KR20190046147A - Adopting Method of Communication Policy for Smart Grid and Server using the same - Google Patents

Abstract

According to the present invention, an adopting method of a communication scheme for a smart grid comprises the steps of: setting a test schedule for a communication channel established between a data source and a data sink constituting a smart grid; performing a plurality of test communications with the data source and the data sink in each of a polling method, a push method, and a publish/subscribe method according to the test schedule; calculating at least two metrics among a metric for time efficiency, a metric for source efficiency, and a metric for communication efficiency in a result of the performing of the plurality of test communications; and adopting a communication scheme to be performed by the data source and the data sink from the calculated metrics.

Description

[0001] The present invention relates to a method of adopting a communication method for a smart grid and a communication policy server using the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of adopting a communication scheme for a smart grid (or Power Grid) and a communication policy server, and more particularly, to a smart grid And a method for optimally determining a communication method between data sinks.

Smart grid technology that combines IT technology with existing power grid is emerging to construct smart power grid through efficient power management of power facilities, industrial facilities and private facilities.

The smart grid environment consists of a hybrid network in which a variety of devices are mixed and a combination of wired and wireless. For example, the smart grid communication network construction method uses a broadband wireless communication (Wimax) as a main network and a high-speed power line communication (PLC) as a subscriber network, Management, electric vehicles, monitoring of solar facilities, etc.).

As such, in a smart grid environment, a smart grid device (for example, a smart meter, a smart outlet, etc.) requiring control at a power facility and a general device (for example, a home appliance, a smart appliance, a personal portable terminal, etc.) In order to manage Smart Grid devices and general devices with different roles and privileges, communication is required.

In order to operate efficiently, communication of control information, sensing information, data, etc. necessary for each smart grid operation should be smooth. However, it is preferable that the smart grid is influenced by a unique environment for each site (place) installed as a distributed power network rather than a centralized power grid, and is preferably set according to the environment.

Korean Patent Publication No. 10-2014-0067219

The present invention improves the efficiency of communication by increasing the efficiency of communication by applying the collection method according to the characteristics of the regular / non-regular data or the continuous / non-continuous measurement cycle of data in various environments of hardware resources of the device, And a method of applying the metrics.

The present invention provides a communication method adopting method and / or a communication policy server capable of determining the most efficient communication method for operating the installed smart grid.

The present invention provides a method and / or a communication policy server that can determine a communication method suitable for an environment of various sites equipped with a smart grid in a unified procedure.

According to an aspect of the present invention, there is provided a communication method adoption method for a smart grid, comprising: setting a test schedule for a communication channel established between a data source and a data sink constituting a smart grid; Performing a plurality of test communications with the data source and the data sink in a pulling manner, a pushing manner, and a publish / subscribe manner, respectively, according to the test schedule; Calculating at least two metrics of a metric for time efficiency, a metric for resource efficiency, and a metric for communication efficiency in a result of performing the test communication a plurality of times; And employing a communication method to be performed by the data source and the data sink from the calculated metrics.

The method may further include applying a predetermined weight to each of the calculated metrics according to an environment parameter of the data source and the data sink.

The step of adopting the communication method may further include multiplying each of the calculated metrics by a predetermined weight according to an environment parameter of the data source and a data sink installed in the data sink; Summing the metrics multiplied by the weights; And determining the maximum value among the values obtained by adding the metrics calculated for the three methods to the data source and the communication method to be performed by the data sink.

The method may further include performing logarithmic scaling on at least one of the at least two metrics.

The method may further include updating environment parameters of the data source and the data sink while performing data communication using the determined communication method.

A communication policy server according to another aspect of the present invention adopts a data communication method of each data source-data sink pair for performing data communication with a smart grid having a plurality of data sources and a plurality of data sinks As a communication policy server,

A source-sink pair storage unit for storing information on each of the data source-data sink pairs; An environment / parameter management unit for managing environment information of the smart grid and parameter information for each data source-data sink pair; A test scheduler for specifying a time at which each data source-data sink pair performs a test communication; A metric calculating unit for calculating a metric for each data source-data sink pair from the test results performed by the data source-data sink pair at a designated time; And a communication mode determination unit for determining a communication mode to be used in operation of each data source-data sink pair from the calculated metrics.

