JP3892547B2 - Grid-connected distributed power system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grid-connected distributed power supply system in which a plurality of distributed power supply apparatuses are connected to an electric power system to perform a linked operation.
[0002]
[Prior art]
A system is adopted in which a distributed power supply device is connected to an electric power system to perform interconnection operation and supply electric power to a consumer load. FIG. 4 shows a distribution line system of a power system to which a distributed power supply device is connected. The distribution line 1 constitutes a part of the power system 2, and the customer loads 3 a to 3 c and the distributed power supply device 4 are connected to the distribution line 1 in parallel.
[0003]
As the distributed power supply device 4, a solar battery, a wind power generator, a storage battery, a flywheel power storage device, or the like is used, and direct current power generated by the distributed power supply device 4 is 50 Hz or 60 Hz by a power conversion device (inverter). It converts into AC power and supplies power to the commercial distribution line 1. When the distributed power supply device 4 is a storage battery or a flywheel power storage device, the power from the distribution line 1 is converted into direct current by a power conversion device (converter) and stored.
[0004]
The single capacity of these distributed power supply devices 4 is generally about several kW to several MW, and is smaller than the distribution capacity of the power system 2. In the future, the number of installations of the distributed power supply 4 will increase, and the total output power capacity of the distributed power supply 4 will occupy, for example, several tens of percent or more of the capacity of the pole transformer of the distribution line 1 It is also expected to be.
[0005]
When such a small-scale distributed power supply device 4 is operated in conjunction with a plurality of distribution lines, each distributed power supply 4 does not hinder the power quality and protective safety measures of the distribution line system. It is important to generate power in such a way.
[0006]
In addition, since each of these distributed power supply devices 4 is a system in which each power source generates power, daily inspection is performed to prevent failure and increase the operating rate. Therefore, it is necessary to prevent an abnormal output such as that which is harmful to the power system 2. At the same time, on the distribution line system side, it is necessary to grasp the output power capacity generated by these distributed power supply devices 4 as a whole and reflect it in the power generation amount of existing power generation systems such as thermal power plants and hydroelectric power plants. .
[0007]
In addition, the distributed power supply 4 has an adverse effect on a control operation that temporarily stops power distribution due to a failure on the power system side, identifies an accident location, isolates the accident location, and restarts power transmission. It is necessary not to.
[0008]
When the number of distributed power supply devices 4 connected to the system increases, the operating status of the distributed power supply device 4 as a whole is grasped. Also, in the unlikely event that an accident occurs in the distribution line system and power transmission is stopped, It is necessary for all the distributed power supply devices 4 to take a means for stopping the power generation operation and disconnecting the electric circuit from the distribution line system.
[0009]
[Problems to be solved by the invention]
However, in order to reliably disconnect all of the multiple distributed power supply devices 4, a signal for disconnecting from the distribution line system must be distributed to all the distributed power supply devices 4. . That is, it is necessary to install a dedicated signal cable for all the distributed power supply devices 4 and provide a receiving device on the distributed power supply device 4 side. Accordingly, the equipment cost is increased and the economic efficiency of the distributed power supply device 4 is lowered. Further, when the number of installed distributed power supply devices 4 increases, it becomes difficult to perform appropriate inspection and repair of all the distributed power supply devices 4.
[0010]
An object of the present invention is to provide a grid-connected distributed power supply system that can easily detect an abnormality in a distributed power supply apparatus that is connected to a power distribution system.
[0011]
[Means for Solving the Problems]
A grid-connected distributed power supply system according to the invention of claim 1 is connected to a distribution line of an electric power system, and direct-current power generated by the distributed power source based on the amount of electricity at the connection point with the distribution line is converted into AC by a power converter. A plurality of units that convert the power into the power or convert the AC power of the distribution line into DC power and send an operation state signal to the communication line to stop the power converter when an abnormality or a disconnection command is received . Based on data sent from a distributed power supply and a distributed power supply that has received an operation state signal from the distributed power supply via a communication line and stopped during normal operation or a distributed power supply that has indicated an abnormal condition solution and manufacturer service computer determines fault location with determining the stop cause or abnormality cause, relative to the dispersed type power supply if the distribution line system management necessary for Te Characterized in that a each of the distributed power supply distribution line management computer that the power generation output power received from the communication line to monitor the power generation amount of the entire distributed power device outputs the command.
