Method and system for time synchronizing sensor units

Abstract

Method and system for time synchronization of sensor units. Method for time synchronization of sensor units in a distributed system, wherein sensor data is acquired by the sensor units and transmitted to a central unit, wherein, upon acquisition of the sensor data, a further current value of an internal time unit of the sensor unit is stored, wherein the sensor data is at least assigned the value of the internal time unit stored upon receipt of a characteristic signal, the transmitter identification of the characteristic signal and the further value of the internal time unit stored upon acquisition of the sensor data and transmitted to the central unit together with the sensor data, wherein the central unit acquires voltage and phase values of at least one phase conductor as current vectors over more than one measurement cycle and aggregates the current vectors to an aggregated current vector and transmits the aggregated current vector to the central unit and calculates the power from the voltage values and the aggregated current vector.

Description

Technical Field

[0001] This invention relates to a method and system for time synchronization of sensor units in a distributed system. Background Technology

[0002] In power distribution infrastructure, such as smart DC and AC distribution networks (i.e., "smart grids"), information about the state of the grid, such as voltage levels, current load, power flow, and load distribution, is collected and determined through data from numerous distributed sensors.

[0003] To monitor and control the power grid, this sensor data is typically transmitted and centrally evaluated.

[0004] Depending on the type of sensor and the method of centralized evaluation of sensor data, sensor values ​​and acquisition time points are important for the evaluation so that, for example, active and reactive power can be calculated based on voltage and current measurements, which may be transmitted by different sensors that may be spatially dispersed.

[0005] In particular, the accurate timing of measurement acquisition and the relationship between them are crucial for determining active and reactive power or complex apparent power.

[0006] In the prior art, time synchronization is achieved through a wired communication connection between the sensor and the evaluation unit, or the voltage measurement value is transmitted as an analog measurement signal to each current measurement sensor via a wired connection.

[0007] As a wireless alternative, it is known to use an additional time synchronization source provided via a radio connection at each sensor, such as a GPS clock, a radio time standard transmitter (such as the longwave transmitter DCF77), or a central NTP reference time server (“Network Time Protocol”, or NTP for short).

[0008] The disadvantage of wired communication solutions is the need for data cables, which may increase installation workload and reduce user acceptance. This can be a significant cost and system complexity factor, especially when retrofitting sensors.

[0009] A drawback of radio time synchronization sources is the limitation on antenna installation location.

[0010] Therefore, receiving GPS / DCF77 / mobile radio time signals, for example, in an enclosed space, is very difficult or even impossible.

[0011] In addition, DCF77 or similar time information services are not accurate enough and are only available in specific areas.

[0012] In addition, such solutions result in undesirable system complexity, stringent installation requirements, and increased costs due to the need for additional radio receivers and associated antennas.

[0013] In the announcement document EP3993290B1, a method for time synchronization of sensor units in a distributed system is described. This method can establish a time relationship between the sensor data collected by the sensor units in the distributed system. However, the internal signal transit time is not considered during signal acquisition, which will adversely affect the accuracy of power consumption determination in the energy distribution network.

[0014] In existing technologies, another problem arises when sensors transmit the collected current or voltage data through shared media, such as wireless networks with limited transmission capabilities (e.g., Bluetooth, Bluetooth Low Energy (BLE), ZigBee, etc.).

[0015] The problem here may be that the total amount of data generated by the individual current or voltage samples from dozens of such sensors is too large for the transmission medium.

[0016] In existing technologies, the solution to the problem of massive measurement data is to calculate the effective values ​​of current and / or voltage within a certain measurement period in the distributed sensors and transmit them to the evaluation unit, rather than transmitting the individual sample values ​​of these sensors.

[0017] The disadvantage of this method, which calculates the effective values ​​of AC current and / or AC voltage separately in a spatially dispersed manner, is that it loses information about the phase of the AC current in the conductor relative to the relevant AC voltage. As a result, it is impossible to calculate the active and reactive power, which is crucial for monitoring load flow in AC distribution networks. Summary of the Invention

[0018] Therefore, the purpose of this invention is to provide a simpler, more efficient, accurate and reliable solution for transmitting sensor data from distributed sensors.

[0019] The purpose of this invention is achieved through a method for time synchronization of sensor units in a distributed system. Each of these sensor units has an internal time unit, and These sensor units collect sensor data and transmit it to the central unit via a wireless network. In this radio network, characteristic signals are transmitted at regular time intervals. The reception of this characteristic signal is monitored in the corresponding sensor unit. Specifically, upon receiving the characteristic time feature of the feature signal, the current value of the internal time unit of the corresponding sensor unit is stored together with at least one transmitter identifier contained in the feature signal. Specifically, when acquiring sensor data, another current value of the internal time unit of the corresponding sensor unit is stored. Specifically, the acquired sensor data is assigned at least the value of an internal time unit stored when the characteristic time feature of the received feature signal is received, the associated transmitter identifier of the feature signal, and another value of the internal time unit stored when the sensor data is acquired, and these values ​​are transmitted to the central unit along with the sensor data. Specifically, based on the transmitter identifier, a reference time base is derived. Furthermore, based on the value of the internal time unit of the corresponding sensor unit stored when the characteristic time feature of the signal is received, and another value of the internal time unit of the corresponding sensor unit stored when the sensor data is acquired, the time relationship between the sensor data transmitted by the corresponding sensor unit and the reference time base is derived. The central unit collects the voltage and phase values ​​of at least one of the three phase conductors of the energy supply network as a voltage vector, with a collection period equal to one or more fundamental oscillation periods of the voltage. The sensor data is aggregated into a current vector as the current vector of the corresponding sensor unit, and the aggregated current vector, instead of the sensor data, is transmitted to the central unit. In the central unit, the power is calculated in a phase-corrected manner based on the voltage value and the aggregated current vector.

[0020] Thus, it is advantageous to achieve that these current vectors are combined with their complex values ​​and that data reduction is performed in the transmission channel from the sensor unit to the central unit.

[0021] Therefore, the amount of data transmitted from the corresponding sensor unit to the central unit can be reduced, and the transmission channel can be used more efficiently.

[0022] The aggregation of AC current vectors or AC voltage vectors allows for a significant reduction in the amount of measurement data that needs to be transmitted from multiple sensor units to a central unit in a distributed measurement system.

[0023] Nevertheless, the average active and reactive power can be calculated with sufficient accuracy for load flow monitoring in AC distribution networks.

[0024] This enables the use of energy-efficient wireless communication technology, which is particularly advantageous for solutions that recover local energy from the current in each phase conductor.

[0025] After receiving the complex AC current vector or aggregate value, taking into account its distribution to the corresponding phase voltage, the complex AC current vector or aggregate value can be directly adopted or rotated ±120°, and then multiplied by the magnitude of the associated, i.e., the corresponding phase voltage, in order to calculate the active and reactive power in a phase-corrected manner.

[0026] Aggregate values ​​are understood as a mapping of multiple measurements to a single value, such as by averaging, especially averaging multiple current and / or voltage vectors, from which aggregate current or voltage vectors are generated by averaging.

[0027] The phase correction calculation for power is understood as: making the voltage and current from multiple phase lines reach the corresponding phase before the multiplication, that is, being rotated or transformed by ±120° in the corresponding direction.

[0028] Clearly, in the central unit, power is calculated based on the voltage value or its (aggregated) voltage vector value and aggregated current vector.

[0029] Therefore, power phase correction calculation can refer to power calculation considering the transformation of each phase of the (aggregate) current vector relative to the selected reference voltage phase.

[0030] In other words, the voltages and currents from multiple phase lines must reach a certain phase so that they have the same relationship with the relevant voltage vector relative to the X-axis of a 2D Cartesian coordinate system, in which the relevant complex-valued current and voltage vectors are shown, such as... Figure 1 , Figure 2 and Figure 3 The figure is shown in the middle.

