FR2992790A1 - Method for optimizing operation of teleprotection system of electric installation, involves setting accumulator size to zero to consider no valid control signal to be received by receiver when size is lower than threshold - Google Patents

Abstract

The method involves measuring power of permanently standby signal (V) and power of control signals (C). The difference value between the power of the control signals and power of the standby signal is calculated (46) and compared with a first predefined threshold. An accumulator size is calculated when the calculated difference value is greater than the threshold. The calculated size value is compared to a second predetermined threshold. The accumulator size is set to zero to consider no valid control signal to be received by a receiver when the size is lower than the second threshold. Independent claims are also included for the following: (1) a system for optimizing operation of a teleprotection system of an electric installation (2) a computer program comprising a set of instructions for optimizing operation of a teleprotection system of an electric installation.

Description

TECHNICAL FIELD The invention is in the field of monitoring of electrical networks and more specifically relates to a method for optimizing the operation of a control system. teleprotection of an electrical installation, said system comprising a transmitter and a receiver, the transmitter being configured to transmit to the receiver, via a transmission channel, a watch signal Sv at a known frequency Fv and a plurality of control signals Sci (i = 1 to N, N being an integer) each having a known frequency Fci (i = 1 to N), a process in which the standby power V and the respective powers C i (i) are measured continuously at the receiver; = 1 to N), of each of the control signals received by the receiver, the highest measured power is selected C is calculated the difference CV between the power C and the power V, the difference C-V is compared to a first predefined threshold S1. The invention also relates to a teleprotection system 25 of an electrical installation comprising a transmitter and a receiver adapted to implement the method according to the invention. The invention further relates to a computer program stored on a recording medium 30 and having instructions for carrying out the steps of the method according to the invention when it is executed on a computer. STATE OF THE PRIOR ART Teleprotection equipment is used to transmit information between the stations or substations of an electricity transmission network at the level of the remote protection devices. These devices are essential in a number of protection schemes, such as locks, stadium accelerations, remote tripping. The performances that a teleprotection must achieve are: a fast transfer time (of the order of ten milliseconds); - high reliability in the presence of noise; - high security in the presence of noise; and, 20 - total availability. A typical technique for transmitting teleprotection signals to the stations or substations of an electricity transmission network is to use the telephony band on which a tone or a combination of tones called standby is continuously emitted using the power line technology (PLC). When an order is to be issued, the watch is cut off and is replaced in this telephony channel by a tone or a combination of tones corresponding to the command.

In order to dedicate as little power as possible to teleprotection when it is on standby, a useful signal of the PLC itself, such as telephone signaling, is frequently used as a stand-by signal. This is called silent teleprotection. In order to avoid the reception of untimely orders by the stations or the substations of the electricity transmission network, these stations or substations are generally equipped with a system of detection of the commands and a system of blocking which inhibits the reception of commands in case of detection of bad conditions on the line (high noise, attenuation jump, loss of signal, etc.).

The object of the invention is to avoid the transmission by the receiver of control signals to the control members of an electrical installation when no control signal has been transmitted from the transmitter to the receiver.

DISCLOSURE OF THE INVENTION The problems described above are solved by a method which takes into account noise and disturbances in a transmission channel through which a transmitter transmits a watch signal Sv or a control signal Sc among several possible control signals Sci (i = 1 to N, N being an integer) to a receiver in a teleprotection system of an electrical installation. For this purpose, the power of the standby signal V and the respective powers C 1, (i = 1 to N, N being an integer) are continuously measured at the receiver, the highest power value C is selected. among the measured powers Ci, the difference CV is calculated for each of these highest powers, the difference CV is compared with a first predefined threshold Si. The process according to the invention also comprises the following steps: if the difference CV is greater than the threshold Si, the quantity Accu (n) = Accu (n-1) + C (n) -V (n) is calculated S1, the calculated quantity is compared with a second predefined threshold S2 and it is considered that a valid control signal is received by the receiver if the value of the calculated quantity is greater than the threshold S2f - if the difference CV is smaller than S1. the Accu (n) quantity is set to zero and it is assumed that no valid control signal is received by the receiver.

The invention exploits the fact that the difference C-V depends on the noise present in the transmission channel. Therefore, the slope of the curve Accu (n) depends on this noise so that the higher the noise, the longer it takes for the magnitude Accu (n) to reach the threshold S2 is long. Thus, decision making relating to the validity of a command received by the receiver is accelerated in the absence of a noise in the transmission channel and delayed in the presence of a noise in said transmission channel.