[0012]
The grid-connected distributed power supply system according to the invention of claim 2 is the system according to claim 1, wherein, when the distributed power supply device is connected to the diesel generator, the diesel generator is started. During the predetermined period of time, the operation control means changes the abnormality determination value of the voltage and frequency at the connection point with the distribution line to an abnormality determination value whose detection sensitivity is lower than the normal value, and continues the operation. It is characterized by doing so .
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a grid-connected distributed power supply system according to an embodiment of the present invention.
[0026]
In FIG. 1, each distributed power supply device 4 is connected to a distribution line 1 of a power system 2 via a branch distribution line 5. On the other hand, each distributed power supply 4 is connected to a communication line 9 via each branch communication line 10, and a manufacturer-side service computer 7 and a distribution line management computer 8 are connected to the communication line 9. Has been. The manufacturer-side service computer 7 determines an abnormality of the distributed power supply device 4 based on an operation state signal obtained from the distributed power supply device 4 through the communication line 9, and the distribution line management computer 8 outputs a disconnection command to the distributed power supply device 4 when necessary for the management of the distribution line system. Here, a public telephone line using the Internet is used as the communication line 9.
[0027]
In addition, the distributed power supply device 4 includes a distributed power supply 11 for supplying power to the distribution line 1 and accumulating power from the distribution line 1. The distributed power source 11 is composed of a solar cell, a wind power generator, a storage battery, a flywheel power storage device, and the like, and normally stores DC power.
[0028]
Therefore, the DC power of the distributed power source 11 is converted into AC power by the power conversion device 12 and supplied to the distribution line 1, and when the distributed power source 11 is a storage battery, a flywheel power storage device or the like, power conversion is performed. The apparatus 12 converts the AC power of the distribution line 1 into DC power and stores it.
[0029]
The power converter 12 is controlled by the operation control means 13. That is, the operation control means 13 performs gate control of the power conversion device 12 based on the amount of electricity at the connection point with the distribution line 1 detected by the amount-of-electricity detector 14, and controls the amount of power to be accommodated and frequency conversion. I do. Then, an operation state signal indicating the operation state is transmitted to the communication line 9 via the communication interface 6. The communication interface 6 receives a disconnection command from the distribution line management computer 8 and various commands from the manufacturer-side service computer 7 via the communication line 9.
[0030]
The operation control means 13 stops the power conversion device 12 when the distributed power supply device 4 becomes abnormal or receives a disconnection command from the distribution line management computer 8, and from the manufacturer service computer, Based on various commands, calculations are performed according to the commands.
[0031]
Next, the operation state signal sent from the communication interface 6 of the distributed power supply 4 to the communication line 9 is sent with an identification signal unique to each distributed power supply. Here, the operation state signal includes the operation / stop state of the distributed power supply 4, the operation output power, the voltage at the connection point, the harmonic distortion factor at the connection point, the breakdown of the cause when the operation is stopped, and the like. The on / off state of each part switch inside the power supply device 4 and the presence / absence of generation of a gate pulse in the power converter 12 are also included.
[0032]
When the distributed power supply device 4 is connected to the distribution line 1 and operated, the power conversion device 12 of the distributed power supply device 4 causes the operation control means 13 to distribute the distribution line 1 by harmonics and reverse power flowing out to the distribution line 1 side. The AC output is adjusted so as not to affect the distribution line 1. Then, when an operation value exceeding a preset harmonic distortion factor or output voltage is measured, the power converter 12 is automatically stopped.
