Power system and communication method therefor

Abstract

A power system according to one embodiment of the present invention may include a first power conversion device; a second power conversion device; a first communication line connecting the first power conversion device and the second power conversion device; and a second communication line connecting the first power conversion device and the second power conversion device. Here, the first power conversion device and the second power conversion device each measure a state value for a monitoring object and exchange the measured state values ​​via the first communication line, and one or more of the first power conversion device and the second power conversion device can communicate via the second communication line to synchronize the measurement time of the state value.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2023-0101504, filed with the Korean Intellectual Property Office on August 3, 2023, and all of the contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a power system and a communication method therefor, and more particularly to a power system and a communication method therefor that can minimize measurement errors between power conversion devices. [Background technology]

[0003] An energy storage system (ESS) is a system that connects renewable energy, batteries that store power, and existing grid power. In recent years, smart grids and renewable energy have become more widespread, and as the efficiency and safety of power systems have become more emphasized, the demand for energy storage systems is increasing to regulate power supply and demand and improve power quality. Depending on the purpose of use, the output and capacity of energy storage systems can vary. Multiple battery systems can be connected to form a large-capacity energy storage system.

[0004] Among ESS systems, ESS systems that are connected to photovoltaic (PV) systems are changing from AC-coupled to DC-coupled systems. In DC-coupled ESS systems, the PV system and battery system operate at DC voltage, while the grid operates at AC voltage. Therefore, a power conversion / conditioning system (PCS) including a DC / AC inverter is installed in each battery section, and a DC / DC converter is installed in the battery system. Here, the PCS controls the power supplied from the grid and the power supplied from the battery section to the outside, and the output of the DC / DC converter is connected to the PCS to control the DC voltage / current of the battery system.

[0005] When an inverter and a converter are operated in cooperation, the inverter and the converter independently measure the state values ​​of the monitored object (e.g., the voltage and current values ​​of the DC link) and use the measured state values ​​for control and diagnosis. Here, if the measurement time points of the state values ​​measured by the inverter and the converter are different from each other, the diagnostic accuracy may decrease or a loss may occur in the power conversion gain.

[0006] Therefore, there is a need for an appropriate communication technique that can synchronize the measurement points between power conversion devices, improve diagnostic accuracy, and minimize loss of power conversion gain. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a power system that can minimize measurement errors between power conversion devices.

[0008] Another object of the present invention to solve the above problems is to provide a communication method for such a power system. [Means for solving the problem]

[0009] To achieve the above object, a power system according to an embodiment of the present invention may include a first power conversion device, a second power conversion device, a first communication line connecting the first power conversion device and the second power conversion device, and a second communication line connecting the first power conversion device and the second power conversion device, wherein the first power conversion device and the second power conversion device each measure a state value of a monitoring target and exchange the measured state values ​​via the first communication line, and one or more of the first power conversion device and the second power conversion device may communicate via the second communication line to synchronize measurement points of the state values.

[0010] The second communication line can be configured as a line separate from the first communication line.

[0011] One of the first power conversion device and the second power conversion device can be configured to transmit a first signal to the other via the second communication line requesting the other to start measuring a state value.

[0012] One of the first power electronics device and the second power electronics device may be predefined and configured as a transmitter of the first signal.

[0013] The first power conversion device and the second power conversion device may be configured to transmit the first signal to each other when a preset measurement time point for each power conversion device arrives.

[0014] The one that transmitted the first signal can measure the state value immediately after transmitting the first signal, and the other that received the first signal can measure the state value immediately after receiving the first signal. Here, the first power electronics device and the second power electronics device can share the measured state values ​​with each other via the first communication line.

[0015] The first power electronics device and the second power electronics device may be preset to have the same period for measuring state values, and one of the first power electronics device and the second power electronics device may be configured to transmit a second signal indicating the arrival of the measurement period to the other of the first power electronics device and the second power electronics device via the second communication line.

[0016] One of the first power electronics device and the second power electronics device, whose measurement period arrives first, may be configured to transmit the second signal to the other.

