CN1045849C - Power swing detection apparatus for electric power system - Google Patents

Abstract

When the impedance relay (32) detects that the impedance change of the power system drops below a predetermined value, and the duration of the impedance relay (32) detection operation is longer than the predetermined time set in the fault detection timer (33), the circuit is released 34 removes the hindrance to the tripping of the protection relay group, so that the protection relay group can be regardless of the relationship between the time-limited reset period of the fluctuation detection and hold timer and the time-limited operation period of the zone 2 protection timer and the zone 3 protection timer, and A trip occurs immediately.

Description

Power Fluctuation Detection Device for Power System

The invention relates to a power fluctuation detection device, which can prevent the protection relay group from tripping according to the power fluctuation detection output in the power system.

Figure 12 is a wiring diagram of a protective relay system for a common direct grounding system (short circuit), which is published in the power standard B-401 "Protective Relay and Protective Relay Group" established by the Japanese Electric Power Company and the Power Development Corporation in accordance with the Japanese Industrial Standards on page 90 of . Figure 13 is a general working waveform obtained when the position of the mho relay (as shown on page 65 of "Electrical Cooperative Research", Volume 37, Issue 1, published by the Electrical Cooperative Research Society in May 1981) is the starting point picture. The horizontal axis of FIG. 13 represents the resistive component R of impedance, and the vertical axis represents the reactive component X of impedance. The phase characteristics of mho relays can be shown in Fig. 13, while Figs. 14 to 17 are timing diagrams illustrating the operation of the prior art.

In Fig. 12, reference numeral 1 represents a protective relay group, which can generate and provide tripping for circuit breakers and switches configured in the power system (not shown in the figure) when a fault in the power system is detected, and reference numeral 2 represents A power fluctuation detection device, which can prevent the protection relay group 1 from tripping according to the power fluctuation detection in the power system. Labels 3, 4 and 5 represent zone 1 short-circuit mho relays (represented by 44S-1X1, 44S-2X1 and 44S-3X1 in the figure), which protect the zone 1 line segments of the first, second and third phases of the power system line segment ; Labels 6, 7 and 8 represent 2-zone short-circuit mho relays (represented by 44S-1X2, 44S-2X2 and 44S-3X2 in the figure), which protect the 2-zone line segments of the first, second and third phases of the line segment; And 9, 10 and 11 represent 3-zone short-circuit mho relays (represented by 44S-1D, 44S-2D and 44S-3D in the figure), which protect the 3-zone line segments of the first, second and third phases of the line segment. Reference numeral 12 represents a short-circuit bias mho relay (represented by 440M in the figure), which is used to detect power fluctuations in the first, second and third phases of the power system line segment; 13, 14 and 15 are "AND" circuits, It is used to receive the output of 1-zone short-circuit mho relay 3 to 5 and the output of 3-zone short-circuit mho relay 9 to 11; 16 is an "or" circuit for receiving the output of "and" circuit 13 to 15 and generating 1 and 17 is a prohibition circuit, which receives the output of the "or" circuit 16 and the output of the power fluctuation detection device 2 as a prohibition input and produces a zone 1 protection output. Reference numerals 18, 19 and 20 represent "AND" circuits which receive the outputs of 2-zone short-circuited mho relays 6 to 8 and the outputs of 3-zone short-circuited mho relays 9 to 11 as inputs; reference numeral 21 represents an "or" circuit which uses To receive the output of "AND" circuit 18 to 20 and produce 2-zone output; 22 and 27 are "OR" circuits for receiving the output of 3-zone short-circuit mho relay 9 to 11 and produce 3-zone output; 23 is Zone 2 protection timer, which is composed of a time-limiting operation circuit, is used to protect zone 2 and receives the output of "or" circuit 22; label 24 is a protection timer for zone 3, which is composed of a time-limiting operation circuit, and is used to protect zone 3 Zone and receive the output of "OR" circuit 22; label 25 is "AND" circuit, used to receive the output of zone 2 protection timer 23 and "or" circuit 21 and generate zone 2 protection output; label 26 is "or" circuit , to receive the zone 1 protection output of the prohibition circuit 17, the zone 2 protection output of the "AND" circuit 25, and the zone 3 protection output of the zone 3 protection timer 24, and to generate a trip; the label 28 is a prohibition circuit for receiving The output of the "OR" circuit 27 and the output of the short-circuit bias mho relay 12 as the prohibition input; the reference numeral 29 is a power fluctuation detection timer, which is composed of a time-limited operation circuit, and is used to receive the output of the prohibition circuit 28; the reference numeral 30 It is a power fluctuation detection and holding timer, which is composed of a time-limited operation and time-limiting reset circuit for receiving the output of the prohibition circuit 28; and reference numeral 31 represents an "or" circuit for receiving power fluctuation detection and holding the timer 30 and the output of the power fluctuation detection timer 29, and generate a power fluctuation detection output.

