JP2007249607A - Transmission system - Google Patents

Abstract

A system capable of highly accurate data transmission using an existing network is provided.
A transmission system 1 for transmitting a measured system frequency to a power feeding system 5 via a network 6 includes a frequency measuring unit 7 for sampling the system frequency every cycle and converting it into a pulse number, and two transmission systems 1 And stores a value obtained by halving the difference between the number of pulses corresponding to the lowest frequency of the system frequency and the number of pulses measured by the frequency measuring unit 7 and rounding down the fraction. And the transmission processing unit 8 for alternately transmitting the difference stored in these two storage areas to the network 6 at least once during one cycle of the system frequency. The reception processing unit 11 that receives the difference transmitted from the unit 8 from the network 6, adds the difference received this time and the difference received last time, restores the original difference, and passes the difference to the power feeding system 5. It is formed.
[Selection] Figure 1

Description

  The present invention relates to a transmission system used for data communication that requires a limitation on transmission delay time and accuracy, such as a measurement value of a system frequency used for power supply control.

  A system for performing power supply control by measuring a system frequency in the operation of a power system is known (see, for example, Patent Document 1). In such a power feeding system, in order to maintain the quality of supplied power, it is necessary to suppress the transmission delay time of the measured value of the system frequency at a predetermined point within a predetermined time, and the measurement accuracy is 0. It is necessary to satisfy 001 Hz.

JP 2005-20916 A

  However, if an existing network is used to transmit such high-accuracy measurement values, the amount of data exceeds the size that can be transmitted in one packet, so it is necessary to divide it into two packets for transmission. However, depending on the division method, there is a problem that processing becomes complicated and errors due to transmission increase.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a transmission system capable of high-accuracy data transmission by simple processing using an existing network.

In order to solve the above problems, a transmission system according to a first aspect of the present invention uses a transmission network capable of transmitting Y-1 bit data in one packet, and uses Y bit data (2 ^Y -1). 2), 2 storage areas are stored, Y-bit data is halved and the fractions are rounded down, and one-bit storage area is stored, and Y-bit data is halved. Then, the rounded-up value is stored in the other storage area, and the division information stored in these two storage areas is transmitted to the transmission network alternately at least once (for example, in the embodiment) A transmission processing unit 8) and reception processing means for receiving the division information transmitted from the transmission processing means from the transmission network, and restoring the Y-bit data by adding the division information received this time and the division information received last time. For example, a, a reception processing unit 11) in the embodiment.

  The transmission system according to the second aspect of the present invention transmits a system frequency measured at a predetermined location to a power feeding system via a transmission network, and samples the system frequency at a predetermined location every cycle. The frequency measurement means (for example, the frequency measurement unit 7 in the embodiment) for converting the number of pulses and two storage areas, and the number of pulses corresponding to the lowest frequency of the system frequency and the frequency measurement means The value obtained by halving the difference pulse number of the pulse number and rounding down the fraction is stored in one storage area, and the value obtained by halving the difference pulse number and rounding up the fraction is stored in the other storage area. Transmission processing means for alternately transmitting the halved number of differential pulses stored in these two storage areas to the transmission network at least once during one cycle of frequency; Receive the halved difference pulse number transmitted from the processing means from the transmission network, and add the halved difference pulse number received this time and the previously received halved difference pulse number to obtain the difference Receiving processing means for restoring the number of pulses and passing it to the power supply system.

  When the transmission system according to the present invention is configured as described above, data larger than the data length that can be transmitted in one packet in the transmission network can be transmitted with desired accuracy, and transmission guaranteed by the transmission network. Data can be transmitted within the range of the delay time. Therefore, it is suitable for transmission of the measured value of the system frequency used for power supply control.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the configuration of the transmission system according to the present invention will be described with reference to FIG. This transmission system is for measuring the system frequency at a predetermined location and transmitting it to the power feeding system. The transmission system 1 measures a system frequency of an electric power system (for example, a bus in a substation) 2 and transmits it via a transmission network 6 (hereinafter referred to as “collection apparatus 3”). The system frequency information transmitted from the collection device 3 is received from the transmission network 6 and passed to the power feeding system 5. The system frequency information reception device (hereinafter referred to as “reception device 4”) is configured.