[0017] The one that transmitted the second signal can measure the state value immediately after transmitting the second signal, and the other that received the second signal can measure the state value immediately after receiving the second signal. Here, the first power electronics device and the second power electronics device can share the measured state values ​​with each other via the first communication line.

[0018] The party that transmitted the second signal can check whether the next measurement period has arrived through its own time measurement device immediately after transmitting the second signal, and the other party that received the second signal can initialize its own time measurement device immediately after transmitting the second signal and check whether the next measurement period has arrived through its initialized time measurement device.

[0019] When a specific signal for synchronizing the measurement time point is transmitted and received via the second communication line, each of the first power conversion device and the second power conversion device can measure the status value, update a pre-stored counter value, and exchange the status value and the counter value via the first communication line.

[0020] To achieve the above-mentioned another object, a communication method according to one embodiment of the present invention is a communication method for a power system including a first power conversion device and a second power conversion device interconnected via a first communication line and a second communication line, and includes a step in which one of the first power conversion device and the second power conversion device transmits a specific signal to the other via the second communication line to synchronize the measurement time of a state value; a step in which the first power conversion device and the second power conversion device each measure a state value for a monitoring object; and a step in which the first power conversion device and the second power conversion device exchange the measured state values ​​via the first communication line.

[0021] The step of transmitting the particular signal to the other party can include the step of transmitting a first signal to the other party via the second communication line, the first signal requesting the start of measurement of the state value.

[0022] The step of transmitting the specific signal to the other may include a step of one of the first power conversion device and the second power conversion device, which has been pre-defined as the sender of the first signal, transmitting the first signal to the other.

[0023] The step of transmitting the specific signal to the other may include a step of one of the first power conversion device and the second power conversion device transmitting the first signal to the other when its own predetermined measurement time point arrives.

[0024] The step of measuring the status values ​​for the monitoring objects may include a step of one of the parties that sent the first signal measuring the status value immediately after sending the first signal; and a step of the other party that received the first signal measuring the status value immediately after receiving the first signal.

[0025] The first power electronics device and the second power electronics device may be preset to have the same period for measuring state values, and the step of transmitting the specific signal to the other device may include transmitting a second signal indicating the arrival of the measurement period to the other device via the second communication line.

[0026] The step of transmitting the particular signal to the other may include a step of one of the first power conversion device and the second power conversion device, the one whose measurement period arrives first, transmitting the second signal to the other.

[0027] The step of respectively measuring the status value for the monitoring object may include a step of one of the parties that transmitted the second signal measuring the status value immediately after transmitting the second signal; and a step of the other party that received the second signal measuring the status value immediately after receiving the second signal.

[0028] The step of measuring the status values ​​of the monitoring objects may further include a step in which the one party that sent the second signal checks whether the next measurement period has arrived through its own time measurement device immediately after sending the second signal; and a step in which the other party that received the second signal initializes its own time measurement device immediately after sending the second signal and checks whether the next measurement period has arrived through its initialized time measurement device.

[0029] The step of measuring the state values ​​of the monitoring targets may further include updating pre-stored counter values, and the step of exchanging the state values ​​may include exchanging the state values ​​and the counter values ​​via the first communication line. [Effects of the Invention]

[0030] According to the above-described embodiment of the present invention, measurement errors between power conversion devices can be minimized by synchronizing measurement time points through a communication channel configured separately from the data communication channel and then performing data communication between the power conversion devices. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a block diagram showing a communication connection structure of a general power system. [Figure 2] 1 is a block diagram of a power system according to an embodiment of the present invention. [Figure 3] FIG. 2 is an operational flow diagram of a communication method for a power system according to the present invention. [Figure 4] FIG. 2 is an operational flow diagram of a communication method for a power system according to a first embodiment of the present invention. [Figure 5] FIG. 10 is an operational flow diagram of a communication method for a power system according to a second embodiment of the present invention. [Figure 6] FIG. 10 is an operational flow diagram of a communication method for a power system according to a third embodiment of the present invention. [Figure 7] FIG. 10 is an operational flow diagram of a communication method for a power system according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, it is understood that this is not intended to limit the present invention to the specific embodiments, but rather to include all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. Like reference numerals are used to refer to like elements throughout the drawings.