The operation of the prior art will be described with reference to FIGS. 13 to 17. FIG. When power fluctuations occur in the power system, the changes in current and voltage are much slower than when system faults occur, and the impedance follows the trajectory shown in Figure 13 when fluctuating. Following the trajectory of this impedance as it fluctuates, the short-circuit bias mho relays 9 to 11 are energized at time t2 after the short-circuit bias mho relays have been energized at time t1. If the time difference t1-t2 between t1 and t2 exceeds the time-limited operating value of the power fluctuation detection timer 29, it is considered that a power fluctuation has occurred in the power system, and the power fluctuation detection device 2 generates a high potential "1" as a power fluctuation detection The output is sent to the disable input of the disable circuit 17. Therefore, even if the short-circuit mho relay circuits 3 to 5 and the short-circuit mho relays 9 to 11 are activated simultaneously or later than them, the prohibition circuit 17 still continues to generate a low potential "0", which is sent to the "or" circuit 26 as an invalid signal. As a result, OR circuit 26 does not trip. In other words, the power fluctuation detection device 2 generates a high potential "1", which is sent to the prohibition input terminal of the prohibition circuit 17 as a power fluctuation detection output, thereby preventing unnecessary tripping of the protection relay group 1 .

When the impedance locus during power fluctuation shown in FIG. 13 moves from within the protection range of the short-circuit mho relays 9 to 11 to within the holding range of the short-circuit bias mho relay 12, the "OR" circuit 27 turns the low potential "0 "Add to the prohibition input terminal of prohibition circuit 28; Prohibition circuit 28 adds high potential "1" to fluctuation detection timer 29 and fluctuation detection and hold timer 30; And "or" circuit 31 according to fluctuation detection timer 29 or fluctuation A short time-limited operation of the detect and hold timer 30 applies a high potential "1" to the disable input of the disable circuit 17. Next, when the impedance locus when the power fluctuates moves from within the protection range of the short-circuit mho relays 9 to 11 to outside the protection range of the short-circuit bias mho relay 12, the prohibition circuit 28 adds a low potential "0" to the fluctuation detection timing Device 29 and fluctuation detection and hold timer 30. When the output of the fluctuation detection timer 29 becomes a low potential "0", the "or" circuit 31 adds the low potential "0" to the prohibition input terminal of the prohibition circuit 17 according to the time limit reset of the fluctuation detection and hold timer 30. Therefore, when the impedance locus when fluctuating moves from within the protection range of the short-circuit mho relays 9 to 11 to outside the protection range of the short-circuit bias mho relay 12, the inhibit circuit 17 can be reset after the time limit of the fluctuation detection and hold timer 30. A high potential "1" is applied to the "OR" circuit 26 as a valid signal to cause a trip. In other words, the power fluctuation detection device 2 adds the low potential "0" as the power fluctuation detection output to the prohibition input terminal of the prohibition circuit 17 after the fluctuation detection and holding timer 30 is time-limited reset, so that the protection relay group 1 returns to a function A tripped condition is generated.

At the same time, see Figures 14-17, the same symbols in the figure represent the signal waveforms of the same devices, where a represents the signal waveform of the short-circuit bias mho relay 1 2, b represents the signal waveform of the short-circuit mho relay 9 to 11, and c represents The signal waveform of the fluctuation detection timer 29, d represents the signal waveform of the fluctuation detection and hold timer 30, and e represents the signal waveforms of the protection timers 23 and 24 of the zone 2 and zone 3. During the fluctuation detection period, within the protection range of the short-circuit mho relays 9 to 11, when a system failure indicated by F1 in Fig. 13 occurs, if the time-limited reset period Tr of the fluctuation detection and hold timer 30 is greater than the protection timing of zone 2 Time-limited operation period Tt (Tr>Tt) of device 23 and 3 district protection timers 24, see Fig. 14, so 2 district protection timers 23 and 3 district protection timers 24 are after their time-limiting operation, will high potential "1" Applied to the "OR" circuit 26 as an operating signal, and the "OR" circuit 26 generates a trip. Conversely, as shown in FIG. 15, if the time-limited reset period Tr of the fluctuation detection and hold timer 30 is less than the time-limited operation period Tt (Tr<Tt) of the 2-zone protection timer 23 and the 3-zone protection timer 24, the fluctuation detection And hold timer 30 just adds low potential "0" to the prohibiting input terminal of prohibiting circuit 17 as operation signal after its limited time reset period, and prohibiting circuit 17 produces "1" to "or" circuit 26, as "or" Circuit 26 generates a valid signal for tripping.