[0031] This transformation can be performed in two different variations: a) A voltage vector is specified as a reference voltage, which determines the coordinate system for all voltage and current vectors, and the coordinate system is determined synchronously not only in the central unit but also in the sensor units. In this case, the direction and orientation of the reference voltage vector correspond to the X-axis of the Cartesian coordinate system, and both the voltage vector and the current vector reference the same coordinate system determined by the current reference voltage vector, thus eliminating the need for rotation. When a new reference voltage vector is specified, the direction and orientation of the X and Y axes of the Cartesian coordinate system will change accordingly, i.e., rotate. In this case, the voltage vector and the current vector still reference the same coordinate system, and therefore there is no need for rotation. However, the voltage vector and current vector, as complex values, are presented in different ways in the previous coordinate system and the rotated coordinate system, and can have different complex values. b) Each of the three voltage vectors—preferably phase voltage vectors—forms its own coordinate system, and only requires rotating the current vector belonging to the corresponding voltage vector by + / - 120°, which is not currently the reference voltage vector or has been rotated by + / - 120° from the reference voltage vector.

[0032] The rotation of the alternating current vector, which is a vector, can be done, for example, by multiplying it by a so-called rotation matrix, which is determined in Cartesian coordinates by its complex value.

[0033] Therefore, the aggregated alternating current vector can be transmitted from the sensor unit to the central unit via a radio connection, along with: the timestamp of the sensor unit, the corresponding number of the first fundamental oscillation period of the reference voltage within the measurement period, and optionally, the numbers of the current measurement period p and / or the previous measurement periods p-1, p-2.

[0034] After receiving this data, the relevant, synchronously acquired complex aggregated AC current vector can be rotated by a corresponding angle of 120° in the corresponding direction in the central unit in order to obtain the correct phase reference for the corresponding phase voltage or the reference voltage of the sensor unit.

[0035] Then, the rotated aggregated AC current vector can be multiplied by the magnitude of the (aggregated) effective value of the phase voltage to obtain the average value of active and reactive power, which corresponds to variant b above.

[0036] Alternatively, the complex aggregated AC current vector may be conjugated and multiplied by the associated complex aggregated AC voltage vector to obtain the average of active and reactive power, corresponding to variant a above).

[0037] Therefore, in order to reduce the amount of measurement data to be transmitted, the current vector can be averaged as a complex value over the measurement period and can be stored as an aggregated complex AC current vector.

[0038] In an extended embodiment of the invention, it is specified that, taking into account the corresponding magnitudes of the current vectors and incorporating the phase values, these current vectors are aggregated by averaging over the measurement period, for example, by averaging the real and imaginary parts of the complex values ​​of these current vectors separately.

[0039] Thus, aggregation can be achieved in a simple way, and this aggregation can be performed at the sensor unit with minimal computational complexity.

[0040] In an extended embodiment of the invention, it is specified that these current vectors are aggregated by averaging over the measurement period, taking into account the corresponding internal time units of the respective sensor units.

[0041] Thus, alternative aggregation can be achieved in a simple way, which can be performed by the sensor unit with minimal computational complexity.

[0042] In an extension of the invention, it is specified that the aggregation of current vectors only considers those periods in which the values ​​of these current vectors are within predefined limits.

[0043] This improves the accuracy and reliability of the measurements used in subsequent power calculations.

[0044] Therefore, during the aggregation process within the measurement period, only the measured effective current vector is used.

[0045] For example, current vectors that are distorted due to interference pulses or energy recovery phases are not included in the aggregation within the measurement period.

[0046] In this case, the effective duration of aggregation within the measurement period, or the effective current vector used for aggregation, constitutes a fragmented set.

[0047] The period of time during which the current is disturbed due to energy recovery in the sensor unit can be reported by the power supply unit within the sensor unit and excluded from the aggregation, which may lead to further fragmentation of the aggregation.

[0048] In an extended embodiment of the invention, it is specified that the aggregated current vector is transmitted from the corresponding sensor unit to the central unit.

[0049] In an extended embodiment of the invention, it is specified that the current vector is determined within one or more fundamental oscillation cycles of the reference (phase) voltage, i.e., within one or more voltage cycles of one of the three phases of the energy supply network, preferably from at least ten cycles, and particularly preferably from at least 100 cycles.

[0050] Thus, efficient aggregation can be achieved in a simple way, which can be performed by the sensor unit with minimal computational complexity.

[0051] In an extended embodiment of the invention, it is specified that: a central unit acquires the voltage and phase values ​​of at least one of the three phase conductors of the energy supply network; based on these voltage and phase values, it determines synchronization data regarding the frequency or period duration and the phase of the voltage of at least one of the three phase conductors relative to the acquisition time point of the voltage and phase values ​​of at least one of the three phase conductors; and transmits this data to a sensor unit. The corresponding sensor units acquire corresponding sensor data in the form of current values ​​associated with these synchronous data, wherein these sensor data are transmitted to the central unit, and the power is calculated in the central unit based on the voltage and current values.

[0052] Thus, synchronous power measurement is achieved by means of radio-based current measurement sensors and a common central voltage acquisition unit. This allows for flexible and efficient subsequent installation and expansion of the equipment for monitoring power distribution networks without increasing wiring work.

[0053] Synchronous measurement of the power of power-consuming electrical systems allows for particularly accurate measurements in a simple manner.

[0054] Clearly, in the central unit, power is calculated based on voltage and current values, taking into account their corresponding phases.

[0055] This is achieved by measuring voltage in the energy supply network at only one location, while current is collected at multiple dispersed locations.

[0056] In practice, this requires less work than additionally sampling voltage at dispersed locations because the required protection costs are higher and overvoltage issues must be addressed separately.

[0057] Furthermore, no additional synchronization source or additional wiring is required for the aforementioned distributed active and reactive power measurements.

[0058] For example, synchronization can be achieved by coordinating the time base of the dominant timer in the central unit with the corresponding follower time base of the corresponding sensor unit.

[0059] The current flowing through the sensor unit can also be used to power the sensor unit, which allows for particularly simple and low-maintenance integration into existing systems.

[0060] Under characteristic signals, for example, the synchronization frames of messages, especially the messages themselves, can be applied to multiple receivers (“multicast”).

[0061] In at least one or all sensor units, during the current measurement cycle, the zero-crossing time of the reference voltage is synchronously determined in the central unit based on the transmitted zero-crossing value and cycle duration, as well as the optional value of the zero-crossing point of the previous cycle. Furthermore, based on the AC current value, a current vector is first generated for each individual voltage fundamental oscillation cycle within the current measurement cycle.

[0062] In an extended embodiment of the invention, it is specified that: by transmitting the time point from the central unit to the corresponding sensor unit, synchronous data related to the phase of the acquisition time point of the voltage and phase value of at least one of the three phase conductors relative to the voltage and phase value of at least one of the three phase conductors is generated.

[0063] Therefore, synchronization data used to compensate for delays can be determined and transmitted in a particularly simple way.

[0064] In an extended embodiment of the invention, it is specified that these synchronization data are transmitted to these sensor units by means of the characteristic signal.

[0065] Therefore, synchronization data used to compensate for delays can be transmitted in a particularly simple way, or the adjustment of the time base can be performed in the sensor unit.

[0066] In an extended embodiment of the invention, it is specified that these synchronization data are determined over one or more cycles of the voltage and phase values ​​of the three phases of the energy supply network, preferably over at least ten cycles, and particularly preferably over at least 100 cycles.

[0067] This results in less load on the radio channel, less data transmitted, and still sufficient accuracy when performing power measurements in the energy supply network.