When the method or the communication policy server according to the present invention having the above-described configuration is implemented, it is possible to determine the most efficient communication method for operating the installed smart grid.

Alternatively, the present invention has the advantage of being able to determine a communication method suitable for the environment of various sites where the smart grid is installed in a unified procedure.

Alternatively, the present invention is advantageous in that the communication efficiency evaluation metric is classified into a time / resource technique so that the efficiency of the system resources in terms of time can be improved through real-time communication visualization.

1 is a conceptual diagram briefly showing a basic communication structure of pulling, pushing, and publisher / subscriber communication schemes.
2 is a conceptual diagram illustrating a smart grid with data sources and data sink pairs using pulling, pushing, and publish / subscribe communication schemes, respectively.
3 is a block diagram illustrating a smart grid system in which a method of adopting a communication scheme according to the principles of the present invention may be implemented.
4 is a flow diagram illustrating a method of adopting a communication scheme for a smart grid according to the principles of the present invention.
5 is a block diagram illustrating the structure of a server capable of performing the communication method adopting method of FIG. 4 according to an embodiment of the present invention;

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In describing the present invention, the terms first, second, etc. may be used to describe various elements, but the elements may not be limited by terms. Terms are for the sole purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being connected or connected to another element, it may be directly connected or connected to the other element, but it may be understood that other elements may be present in between .

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions may include plural expressions unless the context clearly dictates otherwise.

It is to be understood that the term " comprising, " or " comprising " as used herein is intended to specify the presence of stated features, integers, But do not preclude the presence or addition of steps, operations, elements, components, or combinations thereof.

In addition, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

First, the communication methods to be determined in the communication method determination according to the present invention will be described.

Data acquisition in a smart grid system can be performed as an activity that collects the data necessary for smart grid operation utilization in a necessary form with periodicity from inside or outside the system. The communication methods for data collection in a power grid including a smart grid include pulling, pushing, and publisher / subscriber.

Figure 1 is a simplified representation of the basic communication structure of Pulling, Pushing and Publisher / Subscriber communication schemes. The pulling method, the pushing method, and the issuance / subscription method are shown in order from the left side.

First, a pulling method is a method in which a data sink requiring active data directly requests data to a data source having data and fetches necessary data as a return value . This method allows the data sink to fetch necessary data at a desired time. However, you may miss a change in the source value that can occur in the pooling interval. This method can cause overhead of system resources due to frequent data collection while being connected with various systems or sensors.

In other words, while this communication method has an advantage of acquiring data only at a time when a data sink is needed (improves the operation efficiency of the data sink device), data is lost during data exchange and transmission according to a frequent data request, There is a drawback that it can cause a system load.

The pushing method is a method of registering data in a data source having data required by a data sink and then transmitting the data to a registered data sink whenever a data source changes its data value Transmits the changed data value. The data sink (sink) has the advantage of being able to receive all changed values once registered. However, there is an inefficiency in that data is transmitted even when the data sink does not need any changed value.

That is, this communication method has an advantage of improving the operation efficiency of the data source by transmitting the changed data value asynchronously, but it causes the communication inefficiency to be transmitted even when the data value is not needed.

The Publisher / Subscriber method transmits a message that a data value has changed to a data sink, which is a subscriber to which a data source as a publisher is registered, Sink) is a way to fetch data values when they are needed.

This method can reduce unnecessary data transmission overhead, which is a disadvantage of pushing while having the advantage of pushing, and it is possible to subscribe (data communication) between a publisher and a subscriber in a many-to-many relationship.

Subscribers have the advantage that they can import all the changed data asynchronously. However, when frequent data changes occur, there is an overhead that increases the frequency of message exchange between the Publisher and the Subscriber.

That is, this transmission scheme can overcome the disadvantages of the pulling scheme and the pushing scheme in the conventional communication environment in theory, and can only have advantages, but it consumes a certain amount of communication resources / time in the initial negotiation process for each data transmission event , The efficiency may be lowered in an environment in which the number of data is frequent but the amount of each data is not very large.

2 illustrates a smart grid with data sources and data sink pairs using pulling, pushing, and publish / subscribe communication schemes, respectively. The illustrated smart grid consists of three data sources and data sink pairs with a data acquisition / processing unit (data access unit) of 3: 1 for the following three hardware devices. The data acquisition / processing device (Data Acquirer) has three applications for performing pulling, pushing, and issuance / subscription communication.