Preferably, the first and second thresholds S1 and S2 are determined experimentally.

In a first implementation variant, the channel used to transmit the watch signal Sv and the control signals Sci is an electrical line of the network.

Preferably, the watch signal Sv and the control signals Sci are transmitted from the transmitter to the receiver using the CPL powerline carrier technology. The method according to the invention is implemented by a teleprotection system of an electrical installation comprising a transmitter and a receiver, the transmitter being configured to transmit to the receiver, via a transmission channel, a watch signal Sv at a known frequency and a plurality of control signals Sci (i = 1 to N, N being an integer) the receiver comprising a filtering module adapted to detect the standby signal and the control signals transmitted by the transmitter and to measure continuously the power of said received signals, the power of the standby signal V and the power of each of the control signals so as to determine the control signal C having the greatest power, a calculation module adapted to calculate the difference CV between the power C of the control signal and the power V of the standby signal, and to compare the difference CV with a first predefined threshold Si, an adaptive decision module to validate or invalidate a control signal based on the result of the comparison.

According to the invention, the decision module is configured for: - if the difference CV is greater than the threshold S1, - calculate the quantity: accu (n) = accu (n-1) + C (n) -V (n) -S1, and, - comparing the calculated quantity with a second predefined threshold S2 and - considering that a valid control signal is received by the receiver if the value of the calculated quantity is greater than the threshold S2r and, - if the difference CV is less than S1, - reset the quantity Accu (n) and - consider that no valid command signal is received by the receiver. BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will emerge from the description which follows, taken by way of non-limiting example, with reference to the appended figures in which: FIG. 1 schematically illustrates a chain of transmission-reception of a teleprotection system of an electrical installation according to the invention; FIG. 2 illustrates a receiver of the transmission-reception chain of FIG. 1; FIG. 3 is a block diagram illustrating the essential steps of the method according to the invention; FIG. 4 is a curve illustrating the method according to the invention in an exemplary implementation. FIG. 5 is a curve representing the difference C-V between the power C of the control signal and the power V of the standby signal as a function of the signal-to-noise ratio RSB according to the invention; DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS FIG. 1 represents a reception transmission chain of a teleprotection system of an electrical station comprising a transmitter 2 and a receiver 4.

The transmitter 2 comprises a first processing unit 6 intended to detect control signals from an optoelectronic signal supplied by a control management unit (not represented), a command / frequency and gain correspondence table 8, and a modulator 10. The receiver 4 includes a measurement block 12 for continuously measuring the power V of the standby signal Sv and the respective powers Ci (i = 1 to N) of each of the control signals received by the receiver 4, a decision block 14 for validating or invalidating a received control signal, and an output block 16 for transmitting the validated control signals to the control members of the electrical station.

As illustrated in detail in FIG. 2, the measurement block 12 comprises a filter 20, and a power measurement module 22 intended to extract the level of the received control and standby signals.

The decision block 14 comprises a blocking module 24 intended to prevent the reception of the commands when the conditions across the transmission channel are too degraded, particularly because of the attenuation jump or the high level of noise on the transmission line. an alarm module 28, an unlocking module 30 intended to detect a loss of the idle signal not followed by a command, and a detection module 26 configured to calculate the quantity Accu (n) = Accu (n-1) + C (n) -V (n) -S1 if the difference CV, whose variation is illustrated in FIG. 4, is greater than the threshold S1, comparing the quantity calculated with a second threshold S2 predefined, and considering that a valid command signal is received by the receiver if the value of the calculated quantity is greater than the threshold S2, or, reset the quantity Accu (n) and consider that no valid command signal is received by the receiver if the difference CV is less than S1. Furthermore, the decision block 14 comprises a final decision module 32, which validates the control signal in the event of detection of a control signal by the detection module and the absence of blockages or alarms. The output block 16 includes a module for managing the transmission delays of the commands 34 to the control members of the electrical station controlled by the decision block 32. For this purpose, the filter 20 is configured to determine the noise band, the band teleprotection and the band of the previous day, the power measurement module 22 is configured to continuously measure the power V present in the standby channel, and the power C present in each of the control channels and to transmit the measurement results. to the decision module 14. The detection module 26 is configured to compare the difference CV with a first predefined threshold Si. Said detection module 26 is further configured to calculate, for the largest control power, a cumulative difference value CV-S1 given by the expression Accu (n) = accu (n-1) + C (n) - V (n) - S1, and to compare the calculated Accu (n) value with a second predefined threshold 52.

