Power system and communication method thereof

Abstract

Disclosed is an apparatus according to an embodiment of the present invention, comprising: a first power conversion device; a second power conversion device; a first communication line that connects 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, each of the first power conversion device and the second power conversion device measures one or more state values of the monitoring object and exchanges the measured state values through the first communication line, and one or more of the first power conversion device and the second power conversion device perform communication through the second communication line to synchronize the measurement time point of the state value.

Description

Technical Field

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0101504 filed in the Korean Intellectual Property Office on August 3, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an electric power system and a communication method thereof, and more particularly to an electric power system and a communication method thereof capable of minimizing a measurement error between electric power conversion devices. Background Art

[0003] Energy storage systems (ESS) involve renewable energy, batteries that store electricity, and power grids. Recently, as the popularity of smart grids and renewable energy is expanding and the efficiency and stability of power systems are gaining attention, the demand for energy storage systems for power demand control and power quality improvement is increasing. Depending on the purpose of use, energy storage systems can have different outputs and capacities. In order to configure a large-capacity energy storage system, multiple battery systems can be connected.

[0004] The energy storage system connected to the PV (photovoltaic) system is changing from an AC coupling system to a DC coupling system. In the DC coupling energy storage system, the PV system and the battery system operate at a DC voltage, but the grid operates at an AC voltage, and therefore, a power conversion / regulation system (PCS) including a DC / AC inverter is installed in each battery segment, and a DC / DC converter is provided in the battery system. Here, the power conversion system controls the power supplied from the grid and the power supplied externally from the battery segment, 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 the inverter and the converter operate in combination, the inverter and the converter independently measure the state value of the monitoring target (for example, the voltage value and the current value of the DC link), and use the measured state value for control and diagnosis. Here, if the measurement timing of the state values ​​measured by the inverter and the converter is different from each other, the diagnostic accuracy may be reduced or the loss of power conversion gain may occur.

[0006] Therefore, appropriate communication technology is needed to match measurement timing between power conversion devices, improve diagnostic accuracy, and minimize the loss of power conversion gain. Summary of the invention

[0007] Technical issues

[0008] To eliminate one or more problems of the related art, embodiments of the present disclosure provide a power system that can minimize measurement errors between power conversion devices.

[0009] In order to eliminate one or more problems of the related art, embodiments of the present disclosure also provide a communication method for a power system.

[0010] Technical Solution

[0011] In order to achieve the purpose of the present disclosure, the 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. Here, each of the first power conversion device and the second power conversion device measures one or more state values ​​of the monitored object and exchanges the measured state values ​​through the first communication line, and one or more of the first power conversion device and the second power conversion device perform communication through the second communication line to synchronize the measurement time point of the state value.

[0012] Here, the second communication line may be a line separate from the first communication line.

[0013] Either one of the first power conversion device and the second power conversion device may be configured to transmit a first signal requesting initiation of state value measurement to the other via the second communication line.

[0014] One of the first power conversion device and the second power conversion device may be pre-defined as a transmission entity of the first signal.

[0015] The first power conversion device and the second power conversion device may be configured to transmit a first signal to the other when its own predetermined measurement time arrives.

[0016] The one that sends the first signal can measure one or more status values ​​immediately after sending the first signal, the other one that receives the first signal can measure the status values ​​immediately after receiving the first signal, and the first power conversion device and the second power conversion device share the measured status values ​​with each other through the first communication line.

[0017] The measurement cycles of the state values ​​of the first power conversion device and the second power conversion device may be predetermined to be the same cycle.Here, either of the first power conversion device and the second power conversion device may be configured to send a second signal indicating the arrival of its own measurement cycle to the other via the second communication line.

[0018] Of the first power conversion device and the second power conversion device, the one whose measurement period arrives earlier may be configured to transmit the second signal to the other.

[0019] The one that sends the second signal can measure the state value immediately after sending the second signal, and the other that receives the second signal can measure the state value immediately after receiving the second signal. Here, the first power conversion device and the second power conversion device can share the measured state value with each other through the first communication line.

[0020] The one that sends the second signal can determine whether the next measurement period has arrived by its own time measurement device immediately after sending the second signal. Here, the other one that receives the second signal initializes its own time measurement device immediately after receiving the second signal and determines whether the next measurement period has arrived by its initialized time measurement device.