[0068] In an extended embodiment of the invention, it is specified that: the central unit acquires the voltage and phase values ​​of the phase conductors of the power supply network, and acquires first supplementary synchronization data regarding the time delay when transmitting the characteristic signal, the time delay being acquired in the previous time period before the current time period, in the current time period, the synchronization data is acquired, and preferably by means of the characteristic signal, the first supplementary synchronization data is transmitted to the corresponding sensor unit, and the corresponding sensor unit takes the first supplementary synchronization data into account when acquiring the corresponding sensor data.

[0069] Therefore, measurement accuracy can be improved in a simple way.

[0070] Furthermore, synchronization data used to compensate for delays can be determined and transmitted in a particularly simple way.

[0071] The first supplementary synchronization data is the time delay value from the previous measurement cycle.

[0072] First, synchronous data is transmitted in the form of zero-crossing time points in the central control unit and period durations in the phase conductors.

[0073] Only after this, at the start of the next subsequent measurement cycle, is the acquired transmission delay of the synchronization frame transmitted retroactively.

[0074] The aforementioned phase conductors of the energy supply network are the selected reference conductors for these three phase lines, and these reference conductors are regarded as the phase references for the other phase conductors.

[0075] In an extended embodiment of the invention, the central unit further comprises an internal central time unit, the value of which constitutes second supplementary synchronization data. Preferably, this second supplementary synchronization data is transmitted to the corresponding sensor unit by means of a feature signal, and the corresponding sensor unit takes this second supplementary synchronization data into account when acquiring the corresponding sensor data.

[0076] Therefore, measurement accuracy can be improved in a simple way.

[0077] Furthermore, synchronization data used to compensate for delays can be determined and transmitted in a particularly simple way.

[0078] According to the purpose of the invention, a distributed system for time synchronization of sensor units is also provided, which further includes a central unit, wherein the system is configured to perform the method according to the invention. Attached Figure Description

[0079] The invention will be described in more detail below with reference to embodiments in the accompanying drawings. In the drawings: Figures 1-3 An example is shown of adjusting the phase of a voltage or current vector to a reference phase line and its reference voltage; Figure 4 An example of an energy distribution network is shown; Figure 5 The first embodiment of the present invention is shown in the form of a block diagram; Figure 6 A second embodiment of the present invention is shown in the form of a block diagram; Figure 7 The third embodiment of the present invention is shown in the form of a block diagram; Figure 8 A detailed view of the central unit of the present invention is shown; Figure 9 An example of a signal curve in an energy distribution network is shown. Detailed Implementation

[0080] Figure 1An example of voltage vectors in an energy supply network that are 120° out of phase with each other is shown.

[0081] Figure 2 An example of voltage and current vectors for an energy supply network is shown.

[0082] These voltage vectors are 120° relative to each other. The phase of ), where the first voltage vector U 1 is selected as the reference voltage U on the X-axis of the graph. REF .

[0083] These current vectors have phase relative to the corresponding assigned voltage vectors. 1. 2. 3. This is due to the different loads on the phase lines.

[0084] Figure 3 An example of voltage and current vectors for an energy supply network is shown.

[0085] These voltage vectors are 120° out of phase with each other, wherein the second voltage vector... U 2 was selected as the reference voltage U that is not on the X-axis of the graph. REF .

[0086] Figure 4 An example of an energy supply network in the form of a "single-line" circuit diagram is shown.

[0087] Here, these lines represent 3-wire, 4-wire, or 5-wire connections for each branch in the low- and medium-voltage range (commonly named L1, L2, L3 or L1, L2, L3, PEN / E or L1, L2, L3, N and PE / E).

[0088] The sensor unit and / or central unit can be installed in each of the above-mentioned conductors and can be installed in the medium voltage branch / range.

[0089] In a so-called local power plant, high voltage is converted to low voltage range LV by means of one or more transformers TR.

[0090] The central unit is connected to the corresponding assigned sensor units via corresponding wireless networks N1 and N2, which are controlled by correspondingly assigned network control devices NC1 and NC2.

[0091] The sensor unit is used to collect the current in the phase conductors of each branch leading to the final power consumer.

[0092] In a sensor unit installed as an NH fuse group or, for example, in a medium-voltage line / branch, a current vector, i.e., the complex value of the corresponding current, is acquired as a current value or sensor data. Optionally, for the determined current, an average value is calculated and transmitted.

[0093] So-called time-synchronized current vectors can be applied, which are acquired synchronously with the voltage vector at a specific point in time.

[0094] For current, you can use the average value of the current vector, the current value / amplitude, or the effective value of the current, because the average value of alternating current is usually close to zero.

[0095] In the central unit, voltage vectors, i.e., the complex values ​​of the corresponding voltages, are collected as voltage values. Optionally, for the determined voltage, the average value is calculated.

[0096] So-called time-synchronized voltage vectors can be applied, which are acquired synchronously with the current vector at a specific point in time.

[0097] For voltage, you can use the average value of the voltage vector, the voltage value / amplitude, or the effective value of the voltage, because the average value of AC voltage is usually close to zero.

[0098] In the central unit, the average current vector of one or more sensor units is received via short-range radio communication (such as "Zigbee" or Bluetooth).

[0099] With the relevant average voltage vector incorporated, the active and reactive power P and Q in the corresponding phase line are calculated in the central cell.

[0100] The current or voltage vector is understood as the corresponding complex value, that is, the magnitude and phase value of the current or voltage.

[0101] Figure 5 The first embodiment of the present invention is shown in the form of a block diagram.

[0102] The central unit (CU) includes a reference phase transmission device (PHU), which is used for: • Identify zero crossings in the voltage curve; • Calculate the voltage with amplitude and phase information, i.e., the voltage vector; • For the corresponding reference voltage U selected from the grid voltages u1, u2, u3, preferably phase voltages REF_H1 The measurement period p is used for counting; • Determine the reference conductor LREF from the grid phase conductors L1, L2, and L3 of the energy supply network; • Voltage vector of grid voltageU 1. U 2. U The phase sequence of the grid voltages u1, u2, and u3 is determined by the form 3.

[0103] The following period can be regarded as the measurement period p, which can also last for more than one grid voltage cycle, which can also be called the voltage fundamental oscillation cycle. These voltage fundamental oscillation cycles are then counted accordingly.

[0104] Voltage fundamental frequency oscillation usually refers to the first harmonic of the grid voltage, or simply the "H1" of the grid voltage.

[0105] Data from the reference phase transmission device PHU is distributed to the high-frequency module RF_M via a transmitter or receiver UART in the central unit CU or via an internal interface (such as a serial interface) in the central unit.

[0106] Reference voltage U REF_H1 The zero-crossing interrupt signal IS is provided to the reference signal transmitter REF_TX within the high-frequency module RF_M, which in turn obtains the time delay Δt from the central oscillator OSC1 and the connected master counter device LC. EGS Information.

[0107] The time delay Δt at the start of measurement period p EGS It is at time point t0 when the interrupt signal IS is activated. EGSp That is, the reference voltage U REF_H1 The zero-crossing time point and the time point t when the synchronization frame MAC_SYNCF is transmitted to the corresponding sensor unit SU. EGS_SYNCp The delay between them.

[0108] These two time points t0 EGSp and t EGS_SYNCp and the delay Δt EGS In the high-frequency module RF_M, the timing information t is based on the oscillator OSC1 and the connected master counter device LC. EGS To determine.

[0109] Transmitted in the synchronization frame MAC_SYNCF: Regarding the period duration T p-1 The information includes, for example, the estimated current voltage period, which is determined based on, for example, the last 10 to 30 voltage periods of the previous measurement period p-1; and the time delay Δt. EGSp-1 This time delay is determined at the start of the previous measurement cycle p-1, but after the transmit synchronization frame MAC_SYNCF; and at the activation point t0 of the interrupt signal IS. EGSp That is, the reference voltage UREF_H1 The zero-crossing time point is used as the value from the master counter LC.