[0033] Terms such as "first," "second," "A," and "B" may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be termed a "second component," and similarly, a second component may be termed a "first component," without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any of multiple associated listed items.

[0034] When a component is referred to as being "coupled" or "connected" to another component, it is understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. In contrast, when a component is referred to as being "directly coupled" or "directly connected" to another component, it is understood that there are no other components in between.

[0035] The terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise. It should be understood that in this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0036] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless expressly defined in this application.

[0037] FIG. 1 is a block diagram showing a communication connection structure of a general power system.

[0038] 1, the power system may include an inverter 10 and a converter 20. Here, the inverter 10 may be a DC / AC inverter, and the converter 20 may be a DC / DC converter.

[0039] The inverter 10 and the converter 20 may be connected to the link capacitor 30 via a state measurement line. Here, the inverter 10 and the converter 20 may collect state values ​​including the voltage value and the current value of the link capacitor 30 via the state measurement line.

[0040] The inverter 10 and the converter 20 may be connected via a communication line and configured to transmit and receive data to and from each other. Here, the inverter 10 and the converter 20 may exchange and share the state value of the link capacitor 30 with each other via the communication line.

[0041] The inverter 10 and the converter 20 can execute predefined control logic and diagnostic logic using shared state values. However, if there is an error in the measurement time of the shared state value, diagnostic accuracy may decrease or a loss of power conversion gain may occur. To prevent such problems, predefined compensation logic may be additionally applied, but this may burden system operation due to complex data processing processes.

[0042] The present invention relates to a technology for solving such problems, and relates to a power system structure and a communication method for such a power system that can minimize measurement time errors between power conversion devices without applying complex compensation logic.

[0043] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0044] FIG. 2 is a block diagram of a power system according to an embodiment of the present invention.

[0045] Referring to FIG. 2, a power system according to an embodiment of the present invention may include a first power conversion device 100 and a second power conversion device 200.

[0046] The first power conversion device 100 and the second power conversion device 200 may correspond to a converter or an inverter. For example, the first power conversion device 100 may be a DC / AC inverter, and the second power conversion device 200 may be a DC / DC converter.

[0047] The first power conversion device 100 and the second power conversion device 200 may include a control device and a communication module, where the communication module transmits and receives data via a communication line, and the control device may be configured to execute a predefined control process or diagnostic process using the transmitted and received data.

[0048] The first power conversion device 100 and the second power conversion device 200 may be connected to a monitoring target 300 via a state measurement line. Here, the monitoring target 300 may correspond to a link capacitor, but the monitoring target is not limited to a specific individual in the present invention.

[0049] The first power conversion device 100 and the second power conversion device 200 can each measure a state value of the monitoring target 300 via a state measurement line. For example, the first power conversion device 100 and the second power conversion device 200 can collect state values ​​including a voltage value and a current value of a link capacitor via the state measurement line.

[0050] The power system may include a first communication line L1 connecting the first power conversion device 100 and the second power conversion device 200.

[0051] The power system may also include a second communication line L2 connecting the first power conversion device 100 and the second power conversion device 200. Here, the second communication line L2 may be configured as a line separate from the first communication line L1.

[0052] The first communication line L1 can be configured to perform communication for transmitting and receiving data. For example, the first power electronics device 100 and the second power electronics device 200 can transmit and receive state values ​​of the monitoring target 300 to and from each other via the first communication line L1.

[0053] The second communication line L2 can be configured to perform communication for synchronizing the measurement time points of the state values, where one or more of the first power conversion device 100 and the second power conversion device 200 can transmit a specific signal for synchronizing the measurement time of the state values ​​via the second communication line L2.

[0054] The synchronization signal for matching the measurement times of the state values ​​may include one or more of: a first signal requesting the start of measurement of the state value; and a second signal indicating the arrival of a preset measurement period.

[0055] When one of the first power conversion device 100 and the second power conversion device 200 transmits a synchronization signal to the other via the second communication line L2, the first power conversion device 100 and the second power conversion device 200 can measure a status value for the monitored object 300 immediately after transmitting and receiving the synchronization signal, and exchange and share the status values ​​with each other via the first communication line L1.