[0021] When a specific signal for synchronizing the measurement time point is sent and received through the second communication line, each of the first power conversion device and the second power conversion device measures a state value, can update a previously stored counter value, and exchange the state value and counter value through the first communication line.

[0022] According to another embodiment of the present disclosure, a communication method relates to a communication method in an electric power system, the electric power system comprising a first power conversion device and a second power conversion device connected to each other via a first communication line and a second communication line, wherein the method comprises: sending a specific signal for synchronizing a measurement time point of a status value by either one of the first power conversion device and the second power conversion device to the other via the second communication line; measuring one or more status values ​​of a monitored object by each of the first power conversion device and the second power conversion device; and exchanging the measured status values ​​by the first power conversion device and the second power conversion device via the first communication line.

[0023] Transmitting a specific signal for synchronizing the measurement time point of the status value to the other party may include transmitting a first signal requesting initiation of measurement of the status value to the other party via the second communication line.

[0024] Transmitting a specific signal for a measurement time point of a synchronization status value to the other may include transmitting a first signal to the other by any one of the first power conversion device and the second power conversion device, which is pre-defined as a transmission entity of the first signal.

[0025] Transmitting a specific signal of a measurement time point for synchronizing the status value to the other may include transmitting a first signal to the other by either one of the first power conversion device and the second power conversion device whose own predetermined measurement time point has arrived.

[0026] Measuring one or more status values ​​of the monitored object may include: measuring the status value immediately after any one of the transmitting the first signal transmits the first signal; and measuring the status value immediately after the other one of the receiving the first signal receives the first signal.

[0027] The measurement cycles of the state values ​​of the first power conversion device and the second power conversion device are predetermined to be the same cycle.Here, sending a specific signal for synchronizing the measurement time point of the state value to the other may include sending a second signal indicating the arrival of the measurement cycle to the other via the second communication line.

[0028] Transmitting the specific signal of the measurement time point for synchronizing the status value to the other may include transmitting the second signal to the other by any one of the first power conversion device and the second power conversion device whose measurement cycle arrives earlier.

[0029] Measuring one or more status values ​​of the monitored object may include: measuring the status value immediately after the one transmitting the second signal measures the status value; and measuring the status value immediately after the other receiving the second signal measures the status value.

[0030] Measuring one or more status values ​​of the monitored object may include: one sending the second signal determines whether the next measurement cycle has arrived through its own time measurement device immediately after sending the second signal; and another receiving the second signal initializes its own time measurement device immediately after receiving the second signal and determines whether the next measurement cycle has arrived through its initialized time measurement device.

[0031] Measuring one or more status values ​​of the monitored object may also include updating each previously stored counter value.Here, exchanging the status values ​​may include exchanging the status values ​​and the counter values ​​via the first communication line.

[0032] Beneficial Effects

[0033] According to the embodiments of the present invention as described above, it is possible to minimize measurement errors between power conversion devices by synchronizing measurement time points through a communication channel configured separately from a data communication channel and then performing data communication between power conversion devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a block diagram showing a communication connection structure of a general power system.

[0035] Figure 2 is a block diagram of a power system according to an embodiment of the present invention.

[0036] Figure 3 is an operation flow chart of a communication method for a power system according to an embodiment of the present invention.

[0037] Figure 4 is an operation flow chart of the communication method of the electric power system according to the first embodiment of the present invention.

[0038] Figure 5 is an operation flow chart of a communication method for a power system according to a second embodiment of the present invention.

[0039] Figure 6 is an operation flow chart of a communication method for an electric power system according to a third embodiment of the present invention.

[0040] Figure 7 is an operation flow chart of a communication method for an electric power system according to a fourth embodiment of the present invention.

[0041] 100: First power conversion device

[0042] 200: Second power conversion device

[0043] 300: Monitoring object DETAILED DESCRIPTION

[0044] The present invention can be modified in various forms and have various embodiments, and its specific embodiments are shown in the drawings by way of example and will be described in detail below. However, it should be understood that it is not intended to limit the present invention to specific embodiments, on the contrary, the present invention will cover all modifications, equivalents and substitutions that fall within the spirit and technical scope of the present invention. Throughout the description of the drawings, the same reference numerals refer to the same elements.