[0110] The transmission of the characteristic signal or SYNC frame MAC_SYNCF implicitly corresponds to time point t. EGS_SYNCp = t0 EGSp +Δt EGSp .

[0111] In this embodiment, regarding the time delay Δt EGSp The information is only formed after the transmission of the synchronization frame MAC_SYNCF, and is transmitted to the corresponding sensor unit SU at the beginning of the measurement period p+1 using the next synchronization frame MAC_SYNCF.

[0112] Only then, that is, after one measurement cycle, can the time delay Δt of cycle p be compensated. EGSp .

[0113] The high-frequency module RF_M also provides a computing unit CALC for calculating active and reactive power P and Q based on the corresponding voltage / voltage vector and current / current vector.

[0114] Synchronization information is wirelessly transmitted to one or more sensor units SU via a high-frequency transmission link RF_L, and the collected sensor data is transmitted from the sensor unit SU to the central unit CU, for example in the form of “unicast” data transmission UC_D, as described in more detail below.

[0115] The sensor units SU are local control devices used to acquire data through corresponding sensor devices.

[0116] The high-frequency transmission link RF_L can use the MAC layer-based synchronization frame "multicast" to transmit the synchronization frame MAC_SYNCF.

[0117] The sensor unit SU has a time delay Δt in the high-frequency transmission link RF_L. RF_L The compensation device DCOMP, the local oscillator OSC2, and the connected follower counter device FC provide time information t. 3NA .

[0118] Time delay Δt RF_L The time delay in the receiver within the sensor unit SU up to the compensation device DCOMP is also taken into account.

[0119] Time t 3NA It is the local value of the follower counter FC in the local control device (i.e., sensor unit SU).

[0120] In the sensor unit SU, the current vector is acquired and compared with the reference voltage U in the central unit CU. REF_H1 Zero-crossing synchronization.

[0121] After compensating for the time delay of the high-frequency transmission link RF_L in the compensation device DCOMP, at the receiving time point t0 of the synchronization frame MAC_SYNCF at the beginning of measurement periods p and p+1. 3NAp and t0 3NAp+1 Corresponding to the corresponding launch time point t in the central unit CU EGS_SYNCp and t EGS_SYNCp+1 .

[0122] Based on the time point t0 transmitted at the beginning of the measurement period p EGSp and the time point t0 transmitted at the start of measurement period p+1 EGSp+1 And regarding the time delay Δt EGSp and period duration T p In the sensor unit SU, the reference voltage U is first estimated. REF_H1 zero-crossing time point t0 EGSp+1 , as time point t0 EGSp+1 * = t0 3NAp + t0 EGSp+1 - t0 EGSp - Δt EGSp This time point corresponds to the time point t0 of the follower counter FC in the sensor unit SU in the central unit CU. EGSp+1 The estimated value.

[0123] Then, the reference voltage U REF_H1 The zero-crossing point of the next cycle is determined as time t0. 3NAi+101 =t0 EGSp+1 * + T p .

[0124] The time representation with index * is an estimate and corresponds to the follower counter FC.

[0125] The time with index 3NA corresponds to the time in the sensor unit SU and is generated by the follower counter FC.

[0126] The time with index EGS corresponds to the time in the central unit CU and is generated by the master counter LC.

[0127] The actual current measurement or current vector determination in the measurement period p+1 begins at time point t0 in the sensor unit SU. 3NAi+101 .

[0128] Sensor data SD is acquired by sensor unit SU in the form of current value I, processed and calculated as current vector value, and then optionally transferred to aggregation device AGG for processing.

[0129] Sensor data SD could be, for example, the AC current value of a primary current in an energy supply network.

[0130] Aggregation can be understood as averaging multiple measurements, such as multiple AC current cycles within a measurement period, where other statistical methods may also be suitable for mapping measurements.

[0131] In the synchronization frame or frame MAC_SYNCF, information about its transmission time point is expressed as the difference in counter readings Δt. EGSP The voltage curve U from the previous cycle p-1 is transmitted to the sensor unit SU via multicast. REF_H1 Period duration T p-1 and the activation time point t0 of the interrupt signal IS EGSp That is, the reference voltage U REF_H1 The zero-crossing time point, which is taken as the value t0 from the dominant counter LC. EGSp .

[0132] The sensor unit SU transmits information about the acquired sensor data SD via unicast, in the form of a complex current vector with index p. I H1p The form of the value, and the current vector I H1p Depending on whether the implementation is a single value or an aggregated value, it is transmitted to the central unit (CU).

[0133] In the central unit CU, a voltage vector is generated for each cycle i (fundamental oscillation) of the three-phase grid AC voltages u1, u2, and u3. U1 i , U2 i and U3 i .

[0134] Optionally, voltage vectors can also be aggregated.

[0135] Voltages u1, u2, and u3 can be, for example, voltages on phase conductors L1, L2, and L3 of an energy supply network.

[0136] Choose one of these voltages, such as u1, as the reference voltage U. REF_H1 .

[0137] For example, including a reference voltage U REF_H1 For each measurement period p of 100 fundamental oscillation cycles, the reference voltage U is determined.REF_H1 The zero-crossing time point t0 EGSp The zero-crossing time point and the reference voltage U REF_H1 The first fundamental oscillation period begins with phase synchronization, and this involves a time t in the form of a dominant counter LC present in the central unit CU. EGS A microsecond counter.

[0138] The zero-point time t0 EGSp This refers to the current point in time within the central control device, while the zero-crossing time point t0... EGSp-1 It refers to the first zero-crossing point of the previous measurement cycle.

[0139] Additionally, determine the current grid voltage cycle duration T. p .

[0140] Alternatively, the reading Δt from the differential counter can also be determined. EGSP-1 For example, the counter reading Δt in the previous measurement cycle p-1 is used as the form. EGSP-2 and period duration T p-2 The value (not shown in the figure) is transmitted to the sensor unit SU at the time of the characteristic signal, namely the so-called SYNC frame MAC_SYNCF, as additional information.

[0141] Time point △t EGSP-1 Used to correct the time synchronization between the central unit CU and at least one sensor unit SU within the current measurement cycle p.

[0142] Except for the midnight time point t0 EGSp Period duration T p and the optional counter reading difference Δt EGSP-1 In addition, this characteristic signal either introduces the synchronization frame or "SYNC frame" MAC_SYNCF at the beginning of the measurement period p, or the number of the measurement period p itself, and the reference voltage U in that measurement period. REF_H1 The number i of the first fundamental oscillation period and the network source address of the central unit CU, which is used as the transmitter identifier in the SYNC frame MAC_SYNCF.

[0143] The measurement period is defined based on a fundamental oscillation period counter, for example, in the form of time units.

[0144] In at least one or all sensor units SU, within the measurement period p, based on the zero-crossing time point t0 transmitted in the central control unit CU. EGSp and t0 EGSp-1 The value of the current period duration T p and time delay △t EGSP-1The selectable offset time point synchronously determines the reference voltage U in the central unit CU. REF_H1 The zero-crossing time points, where these time points correspond to the values ​​of the corresponding dominant counter LC.

[0145] Based on sensor data SD expressed as alternating current values, a current vector is generated for each individual harmonic cycle i within the measurement period p. I H1 i And it is either alone or as a current vector aggregated within the measurement period p. I H1 p The sensor data is transmitted to the central unit (CU) in a sensor data frame containing sensor data (SD).

[0146] Within the same sensor data frame, for example, the timestamp t of the corresponding sensor unit SU can also be included. 3NA The reference voltage U during the measurement period p REF_H1 The number i of the first fundamental oscillation period, and optionally, the number of the current measurement period p and / or the previous measurement period p-1, p-2.

[0147] After receiving the sensor data SD in the central unit CU, the relevant, synchronously acquired voltage and current vectors are used to calculate the active and reactive power values ​​P. p and Q p .