In a communication channel established between a specific data source and a specific data sink constituting the smart grid system, a data acquisition operation can be performed by any one of the three communication methods. In the present invention, We propose a method to determine the optimal communication method to be performed in the communication channel established between data sinks.

First, a metric is defined for evaluating the efficiency of the above three data acquisition methods in terms of time and resources. We use this to evaluate the quantitative data acquisition efficiency and select the optimal data acquisition method.

First, as a metric for the change data acquisition efficiency, this description will be defined as a communication efficiency metric.

This metric is a metric that evaluates the changed data of the data source, that is, how much of the changed state value is delivered to the data sink. For example, the Effi_SCA metric can be calculated as shown in the following equation (1).

[Equation 1]

Effi_SCA = Efficiency of Acquired StateChanges

TimeDuration = Time unit to measure efficiency

TotalStateChanges = all changed state values

AcquiredStateChanges = AcquiredStateChanges = AcquiredStateChanges

In the above equation, the denominator denotes a time unit for measuring the efficiency, for example, 10 minutes, and an interval of one hour, and the numerator denotes the number of state values transmitted to the data sink among the changed state values. In the above equation, the difference in the number of changes obtained in the actual control center is used in the total number of state changes. The metric according to the above equation has a maximum value of 1 and a minimum value of 0. The higher the metric value, the higher the efficiency of securing change data.

This metric can be measured (collected) in a manner that monitors the communication efficiency through three transmission methods (patterns).

The second is a time-based efficiency metric, which we define as a time efficiency metric.

This metric is the efficiency with respect to the time taken to transfer the changed status values to the data sink, and can be calculated according to the following equations (2) to (4).

&Quot; (2) "

&Quot; (3) "

&Quot; (4) "

Effi_Time = Time spent (sum of data transfer time and exchange time) divided by the value for the change data Efficiency

Equation (2) and Equation (3) represent time elapsed time according to message exchange and time elapsed time according to data transmission, respectively. Equation (4) represents the time efficiency obtained by dividing the time spent by the number of changed state values. The time efficiency metric according to Equation (4) means that the higher the metric value, the more time is spent in state / control information communication.

According to the implementation, in order to express the positive meaning that the higher the metric value, such as the communication efficiency metric, the less time is spent in state / control information communication, a negative sign is added to the Effi_Time value of Equation (4) Or a value obtained by subtracting the Effi_Time value from a predetermined fixed value can be used.

Depending on the implementation, a log or exponent may be applied to the Effi_Time value of Equation (4) such that the maximum value converges to 1, such as the communication efficiency metric. (E.g., logarithmic or exponential scaling) The Effi_Time value corrected by the following Equation (4-1) can be used as the time efficiency metric value.

[Mathematical expression 4-1]

Effi_Time_mod = 1 - e- ^Effi_Time

Effi_Time_mod = Time efficiency converted for metric summation

This metric can be measured (collected) while performing the message exchange at a desired time to receive the transmission via various communication methods.

Third, we will define resource efficiency metrics as resource efficiency efficiency metrics. That is, this metric is an efficiency evaluation of the resource utilization used to receive the changed status of the data sink.

&Quot; (5) "

&Quot; (6) "

Effi_Resource = Efficiency of software system resource utilization divided by change data value

Resouce_Comsumed = Resource usage. The elapsed time multiplied by the resource requirement ratio

In Equation (5), the used resource amount is calculated, and Equation (6) takes into account the total resource usability consumed in obtaining the changed change values.

The resource efficiency metric according to Equation (6) means that the higher the metric value, the more resources are used in state / control information communication. Here, the resource may be a physical wired / wireless communication channel occupancy rate, a data source / sink device CPU occupancy rate, or the like.

According to the implementation, a minus sign is added to the Effi_Resource value of Equation (6) to indicate that the higher the metric value as the communication efficiency metric, the less the resource is used in the state / control information communication, Or a value obtained by subtracting the Effi_Resource value from a predetermined fixed value may be used.

Also, depending on the implementation, a log or exponent may be applied to the Effi_Resource value of Equation (6) (i.e., logarithmic or exponential scaling) so that the maximum value converges to 1 as in the communication efficiency metric, The Resource_Consumed value in Equation 6 can be applied as the percent utilization rate for 100% of the total resources. For example, the Effi_Resource value corrected by the following Equation (6-1) can be used as a time efficiency metric value.