[0056] According to the present invention, the power conversion devices measure the status values ​​and exchange data after synchronizing the measurement time points via a communication channel L2 configured separately from the data communication channel L1, thereby preventing measurement errors from occurring between the power conversion devices.

[0057] FIG. 3 is an operational flow diagram of the communication method for the power system according to the present invention.

[0058] One of the first power conversion device and the second power conversion device may transmit a synchronization signal for synchronizing measurement times of the state value via the second communication line (S310), where the synchronization signal may include one or more of a first signal requesting the start of measurement of the state value and a second signal indicating the arrival of a preset measurement period.

[0059] The entity that transmits the synchronization signal can be predefined.

[0060] For example, the first power electronics device may be preset as the transmitting subject, or the second power electronics device may be preset as the transmitting subject.

[0061] As another example, if measurement times or measurement periods are predefined for the first power conversion device and the second power conversion device, the device whose own measurement time or measurement period has arrived may send a synchronization signal to the other device.

[0062] After the synchronization signal is transmitted by the transmitting entity, the first power electronics device and the second power electronics device may each measure a state value for a monitoring target (S320).

[0063] Specifically, when a power electronics device (transmitter) that has transmitted a synchronization signal transmits the synchronization signal to another power electronics device (receiver), the transmitter can measure the state value immediately after transmitting the synchronization signal, and the receiver can measure the state value immediately after receiving the synchronization signal. That is, the first power electronics device and the second power electronics device can each measure the state value of the monitoring target immediately after transmitting and receiving the synchronization signal.

[0064] Thereafter, the first power conversion device and the second power conversion device can exchange the state values ​​measured in S320 with each other via the first communication line (S330).

[0065] The first power converter and the second power converter may execute a predefined control process or diagnostic process using shared state values, where the shared state values ​​are values ​​measured at the same time, thereby preventing a decrease in diagnostic accuracy or a loss of power conversion gain.

[0066] FIG. 4 is an operational flow diagram of a communication method for a power system according to the first embodiment of the present invention.

[0067] The communication method for the power system shown in FIG. 4 is an embodiment in which the transmitter of the synchronization signal is set to the first power electronics device, and the synchronization signal is defined as a first signal that is a measurement start request signal.

[0068] The first power conversion device set as the transmitting subject can transmit a first signal, which is a signal requesting the start of measurement of the state value, to the second power conversion device via the second communication line when its own predetermined measurement time point or measurement period arrives (S410).

[0069] The first power conversion device can measure a status value for the monitoring target (S421) immediately after transmitting the first signal, and the second power conversion device can measure a status value for the monitoring target (S422) immediately after receiving the first signal.

[0070] The first power conversion device and the second power conversion device can exchange individually measured state values ​​with each other via the first communication line (S430).

[0071] The first power converter can then check whether its measurement time or measurement period has arrived.

[0072] When the corresponding measurement time point or measurement period arrives, the first power electronics device can transmit a first signal to the second power electronics device via the second communication line (S440).

[0073] The first power conversion device can measure a status value for the monitoring target (S451) immediately after transmitting the first signal, and the second power conversion device can measure a status value for the monitoring target (S452) immediately after receiving the first signal.

[0074] The first power electronics device and the second power electronics device can exchange individually measured state values ​​with each other via the first communication line (S460).

[0075] The first power electronics device and the second power electronics device can communicate with each other by repeatedly performing S410 to S430 until the power system is switched to the stop mode.

[0076] FIG. 5 is an operational flow diagram of a communication method for a power system according to the second embodiment of the present invention.

[0077] The communication method for an electric power system shown in FIG. 5 is an embodiment in which a step of sharing counter values ​​is added to the communication method of FIG.

[0078] The first power conversion device set as the transmitting subject can transmit a first signal, which is a signal requesting the start of measurement of the state value, to the second power conversion device via the second communication line when its own predetermined measurement time point or measurement period arrives (S510).

[0079] The first power conversion device can measure a status value for the monitoring target (S521) immediately after transmitting the first signal, and the second power conversion device can measure a status value for the monitoring target (S522) immediately after receiving the first signal.