[0148] In other words, in Figure 5 In this embodiment, the transmission time of the SYNC frame MAC_SYNCF is provided by the reference signal transmitter REF_TX as the start of the SYNC frame “header” MAC_SYNCF, and additionally as the counter reading (difference) of the counter LC of the central unit CU, preferably corresponding to a time resolution in the microsecond range.

[0149] Therefore, in the subsequent SYNC frame MAC_SYNCF, the transmission passes through zero point t0. EGSp As the start of the synchronization frame MAC_SYNCF and as the zero-crossing time point t0 EGSp The current counter reading is transmitted, and the difference Δt between the counter readings between the previous reference zero-crossing point and the previous transmission time point is transmitted. EGSp-1 .

[0150] Therefore, in the current embodiment, the signal transit time is corrected in the corresponding sensor unit SU at the beginning of the current measurement period p by using the zero-crossing point t0 from the previous SYNC frame MAC_SYNCF of the measurement period p-1. EGSp-1, and the zero-crossing point t0 from the current measurement period p in the currently received SYNC frame MAC_SYNCF. EGSp and launch delay Δt EGSP-1 .

[0151] When performing compensation in DCOMP, a time delay Δt can be considered. RF_L However, this time delay is very small and can be ignored for the sake of simplicity.

[0152] Therefore, in this case, two consecutive SYNC frames are always required to determine the reference voltage U in the sensor unit SU. REF_H1 The point crossing zero.

[0153] Therefore, the first embodiment can also be described as follows.

[0154] The method for time synchronization of sensor units in a distributed system is used to determine reactive and active power in a central unit CU using at least one sensor unit SU, and is based on the synchronization of the zero-crossing point of the reference voltage between the central unit CU and the sensor unit SU, i.e., between the first dominant counter LC of the central unit CU having a first central oscillator OSC1 and the second follower counter FC of the corresponding sensor unit SU having a second local oscillator OSC2.

[0155] Here, the start time point and subsequent time curves used to calculate the current vector in the sensor unit SU are synchronized with the zero-crossing time point of the voltage fundamental oscillation.

[0156] This corresponds to time synchronization between the central unit CU and the sensor unit SU, i.e., the time base t of the dominant timer or counter LC within the central unit CU. EGS The corresponding follower time base t of the internal dominant counter FC of the corresponding sensor unit SU 3NA Coordination between them.

[0157] This does not have to be an absolute clock time, but can involve the fundamental oscillation period of each voltage and / or the clock period of the corresponding counters LC, FC.

[0158] These sensor units SU each have an internal time unit FC, wherein these internal counters serve as time units, which are based on numbered grid voltage cycles and / or in microsecond-based time units (t). 3NA (To generate the time base)

[0159] These sensor units SU periodically acquire sensor data SD in the form of a current vector with a specified time resolution of, for example, 1 microsecond, and / or assign it a grid voltage cycle number, and transmit it to the central unit CU via a radio network RL_L.

[0160] In a radio network or on a high-frequency transmission link RF_L, a characteristic signal is transmitted at regular time intervals, such as transmitting a SYNC frame MAC_SYNCF from the central unit CU to the corresponding sensor unit SU every two seconds.

[0161] The reception of the characteristic signal SYNC frame MAC_SYNCF is monitored in the corresponding sensor unit SU.

[0162] Upon receiving a characteristic timestamp of a feature signal, the current value of the internal time unit FC of the corresponding sensor unit SU is stored together with at least one transmitter identifier contained in the feature signal. That is, the data contained therein, such as the source address and / or authentication data of the RF module RF_M in the central unit CU; the characteristic time features contained therein, such as timestamps, time delay information, the number of the corresponding grid voltage cycle, etc.; and the current value of the corresponding sensor unit SU's own time unit, such as the received timestamp from the SYNC frame MAC_SYNCF.

[0163] When acquiring sensor data SD, another current value of the internal time unit FC of the corresponding sensor unit SU is stored. For example, the current timestamp of the time unit of the corresponding sensor unit SU and the number of the corresponding power grid voltage cycle are assigned respectively, and stored together with these sensor data SD.

[0164] Therefore, the zero crossing is synchronized to the local time unit in the sensor, where it is only necessary to reproduce the zero crossing in the sensor as accurately as possible, and there is no need to refer to the time unit in the central unit.

[0165] The acquired sensor data SD is assigned at least the value of the internal time unit FC stored when the characteristic time feature of the received feature signal is received, the corresponding transmitter identifier of the feature signal MAC_SYNCF, and another value of the internal time unit stored when the sensor data SD is acquired, and these are transmitted together with the sensor data SD to the central unit CU.

[0166] This can be achieved through data messages transmitted by the corresponding sensor unit SU to the central unit CU. The data message contains the number of the grid voltage cycle involved in the measurement data, the relevant address of the central unit CU, i.e. the transmitter identifier sent to the central unit as a characteristic signal, and the current timestamp of the time unit of the corresponding sensor unit SU, which is assigned when the data is acquired.

[0167] Based on the transmitter identifier, a reference time base is derived, and based on the value of the internal time unit FC of the corresponding sensor unit SU stored when the characteristic time feature of the characteristic signal is received and another value of the internal time unit FC of the corresponding sensor unit SU stored when the sensor data SD is acquired, the time relationship between the sensor data SD transmitted by the corresponding sensor unit SU and the reference time base is derived, for example, based on the corresponding power grid cycle number and / or the timestamp contained therein in the received data message.

[0168] The central unit (CU) acquires the voltage and phase values ​​of at least one of the three phase conductors of the energy supply network. Based on these voltage and phase values, it determines synchronization data t0 regarding the frequency or period duration and the phase of the voltage of at least one of the three phase conductors relative to the acquisition time point of the voltage and phase values ​​of at least one of the three phase conductors. EGSp And Tp, and transmit it to the sensor unit SU.

[0169] The corresponding sensor unit SU collects corresponding sensor data SD in the form of current value, which is synchronized with the synchronization data t0. EGSp and T p Relatedly, this sensor data is transmitted to the central unit (CU).

[0170] In the central unit (CU), power, especially active and reactive power, is calculated based on voltage and current values.

[0171] By transmitting the SYNC frame MAC_SYNCF from the central unit CU to the corresponding sensor unit SU at the time point, synchronization data t0 is generated that is phase-dependent with respect to the acquisition time point of the voltage and phase values ​​of at least one of the three phase conductors relative to the voltage and phase values ​​of at least one of the three phase conductors. EGSp .

[0172] Synchronize data t0 EGSp T p It can be transmitted to the sensor unit SU using the characteristic signal MAC_SYNCF.

[0173] These synchronized data t0 EGSp T pThe voltage and phase values ​​of the three phases of the energy supply network can be determined within one or more cycles, preferably from at least ten cycles, and particularly preferably from at least 100 cycles.

[0174] The central unit (CU) can also collect the voltage and phase values ​​of the phase lines of the energy supply network, as well as the first supplementary synchronization data Δt. EGSp-1 It was collected in the previous time period before the current time period. In the current time period, the synchronous data t0 is collected. EGSp T p .

[0175] These first supplementary synchronization data △t EGSp-1 It can be transmitted to the corresponding sensor unit SU, preferably by means of the characteristic signal MAC_SYNCF.

[0176] When the corresponding sensor unit SU acquires the corresponding sensor data SD, these first supplementary synchronization data △t can be considered. EGSp-1 .

[0177] In order to use the counter reading difference Δt EGSP-1 It is obvious that periodic synchronization is required.

[0178] Therefore, the central unit (CU) collects the voltage and phase values ​​of at least one of the three phase conductors of the energy supply network as a current vector, with a collection period of more than one fundamental oscillation period of the voltage.

[0179] The current vectors of the corresponding sensor units SU are aggregated into a aggregated current vector ( I H1p Furthermore, the aggregate current vector I H1p It is transmitted to the central unit (CU).