[Equation 6-1]

Effi_Resource_mod = 1 - e- ^{Effi_Resource}

Effi_Resource_mod = Resource efficiency converted for metric summation

This metric can be measured (collected) by a system resource manager that monitors the resource utilization through real-time communication priority processing after self-load and memory monitoring.

FIG. 3 illustrates a smart grid system in which a method of adopting a communication scheme according to an aspect of the present invention may be performed.

The figure shows a smart grid system including smart grids (GRID1, GRID2, GRID3) of various environments having a plurality of data sources and a plurality of data sinks.

In the illustrated smart grid system, the communication policy server 100 is used to perform a communication method adoption method according to an embodiment of the present invention to perform a communication (communication) used by a pair of each data source and a data sink And determines the data communication method of the channel.

The pair of the data source and the data sink is abbreviated as a data source-data sink pair, a data source-sink pair, or a pair of very briefly.

In the illustrated smart grid system, one communication policy server 100 has been described as adopting (determining) communication schemes of data source-sink pairs belonging to three smart grids (GRID1, GRID2, GRID3) Of the communication policy server may be responsible for only one grid or three or more grids.

The communication policy server 100 shown in the figure adopts a communication method of data source-sink pairs of three types of smart grids (GRID1, GRID2, GRID3) to be managed. One of the three smart grids (GRID1, GRID2, GRID3) (GRID2) forms a pair with each of a large number of data sources, one centralized data sink. On the other hand, the other (GRID1) has a plurality of distributed data sinks forming a pair with the plurality of data sources on a one-to-one basis.

And the last one (GRID3), the multiple data sinks subscribe to one data source and receive the information when data change occurs. Here, some data sinks may be subscribers from multiple data sources. In such a communication method, data can be analyzed by subscribing to the change notification without frequent change of data and applying the subscription / publication communication method when deciding whether to receive the change.

The three smart grid structures shown in the figure represent a centralized centralized structure and a distributed / integrated structure. In fact, a smart grid to which the idea of the present invention is applied includes a plurality of data sinks and a larger number of data sources, N (where N is an integer not too large). One-to-one or 1: N can be viewed as a pair of one data source and one data sink as a viewpoint of one communication channel. In the description of the present invention, the data source-sink pair of this aspect will be described.

4 is a flowchart illustrating a method of adopting a communication scheme for a smart grid according to an embodiment of the present invention.

As shown in FIG. 4, a method of adopting a communication method according to the present invention includes: (S110) setting a test schedule for a communication channel established between a data source and a data sink constituting a smart grid system; Performing (S120) a plurality of test communications of the data source and the data sink in each of the pulling method, the pushing method, and the publish / subscribe method in accordance with the test schedule; (S140) calculating at least two metrics among the metrics for the required time, the metrics for the required resources, and the metrics for the communication efficiency in the result of performing the test communication a plurality of times for each of the three schemes; And a step (S160) of adopting a communication method to be performed by the data source and the data sink from the calculated metrics.

In the test schedule setting step (S110), for each of a plurality of data source-sink pairs included in the target smart grid, points of time for performing the data communication of the pooling method, And time points at which the issuance / subscription type data communication is to be performed.

The communication time required for the data communication time specified for each of the plurality of data source-sink pairs may be specified so as not to overlap with the communication time for other data source-sink pairs. However, Some may be specified to overlap with the communication time of another data source-sink pair.

In the step of performing the test communication (S120), when the data communication time point designated in the step S120 is reached for each of the plurality of data source-sink pairs, the corresponding data source-sink pair transmits test data communication . Here, the number of times of performing the test data communication is also determined to be the number of times specified in step S120.

In the step of performing the test communication (S120), information on the result of the test communication performed (e.g., test data transmission success, communication time, retry count, error count, data loss degree, SNR, Can be recorded in the storage of

In step S140 of calculating the metrics, three metrics (resource efficiency metric, time efficiency metric, and communication efficiency metric) can be calculated by the processes according to Equations (1) to (6). According to an implementation, the method may further comprise performing log scaling on at least one of the at least two metrics.