[0033]
When the distributed power supply device 4 is connected to the distribution line 1, the voltage or frequency at the connection point is detected by the electric quantity detector 14 of the distributed power supply device 4, and if an abnormal value is measured, the distributed power supply device 4 is dispersed. The mold power supply 4 is stopped. Here, there is sometimes no abnormality on the distributed power supply device 4 side. For example, the distribution line voltage becomes high due to some cause, or the harmonic distortion of the distribution line 1 increases, and the power of the distributed power supply device 4 is influenced by the influence. The harmonic current distortion contained in the output current of the converter 12 may increase. In such a case, even if the distributed power supply 4 stops, if it appears as if the distributed power supply 4 has stopped due to a failure on the distributed power supply 4 side, the distributed power supply by a supplier who performs maintenance and inspection of the distributed power supply 4 A business trip and inspection to the installation site of the apparatus 4 are required.
[0034]
Therefore, when the distributed power supply 4 stops, the communication interface 6 automatically transmits the voltage of the distribution line 1 to which the distributed power supply 4 is connected and the harmonic voltage or voltage waveform data of the distribution line voltage to the communication line 9. To send. The information is received by the manufacturer-side service computer 7, and the manufacturer-side service computer 7 operates by an operator to store information on the data sent from the distributed power supply 4 and the storage in the manufacturer-side service computer 7. Refer to the model, rating, and operation data related to the distributed power supply device 4 registered in advance in the device, and select multiple possible causes of stoppage from past stop cases, other similar model stop cases, supplementary items, etc. ,Identify.
[0035]
Next, it is confirmed whether any of the plurality of candidate factors is the first factor. In other words, the operator who operates the manufacturer-side service computer 7 is set to which value the setting value that determines that the distributed power supply device 4 is stopped due to voltage abnormality or harmonic abnormality of the corresponding distributed power supply device 4 is set. The distributed power supply 4 is instructed to the distributed power supply 4 via the communication line 9 so that information such as whether the waveform is not abnormal or the peripheral switches are normally turned on is transmitted from the distributed power supply 4 side. to recover. The operator examines and judges this data, so that the stop is temporary due to an electrical environment outside the distributed power supply 4 or is sustained due to an internal failure of the distributed power supply 4. To determine whether
[0036]
Next, when it is found that the distributed power supply 4 is out of order, the operator of the manufacturer-side service computer 7 can execute either the main circuit portion inside the distributed power supply device 4 or the operation control means 13. In order to check which part of which control board is malfunctioning at any part, information on the storage device that records the control event placed in the control board is sent via the communication line 9 to the manufacturer side service computer. Recover to 7. Examine this information and identify the fault location as much as possible. The service personnel on the manufacturer side prepares a repair / replacement part that has been clarified by this specific work, and after having obtained the retrieved information, makes a business trip to the site to repair the relevant part. In addition, when it is confirmed that the replacement part can be easily replaced even by the user who installed the distributed power supply device 4, the repair can be performed only by transporting the corresponding part to the user.
[0037]
As described above, when each of the distributed power supply devices 4 breaks down in a state where a large number of distributed power supply devices 4 are connected to the power system 2, before the manufacturer's service personnel make a business trip to investigate the cause of the failure. It is possible to identify the cause of failure or stoppage due to external factors to the extent possible, and to consider and prepare for possible countermeasures before taking action, so it is possible to reduce the waiting time for quick service response and resumption of operation Become.
[0038]
Here, the method in which the operator operates the manufacturer-side service computer 7 and collects necessary data has been described. However, before the operator operates and makes a determination, the same distributed power supply 4 can be used by a program inside the computer. It is also possible to automatically search for unique data, identify the cause of the cause of the stoppage of operation, perform recovery processing considered necessary, and determine replacement parts.
[0039]
Then, by sending measurement data of the operation output power of the distributed power supply 4 via the communication line 9 to the distribution line management computer 8, the power generation output of the entire distributed power supply 4 and its overall tendency are known every moment. Can do.
[0040]
Also, when there is a planned power outage on the distribution line 1 side, the information is sent from the distribution line management computer 8 to the communication interface 6 of the distributed power supply device 4 via the communication line 9 and distributed. A message is transmitted to the user of the power supply device 4 or, if necessary, the distributed power supply device 4 can be forced to operate independently during a power failure.
