JP5468883B2 - Micro grid system - Google Patents

Description

  The present invention relates to a microgrid system, and more particularly to a microgrid system capable of improving power quality at a grid connection point.

In general, in a power generation system using a natural power supply device, for example, a solar power generation system, a power generation amount that fluctuates depending on weather conditions is output as it is to a connected power system. When the scale increases, there is a problem that the generated frequency fluctuates greatly or the generated voltage fluctuates greatly as the generated power fluctuates.
Therefore, conventionally, the tidal current target value at the grid connection point is determined by predicting the photovoltaic power generation output in advance, and then combined operation with other power generation systems is performed to compensate for the fluctuation in power generation amount. A system stabilizing device that stabilizes the entire power system connected to the photovoltaic power generation system is used.

  As this system stabilization device, for example, in Patent Document 1, when the tidal current target value at the grid connection point is determined in advance, it is determined based on the predicted power generation value of photovoltaic power generation that is determined in advance based on weather prediction information. Has been. Further, for example, in Patent Document 2, a target current value at a grid interconnection point is determined by predicting an error between the predetermined power generation predicted value of solar power generation and actual solar power generation power.

JP 2004-312797 A JP 2008-54385 A

  In the conventional system stabilizing device disclosed in Patent Document 1 or Patent Document 2, it is predetermined based on data correlated with weather forecast information such as season, weather, wind speed, wind direction, temperature, and terrain data. Since the tidal current target value at the grid connection point is determined based on the predicted power generation value of photovoltaic power generation, a natural energy prediction device that always has weather prediction information is required, making the device complicated and expensive. There was a problem.

  In areas where there is no weather forecast information such as remote islands where demand for microgrid (small power grid) systems is expected, it was necessary to collect weather forecast information in advance. Furthermore, in a system that performs self-sufficiency of energy within the area of the microgrid system using information that is uncontrollable due to natural events, such as weather forecast information, the power of the entire system is affected by fluctuations in the power generation of the photovoltaic power generation system There has been a problem that the quality (frequency change allowable value, voltage fluctuation allowable value, etc.) cannot be satisfied.

  The present invention has been made to solve the above-mentioned problem, and without using weather prediction information when determining a tidal current target value at a grid interconnection point based on a power generation prediction value of a naturally varying power supply device. In addition to improving the power quality at the grid connection point, a simple and inexpensive microgrid system is provided.

The microgrid system according to the present invention includes a natural variation power supply device having a power conditioner that converts direct current power into alternating current power, a secondary battery power source having a control mode automatic transition function in the interconnection operation mode and the independent operation mode, A microgrid system that supplies power to a load, the system stabilizing device including a natural fluctuation power supply device and a system stabilizing device that monitors and controls an operating state of the secondary battery power supply, A first means for calculating a tidal current target value at a connection point before a set time during the mode, and calculating an output of the natural variation power supply device and a prediction of a change in the load by comparing with a past value. When the output of the natural variability power unit, and the prediction of changes in the load, a second means for calculating a current value continues, the first means and the second And a switching means for switching between stages, the calculation of the power flow target value, by the switching means, the first means, and executes the one of said second means.

  A grid stabilization device for a microgrid system according to the present invention calculates a target power value at a connection point before a set time in a grid connection operation mode, and the calculation is performed by an output of a naturally varying power supply device. , And the load change is predicted by comparing with the past value, so when determining the tidal current target value at the grid connection point, it is determined without using the weather forecast information, and at the grid connection point, In addition to improving power quality, a simple and inexpensive microgrid system can be provided.

1 is a configuration diagram of a microgrid system according to Embodiment 1 of the present invention. FIG. It is a figure which shows the internal structure of the system | strain stabilization apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the formulation method of the target tidal current value which concerns on the grid connection point in the grid stabilization apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows the internal structure of the system | strain stabilization apparatus which concerns on Embodiment 2 of this invention.

  Preferred embodiments of a microgrid system according to the present invention will be described below with reference to the accompanying drawings. It should be noted that the present invention is not limited to this embodiment, and includes various design changes.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a microgrid system according to the first embodiment. In FIG. 1, a microgrid system 1 mainly includes a photovoltaic power generation panel 2, a photovoltaic power conditioner 3, a secondary battery device (hereinafter referred to as a storage battery power supply) 4, a storage battery power bidirectional inverter 5, a heat engine. The power generator is composed of a diesel power generator 6 and a system stabilizing device 7. The circuit breaker 8 is connected to the system to supply power to the load 9. The storage battery power supply 4 has a control mode automatic transition function of the interconnection operation mode and the independent operation mode. The diesel power generator 6 is stopped during the interconnected operation, and is operated when the power supplied during the independent operation is insufficient. The photovoltaic power generation device 10 is configured by the photovoltaic power generation panel 2 and the photovoltaic power conditioner 3. Reference numerals 11 to 14 in FIG. 1 denote circuit breakers, respectively.