Here, the three metrics are preferably given a predetermined weight so that a communication strategy suitable for a given situation can be selected for each smart grid. For example, in the case of a data source-sink pair installed at a site with high usage cost per hour of the communication channel, a high weight can be given to the time efficiency metric.

Also, for example, in a data source-sink pair that is responsible for the transmission of information that is very important for smart grid operations, a high weighting can be given to the communication efficiency metric. Also, for example, in the case of a smart grid or a data source-sink pair with aging or low specification hardware, the resource efficiency metric can be weighted high.

For the strategy described above, it is possible to assign a unique weight to each of the three metrics for a particular situation, wherein in determining the weights of each of the three metrics of the data source-sink pair, Parameter information for the installation / communication environment or parameter information for the installation / communication environment of the smart grid can be reflected.

For example, as the environmental information of the smart grid itself, it is possible to reflect the load fluctuation rate and the abrupt degree (slope) of the fluctuation, the degree of the system stabilization means, the computing capacity of the main management apparatus, and the price of data communication.

In addition, for example, it is possible to set the parameters of the data source device and the data sink device constituting the target data source-sink pair, environment information (temperature / humidity, electromagnetic noise level, etc.) Communication channel parameters, and the like.

Also, for example, rate, average SNR, price of data communication, channel information, and the like may be reflected as parameter information for a data communication channel formed between the target data source and the sink pair.

To this end, the method may further include obtaining an environment parameter (S240) as a criterion for determining a weight for each target data source-sink pair prior to the step S160 of adopting the communication method.

In order to apply the above-mentioned weight, as shown in FIG. 4, the step of adopting the communication method (S160) may include, for each of the calculated metrics, Applying (multiplying) the weight (S162); Summing the metrics multiplied by the weights (S164); (S166) of determining the maximum value among the values obtained by adding the metrics obtained for the three schemes to the data source and the communication method to be performed by the data sink.

According to the implementation, in step S162 of multiplying the weight values, the metrics values according to the equations (2), (4) and (6) are multiplied by predetermined weights respectively, The metric values according to Equation (6-1) can be multiplied by predetermined weights, respectively.

The weight may be a value individually assigned to a data source-sink pair that performs test data communication to be a subject of metric calculation. Alternatively, the weight may be a value individually assigned to a combination of a data source-sink pair and a corresponding data communication method (pulling, pushing, issuing / subscription) for performing test data communication to be a subject of metric calculation.

The communication method determined for the target data source-sink pair in the determination of the communication method (S166) may be stored in a predetermined storage (e.g., a memory provided in the server or the target data source-sink device). Then, it communicates with the determined communication method during the operation period of the target data source-sink pair.

4, a method of adopting a communication method according to the present invention includes installing hardware facilities of a target smart grid, establishing a physical communication channel between data sink-source pairs and establishing the target smart grid on a corresponding site, Can be performed before the operation of the grid.

According to the implementation, the method of adopting the communication method of the present invention is characterized in that not only immediately after the construction of the target smart grid but also after a target smart grid is built in the site and operated for a considerable predetermined period of time (e.g., one year) ≪ / RTI >

In this case, the step of obtaining the environment parameter (S240) may be a step of updating the environment parameter in which the data source and the data sink are installed while performing data communication in the determined communication method.

For example, an excessive amount of communication costs required for the operation of the smart grid itself is determined as operational information obtained during the operation period of the target smart grid, and when the cost is excessive, the environment parameter is updated (corrected) to increase the weight of the time efficiency metric as a whole )can do.

In this case, the data source-sink pair is operated in a communication method determined by a metric applying a weight determined in a predetermined period (for example, one year), and when a periodic communication method determination time comes, , The sample state change information, and the result of performing the data transmission. Then, the data communication is performed during the next operation period with the communication method having the largest total sum reflecting the weight values.

FIG. 5 illustrates a structure of a server capable of performing the communication method adopting method of FIG. 4 according to an embodiment of the present invention. The server of FIG. 5 may be the server shown in FIG.

In the smart grid system including one or more smart grids having a plurality of data sources and a plurality of data sinks, the communication policy server 100 shown in FIG. 1 includes a pair of data sources and data sinks To determine the data communication method.