[0045] It should be understood that although various elements may be described herein using terms such as first, second, A, B, etc., these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the present invention. As used herein, the term "and / or" includes a combination of any of a plurality of associated listed items or a plurality of associated listed items.

[0046] It should be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element, or there can be intervening elements. Conversely, when an element is referred to as being "directly coupled" or "directly connected" to another element, there are no intervening elements.

[0047] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include plural forms unless the context clearly indicates otherwise. It will be further understood that when used herein, the terms "include", "comprise", "contain", and / or "have" specify the presence of stated features, integers, steps, operations, constituent elements, components and / or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, constituent elements, components and / or combinations thereof.

[0048] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0049] Figure 1 It is a block diagram showing a communication connection structure of a general power system.

[0050] refer to Figure 1 , a general 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.

[0051] The inverter 10 and the converter 20 may be connected to the link capacitor 30 through a state measurement line. Here, the inverter 10 and the converter 20 may collect state values ​​including a voltage value and a current value of the link capacitor 30 through the state measurement line.

[0052] The inverter 10 and the converter 20 may be connected through a communication line and exchange data with each other. Here, the inverter 10 and the converter 20 may share the state value of the link capacitor 30 with each other by exchanging the state value of the link capacitor 30 through the communication line.

[0053] The inverter 10 and the converter 20 can use the shared state value to execute the predefined control logic and diagnostic logic. However, if there is a difference in the measurement time of the shared state value, the diagnostic accuracy may be reduced or the loss of power conversion gain may occur. A predefined compensation logic may be additionally applied to prevent this problem, but in this case, the complex data processing process burdens the system operation.

[0054] The present invention relates to a technology for solving this problem, and proposes a power system structure and a communication method for such a power system that can minimize a measurement timing error between power conversion devices without applying a complex compensation logic.

[0055] Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

[0056] Figure 2 is a block diagram of a power system according to an embodiment of the present invention.

[0057] refer to Figure 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 .

[0058] 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.

[0059] The first power conversion device 100 and the second power conversion device 200 may include a control device and a communication module. Here, the communication module may transmit and receive data through a communication line, and the control device may be configured to perform a predefined control process or a diagnostic process using the transmitted and received data.

[0060] The first power conversion device 100 and the second power conversion device 200 may be connected to the monitoring object 300 through a state measurement line. Here, the monitoring object 300 may correspond to a link capacitor, but the monitoring object is not limited to a specific entity in the present invention.

[0061] The first power conversion device 100 and the second power conversion device 200 may each measure the state value of the monitoring object 300 through the state measurement line. For example, the first power conversion device 100 and the second power conversion device 200 may collect state values ​​including voltage and current values ​​of the link capacitor through the state measurement line.

[0062] The power system may include a first communication line L1 connecting the first power conversion device 100 and the second power conversion device 200 .

[0063] In addition, the power system may 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.

[0064] The first communication line L1 may be configured to perform communication for transmitting and receiving data. For example, the first power conversion device 100 and the second power conversion device 200 may transmit and receive one or more state values ​​of the monitoring object 300 through the first communication line L1.

[0065] The second communication line L2 may be configured to perform communication to synchronize the measurement time of the state value. Here, one or more of the first power conversion device 100 and the second power conversion device 200 may transmit a specific signal for synchronizing the measurement time of the state value through the second communication line L2.

[0066] The synchronization signal for matching the measurement time of the status value may include one or more of: a first signal requesting to start measuring the status value; and a second signal indicating the arrival of a preset measurement period.

[0067] When one of the first power conversion device 100 and the second power conversion device 200 sends a synchronization signal to the other through the second communication line L2, the first power conversion device 100 and the second power conversion device 200 can measure the state value of the monitored object 300 immediately after sending and receiving the synchronization signal and exchange the state value through the first communication line L1 to share the state value with each other.

[0068] According to the embodiment of the present invention, the power conversion devices measure state values ​​and exchange data after synchronizing measurement time through the communication channel L2 configured separately from the data communication channel L1, thereby causing no measurement error between the power conversion devices.