[0080] Furthermore, the first power electronics device may update a pre-stored counter value immediately after transmitting the first signal (S523), and the second power electronics device may update a pre-stored counter value immediately after receiving the first signal (S524). Here, the counter values ​​may be stored in respective storage devices of the first power electronics device and the second power electronics device, and may have the same value.

[0081] For example, when a first signal is transmitted and received, the first power conversion device can increment the counter value (n) stored in its own memory device by 1 to update it (n+1), and the second power conversion device can also increment the counter value (n) stored in its own memory device by 1 to update it (n+1).

[0082] The first power electronics device and the second power electronics device can exchange individually measured state values ​​and counter values ​​via the first communication line (S530).

[0083] The first power converter can then check whether its measurement time or measurement period has arrived.

[0084] When the corresponding measurement time point or measurement period arrives, the first power converter can transmit a first signal to the second power converter via the second communication line (S540).

[0085] The first power conversion device can measure a status value for the monitoring target (S551) and update its own counter value (S553) immediately after transmitting the first signal, and the second power conversion device can measure a status value for the monitoring target (S552) and update its own counter value (S554) immediately after receiving the first signal.

[0086] The first power electronics device and the second power electronics device can exchange individually measured state values ​​and counter values ​​via the first communication line (S560).

[0087] The first power electronics device and the second power electronics device can communicate with each other by repeatedly performing S510 to S530 until the power system is switched to the stop mode.

[0088] According to this embodiment, the first power conversion device and the second power conversion device share a counter value that is managed to be the same value as the state value measured at the same time, thereby preventing the measurement order of the shared state value from being shifted or extended.

[0089] FIG. 6 is a flowchart showing an operation of a communication method for a power system according to a third embodiment of the present invention.

[0090] The communication method of the power system shown in Figure 6 is an example in which the state value measurement periods of the first and second power conversion devices are preset to be the same period, the transmitter of the synchronization signal is preset to the device whose measurement period arrives first, and the synchronization signal is defined as a second signal that is a signal notifying the arrival of the measurement period.

[0091] The first power conversion device and the second power conversion device can check whether the measurement period has arrived through their own time measurement devices (for example, timers).

[0092] If the measurement period of the first power conversion device arrives first (S610), the first power conversion device can transmit a second signal, which is a measurement period arrival notification signal, to the second power conversion device via the second communication line (S620).

[0093] The first power conversion device can measure a status value for the monitoring object (S631) immediately after transmitting the second signal, and the second power conversion device can measure a status value for the monitoring object (S632) immediately after receiving the second signal.

[0094] Here, the second power electronics device that has received the second signal can initialize its own time measurement device (S633) to synchronize with the time measurement device of the first power electronics device, and then the first power electronics device and the second power electronics device can check whether the next measurement period has arrived through their own time measurement devices.

[0095] The first power conversion device and the second power conversion device can exchange individually measured state values ​​with each other via the first communication line (S640).

[0096] Thereafter, if the measurement period of the second power conversion device arrives first (S650), the second power conversion device can transmit a second signal, which is a measurement period arrival notification signal, to the first power conversion device via the second communication line (S660).

[0097] The second power conversion device can measure (S672) a status value for the monitoring object immediately after transmitting the second signal, and the first power conversion device can measure (S671) a status value for the monitoring object immediately after receiving the second signal.

[0098] Here, the first power electronics device that has received the second signal can initialize its own time measurement device (S673) to synchronize with the time measurement device of the second power electronics device, and then the first power electronics device and the second power electronics device can check whether the next measurement period has arrived through their own time measurement devices.

[0099] The first power conversion device and the second power conversion device can exchange individually measured state values ​​with each other via the first communication line (S680).

[0100] The first power electronics device and the second power electronics device can communicate with each other by repeatedly performing S610 to S640 until the power system is switched to the stop mode.

[0101] According to this embodiment, even when the power conversion devices are set to the same measurement period, it is possible to prevent minute errors in the measurement time points that may occur due to the time measurement device.