[0180] In the central unit CU, based on the voltage value and the aggregated current vector ( I H1p ), to calculate power.

[0181] In the corresponding sensor unit SU, within the measurement period p, p+1, ..., the complex value AC current or voltage vector formed by the AC current or AC voltage for each AC voltage fundamental oscillation period is averaged and provided as a complex average value for reference to the start of the measurement period.

[0182] Therefore, the period i of the AC voltage and the measurement periods p, p+1, ... are numbered in the central unit CU and transmitted to the sensor unit SU.

[0183] Therefore, the period number of the reference AC voltage can be considered as: the fundamental oscillation period of the reference voltage is applicable, or the local reference time of the internal time of the follower counter FC, which is transmitted to the sensor unit SU together with the time of the central unit CU with the dominant counter LC.

[0184] Here, by means of a synchronization message, the continuous measurement cycle in the sensor unit SU is synchronized with the continuous measurement cycle in the central unit CU, so as to report the exact start time of the measurement cycle to the corresponding sensor unit SU.

[0185] However, the central unit (CU) can also collect voltage and phase values ​​from two or more of the three phase conductors of the energy supply network.

[0186] The aggregation of current vectors can be performed by averaging over a measurement period p, taking into account the corresponding amplitude and phase values ​​of these current vectors, wherein the aggregation of current vectors is performed by averaging over a measurement period p, taking into account the corresponding internal following time unit FC of the corresponding sensor unit SU.

[0187] Optionally, aggregation of current vectors I H1p Only those fundamental oscillation periods of the grid voltage whose current vector values ​​are within predefined limits can be considered, in order to, for example, ignore interference on the grid lines.

[0188] Therefore, during the averaging period within the measurement period p, only the effective current or voltage vector of each AC voltage fundamental oscillation period is used.

[0189] For example, current vectors or values ​​that are distorted due to interference pulses or energy recovery phases are not included in the averaging.

[0190] In this case, the effective averaging time within the measurement period p, or the effective current / voltage vector used for averaging, constitutes a fragmented set.

[0191] Aggregate Current Vector I H1p Transmission is made from the corresponding sensor unit SU to the central unit CU, especially after the end of the corresponding measurement cycle, which is related to the corresponding number of the fundamental oscillation at the start of the measurement cycle and optionally to the number of the current measurement cycle p and / or the previous measurement cycles p-1, p-2.

[0192] Since the measurement cycles in one or more sensor units SU and central unit CU are synchronized, the central unit CU establishes a clear time relationship between the received complex AC current and voltage vector average value based on the reference information transmitted together.

[0193] The current vector can be determined within one or more fundamental oscillation cycles of the reference (phase) voltage, i.e., one or more voltage cycles of one of the three phases of the energy supply network, preferably from at least ten cycles, and particularly preferably from at least 100 cycles.

[0194] In a 3-phase 4-wire power distribution network, the phase angles between the phase voltages can be exactly 120° apart, or they can simply differ in amplitude.

[0195] Under this assumption, only one phase of the phase voltage can be used as a reference for the measurement period p in the central unit CU and therefore in the corresponding sensor unit CU after synchronization.

[0196] After receiving a complex AC current vector or aggregate value, taking into account its distribution to the corresponding phase voltage, the complex AC current vector or aggregate value can be directly used or rotated ±120°, and then the complex AC current vector or aggregate value is multiplied by the amplitude of the phase voltage to calculate the average active and reactive power.

[0197] The rotation of the alternating current vector, which is a vector, can be done, for example, by multiplying it by a so-called rotation matrix, which is determined in Cartesian coordinates by its complex value.

[0198] Alternatively, the complex AC current vector or aggregate value can be rotated immediately after it has been calculated in the sensor unit SU.

[0199] Therefore, the allocation information for the corresponding phase voltage conductors must be continuously transmitted from the central unit CU to the sensor unit SU, especially when the reference voltage used for time synchronization of the measurement cycle in the central unit CU and therefore in the sensor unit SU has changed.

[0200] If one or even both phase voltages fail, the next available phase voltage is used as a reference voltage for synchronizing the measurement cycles in the central unit CU and the sensor unit SU.

[0201] In this case, the received complex AC voltage vector and / or AC current vector must be rotated accordingly before power calculation.

[0202] The aggregation of complex current vectors can be performed, for example, by applying the following relationship: in N p It is the number of current samples during the fundamental oscillation period of the reference voltage within the measurement period p; These are the current sampled values / measured data within the reference voltage period k; I H1k_RE The complex current vector IH1 is the fundamental oscillation period k of the reference voltage within the measurement period p. k The real part; I H1k_IM The complex current vector IH1 is the fundamental oscillation period k of the reference voltage within the measurement period p. k The imaginary part; and k It is the index / number of the reference voltage period k within the measurement period p.

[0203] One advantage is that the sampling time point of the sensor data of the corresponding sensor in the sensor unit can be adjusted to the corresponding period length, so that it is easier to take into account the changes in period length caused by the influence of the power grid.

[0204] This can be achieved through corresponding conversion of the measured data or adjustment of the sampling rate of the corresponding sensor in the sensor unit.

[0205] The following relation also needs to be applied: , , in M p The measured value / current vector I within the measurement period p H1k Quantity; M vp ≤ M p The effective attribute V within the measurement period p k = 1 Measured value / Current vector I H1k The quantity, among which, is affected by the energy gain during the fundamental oscillation period k = i+1, i+2, ..., and has a corresponding effective attribute V k Those measurements I = 0 H1k Or actually part I H1k_RE and the imaginary part I H1k_IM It was marked as invalid, and the valid measurement value obtained the valid attribute V. k = 1; IH1k_RE The complex current vector I is the fundamental oscillation period k of the reference voltage within the measurement period p. H1k The real part; I H1k_IM The complex current vector I is the fundamental oscillation period k of the reference voltage within the measurement period p. H1k The imaginary part; I H1p_RE It is the complex aggregate current vector I with measurement period p. H1p The real part; and I H1p_IM It is the complex aggregate current vector I with measurement period p. H1p The imaginary part.

[0206] Then, the measured value I is calculated for each individual cycle. H1k_RE and I H1k_IM They are aggregated into the desired current vector I within the measurement period p. H1p_RE and I H1p_IM As mentioned above.

[0207] M p The value is typically chosen as 100 fundamental oscillations per measurement cycle for a 50 Hz system, or 120 fundamental oscillations per measurement cycle for a 60 Hz system.

[0208] Due to possible fluctuations in the power grid frequency, the measurement period p may also contain fewer than 100 or 120 fundamental oscillations.

[0209] Then, the polymerization current value I H1p_RE or I H1p_IM As a complex current vector IH1 p It is transmitted to the central unit (CU).

[0210] Figure 6 A second embodiment of the present invention is shown in the form of a block diagram.

[0211] In this embodiment, the difference Δt between the counter readings is measured in the characteristic signal of the measurement period p or in the SYNC frame MAC_SYNCF. EGSP-1 The information was not transmitted.

[0212] Assumptions: The transmission of the SYNC frame MAC_SYNCF in the central unit CU, and especially in the transmitter REF_TX, is related to the reference voltage U. REF_H1 The zero-crossing time points are synchronized, and the transit time correction is performed only for the reception of the SYNC frame MAC_SYNCF in the sensor unit SU, so as to establish the time synchronization between the central unit CU and the corresponding sensor unit SU.

[0213] In this embodiment, when the reference signal transmitter REF_TX of the central unit CU is transmitting, the counter reading is handed over, and at this counter reading, the SYNC frame header MAC_SYNCF is to be transmitted.

[0214] Unlike the first embodiment, at the start of the measurement period p, at the time point t0 when the interrupt signal IS is activated. EGSp That is, the reference voltage U REF_H1 The zero-crossing time point and the time point t when the synchronization frame MAC_SYNCF is transmitted to the corresponding sensor unit SU. EGS_SYNCp The time delay Δt between EGS It can be ignored, and therefore no transmission is required.