[0069] Figure 3 is an operation flow chart of a communication method for a power system according to an embodiment of the present invention.

[0070] Either the first power conversion device or the second power conversion device may send a synchronization signal for synchronizing the measurement time of the state value through the second communication line (S310). Here, the synchronization signal may include one or more of the following: a first signal requesting to start measuring the state value; and a second signal indicating the arrival of a preset measurement cycle.

[0071] Here, the sending entity of the synchronization signal may be predefined.

[0072] For example, the first power conversion device may be preset as a transmission entity, or the second power conversion device may be preset as a transmission entity.

[0073] For another example, if a measurement time point or a measurement period is predefined in each of the first power conversion device and the second power conversion device, the device whose measurement time or measurement period has arrived may send a synchronization signal to the other device.

[0074] After the synchronization signal is sent by the transmitting entity, the first power conversion device and the second power conversion device may each measure a state value of the monitoring object ( S320 ).

[0075] Specifically, when the power conversion device (transmitting entity) that should send a synchronization signal sends a synchronization signal to another power conversion device (receiving entity), the transmitting entity measures the state value immediately after sending the synchronization signal, and the receiving entity can measure the state value immediately after receiving the synchronization signal. In other words, the first power conversion device and the second power conversion device can each measure the state value of the monitored object immediately after sending and receiving the synchronization signal.

[0076] Thereafter, the first power conversion device and the second power conversion device may exchange the state value measured in S320 with each other through the first communication line ( S330 ).

[0077] The first power conversion device and the second power conversion device can use the shared state value to perform a predefined control process or a diagnostic process. Here, the shared state value is a value measured at the same time point, so the reduction of diagnostic accuracy or the loss of power conversion gain can be prevented.

[0078] Figure 4 is an operation flow chart of the communication method of the electric power system according to the first embodiment of the present invention.

[0079] Figure 4 The communication method of the electric power system shown in is an embodiment in which a transmission entity of a synchronization signal is determined to be a first power conversion device and the synchronization signal is defined as a first signal which is a measurement start request signal.

[0080] The first power conversion device set as a transmitting entity may transmit a first signal ( S410 ) to the second power conversion device via a second communication line when a preset measurement time point or measurement cycle thereof arrives. The first signal is a signal requesting to start status value measurement.

[0081] The first power conversion device may measure one or more state values ​​of the monitoring object immediately after transmitting the first signal ( S421 ), and the second power conversion device may measure one or more state values ​​of the monitoring object immediately after receiving the first signal ( S422 ).

[0082] The first power conversion device and the second power conversion device may exchange individually measured state values ​​with each other through the first communication line ( S430 ).

[0083] Thereafter, the first power conversion device may check whether its measurement time point or measurement cycle has arrived.

[0084] When the corresponding measurement time point or measurement period arrives, the first power conversion device may send a first signal to the second power conversion device through the second communication line ( S440 ).

[0085] The first power conversion device may measure one or more state values ​​of the monitoring object immediately after transmitting the first signal ( S451 ), and the second power conversion device may measure one or more state values ​​of the monitoring object immediately after receiving the first signal ( S452 ).

[0086] The first power conversion device and the second power conversion device may exchange individually measured state values ​​with each other through the first communication line ( S460 ).

[0087] The first power conversion device and the second power conversion device may perform communication with each other by repeatedly performing S410 to S430 until the power system is shifted to the stop mode.

[0088] Figure 5 is an operation flow chart of a communication method for a power system according to a second embodiment of the present invention.

[0089] Figure 5 The communication method of the power system shown in FIG. 1 is a method in which the step of sharing the counter value is added to Figure 4 Embodiment of the communication method.

[0090] The first power conversion device determined as the transmitting entity may transmit a first signal to the second power conversion device through the second communication line when its preset measurement time or measurement cycle arrives ( S510 ), where the first signal is a signal requesting to start status value measurement.

[0091] The first power conversion device may measure one or more state values ​​of the monitoring object immediately after transmitting the first signal ( S521 ), and the second power conversion device may measure one or more state values ​​of the monitoring object immediately after receiving the first signal ( S522 ).