If the calculated difference C-V is greater than the first threshold S1, the decision calculation module 32 then calculates the quantity C-V-S1. The invention exploits the fact that the decision-making time depends on the slope of the curve of variation as a function of time of the magnitude Accu (n). Indeed, the difference CV-Sl varies inversely proportional to the noise level as shown in Figure 5. This has the consequence that the higher the noise on the transmission channel, the longer the time required for the size Accu ( n) reaches the threshold S2 is long.

Figure 3 schematically illustrates the main steps of the method according to the invention. As is schematically illustrated in FIG. 1, in operation, the transmitter 2 transmits to the receiver 4 a signal r (n) carrying either a signal having a single pure frequency which is the watch signal Sv, that is, that is, the mathematical expression of which is a complex exponential at the frequency Fv, ie a signal whose spectrum comprises a single pure frequency or a combination of several pure frequencies representing the control signal. On the receiver 4 side, the frequencies present in received signal r (n) received are determined. For this, a band-pass filter centered on the frequency Fv of the standby signal (step 40) is applied to the received signal r (n). This low-pass filter is chosen so as to let the frequency Fv pass and to eliminate the frequencies contained in the spectrum of the control signal, and then the power V (in dB) of the filtered signal is measured. The same is applied (step 40) to the received signal r (n) of the bandpass filters centered on the frequencies Fi (i = 1 to N) contained in the spectrum of the control signal and the power (step 42) is measured. Ci, (i = 1 to N) (in dB) of each of the filtered signals. For this purpose, the bandpass filters are chosen so as to let the frequency around which they are centered and to eliminate the others. Therefore, if the standby signal has been transmitted, then on the side of the receiver 4, at the output of the bandpass filter centered around the standby frequency Fv, the standby signal and a filtered noise are recovered. At the output of the bandpass filters centered around the frequencies Fi (i = 1 to N) of the spectrum of the control signals, only filtered noise is recovered. On the other hand, if a control signal has been emitted, for example, a control signal whose spectrum comprises a first frequency F1 and a second frequency F2, then on the receiver 4 side, at the output of the bandpass filter centered on the standby frequency, a filtered noise is recovered and also filtered noise at the output of the bandpass filters centered on the frequencies Fi (i = 3 to N). At the output of the band-pass filter centered on the frequency F1, a signal having the frequency F 1 and a filtered noise is recovered, and at the output of the band-pass filter centered on the frequency F 2, a signal having the frequency F 2 is recovered and a filtered noise. Next, the power V (in dB) of the filtered signal at the output of the bandpass filter centered around the standby frequency is measured. Similarly, the power Ci (i = 1 to N) (in dB), respectively, of each of the signals contained in the spectrum of the control signal at the output of each of the bandpass filters centered on each other is measured (step 42). Fi, (i = 1 to N), and the value C of the highest power is selected (step 44). In step 46, the difference C-V between the power of the idle signal and that of the most powerful control signal is calculated.

In step 48, the value of the difference CV is compared with the threshold Si. If the difference CV is greater than Si, in step 50, the value Accu (n) = Accu (n5 1) + C ( n) -V (n) -S1 and this quantity is compared with the second threshold S2 (step 52). If Accu (n) = Accu (n-1) + C (n) -V (n) -S1 is greater than S2, then the decision module 14 validates (step 54) the presence of a control signal, which is then transmitted to the output block 16. If Accu (n) = Accu (n-1) + C (n) -V (n) -S1 is less than S2, then the decision module 14 considers that no signal has not been transmitted by the transmitter, and no control signal is transmitted output block 16. If the difference CV is less than Si, then Accu (n) is reset (step 60) and no signal The control circuit is transmitted as an output block 16. FIG. 4 illustrates the decision times for a S / N signal-to-noise ratio equal to 6 dB and a S / N ratio of 40 dB, respectively. A command in the noisy channel is sent at t = 0, and the quantity Accu (n) is compared with a noise corresponding to a signal-to-noise ratio S / N equal to 6 dB and a noise corresponding to a signal-to-noise ratio S / N equal to 40 dB. In both cases, the value CV becomes greater than S1 after about 4 ms, accu is zero to 4ms and then becomes positive. By choosing a second detection threshold S2 equal to 1000, the command is detected after 10 ms in the channel with a S / N equal to 40 dB and after 19 ms in the channel with S / N equal to 6 dB.