[0041]
Furthermore, in the unlikely event that there is an abnormality in the distribution line, when power transmission to the distribution line 1 is stopped, all the distributed power supply devices 4 are disconnected from the distribution line system via the communication line 9 and the operation is stopped. It is also possible to give an instruction not to send power to the distribution line 1. However, when such a rapid response is required, a public telephone line using the Internet that passes information one after another takes too much time and is dangerous.
[0042]
Therefore, in order to send a signal that requires a quick response, such as a disconnection command, the signal is sent at high speed using, for example, signal transmission using a power distribution line. On the other hand, there is no particular problem in exchanging data during normal driving and data used for studying the situation after the stop, so there is no problem even if it takes several seconds or more, so a public telephone line using the Internet should be used. Is possible.
[0043]
For example, the communication line 9 is not a public line for communication business, but a line for cable television or an optical cable installed for automation of distribution line control. When the communication line 9 is an optical cable, an optical-analog conversion device is installed on a utility pole stretched as an overhead line, and the analog electric signal line is branched to individual distributed power supply devices 4.
[0044]
In addition, when the customer installs the distributed power supply device 4 in order to cover his load, the distributed power supply device 4 is a small distributed power supply device 4. In other words, the distributed power unit 4 is not installed in a power supply company's substation, but in a medium or large power supply of several tens of kW or more, and is installed in a medium or individual house of several tens of kW installed in a factory or building. This is a small distributed power supply device 4 of several kW.
[0045]
Since these distributed power supply devices 4 are installed in individual consumers, it is rare to use a dedicated communication line 9 like the distributed power supply device 4 installed in an electric power company. In general, a communication line 9 or a public telephone line that is widely used is used.
[0046]
FIG. 2 is a flowchart showing the calculation processing contents of the operation control means 13 of the distributed power supply device 4. In FIG. 2, the operation control means 13 of the distributed power supply device 4 determines whether or not a disconnection command is input from the outside via the communication line 9 (S1), and when the disconnection command is not input Executes the driving situation communication program (S2). That is, the output power value of the distributed power supply device 4 is measured by executing the operation status communication program, and the output power value is sent to the communication line 9. On the other hand, when a disconnection command is input via the communication line 9, an interrupt processing program is executed (S3), the power converter 12 in the distributed power supply 4 is stopped, and the connection point is disconnected. I do.
[0047]
Then, when the disconnection is completed, the operation control means 13 of the distributed power supply device 4 starts an operation status communication program and sends a disconnection completion signal to the communication line 9. Thereafter, it is determined whether or not a long-term stop operation is to be performed in a periodic inspection or the like (S4).
[0048]
FIG. 3 is a flowchart showing the calculation contents of the operation status communication program part in step S2 of FIG. In FIG. 3, always-on operation data such as power generation output power and charging power consumption of the distributed power supply 4 is collected and transmitted to the communication line 9 (S11). Further, in a system in which a daily inspection by an operator is hardly performed in a solar power generation system or the like, an operation set value and a protection set value in the power conversion device 12 at the time of sunrise or a fixed time before the start of daily operation. Then, the status of other control devices is checked, and then the operation program is started (S12). In addition, after the operation program of the distributed power supply device 4 is normally started, necessary data such as the amount of generated power of the previous day and the occurrence of the stop are automatically transmitted via the communication line (S13).
[0049]
Here, if a system abnormality is detected during system confirmation before starting operation or during processing of the operation program (S14), further activation is prohibited and the interconnection switch etc. is automatically turned on. An interlock is taken so as not to occur, and a signal notifying the occurrence of an abnormality and an abnormal condition such as the location is transmitted to the communication line 9 (S15). On the other hand, when it is determined that the system is normal, the operation is started or the operation is continued (S16).