The communication policy server 100 includes a source-sink pair storage unit 120 for storing information on data source-sink pairs included in a target smart grid; An environment / parameter management unit 140 for recording environment information of the target smart grid itself and parameter information for each data source-sink pair; A test scheduler (150) that specifies when each data source-sink pair is to perform test communication; A metric calculating unit 160 for calculating a metric for each data source-sink pair from test results performed by the data source-sink pairs at a designated time; And a communication mode determination unit 180 for determining a communication mode to be used by each data source-sink pair from the calculated metrics.

The source-sink pair storage unit 120 may store information in the form of a table for the data source-sink pairs. For example, the records in the table may be assigned to each data source-sink pair one at a time. For example, column items of the assigned records in the table include smart grid identification information (e.g., smart grid ID) to which the smart grid belongs, data source device (device) identification information (e.g., device ID or device MAC) (For example, communication frequency, modulation scheme, VPN information, etc.) of the data sink device identification information (e.g., device ID or device MAC) constituting each pair, the data source device constituting each pair, A communication service ID, etc.), a communication method designated for each pair (pooling, pushing, issuing / driving), and the like.

According to the implementation, parameter information on the communication environment of each data source-sink pair recorded by the environment / parameter management unit 140 may be stored as a part of the columns of the table.

The environment / parameter management unit 140 may be configured to store environment information of the target smart grid itself, such as a load fluctuation rate and a sudden degree (slope) of fluctuation, degree of the system stabilization means, calculation capacity of the main management apparatus, Recording and managing.

The parameters managed and / or recorded by the environment / parameter management unit 140 include parameters of the data source device and the data sink device constituting each data source-sink pair, environmental information of a site (site) where the respective devices are installed (Temperature / humidity, electromagnetic noise level, etc.), communication channel parameters between the devices, and the like.

The environment / parameter management unit 140 records the rate, the average SNR, the price of the data communication, the information on the interference and the interference of the channel, etc. as parameter information on the data communication channel formed between each data source and the sink pair Can be managed.

The test scheduler 150 performs step S110 shown in FIG. 4, the metric calculating part 160 performs step S140, and the communication method determining part 180 may perform step S160.

It should be noted that the above-described embodiments are intended to be illustrative, not limiting. In addition, it will be understood by those of ordinary skill in the art that various embodiments are possible within the scope of the technical idea of the present invention.

100: communication policy server 120: source-sink pair storage unit
140: environment / parameter management unit 150: test scheduler
160: Metric calculation unit 180: Communication method determination unit

Claims (6)

Setting a test schedule for a communication channel established between a data source and a data sink constituting a smart grid;
Performing a plurality of test communications with the data source and the data sink in a pulling manner, a pushing manner, and a publish / subscribe manner, respectively, according to the test schedule;
Calculating at least two metrics of a metric for time efficiency, a metric for resource efficiency, and a metric for communication efficiency in a result of performing the test communication a plurality of times; And
Adopting a communication scheme to be performed by the data source and the data sink from the calculated metrics
The method comprising the steps of:
The method according to claim 1,
Applying a predetermined weight to each of the calculated metrics according to environment parameters in which the data source and the data sink are installed
Further comprising the steps of:
The method according to claim 1,
The method of claim 1,
Multiplying each of the calculated metrics by a predetermined weight according to the environment parameters in which the data source and the data sink are installed;
Summing the metrics multiplied by the weights;
Determining a method of the largest value among the values obtained by summing up the metrics obtained for the three methods as a communication method to be performed by the data source and the data sink
The method comprising the steps of:
The method according to claim 1,
And performing log scaling on at least one of the at least two or more metrics.
The method according to claim 1,
Updating an environment parameter in which the data source and the data sink are installed while performing data communication using the determined communication method
Further comprising the steps of:
A communication policy server adopting a data communication method of each data source-data sink pair for performing data communication with a smart grid having a plurality of data sources and a plurality of data sinks,
A source-sink pair storage unit for storing information on each of the data source-data sink pairs;
An environment / parameter management unit for managing environment information of the smart grid and parameter information for each data source-data sink pair;
A test scheduler for specifying a time at which each data source-data sink pair performs a test communication;
A metric calculating unit for calculating a metric for each data source-data sink pair from the test results performed by the data source-data sink pair at a designated time;
A communication method determination unit for determining, from the calculated metrics, a communication method to be used at the time of operation of each data source-
And a communication policy server.

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