Claims (8)

REVENDICATIONS1. A method for optimizing the operation of a teleprotection system of an electrical installation, said system comprising a transmitter (2) and a receiver (4), the transmitter (2) being configured to transmit to the receiver (4) a signal watch Sv at a known frequency Fv and a plurality of control signals Sci (i = 1 to N) each having a known frequency Fci (i = 1 to N, N being an integer), a method in which a constant measurement is taken at the receiver (4) the power V of the standby signal Sv and the respective powers Ci (i = 1 to N) of each of the control signals received by the receiver (4), the highest measured power C is selected among the powers Ci, the difference CV between the power C and the power V is calculated, the difference CV is compared with a first predefined threshold Si, characterized in that it furthermore comprises the following steps: - if the difference CV is above the threshold Sl, - on calculates the quantity accu (n) = accum (n-1) + C (n) -V (n) -S1, - the calculated quantity is compared with a second predefined threshold S2, and, - a signal is considered is received by the receiver (4) if the value of the calculated quantity is greater than the threshold S2, - if the difference CV is less than the threshold S1, the quantity Accu (n) is set to zero and it is considered that no valid control signal is received by the receiver (4). The method of claim 1, wherein the spectrum of the idle signal comprises a pure frequency and the spectrum of each control signal Sci has one or more distinct pure frequencies. The method of claim 1, wherein the first and second thresholds S1 and S2 are determined experimentally. 4. The method according to claim 1, wherein the transmitter (2) transmits to the receiver (4) the watch signal Sv and the control signals Soi (i = 1 to N) through a power line of said network. The method of claim 4, wherein said Sv watch signals and said Sci control signals (i = 1 to N) are transmitted using the CPL in-line carrier technology. 6. Teleprotection system of an electrical installation comprising a transmitter (2) and a receiver (4), the transmitter (2) being configured to transmit to the receiver (4) a watch signal Sv at a known frequency Fv and a plurality of control signals Sci (i = 1 to N) each having a known frequency Fci (i = 1 to N, N being an integer), the receiver (4) comprises a filter module (20) adapted to filtering the standby signal Sv and the control signals Sci (i = 1 to N) and for continuously measuring at the receiver (4) the power V of the standby signal Sv and the respective powers Ci (i = 1 to N) of each of the control signals received by the receiver (4) and to determine the largest measured power C among the powers Ci, a calculation module adapted to calculate the difference CV between the power C of the control signal and the power .V the standby signal, and to compare the difference CV to a first one S1 predefined, a decision module (14) adapted to validate or invalidate a control signal according to the result of the comparison, system characterized in that said decision module (14) is configured for: - if the difference CV is above the threshold S1, - calculate the quantity: accu (n) -accu (n-1) + C (n) -V (n) -S1, and, - compare the calculated quantity with a second predefined threshold S2 and - consider that a valid command signal is received by the receiver if the value of the calculated quantity is greater than the threshold S2r and, if the difference CV is smaller than Si, - reset the quantity Accu (n) and - consider that no valid command signal is received by the receiver. 30 Receiver (4) configured to receive a watch signal Sv at a known frequency and a plurality of control signals Sci (i = 1 to N) each having a known frequency transmitted by a transmitter (2) in a teleprotection system said receiver (4) having a filter module (20) adapted to detect the watch signal Sv and the control signals Sci (i = 1 to N) and to continuously measure the power V of the standby signal Sv and the respective powers Ci (i = 1 to N) of each of the control signals and to determine the largest measured power C among the powers Ci, a calculation module adapted to calculate the difference CV between the power C of the control signal and the power V of the standby signal and for comparing the difference CV to a first threshold S1 predefined, a decision module (14) adapted to validate or invalidate a control signal according to the result of the comparison, receiver characterized in said decision module (14) is configured to: - calculate the accumulator quantity (n) = accumulator (n1) + C (n) -V (n) -S1, and to compare the calculated quantity with a second threshold S2 predefined if the difference CV is greater than the threshold SI, and consider that a valid command signal is received by the receiver if the value of the calculated quantity is greater than the threshold S2, or, - reset the quantity Accu (n) and consider that no valid control signal is received by the receiver (4) if the difference CV is less than S1. A computer program stored on a recording medium and having instructions for performing the steps of the method of claim 1 when executed on a computer.