[0215] In the synchronization frame MAC_SYNCF, only information about the period duration T is transmitted. p-1 The information, namely, the estimated current voltage cycle, is determined, for example, based on the last 10 to 30 voltage cycles of the previous measurement cycle p-1.

[0216] The start of the transmission of the SYNC frame MAC_SYNCF implicitly corresponds to time point t. EGS_SYNCp ≈ t0 EGSp Because of the delay Δt EGSp The value is usually negligible.

[0217] This means that at the start of the same measurement period p, the time delay of the SYNC frame MAC_SYNCF of that measurement period p on the receiving side is immediately compensated, and synchronization is performed between the central unit CU and the corresponding sensor unit SU.

[0218] The central unit CU delays the signal by one fundamental oscillation period, and the reference voltage U is... REF_H1 The zero-crossing time point is exactly synchronized, and the SYNC frame MAC_SYNCF is transmitted.

[0219] With the transmission of the SYNC frame MAC_SYNCF, information about time point t0 is implicitly transmitted. EGSp Information.

[0220] In this example, there is no need to transmit other counter readings of the central unit (CU) in the SYNC frame MAC_SYNCF.

[0221] The RF receiver unit in the sensor unit SU provides counter readings at the time of reception of the SYNC frame header MAC_SYNCF.

[0222] As the corresponding sensor unit at time point t0 EGSp Received SYNC frame MAC_SYNCF, time t0 EGSp* =t0 3NAp .

[0223] In the current embodiment, the signal transit time on the high-frequency transmission link RF_L is corrected in the corresponding sensor unit SU by directly using the reference voltage U. REF_H1 The zero-crossing time point is used as the corrected reception time point for the SYNC frame header.

[0224] For this method, the reference voltage U can be determined in the sensor unit SU based on each SYNC frame MAC_SYNCF. REF_H1 The point in time that crosses zero.

[0225] Figure 7 The third embodiment of the invention is shown in block diagram form, wherein the time value t of the counter in the central unit CU is... EGS A separate time synchronization frame is transmitted to the sensor unit SU, and the value t of the time base is transmitted through the central unit CU. EGS For the time base t in the sensor unit SU 3NA It was adopted after transit time correction.

[0226] This can be achieved by pre-preparing a separate time synchronization frame in the central unit CU and transmitting the time points contained in the frame to the sensor unit SU. 3NA = t EGS Correction.

[0227] This allows the central unit CU to start each measurement cycle p without being related to the reference voltage U. REF_H1 The zero-crossing time point t0 EGSp Synchronously, but at the reference voltage U REF_H1 During the first cycle, the aforementioned SYNC frame MAC_SYNCF is transmitted because information about the zero-crossing time is contained in the value t0. EGSp In this context, the value involves not only time t EGS Furthermore, it involves the time base t of the continuous synchronization of the sensor unit SU. 3NA .

[0228] Therefore, there is no need to transmit the transmit delay Δt in the SYNC frame MAC_SYNCF. EGSP-1 The time value, and at the beginning of the measurement period p, from Figure 3 The previous time reference point t0 in the first embodiment EGSp-1 The time interval between them is shortened to the reference point t0. EGSp .

[0229] In other words, the central unit (CU) can also have an internal central time unit (LC), the value of which constitutes the second supplementary synchronization data (t). EGS Furthermore, preferably by means of the characteristic signal MAC_SYNCF, these second supplementary synchronization data can be transmitted to the corresponding sensor unit SU, and the corresponding sensor unit SU can take these second supplementary synchronization data t into account when acquiring the corresponding sensor data SD. EGS .

[0230] The current values ​​of the corresponding sensor unit SU can be aggregated into an aggregated current vector. I H1p Furthermore, it can aggregate current vectors I H1p Transmitted to the central unit CU, and can be processed in the central unit CU based on voltage value and aggregated current vector. I H1p To calculate power.

[0231] Figure 8 A detailed view of the central unit CU of the present invention is shown.

[0232] All three embodiments described above can be used when the central unit CU and at least one sensor unit SU communicate directly or via multiple nodes / hops through a wired connection, such as in an Ethernet-based daisy-chain.

[0233] Here, on the corresponding sensor unit SU side, when the SYNC frame MAC_SYNCF is received, the transit time correction is performed according to the position of the sensor unit SU in the daisy chain.

[0234] The transit time correction value is preferably determined for each sensor unit SU in the periodic transit time correction value determination or at the start of communication, i.e., for example by transmitting periodic transit time measurement frames.

[0235] The analog data acquisition device AFE samples voltages U2, U2, and U3.

[0236] The zero-crossing identification device ZCD identifies the reference voltage U. REF_H1 The zero-crossing of the time curve is counted, and the voltage cycles of the corresponding voltage are counted.

[0237] A high-frequency module RF_M can, for example, be formed by a "Zigbee" module ZB_M and a "Zigbee" application ZB_APP, where the latter provides the results RES for current, voltage, and power.

[0238] The computing device CALC1 is used to calculate active power P and reactive power Q based on the corresponding voltage and current or based on voltage and current vectors.

[0239] The CALC2 computing device is used for: • The voltage value is calculated based on the amplitude and phase information, where the counting point corresponds to the previous counting point; • Provides a reference voltage U for counting in the zero-crossing identification device ZCD. REF_H1 The measurement cycle; • Determine the reference line LREF for the grid phase conductors L1, L2, and L3 of the energy supply network; • Determine the minimum voltage U MIN To improve error resistance, if the voltage is below this minimum voltage, the zero-crossing point of the voltage will not be determined or counted. • Optionally, the voltage vector of the grid voltage. U 1. U 2. U The phase sequence of the grid voltages u1, u2, and u3 is determined by the form 3; • Determine the voltage vector based on the grid voltages u1, u2, and u3. U 1. U 2. U 3.

[0240] The calculations of the calculation device CALC2 are periodically checked by the corresponding verification device VAL during the measurement cycle, especially regarding the consistency of the voltage and current cycle numbers.

[0241] The data from the reference phase transmission device PHU is correspondingly distributed to the high-frequency module RF_M via the transmitter or receiver UART in the central unit CU.

[0242] Reference voltage U REF_H1 The zero-crossing interrupt signal IS is provided to the reference signal transmitter REF_TX within the high-frequency module RF_M, which in turn obtains the zero-crossing point t0 of the reference voltage from the central oscillator OSC1 and the master counter device LC. EGS and the time delay Δt when transmitting the Sync frame MAC_SNCF EGS Information.

[0243] Using the minimum voltage U MIN This ensures that only the minimum allowable voltage is considered for power calculations in subsequent evaluations, thereby improving error resilience.

[0244] Figure 9 An example of a signal curve in an energy distribution network is shown, where the data acquisition process of sensor data SD over time is illustrated.

[0245] The time ranges ALL_A, ALL_B, and ALL_C display all sensor units SU that transmit the corresponding current within the measurement periods p-1, p, p+1, and p+2 to the central unit CU.

[0246] The time ranges CALC_A, CALC_B, CALC_C, and CALC_D display the corresponding calculations of the aggregate current within the measurement periods p-1, p, p+1, and p+2 in the sensor unit SU.

[0247] The time ranges ADJ_A and ADJ_B display the values ​​based on the corresponding SYNC frame SF. p-1 SF p SF p+1 SF p+2 The synchronization data is used to adjust the timing unit of the corresponding sensor unit SU. These frames are usually called SYNC frames MAC_SYNCF.

[0248] The SYNC frame SF is not shown in the diagram. p-1 .