[0050]
Next, there is a case where a rotating machine power source such as a diesel generator is installed in the same premises where the distributed power supply device 4 is installed, and the distributed power supply device 4 and the diesel generator are used in parallel. is there. Diesel generators are used to secure emergency power in the power station in the event of a power failure.
[0051]
In this case, the distribution line in the station is disconnected at the power receiving point from the power system, and the diesel generator is started. That is, when the rotary engine of the diesel generator is started and started to operate, the frequency is not constant during the period until the rotational speed reaches a steady value. Further, when an emergency load is selectively input, the load on the diesel generator varies, so the voltage and frequency of the generator output vary.
[0052]
Since the degree of this fluctuation is greater than when the power system is connected to the on-site distribution line system, it depends on the protective set value of the voltage and frequency of the distributed power supply device 4 and the protective operation is activated to operate the distributed power supply device. 4 may be stopped and disconnected. When the distributed power supply device 4 is disconnected, the load on the diesel generator increases more and more, so the rotation speed of the diesel generator may decrease, and the diesel generator may stop due to a decrease in frequency.
[0053]
Therefore, when the on-site power supply is disconnected from the distribution line system and the diesel generator starts operation, the operation start signal is obtained from the contact signal of the breaker at the connection point in the station and the start signal of the diesel generator. When this signal is received, the voltage and frequency protection settling values of the distributed power supply device 4 are set to values which are less than normal values for a predetermined period, and the distributed power supply device 4 is stopped and turned off. Make it difficult to line up.
[0054]
In this case, in addition to the disconnection signal (contact signal) at the receiving point and the start signal of the diesel generator, a signal notifying the power outage is transmitted from the distribution line system, and this is received to start the power outage and the diesel generator It is also possible to use this for the determination.
[0055]
【The invention's effect】
As described above, according to the present invention, in a grid-connected distributed power supply system that uses a large number of distributed power supply devices connected to the distribution lines of the power system, the operating status and failures of the individual distributed power supply devices. It is possible to collect data such as the situation or cause of stoppage via the communication line, and to send a signal for disconnecting all the distributed power supply units from the distribution line due to a failure on the distribution line side etc. .
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a grid-connected distributed power supply system according to an embodiment of the present invention.
FIG. 2 is a flowchart showing calculation processing contents of an operation control unit of the distributed power supply device according to the embodiment of the present invention.
FIG. 3 is a flowchart showing the calculation processing contents of step S2 shown in FIG. 2;
FIG. 4 is an explanatory diagram of a distribution line system of a power system to which a distributed power supply device according to a conventional example is connected.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Distribution line 2 Power system 3 Consumer load 4 Distributed power supply 5 Branch distribution line 6 Communication interface 7 Manufacturer side service computer 8 Distribution line management computer 9 Communication line 10 Branch communication line 11 Distributed power supply 12 Power conversion device 13 Operation control means 14 Electric quantity detector

Claims (2)

DC power generated by a distributed power source based on the amount of electricity connected to the distribution line of the power system is converted to AC power by a power converter, or the AC power of the distribution line is converted to DC power. And a plurality of distributed power supply devices that stop the power conversion device when an abnormal state or a disconnection command is received by sending an operation state signal to the communication line and operating state from the distributed power supply device Based on data sent from a distributed power supply that has received a signal via a communication line and stopped during normal operation or from a distributed power supply that has indicated an abnormal condition, the cause of the stop or the abnormality is determined and the failure location is determined. power of each of the dispersed type power supply apparatus and outputs the manufacturer service computer, the disconnecting command to the distributed power supply device when management required of the distribution line system System interconnection distributed power supply system, characterized in that a distribution line management computer for receiving a force power from the communication line to monitor the power generation amount of the entire distributed power system.   In the case where the distributed power supply device performs the interconnection operation with the diesel generator, the operation control means is configured to set the interconnection point with the distribution line for a predetermined period after the diesel generator is activated. 2. The grid-connected distributed power supply system according to claim 1, wherein the operation is continued by changing the abnormality determination value of the voltage and frequency to an abnormality determination value in which the detection sensitivity is lower than the normal value.

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