  The photovoltaic power conditioner 3 converts the DC power output from the photovoltaic panel 2 into AC power, and the storage battery power bidirectional inverter 5 converts the DC power from the storage battery power 4 into AC power. To convert. The photovoltaic power conditioner 3 and the storage battery power bidirectional inverter 5 are each monitored and controlled by the optical loop network 15 from the system stabilizing device 7.

  The system stabilizing device 7 communicates with the photovoltaic power conditioner 3, the storage battery power bidirectional inverter 5, and the diesel power generating device 6 through the optical loop network 15, and has a system stabilizing function as described later. It is.

FIG. 2 is a diagram showing an internal configuration of the system stabilizing device 7. As shown in FIG. 2, the grid stabilization device 7 determines the output of the photovoltaic power generation panel 2 and the remaining amount of the storage battery power supply 4 in the grid stabilization function (tidal distribution notification control), that is, in the grid interconnection operation mode. In consideration of this, it has a function of developing a target tidal current value at a connection point before a set time (t minutes). In addition, the grid stabilization device 7 includes grid interconnection operation switching control, startup / stop control of the photovoltaic power generation panel 2, output suppression control of the photovoltaic power generation panel 2, startup / stop control of the diesel power generation device 6, and startup of the storage battery power source 4. It also has stop control and other control functions.

  The microgrid system 1 according to the first embodiment is configured as described above. Next, a method for formulating a target power flow value at a grid interconnection point in the grid stabilization device 7 will be described.

  FIG. 3 is a diagram for explaining a method of formulating a target power flow value at the grid connection point (breaker 8 in FIG. 1). In the grid stabilization device 7 of FIG. 1, a set time (for example, a variable time of 0 to 30 minutes) in consideration of the output of the power conditioner 3 for photovoltaic power generation and the remaining amount of the storage battery power supply 4 in the grid connection operation mode. ) Notify the target power flow value to the electric power company before, and implement the control to maintain the notification value for 30 minutes after the notification.

  The data used for formulating the target power flow value at the grid connection point is the remaining amount (SOC) of the storage battery power supply 4 and the output of the power conditioner 3 for photovoltaic power generation 3 every 30 minutes from the present for the past week. The integrated value (ΣtPpv) and the 30-minute integrated value (ΣtPld) of the load 9 every 30 minutes from the present time for the past one week. Hereinafter, “integrated value” means “30 minutes integrated value”. The “past week” or “every 30 minutes” is an example, and the present invention is not limited to this.

First, a method for selecting an output pattern of a similar photovoltaic power conditioner 3 will be described.
As shown in FIG. 3, the comparison with the past integrated value is performed when the deviation between the 30-minute integrated value ΣtPpva at the current point and the past integrated value ΣtPpv− is within the allowable value α.
| ΣtPpva−ΣtPpv− | ≦ α (1)
However, α is 10% of ΣtPpv−.

  Here, collation with the integrated value for 30 minutes at the same time on the previous day is performed. If this integrated value does not satisfy the expression (1), the integrated value at the same time in the past one week is collated and an integrated value in a similar power generation state is selected. If there is no match in the data for the past one week, the integrated value ΣtPpva at the current point is selected. If there is a past integrated value that can be selected, it is set as ΣtPpv−.

Next, a method of selecting a similar load 9 pattern will be described.
Similarly, referring to FIG. 3, the comparison with the past integrated value is performed when the deviation between the 30-minute integrated value ΣtPlda at the current point and the past integrated value ΣtPld− is within the allowable value β.
| ΣtPlda−ΣtPld− | ≦ β (2)
However, β is 10% of ΣtPld−.

  Here, collation with the integrated value for 30 minutes at the same time on the previous day is performed. If this integrated value does not satisfy the expression (2), the integrated value of the similar load pattern is selected by comparing with the integrated value at the same time in the past week. If there is no match in the data for the past week, the integrated value ΣtPlda at the current point is selected. If there is a past integrated value that can be selected, it is set as ΣtPld−.

From the above, how to obtain the predicted value power will be described.
The integrated value for the next 30 minutes of the selected past integrated value “ΣtPpv−, ΣtPld−” is set to “ΣtPpv0, ΣtPld0”, and the integrated value for 30 minutes to 60 minutes is set to “ΣtPpv1, ΣtPld1” for 30 minutes, 1 hour. The predicted value is obtained as a proportional value from the past value as follows.

In the output of the power conditioner 3 for photovoltaic power generation, the predicted power integration value (power amount) ΣEtPpv0 after the current time to t minutes in FIG. 3 is ΣtPpva as seen from the current integration value for the next 30 minutes is ΣtPpv0. Is proportional to the ratio of ΣtPpv−, and the time ratio is t / 30 until t minutes later.
ΣEtPpv0 =
ΣtPpv0 × (ΣtPpva / ΣtPpv−) × t / 30 (3)

Similarly, the predicted power integrated value (power amount) ΣEPpv1 after t minutes (control start at this notification value) to (t + 30 minutes) is
ΣEPpv1 =
(ΣtPpv0 × (30−t) / 30 + ΣtPpv1 × t / 30) ×
(ΣtPpva / ΣtPpv−) (4)
It is calculated as follows.