  The collection device 3 includes a frequency measurement unit 7 that measures the system frequency of the power system 2, a transmission processing unit 8 that converts system frequency information measured by the frequency measurement unit 7 into transmittable transmission data, and a transmission network 6. Is composed of a transmission function unit 9 for transmitting data. The reception device 4 also includes a reception function unit 10 that receives transmission data from the transmission network 6, and a reception processing unit that converts transmission data received by the reception function unit 10 into system frequency information and passes it to the power feeding system 5. 11.

  Note that the transmission network 6 in the present embodiment alternately transmits transmission data having a predetermined word length (14 bits in this embodiment) and synchronization data, thereby ensuring a predetermined transmission delay time. A click digital transmission system (CDT system) is used.

The frequency measuring unit 7 of the collection device 3 is configured to measure the system frequency from the system voltage. Specifically, as shown in FIG. 2A, the input of the voltage value is half-rectified to extract only a positive (or negative) value, and further, rectangular wave shaping is performed to convert it into a rectangular wave. The rectangular wave is sampled with a pulse signal having a predetermined sampling frequency (10 MHz in this embodiment) as shown in FIG. 2B, and the number of sampling pulses is set for each cycle of the system frequency. It is done by measuring. For example, in FIG. 2B, counting is started from time t _{1 when the} system voltage rises, and the number of pulses up to time t ₂ when the system voltage rises next is counted as the number of pulses for one cycle.

  Here, the relationship of the number of pulses for one cycle of the system frequency when the sampling frequency is 10 MHz is as shown in Table 1 below. By sampling the system frequency as the number of pulses in this way, the measured value of the system frequency can be expressed by an integer (number of pulses).

(Table 1)
System frequency [Hz] Number of pulses for one cycle 46.000 217,391
50,000 200,000
54.000 185,185

  In the power feeding system 5 according to the present embodiment, the range of the system frequency to be measured is between 46.000 and 54.000 Hz as shown in Table 1, and therefore the system frequency in this range (in terms of the number of measurement pulses). In order to transmit a maximum of 217,391 pulses), the data length is 18 bits. However, in the transmission network 6 according to the present embodiment, since only 14-bit data can be transmitted in one packet, the transmission processing unit 8 divides the number of measurement pulses and transmits it in two packets. There is a need.

  Now, the process of the transmission processing unit 8 will be described with reference to FIG. When the transmission processing unit 8 takes in the number of measurement pulses from the frequency measurement unit 7 (step S100), the transmission processing unit 8 calculates the difference from the minimum value of the number of measurement pulses (that is, 185,185 pulses when the system frequency is 54.000 Hz). The number of pulses X is calculated (step S101). Specifically, the values are as shown in Table 2 below. That is, by setting the number of differential pulses to X, the number of bits for transmitting the system frequency in this measurement range (32,206 pulses when the maximum value is 46.000 Hz) can be compressed to 15 bits.

(Table 2)
System frequency [Hz] Number of differential pulses X
46.000 32,206
50.000 14,815
54.000 0

  Next, the number of pulses X of the difference is divided into two to make 14 bits that can be transmitted in one packet of the transmission network 6 and stored in the two storage areas A and B, respectively. The transmission processing unit 8 first checks whether or not the number of differential pulses X is an even number (step S102). If it is determined that the number is even, the difference pulse number X can be expressed by 2N, and therefore N is stored in each of the storage areas A and B (step S103). On the other hand, if it is determined in step S102 that the number is not an even number (odd number), the difference pulse number X can be expressed by 2N + 1, so that N is stored in the storage area A and N + 1 is stored in the storage area B (step S102). S104). That is, by the processing of these steps S102 to S104, the difference pulse number X is halved, the value rounded down is stored in the storage area A, and the value rounded up is stored in the storage area B. Yes. Of course, the values stored in the storage areas A and B may be reversed.

