an operation waveform diagram when a conventional individual control method is adopted in the distribution system shown in FIG. 1;

FIG. 5 shows an operation waveform diagram of the power generation system according to the present invention shown in FIG.

FIG. 6 is a diagram showing another power distribution system using the power generation system according to the present invention.

FIG. 7 is an operation waveform diagram in the individual control system when the power distribution system of FIG. 6 is adopted.

8 is an operation waveform diagram of the power generation system according to the present invention shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Distribution system 7, 9 Power generation device 11 Central device 13 Power generation source 15 Power conversion device 17 Control part 19, 20 Service line 21 Load R1, R2 Electricity consumer

Claims (19)

[Claims] 1. A power generation system including a plurality of power generation devices and a central device, wherein each of the power generation devices is installed in a power consumer, and includes a power conversion device and a control unit. Wherein the power conversion device converts the generated power of the power generation source into power operable to be interconnected with the power distribution system, and supplies the power to the power distribution system. The control unit has a function of controlling the power conversion device and a communication function of communicating with the outside, and the communication function transmits information of an operating voltage of the power generation device to the outside, and
The central device includes a function of receiving a signal supplied from the outside, the central device monitors information of the operating voltage transmitted from the control unit, and based on the information of the operating voltage, the central device monitors the power generation device. A power generation system that calculates a remote control signal corresponding to each of the power generation devices and provides the calculated remote control signal to each of the power generation devices to remotely control the operation of the power generation device. 2. The power generation system according to claim 1, wherein the remote control signal adjusts an active power adjustment signal for adjusting an output active power of the power generation device and an operating power factor of the power generation device. A power generation system including a driving power factor adjustment signal. 3. The power generation system according to claim 1, wherein the control unit controls the power conversion device based on information on an operation voltage of the power generation device to which the control unit belongs. The control unit further includes a switching unit, and the switching unit switches between the self-control and the remote control. 4. The power generation system according to claim 3, wherein the control unit includes a communication monitoring unit, and the communication monitoring unit includes:
The communication operation is monitored, and when it is determined that the communication operation is normal, the switching unit is switched to the remote control side, and when it is determined that the communication operation is abnormal, the switching unit is controlled by itself. Power generation system to switch to the side. 5. The power generation system according to claim 1, wherein the central device is configured to determine whether a maximum value of an AC operation voltage of the plurality of power generation devices is out of a set range. While keeping the output active power constant,
The operating power factor is adjusted.Next, even if the operating power factor is adjusted within a predetermined range, if the maximum values of the AC operating voltages of the plurality of generators are out of the set range, the output active power is reduced. A power generation system that controls so that the maximum value of the AC operation voltage of a plurality of power generation devices is limited to fall within a set range. 6. The power generation system according to claim 5, wherein the central device is configured such that a change ratio of an operating power factor and a limit ratio of an output active power are the same in a plurality of power generation devices. Power generation system to control. 7. The power generation system according to claim 5, wherein the central device includes a maximum value detection unit, a determination unit, and a remote control signal calculation unit, The detection unit is a unit that detects a maximum one of the AC operating voltages of the power generation device within the monitoring range, and the determination unit is a unit that determines whether the detected maximum value is within a set range. A power generation system that calculates a remote control signal for each of the power generation devices when the detected maximum value is higher than a set value; 8. The power generation system according to claim 5, wherein the central device further includes a stop signal generator, wherein the stop signal generator includes a driving power factor, and A power generation system that generates a signal to stop a specific power generation device when the maximum value deviates from a set range of the AC operating voltage despite adjustment of output active power. 9. The power generation system according to claim 8, wherein the stop signal generation unit generates a stop signal for sequentially stopping power generation devices having higher interconnection point voltages. 10. A power generation device including a power conversion device and a control unit, which is installed in a power consumer and connected to a power distribution system, wherein the power conversion device supplies the generated power of a power generation source to the power distribution system. The control unit has a function of controlling the power conversion device and a communication function of communicating with the outside, converting the power into power operable to be connected to a grid and supplying the power to the power distribution system, and the communication function. The power generation device includes a function of transmitting information of an operation voltage to the outside and receiving a signal supplied from the outside, and the output active power and the operation power factor can be adjusted by the signal supplied from the outside. 11. The power generation device according to claim 10, wherein the control unit is capable of performing self-power control for controlling the power conversion device based on information on an operating voltage detected by the control unit. The power generation device, further comprising a switching unit, wherein the switching unit switches between the self-control and the remote control. 12. The power generator according to claim 11, wherein the control unit includes a communication monitoring unit, and the communication monitoring unit includes:
The communication operation is monitored, and when it is determined that the communication operation is normal, the switching unit is switched to the remote control side, and when it is determined that the communication operation is abnormal, the switching unit is switched. A power generator that switches to the self-control side. 13. A central device for remotely controlling a plurality of power generation devices, wherein each of the power generation devices is installed in a power consumer, and includes a power conversion device and a control unit, and The power converter is distributed and connected to the power distribution system, the power converter converts the generated power of the power generation source into power operable to be connected to the power distribution system and supplies the power to the power distribution system, and the control unit includes: Has a function of controlling the power conversion device, and a communication function of communicating with the outside, the communication function transmits information of the operating voltage output from the power generation device to the outside, and The central device monitors the information of the operating voltage transmitted from the control unit, and each of the power generation devices based on the information of the operating voltage. Calculate the remote control signal corresponding to each The computed the remote control signal given to each of the power generation device, a central device for remotely controlling the operation. 14. The central unit according to claim 13, wherein the output active power is kept constant when the maximum value of the AC operating voltages of the plurality of generators is out of the set range.
The operating power factor is adjusted.Next, even if the operating power factor is adjusted within a predetermined range, if the maximum values of the AC operating voltages of the plurality of generators are out of the set range, the output active power is reduced. A central device that controls so that the maximum value of the AC operating voltage of a plurality of power generating devices is limited to fall within a set range. 15. The central device according to claim 14, wherein the changing ratio of the operating power factor and the limiting ratio of the output active power are controlled to be the same in a plurality of power generating devices. 16. The central device according to claim 1, further comprising a maximum value detection unit, a determination unit, and a remote control signal calculation unit, wherein the maximum value detection unit monitors Among the AC operating voltages of the power generating device within the range, the maximum value is detected, the determination unit determines whether the detected maximum value is within a set range, and the remote control signal calculation unit performs the detection. A central unit that calculates a remote control signal for each of the power plants when the maximum value obtained is higher than a set value. 17. The central device according to claim 16, further comprising a stop signal generator, wherein the stop signal generator comprises:
Despite adjustment of operating power factor and output active power,
A central unit that generates a signal to stop a specific power generation device when the maximum value is out of the set range; 18. The central device according to claim 17, wherein the stop signal generation unit generates a stop signal for sequentially stopping the power generation devices having higher interconnection point voltages. 19. A power distribution system including at least one power distribution system and a power generation system, wherein the power generation system is any one of claims 1 to 9 and is connected to the power distribution system. Power distribution system.