[0102] FIG. 7 is a flowchart showing an operation of a communication method for a power system according to a fourth embodiment of the present invention.

[0103] The communication method for an electric power system shown in FIG. 7 is an embodiment in which a step of sharing counter values ​​is added to the communication method of FIG.

[0104] The first power conversion device and the second power conversion device can check whether the measurement period has arrived through their own time measurement devices (for example, timers).

[0105] If the measurement period of the first power conversion device arrives first (S710), the first power conversion device can transmit a second signal, which is a measurement period arrival notification signal, to the second power conversion device via the second communication line (S720).

[0106] The first power conversion device can measure a status value for the monitoring target (S731) immediately after transmitting the second signal, and the second power conversion device can measure a status value for the monitoring target (S732) immediately after receiving the second signal.

[0107] In addition, the first power conversion device can update the pre-stored counter value (S733) immediately after transmitting the second signal, and the second power conversion device can update the pre-stored counter value (S734) immediately after receiving the second signal.

[0108] Here, the second power electronics device that has received the second signal may initialize its own time measurement device (S735) to synchronize with the time measurement device of the first power electronics device, and then the first power electronics device and the second power electronics device may check whether the next measurement period has arrived through their own time measurement devices.

[0109] The first power conversion device and the second power conversion device can exchange individually measured state values ​​and counter values ​​with each other via the first communication line (S740).

[0110] Thereafter, if the measurement period of the second power conversion device arrives first (S750), the second power conversion device can transmit a second signal to the first power conversion device via the second communication line (S760).

[0111] The second power conversion device can measure the status value for the monitoring object (S772) and update its own counter value (S774) immediately after transmitting the second signal, and the first power conversion device can measure the status value for the monitoring object (S771) and update its own counter value (S773) immediately after receiving the second signal.

[0112] Here, the first power electronics device that has received the second signal can initialize its own time measurement device (S775).

[0113] The first power conversion device and the second power conversion device can exchange individually measured state values ​​and counter values ​​with each other via the first communication line (S780).

[0114] The first power electronics device and the second power electronics device can communicate with each other by repeatedly performing S710 to S740 until the power system is switched to the stop mode.

[0115] The operations of the methods according to the embodiments of the present invention can be embodied as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all kinds of storage devices in which data that can be read by a computer system is stored. In addition, the computer-readable recording medium can be distributed among computer systems connected via a network, so that the computer-readable program or code can be stored and executed in a distributed manner.

[0116] Some aspects of the invention have been described in the context of an apparatus, but they may also be described in terms of a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may be described in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0117] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and variations of the present invention can be made without departing from the spirit and scope of the present invention as set forth in the following claims. [Explanation of symbols]

[0118] 100: First power conversion device 200: Second power conversion device 300: Monitoring target

Claims

1. a first power converter; a second power converter; a first communication line connecting the first power conversion device and the second power conversion device; and a second communication line connecting the first power conversion device and the second power conversion device; The first power conversion device and the second power conversion device measuring a state value for each monitoring target and exchanging the measured state values ​​via the first communication line; One or more of the first power conversion device and the second power conversion device The power system performs communication via the second communication line to synchronize the measurement points of the state values.

2. The second communication line includes: The power system of claim 1 , configured as a line separate from the first communication line.

3. One of the first power conversion device and the second power conversion device is The power system of claim 1 , configured to transmit a first signal to the other via the second communication line, the first signal requesting initiation of measurement of a state value.

4. The power system according to claim 3 , wherein one of the first power conversion device and the second power conversion device is predefined and configured as a transmitter of the first signal.

5. The first power conversion device and the second power conversion device The power system of claim 3 , configured to transmit the first signal to the other when a preset measurement time point for the other power system arrives.

6. the one that transmitted the first signal measures the state value immediately after transmitting the first signal; the other device that receives the first signal measures the state value immediately after receiving the first signal; The first power conversion device and the second power conversion device The power system of claim 3 , wherein measured state values ​​are shared with each other via the first communication line.

7. The first power conversion device and the second power conversion device The measurement intervals of the state values ​​are set in advance as the same period, One of the first power conversion device and the second power conversion device is The power system of claim 1 , configured to transmit a second signal indicating the arrival of the measurement period to the other via the second communication line.