After the remote system failure indicated by F2 in Figure 13 (in which the short-circuit bias mho relay is activated and the short-circuit mho relays 9 to 11 are not activated), the short-circuit mho relay in Figure 13 referred to by F1 in Figure 13 occurs. When the system failure within the protection range of European relays 9 to 11, if as shown in Figure 16, the time-limited reset period Tr of the fluctuation detection and hold timer 30 is greater than the time-limited operation of the 2-zone protection timer 23 and the 3-zone protection timer 24 Period Tt (Tr>Tt), then the 2-zone protection timer 23 and the 3-zone protection timer 24 will add the high potential "1" as an operation signal to the "or" circuit 26 after its time-limited operation period, so that the "or" circuit 26 produces a trip. Conversely, if, as shown in FIG. 17, the time-limited reset period Tr of the fluctuation detection and hold timer 30 is less than the time-limited operation period Tt (Tr<Tt) of the 2-zone protection timer 23 and the 3-zone protection timer 24, then the fluctuation detection And hold timer 30 adds low potential "0" to the prohibition input terminal of prohibition circuit 17 as operation signal after its time-limited reset period, and then prohibition circuit 17 adds "1" to "or" circuit 26, as "or" Circuit 26 is used to generate a valid signal for tripping.

In addition, even if a ground fault occurs in one phase of the protected section of the not shown ground protection relay group, the short circuit bias mho relay circuit 12 will still energize due to its wide protection range. As a result, the power fluctuation detecting device 2 supplies a high potential "1" as a power fluctuation detection output to the prohibit input terminal of the prohibit circuit 17, preventing the protective relay group 1 from unnecessary tripping. When a system fault occurs in two or more phases after a ground fault occurs in one phase, the short-circuit bias mho relay 12 is activated, and also according to the time-limited reset period Tr of the ripple detection and hold timer 30 and Relationship between the time-limited operation period Tt of the zone 2 protection timer 23 and the zone 3 protection timer 24, after the time-limited operation period of the zone 2 protection timer 23 and the zone 3 protection timer 24 or the fluctuation detection and hold timer 30 After a time-limited reset period of , the OR circuit 26 of the self-protective relay group 1 generates a trip to cut off the power system.

Since the prior art power fluctuation detection device 2 is constituted as described above, when a system fault occurs during power fluctuation detection, a system fault occurs in the protected section after a remote system fault occurs, or when a ground fault occurs in one phase When a system failure occurs in two or more phases after a failure, there is a problem that if the time-limited reset period Tr of the fluctuation detection and hold timer 30 is smaller than the 2-zone protection timer 23 and the 3-zone protection timer 24 The time-limited operation period Tt (Tr<Tt), then the protective relay group 2 can only trip after the time-limited reset period of the power fluctuation detection and hold timer 30.

System power fluctuations may change the power frequency. In this case, the system power fluctuation detection device 2 is activated according to the setting of the zero-phase overcurrent relay detection operation constituting the ground fault detection means, so that the ground fault protection relay group generates unnecessary tripping.

The present invention is to solve the above-mentioned problems, and the first object of the invention is to immediately eliminate the generation of tripping of the protection relay group by a system fault occurring during power fluctuation in the power system and the system power fluctuation detection device prevents the protection relay group from tripping. Blocking of tripping and allowing protection relay groups to trip regardless of the relationship between the time-limited reset period of the fluctuation detection and hold timer and the time-limited operation period of the zone 2 protection timer and the zone 3 protection timer, thereby protecting the power system.