Based on the same idea, the predicted power integrated value (power amount) ΣEtPld0 after the current to t minutes in the load 9 is
ΣEtPld0 =
ΣtPld0 × (ΣtPlda / ΣtPld−) × t / 30 (5), and the predicted power integrated value (power amount) ΣEPld1 after t minutes (control start at the current notification value) to (t + 30 minutes)
ΣEPld1 =
(ΣtPld0 × (30−t) / 30 + ΣtPld1 × t / 30) ×
(ΣtPlda / ΣtPld−) (6)
It is calculated as follows.

  As described above, in the system stabilizing device 7 of the microgrid system 1 according to the first embodiment, the past value is used without using the weather prediction information, and the integrated output amount and load of the photovoltaic power conditioner 3 are used. The integrated amount of 9 can be obtained, and the target power flow value at the grid connection point can be established. Therefore, it is possible to improve the power quality at the grid connection point and provide a simple and inexpensive microgrid system.

Embodiment 2. FIG.
Next, a microgrid system according to Embodiment 2 will be described. In Embodiment 1, although the system stabilization apparatus 7 demonstrated the method of implementing the output of a photovoltaic power conditioner, and prediction of a load change by collation with a past value, Embodiment 2 is The output of the power conditioner for photovoltaic power generation and the prediction of the load change are carried out assuming that the current value continues.

  FIG. 4 is a diagram illustrating an internal configuration of the system stabilizing device according to the second embodiment. As shown in FIG. 4, the system stabilization device 7 according to the second embodiment continues to output changes of the power conditioner for photovoltaic power generation and the load as a system stabilization function (tidal distribution notification value control). As a result, it has a function to formulate the target tidal current value of the connection point. Other configurations are the same as those in the first embodiment.

In the system stabilizing device 7 according to Embodiment 2, the predicted power integrated value (power amount) ΣEtPpv0 after the current to t minutes in the output of the power conditioner 3 for photovoltaic power generation is
ΣEtPpv0 = ΣtPpva × t / 30 (7)

Similarly, the predicted power integrated value (power amount) ΣEPpv1 after t minutes (control start at this notification value) to (t + 30 minutes) is
ΣEPpv1 = ΣtPpva (8)
It is calculated as follows.

Based on the same idea, the predicted power integrated value (power amount) after t minutes from the present time in the load 9 is
ΣEtPld0 = ΣtPlda × t / 30 (9)
The predicted power integrated value (power amount) ΣEPld1 after t minutes (control start at this notification value) to (t + 30 minutes) is
ΣEPld1 = ΣtPlda (10)
It is calculated as follows.

  As described above, in the grid stabilization device 7 of the microgrid system 1 according to the second embodiment, when the output of the photovoltaic power conditioner 3 and the load 9 are not matched in past data. In addition, it is possible to formulate the target tidal current value at the connection point. Therefore, as in the first embodiment, it is possible to improve the power quality at the grid connection point and provide a simple and inexpensive microgrid system.

  As described above, the microgrid system 1 according to the first embodiment or the second embodiment has been illustrated and described. However, the system stabilization apparatus having the function according to the first embodiment and the function according to the second embodiment in the microgrid system 1. 7 and means for switching between the two may be used to formulate the target flow value at the interconnection point by the method described above. In this case, the system stabilizing device 7 having both the function according to the first embodiment and the function according to the second embodiment, and the means for switching both may be configured integrally or separately. .

DESCRIPTION OF SYMBOLS 1 Microgrid 2 Solar power generation panel 3 Photovoltaic power conditioner 4 Storage battery power supply 5 Bidirectional inverter 6 for storage battery power supply Diesel power generation apparatus 7 System stabilization apparatus 8, 11-14 Breaker 9 Load 10 Solar power generation apparatus 15 Light Loop network

Claims (2)

Naturally-variable power supply device having a power conditioner that converts DC power into AC power, a secondary battery power supply having a control mode automatic transition function in the interconnection operation mode and the independent operation mode, the natural-variable power supply device, and the secondary battery A grid stabilization device that monitors and controls the operating state of a power supply, and supplies power to a load,
The grid stabilization device calculates a power flow target value at a grid connection point before a set time during the grid grid operation mode , and predicts the output of the natural variation power supply device and the load change. A first means for calculating by collating with past values; a second means for calculating the output of the natural variation power supply device and a prediction of the change of the load as a current value continues; the first means and the first A microgrid system characterized in that the tidal current target value is calculated by the first means and the second means by the switching means . The past value of the output of the natural variation power supply apparatus is an integrated value of the output of the natural variation power supply apparatus for every predetermined time from the present time point for the past predetermined period, and the past value of the load is the past predetermined period. The microgrid system according to claim 1, wherein the load is an integrated value of the load every predetermined time from the current time point of minutes .

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