[0249] List of reference numerals Phase voltage vectors α1, α2, and α3 U 1. U 2 and U Angle between 3 ADJ_A and ADJ_B time unit adjustment process AFE (Analog Frontend) AGG polymerization unit ALL_A, ALL_B, and ALL_C are used to transmit current information. CALC_A, CALC_B, CALC_C, and CALC_D are used to calculate the polymerization current. CU Central Control Unit △t EGSP-1 , △t EGSP Time delay value in measurement period p-1 or p DCOMP is a time delay compensation device used in high-frequency transmission links. The internal counter device of the FC sensor, also known as the follower clock. i, k Period numbering I Current I H1 Complex current vector I H1p (Aggregate) Complex Current Vector IS Interruption signal when the reference voltage crosses zero. L1, L2, L3 power grid phase conductors L REF Reference conductor LC leader clock LV low voltage range MAC_SYNCF, SF p-1 SF p SF p+1 SF p+2 Synchronization frames using MAC layer-based synchronization frames "multicast" N1 and N2 networks NC1 and NC2 network control devices OSC1 and OSC2 oscillators p Measurement period 1. 2. 3. Phase between current and voltage in a phase line Pp is the (aggregate) active power within the measurement period p. PHU Reference Phase Transmission Device Qp is the (aggregate) reactive power within the measurement period p. REF_TX Reference Signal Transmitter RES: Results of current, voltage, and power RF_L stands for "radio frequency link". RF_M high-frequency module SD sensor data, such as primary current (x n The current vector I of the alternating current value H1p SU local control device, sensor device t0 EGSp Zero-crossing time point in the central control unit t0 EGSp-1 The zero-crossing time point in the previous measurement cycle p-1 t 3NA The count value of the locally determined grid voltage cycle duration in the local control device. t EGS Time provided by counter LC T p Current cycle duration of grid voltage TR Transformer Time curves of the grid voltage at the input terminals u1, u2, and u3 of the central unit. U1 , U2 , U3 Voltage vector of grid voltage U MIN Minimum values ​​of voltages u1, u2, and u3 U REF Reference voltage UART transmitter / receiver (Universal Asynchronous Receiver Transmitter) UC_D "Unicast" data transmission Periodic verification of VAL measurement cycle x, y coordinate axes ZB_APP Zigbee application ZB_M Zigbee module ZCD (Zero Crossing Detection)

Claims

1. A method for time synchronization of sensor units (SUs) in a distributed system. in, The sensor units (SU) each have an internal time unit (FC), and The sensor unit (SU) acquires sensor data (SD) and transmits it to the central unit (CU) via a radio network. In the radio network, a characteristic signal (MAC_SYNCF) is transmitted at regular time intervals. Specifically, the reception of the characteristic signal (MAC_SYNCF) is monitored in the corresponding sensor unit (SU). Specifically, upon receiving the characteristic time feature of the feature signal (MAC_SYNCF), the current value of the internal time unit (FC) of the corresponding sensor unit (SU) is stored together with at least one transmitter identifier contained in the feature signal. Specifically, when acquiring sensor data (SD), another current value of the internal time unit (FC) of the corresponding sensor unit (SU) is stored. Specifically, the acquired sensor data (SD) is assigned at least the value of the internal time unit stored when the characteristic time feature of the received feature signal is received, the associated transmitter identifier of the feature signal, and another value of the internal time unit (FC) stored when the sensor data (SD) is acquired, and these values ​​are transmitted together with the sensor data (SD) to the central unit (CU). Specifically, based on the transmitter identifier, a reference time base is derived; and based on the value of the internal time unit (FC) of the corresponding sensor unit (SU) stored when the characteristic time feature of the received signal is received, and another value of the internal time unit (FC) of the corresponding sensor unit (SU) stored when the sensor data (SD) is acquired, the time relationship between the transmitted sensor data (SD) and the reference time base is derived, characterized in that... The central unit (CU) acquires the voltage and phase values ​​of at least one of the three phase conductors of the energy supply network as voltage and / or current vectors, with an acquisition period equal to one or more fundamental oscillation periods of the voltage. The current vectors of the corresponding sensor units (SU) are aggregated into a aggregated current vector. I H1p ), and the aggregated current vector ( I H1p Instead of the sensor data, the data is transmitted to the central unit (CU), and in the central unit (CU), the voltage value and the aggregated current vector are used to... I H1p Power is calculated using phase correction.

2. The method according to claim 1, wherein, Taking into account the corresponding magnitude of the current vector and incorporating the phase value, the current vector is aggregated by averaging over the measurement period (p).

3. The method according to claim 1, wherein, Taking into account the corresponding internal time unit (FC) of the corresponding sensor unit (SU), the current vector is aggregated by averaging over the measurement period (p).

4. The method according to any one of the preceding claims, wherein, The aggregation of the current vector ( I H1p Only those cycles in which the value of the current vector is within the predefined limit are considered.

5. The method according to any one of the preceding claims, wherein, The aggregate current vector ( I H1p The data is transmitted from the corresponding sensor unit (SU) to the central unit (CU).

6. The method according to any one of the preceding claims, wherein, The current vector is determined over one or more cycles of the voltage and phase values ​​of the three phases of the energy supply network, preferably over at least ten cycles, and particularly preferably over at least 100 cycles.

7. The method according to any one of the preceding claims, wherein, The central unit (CU) acquires the voltage and phase values ​​of at least one of the three phase conductors of the energy supply network, and determines, based on the voltage and phase values, synchronization data (t0) regarding the frequency or period duration and the phase of the voltage of at least one of the three phase conductors relative to the acquisition time point of the voltage and phase values ​​of at least one of the three phase conductors. EGSp T p ), and transmit it to the sensor unit (SU), and The corresponding sensor unit (SU) synchronizes with the data (t0). EGSp T p The system acquires corresponding sensor data (SD) in the form of relevant current values, transmits the sensor data (SD) to the central unit (CU), and calculates the power based on the voltage and current values ​​in the central unit (CU).

8. The method according to any one of the preceding claims, wherein, Synchronous data (t0) is generated by transmitting the time points from the central unit (CU) to the corresponding sensor units (SU), which are phase-dependent with respect to the acquisition time points of the voltage and phase values ​​of at least one of the three phase conductors. EGSp ).

9. The method according to any one of the preceding claims, wherein, The synchronization data (t0) EGSp T p The characteristic signal (MAC_SYNCF) is transmitted to the sensor unit (SU).

10. The method according to any one of the preceding claims, wherein, The synchronization data (t0) EGSp T p The voltage and phase values ​​of the three phases of the energy supply network are determined over one or more cycles, preferably from at least ten cycles, and particularly preferably from at least 100 cycles.

11. The method according to any one of the preceding claims, wherein, The central unit (CU) acquires the voltage and phase values ​​of the phase conductors of the power supply network, and acquires first supplementary synchronization data (Δt) regarding the time delay when transmitting the characteristic signal (MAC_SYNCF). EGSp-1 The time delay mentioned refers to the data collected in the previous time period before the current time period. In the current time period, synchronized data (t0) is collected. EGSp T p ), and preferably by means of the characteristic signal (MAC_SYNCF), the first supplementary synchronization data (△t) EGSp-1 The data is transmitted to the corresponding sensor unit (SU), and the corresponding sensor unit (SU) considers the first supplementary synchronization data (Δt) when acquiring the corresponding sensor data (SD). EGSp-1 ).

12. The method according to any one of the preceding claims, wherein, The central unit (CU) also has an internal central time unit, the value of which constitutes the second supplementary synchronization data (t). EGS Furthermore, preferably by means of the characteristic signal (MAC_SYNCF), the second supplementary synchronization data is transmitted to the corresponding sensor unit (SU), and the corresponding sensor unit (SU) takes the second supplementary synchronization data (t) into account when acquiring the corresponding sensor data (SD). EGS ).

13. A distributed system for time synchronization of sensor units (SUs), comprising a central unit (CU), wherein, The system is configured to perform the method according to any one of the preceding claims.

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