  Then, the transmission processing unit 8 passes the value of the storage area A or B to the transmission function unit 9 and transmits it to the transmission network 6 as transmission data. First, it is checked whether or not the previously transmitted area is the storage area B (step S105). If the storage area B has been transmitted, the value of the storage area A is passed to the transmission function unit 9 (step S106). When it is not the storage area B (when the storage area A is transmitted), the value of the storage area B is passed to the transmission function unit 9 (step S107) and transmitted to the transmission network 6.

  Then, it is checked whether a new number of measurement pulses is measured from the frequency measurement unit 7 (step S108). If not, the process returns to step S105, and the value of the storage area different from the previously transmitted storage area is set. If a new measurement pulse number is measured (that is, if the system frequency has shifted to the next cycle), the process returns to step S100 to transmit a new measurement value.

  Since the transmission network 6 in this embodiment can transmit 14-bit data in one packet and adopts the CDT method with a transmission speed of 9600 bps, the rate is about once every 9.16 milliseconds. The packet is transmitted. Therefore, for a system frequency of 46 to 54 Hz (one cycle is 18.52 to 21.74 milliseconds), as shown in FIG. 4, two or three packets during one cycle. Can be sent. Therefore, as described above, even if the configuration is such that the number of measurement pulses is divided into two packets and transmitted, both pieces of divided information can be transmitted.

On the other hand, the reception function unit 10 of the reception device 4 that has received the transmission data transmitted as described above passes the information (number of divided difference pulses) to the reception processing unit 11. As shown in FIG. 5, when receiving the transmission data D _n from the reception function unit 10 (step S200), the reception processing unit 11 transmits the transmission data D _n-1 received in the previous process and the transmission received in the current process. The data D _n is added to restore the differential pulse number X ′. Then, the restored pulse number X ′ of the difference is passed to the power feeding system 5 (step S202). Finally, the transmission data D _n passed from the reception function unit 10 this time is stored as the transmission data D _n-1 of the previous process, the process returns to step S200, and the above-described process is repeated.

  As described above, the reception processing unit 11 causes the collection device 3 to transmit the currently received transmission data and the previously received transmission regardless of whether transmission data is transmitted twice or three times for one cycle of the system frequency. The number of pulses X ′ is restored by summing the data. That is, as shown in FIG. 6, the collection device 3 transmits the number of differential pulses divided for each transmission timing of the transmission network 6, but the reception device 4 restores each transmission timing of the transmission network 6. The pulse number X ′ of the difference is transferred to the power feeding system 5. For this reason, the system frequency measured within the transmission delay time guaranteed by the transmission network 6 can be passed to the power feeding system 5, and when the system frequency changes from one cycle to the next cycle, The pulse number X ′ can be passed as a measured value of the system frequency to the power feeding system 5 as a value for interpolating the difference between the changes (for example, in FIG. 6, the system frequency is changed from the second cycle to the third cycle). When changing).

  As described above, in this embodiment, the difference pulse number X is divided into two and transmitted as two packets, and when the difference pulse number X is an odd number, either one is rounded down, The other is rounded up and transmitted. The accuracy will be described with reference to FIG.

  FIG. 7A shows a case where the frequency (number of pulses) measured in one packet is transmitted by rounding down the difference pulse number X to ½ and rounding off if there is a fraction. In this case, when the number of differential pulses X is an odd number, the equivalent value of the differential pulse restored in the receiving device 4 is shifted by 1 bit, so that an error occurs in the value on the order of 0.0001 Hz. The error is included in the value of the order of 0.001 Hz requested in (the measured value is 53.001 Hz, the received value is 53.002 Hz). On the other hand, as shown in FIG. 7B, in the case of the present embodiment, the equivalent value of the differential pulse restored from the number of divided pulses (A, B) is the same as the measured value. The error is not included.

  In this embodiment, since the measured system frequency is transmitted to the power supply system 5 as the number of pulses sampled, the power supply system 5 counts the number of pulses, thereby realizing the measured value of the system frequency. The time can also be calculated (of course, it is necessary to consider the transmission delay time in the transmission network 6).

  In the embodiment of the present invention described above, the main effects achieved can be summarized as follows. First, the collection device 3 reduces the number of bits of data to be transmitted by transmitting the measured value (number of pulses) of the system frequency as a difference from the minimum value of the measurement range, and further divides the data into two, Measurement data (measured value of system frequency) larger than the data length that can be transmitted in one packet of the transmission network can be transmitted with a desired accuracy (0.001 Hz) using a conventional transmission network.