[0092] In addition, the first power conversion device may update the previously stored counter value immediately after transmitting the first signal (S523), and the second power conversion device may update the previously stored counter value immediately after receiving the first signal (S524). Here, the counter value may be stored in a storage device of each of the first power conversion device and the second power conversion device, and may have the same value.

[0093] For example, when transmitting and receiving the first signal, the first power conversion device updates the counter value (n) by increasing the counter value (n) stored in its own storage device by 1 (n+1), and the second power conversion device also updates the counter value (n) stored in its own storage device by increasing the counter value (n) stored in its own storage device by 1 (n+1).

[0094] The first power conversion device and the second power conversion device may exchange individually measured state values ​​and counter values ​​through the first communication line ( S530 ).

[0095] Thereafter, the first power conversion device may check whether its measurement time or measurement cycle has arrived.

[0096] When the corresponding measurement time or measurement cycle arrives, the first power conversion device may send a first signal to the second power conversion device through the second communication line ( S540 ).

[0097] The first power conversion device can measure one or more state values ​​of the monitored object immediately after sending the first signal (S551) and update its own counter value (S553), and the second power conversion device can measure one or more state values ​​of the monitored object immediately after receiving the first signal (S552) and update its own counter value (S554).

[0098] The first power conversion device and the second power conversion device may exchange individually measured state values ​​and counter values ​​through the first communication line ( S560 ).

[0099] The first power conversion device and the second power conversion device may perform communication with each other by repeatedly performing S510 to S530 until the power system is shifted to the stop mode.

[0100] According to this embodiment, the first power conversion device and the second power conversion device share the status values ​​measured at the same time point and the counter values ​​managed as the same value, and therefore, the problem of the measurement order of the shared status values ​​being shifted or pushed back can be prevented.

[0101] Figure 6 is an operation flow chart of a communication method for an electric power system according to a third embodiment of the present invention.

[0102] Figure 6 The communication method of the power system shown in is an embodiment in which the state value measurement period of the first power conversion device and the second power conversion device is preset to the same period, the sending entity of the synchronization signal is preset to the device whose measurement period first arrives, and the synchronization signal is defined as a second signal, which is a notification signal of the arrival of the measurement period.

[0103] The first power conversion device and the second power conversion device may each check whether the measurement period has arrived by its own time measurement device (eg, timer).

[0104] When the measurement period of the first power conversion device arrives first ( S610 ), the first power conversion device may transmit a second signal, which is a notification signal of the arrival of the measurement period, to the second power conversion device through the second communication line ( S620 ).

[0105] The first power conversion device may measure one or more state values ​​of the monitoring object immediately after transmitting the second signal ( S631 ), and the second power conversion device may measure one or more state values ​​of the monitoring object immediately after receiving the second signal ( S632 ).

[0106] Here, the second power conversion device that has received the second signal can initialize its own time measurement device (S633) so that its own time measurement device is synchronized with the time measurement device of the first power conversion device. Thereafter, the first power conversion device and the second power conversion device can each check whether the next measurement cycle has arrived through their own time measurement devices.

[0107] The first power conversion device and the second power conversion device may exchange individually measured state values ​​with each other through the first communication line ( S640 ).

[0108] Thereafter, when the measurement period of the second power conversion device arrives first ( S650 ), the second power conversion device may transmit a second signal, which is a notification signal of the arrival of the measurement period, to the first power conversion device through the second communication line ( S660 ).

[0109] The second power conversion device may measure one or more state values ​​of the monitoring object immediately after sending the second signal ( S672 ), and the first power conversion device may measure one or more state values ​​of the monitoring object immediately after receiving the second signal ( S671 ).

[0110] Here, the first power conversion device that has received the second signal can initialize its own time measurement device (S673) so that its own time measurement device is synchronized with the time measurement device of the second power conversion device. Thereafter, the first power conversion device and the second power conversion device can each check whether the next measurement cycle has arrived through their own time measurement devices.

[0111] The first power conversion device and the second power conversion device may exchange individually measured state values ​​with each other through the first communication line ( S680 ).

[0112] The first power conversion device and the second power conversion device may perform communication with each other by repeatedly performing S610 to S640 until the power system is shifted to the stop mode.

[0113] According to this embodiment, even when the power conversion devices are set to the same measurement period, a minute error in measurement timing that may be caused by the time measurement device can be prevented.