8. The power system according to claim 7 , wherein one of the first power conversion device and the second power conversion device, whose measurement period arrives first, is configured to transmit the second signal to the other of the first power conversion device and the second power conversion device.

9. the one that transmitted the second signal measures the state value immediately after transmitting the second signal; the other device that receives the second signal measures the state value immediately after receiving the second signal; The first power conversion device and the second power conversion device The power system of claim 8 , wherein measured state values ​​are shared with each other via the first communication line.

10. the one that transmitted the second signal checks whether or not the next measurement period has arrived through its own time measurement device immediately after transmitting the second signal; The power system of claim 8, wherein the other party that receives the second signal initializes its own time measurement device immediately after transmitting the second signal and checks whether the next measurement period has arrived through its own initialized time measurement device.

11. When a specific signal for synchronizing the measurement time point is transmitted and received via the second communication line, Each of the first power electronics device and the second power electronics device comprises: The power system of claim 1 , wherein the state value is measured, a pre-stored counter value is updated, and the state value and the counter value are exchanged via the first communication line.

12. A communication method for a power system including a first power conversion device and a second power conversion device interconnected via a first communication line and a second communication line, the method comprising: one of the first power conversion device and the second power conversion device transmitting a specific signal to the other of the first power conversion device and the second power conversion device via the second communication line for synchronizing measurement points of state values; The first power conversion device and the second power conversion device each measure a state value for a monitoring target; and A communication method for a power system, comprising the step of the first power conversion device and the second power conversion device exchanging the measured state values ​​via the first communication line.

13. The step of transmitting the specific signal to the other party includes: The communication method for a power system according to claim 12 , further comprising the step of transmitting a first signal to the other via the second communication line, the first signal requesting initiation of measurement of a state value.

14. The step of transmitting the specific signal to the other party includes:

14. The communication method for a power system according to claim 13, further comprising a step in which one of the first power conversion device and the second power conversion device, which is predefined as a transmitter of the first signal, transmits the first signal to the other of the first power conversion device and the second power conversion device.

15. The step of transmitting the specific signal to the other party includes:

14. The communication method for a power system according to claim 13, further comprising a step in which one of the first power conversion device and the second power conversion device, when its own measurement time point set in advance, transmits the first signal to the other of the first power conversion device and the second power conversion device.

16. The step of measuring each state value for the monitoring object includes: measuring one of the first state value and the second state value immediately after transmitting the first signal; and The communication method for a power system according to claim 13 , further comprising the step of the other receiving the first signal measuring the state value immediately after receiving the first signal.

17. The first power conversion device and the second power conversion device The measurement intervals of the state values ​​are set in advance as the same period, The step of transmitting the specific signal to the other party includes: The communication method for a power system according to claim 12 , further comprising the step of transmitting a second signal indicating the arrival of the measurement period to the other via the second communication line.

18. The step of transmitting the specific signal to the other party includes:

18. The communication method for a power system according to claim 17, further comprising a step in which one of the first power conversion device and the second power conversion device, whose measurement period arrives first, transmits the second signal to the other of the first power conversion device and the second power conversion device.

19. The step of measuring each state value for the monitoring object includes: measuring the state value immediately after transmitting the second signal; and The communication method for a power system according to claim 18, further comprising the step of the other of the receivers of the second signal measuring the state value immediately after receiving the second signal.

20. The step of measuring each state value for the monitoring object includes: The one that transmitted the second signal checks whether the next measurement period has arrived through its own time measurement device immediately after transmitting the second signal; and 19. The communication method for a power system according to claim 18, further comprising a step in which the other party that has received the second signal initializes its own time measurement device immediately after transmitting the second signal, and checks whether the next measurement period has arrived through its own initialized time measurement device.

21. The step of measuring each state value for the monitoring object includes: further comprising the step of respectively updating the pre-stored counter values; The step of exchanging the first state value and the second state value comprises: The method of communication for a power system according to claim 12 , comprising exchanging the state value and the counter value over the first communication line.

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