  Secondly, in the receiving device 4, among the differential pulses transmitted in this way, two consecutive differential pulses (the differential pulse received in the current process and the received differential pulse in the previous process) are transmitted. Since the number of pulses of the system frequency measured by summing is restored, the number of pulses of the system frequency can be restored and passed to the power feeding system 5 by a simple process, and the transmission network 6 It is possible to transmit within the transmission delay time guaranteed by.

  Third, in the collection device 3, when dividing the number of differential pulses, two storage areas A and B are prepared, one of which stores a rounded down value obtained by halving the differential pulse, and the other is a rounded up value. Further, since the values of the two storage areas A and B are alternately transmitted, the receiving device 4 restores the values of the two storage areas A and B. When the exact frequency can be restored and the cycle of the system frequency changes, the number of pulses of the restored difference becomes a value that interpolates the difference between the changes, so that the transmitted error can be minimized. .

In the above-described embodiment, the number of differential pulses having a size of 15 bits (provided that the number of pulses is 2 ¹⁵ −) with respect to the transmission network 6 capable of transmitting 14-bit data in one packet. However, the present invention is not limited to this number of bits, and Y-1 bit data can be transmitted in one packet by the same method. Y-bit data (except 2 ^Y −1) can be transmitted using a possible transmission network.

It is a block diagram which shows the structure of the transmission system which concerns on this invention. It is explanatory drawing for demonstrating the measuring method of system frequency, (a) is explanatory drawing of the method of shaping a system voltage into a rectangular wave, (b) is explanatory drawing of the method of sampling this rectangular wave It is. It is a flowchart which shows the process of the transmission process part in a collection apparatus. It is explanatory drawing for demonstrating a system | strain frequency and transmission timing, (a) shows the case where it transmits 3 times with respect to 1 cycle of system frequency, (b) shows the case where it transmits twice. It is a flowchart which shows the process of the reception process part in a receiver. It is explanatory drawing explaining the relationship between the measured differential pulse and the transmitted restoration pulse. It is explanatory drawing for demonstrating the difference in the transmission error by the division | segmentation method of a measurement pulse, Comprising: (a) is a case where the fraction of the data divided by 1/2 is cut off and it transmits with 1 packet, (b) This is a case of transmission by the method according to the present invention.

Explanation of symbols

1 Transmission System 6 Transmission Network 7 Frequency Measurement Unit (Frequency Measurement Means)
8 Transmission processing unit (transmission processing means)
11 Reception processing unit (reception processing means)

Claims (2)

A transmission system for transmitting Y-bit data (excluding 2 ^Y -1) using a transmission network capable of transmitting Y-1 bit data in one packet,
A value that has two storage areas, stores the value obtained by halving the Y-bit data and rounding down the fraction in one storage area, and halving the Y-bit data and rounding up the fraction Transmitting processing means for alternately storing the division information stored in the two storage areas to the transmission network at least once,
Receiving the division information transmitted from the transmission processing means from the transmission network, adding the division information received this time and the division information received last time to restore the Y-bit data; A transmission system comprising: A transmission system that transmits a system frequency measured at a predetermined location to a power feeding system via a transmission network,
A frequency measuring means for sampling the system frequency of the predetermined portion every cycle and converting it into a pulse number;
It has two storage areas and stores one of the values obtained by halving the number of pulses corresponding to the lowest frequency of the system frequency and the number of differential pulses between the number of pulses measured by the frequency measuring means and rounding down the fraction. A value obtained by halving the difference pulse number and rounding up the fraction is stored in the other storage area, and the 1 stored in the two storage areas during one cycle of the system frequency. A transmission processing means for alternately transmitting the number of differential pulses divided by at least once to the transmission network;
The ½ difference pulse number transmitted from the transmission processing means is received from the transmission network, the ½ difference pulse number received this time and the ½ difference pulse number received last time. And a reception processing means for restoring the number of differential pulses and passing it to the power supply system.

Images