[0114] Figure 7 is an operation flow chart of a communication method for an electric power system according to a fourth embodiment of the present invention.

[0115] Figure 7 The communication method of the power system shown in FIG. 1 is a method in which the step of sharing the counter value is added to Figure 6 Embodiment of the communication method.

[0116] The first power conversion device and the second power conversion device may each check whether the measurement period has arrived by its own time measurement device (eg, timer).

[0117] When the measurement period of the first power conversion device arrives first ( S710 ), the first power conversion device may transmit a second signal, which is a notification signal of the arrival of the measurement period, to the second power conversion device through the second communication line ( S720 ).

[0118] The first power conversion device may measure one or more state values ​​of the monitoring object immediately after transmitting the second signal ( S731 ), and the second power conversion device may measure one or more state values ​​of the monitoring object immediately after receiving the second signal ( S732 ).

[0119] In addition, the first power conversion device may update its previously stored counter value immediately after transmitting the second signal ( S733 ), and the second power conversion device may update its previously stored counter value immediately after receiving the second signal ( S734 ).

[0120] Here, the second power conversion device that has received the second signal can initialize its own time measurement device (S735) so that its own time measurement device is synchronized with the time measurement device of the first power conversion device. Thereafter, the first power conversion device and the second power conversion device can each check whether the next measurement cycle has arrived through their own time measurement devices.

[0121] The first power conversion device and the second power conversion device may exchange individually measured state values ​​with each other through the first communication line ( S740 ).

[0122] Thereafter, when the measurement period of the second power conversion device arrives first ( S650 ), the second power conversion device may transmit a second signal, which is a notification signal of the arrival of the measurement period, to the first power conversion device through the second communication line ( S760 ).

[0123] The second power conversion device may measure one or more state values ​​of the monitoring object immediately after sending the second signal (S772) and update its own counter (S774). In addition, the first power conversion device may measure one or more state values ​​of the monitoring object immediately after receiving the second signal (S771) and update its own counter (S773).

[0124] Here, the first power conversion device having received the second signal may initialize its time measurement device ( S775 ).

[0125] The first power conversion device and the second power conversion device may exchange individually measured state values ​​and counter values ​​through the first communication line ( S780 ).

[0126] The first power conversion device and the second power conversion device may perform communication with each other by repeatedly performing S710 to S740 until the power system is shifted to the stop mode.

[0127] The operation of the method according to an embodiment of the present invention can be implemented as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices having data readable by a computer system stored therein. In addition, the computer-readable recording medium can be distributed in a network-connected computer system, so as to store and execute the computer-readable program or code in a distributed manner.

[0128] Although some aspects of the present invention have been described in the context of an apparatus, it can also be represented by a description according to a corresponding method, wherein a block or apparatus corresponds to a method step or a feature of a method step. Similarly, the aspects described in the context of a method can also represent a corresponding block or item or a feature of a corresponding apparatus. Some or all of the method steps can be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps can be performed by such an apparatus.

[0129] In the foregoing, the present invention has been described with reference to exemplary embodiments thereof, but those skilled in the art will appreciate that various corrections and changes may be made to the present invention within the scope without departing from the spirit and scope of the invention described in the appended claims.

Claims

1. A power system comprising: a first power conversion device; a second power conversion device; a first communication line, the first communication line connecting the first power conversion device and the second power conversion device; as well as a second communication line, the second communication line connecting the first power conversion device and the second power conversion device, wherein each of the first power conversion device and the second power conversion device measures one or more state values ​​of a monitoring object and exchanges the measured state values ​​through the first communication line, and One or more of the first power conversion device and the second power conversion device perform communication through the second communication line to synchronize the measurement time point of the state value.

2. The power system according to claim 1, wherein: The second communication line is a line separate from the first communication line. 3 . The electric power system according to claim 1 , wherein either one of the first power conversion device and the second power conversion device is configured to transmit a first signal requesting initiation of state value measurement to the other via the second communication line.

4. The power system according to claim 3, wherein: One of the first power conversion device and the second power conversion device is predefined as a transmission entity of the first signal.

5. The power system according to claim 3, wherein: The first power conversion device and the second power conversion device are configured to transmit the first signal to the other when its own predetermined measurement time arrives.

6. The power system according to claim 3, wherein: the one sending the first signal measures the one or more state values ​​immediately after sending the first signal, the other receiving the first signal measures the state value immediately after receiving the first signal, and The first power conversion device and the second power conversion device share measured state values ​​with each other through the first communication line.

7. The power system according to claim 1, wherein: The measurement cycles of the state values ​​of the first power conversion device and the second power conversion device are predetermined to be the same cycle, and Wherein, either one of the first power conversion device and the second power conversion device is configured to transmit a second signal indicating the arrival of its own measurement period to the other via the second communication line.

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

9. The power system according to claim 8, wherein: the one sending the second signal measuring the state value immediately after sending the second signal, another receiving the second signal measures the state value immediately after receiving the second signal, and The first power conversion device and the second power conversion device share measured state values ​​with each other through the first communication line.

10. The power system according to claim 8, wherein: the one sending the second signal determines, immediately after sending the second signal, by means of its own time measuring means whether the next measuring period has arrived, and Therein, the other one receiving the second signal initializes its own time measuring device immediately after receiving the second signal and determines by means of its initialized time measuring device whether the next measuring cycle has arrived.

11. The power system according to claim 1, wherein: 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 measures the state value, updates a previously stored counter value, and exchanges the state value and the counter value through the first communication line.

12. A communication method in an electric power system, the electric power system comprising a first electric power conversion device and a second electric power conversion device connected to each other via a first communication line and a second communication line, the method comprising: Sending a specific signal for synchronizing the measurement time point of the state value by either one of the first power conversion device and the second power conversion device to the other through the second communication line; measuring one or more state values ​​of a monitoring object by each of the first power conversion device and the second power conversion device; as well as The measured state values ​​are exchanged by the first power conversion device and the second power conversion device via the first communication line.

13. The communication method according to claim 12, wherein: The sending of the specific signal for the measurement time point of the synchronization status value to another comprises: A first signal requesting initiation of measurement of a status value is sent to the other via the second communication line.

14. The communication method according to claim 13, wherein: The sending of the specific signal for the measurement time point of the synchronization status value to another comprises: The first signal is transmitted from one of the first power conversion device and the second power conversion device, whichever is pre-defined as a transmission entity of the first signal, to the other.

15. The communication method according to claim 13, wherein: The sending of the specific signal for the measurement time point of the synchronization status value to another comprises: The first signal is transmitted from either one of the first power conversion device and the second power conversion device, whose own predetermined measurement time point has arrived, to the other.

16. The communication method according to claim 13, wherein: Measuring one or more state values ​​of the monitored object includes: measuring the state value immediately after sending the first signal by any one of the sending the first signal; and The state value is measured by the other device that receives the first signal immediately after receiving the first signal.

17. The communication method according to claim 12, wherein: The measurement cycles of the state values ​​of the first power conversion device and the second power conversion device are predetermined to be the same cycle, and The sending of the specific signal for the measurement time point of the synchronization status value to another device comprises: A second signal indicating the arrival of the measurement period is sent to the other via the second communication line.

18. The communication method according to claim 17, wherein: The sending of the specific signal for the measurement time point of the synchronization status value to another comprises: The second signal is transmitted from one of the first power conversion device and the second power conversion device, the measurement period of which arrives earlier, to the other.

19. The communication method according to claim 18, wherein measuring one or more status values ​​of the monitored object comprises: measuring, by the one sending the second signal, the state value immediately after sending the second signal; as well as The state value is measured by the other device receiving the second signal immediately after receiving the second signal.

20. The communication method according to claim 18, wherein: Measuring one or more state values ​​of the monitored object includes: determining, by the one sending the second signal, immediately after sending the second signal, by its own time measuring device, whether the next measurement period has arrived; and The other device receiving the second signal initializes its own time measuring device immediately after receiving the second signal and determines via its initialized time measuring device whether the next measuring period has arrived.

21. The communication method according to claim 12, wherein: Measuring one or more status values ​​of the monitored object further comprises updating each previously stored counter value, and Wherein exchanging the status value comprises exchanging the status value and the counter value via the first communication line.

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