A second object of the present invention is to eliminate the hindrance to tripping of the protection relay group immediately and allow the protection when a fault occurs in the protected section even after a remote fault in which only the power fluctuation detection relay energizes. The relay group protects the power system by tripping regardless of the relationship between the time-limited reset period of the fluctuation detection and hold timer and the time-limited operation period of the zone 2 protection timer and the zone 3 hold timer.

A third object of the present invention is to eliminate the hindrance to the tripping of the protection relay group immediately and allow the protection relay group regardless of the power even when a fault occurs in two or more phases Regardless of the setting period of the fluctuation detection relay, a trip can be generated to protect the power system.

A fourth object of the present invention is to prevent unnecessary tripping of the ground protection relay group even when the power frequency is changed by fluctuations in the power system.

According to a first aspect of the present invention as claimed in claim 1, there is provided a power fluctuation detection device comprising an impedance change rate detection circuit, a failure detection timer and a release circuit.

According to the second aspect of the present invention as claimed in claim 2, there is provided a power fluctuation detecting device, wherein the system power flow fixing circuit makes the output of the impedance change rate detecting circuit of the first aspect of the present invention the same as that of the first aspect of the present invention The input of the fault detection timer is coupled to receive the output of the power fluctuation detection.

According to a third aspect of the present invention claimed in claim 3, there is provided a power fluctuation detecting device, wherein the system power flow fixing circuit of the second aspect of the present invention is made of a three-input terminal logic circuit which can receive impedance changes The output of the power detection circuit, the output of the power fluctuation detection and the output of the fault detection circuit used to detect the overcurrent in the power system are taken as input.

According to a fourth aspect of the present invention as claimed in claim 4, there is provided a power fluctuation detection apparatus in which each phase of the power system is equipped with the impedance change rate detection circuit of the first aspect of the present invention, the fault detection timer and the release circuit.

According to a fifth aspect of the present invention claimed in claim 5, there is provided a power fluctuation detecting device in which the impedance change rate detecting circuit of the fourth aspect of the present invention is provided for each line segment and each phase of the electrosurgical knife system.

According to a sixth aspect of the present invention as claimed in claim 6, there is provided a power fluctuation detecting device, in which a single-phase grounding detection circuit is provided so that the detection output of the single-phase grounding detection circuit suppresses the Power fluctuation detection output for power fluctuation detection relay.

In the power fluctuation detection device according to the first aspect of the present invention, when the impedance change rate detection circuit detects that the impedance of the power system has dropped below a predetermined value, and the detection operation of the impedance change rate detection circuit lasts longer than the time predetermined in the fault detection timer When the time interval is long, the release circuit cancels the obstruction to the tripping of the protective relay group.

In the power fluctuation detecting device of the second aspect of the present invention, the system power flux fixing circuit which has received the output of the impedance change rate detecting circuit activates the failure detection timer in response to the power fluctuation detecting output as necessary.

In the power fluctuation detection device of the third aspect of the present invention, the system power flux fixing circuit that has received the output of the impedance change rate detection circuit responds to the power fluctuation detection output or the overcurrent detection output when the power system fails when necessary, and excites the fault. Detection timer.

In the power fluctuation detection device of the fourth aspect of the present invention, even when the power fluctuation in the power system changes the frequency of the power supply, the impedance change rate detection circuit provided for each phase of the power system can prevent unnecessary generation of grounding protective relay groups. tripping.

In the power fluctuation detection device of the fifth aspect of the present invention, when the power fluctuation in the power system changes the frequency of the power supply, the impedance change rate detection circuit equipped for each phase and each line segment of the power system can prevent the grounding protective relay group from Unnecessary tripping occurs.

In the power fluctuation detection device according to the sixth aspect of the present invention, when a ground fault occurs in one phase and then a fault occurs in two or more phases, the single-phase ground detection circuit will suppress the power fluctuation detection relay from generating power fluctuations detection output.

The above and other objects, features and advantages of the present invention will become more apparent from the following description in conjunction with the accompanying drawings.

Fig. 1 is a wiring diagram of a power fluctuation detection device having a protective relay group according to Embodiment 1 of the present invention;

Fig. 2 is a working waveform diagram of the mho relay illustrating the function of embodiment 1;

Fig. 3 is a figure illustrating the function of the impedance relay of embodiment 1;

Fig. 4 is a wiring diagram of a power fluctuation detection device having a protective relay group according to Embodiment 2 of the present invention;

Fig. 5 is a wiring diagram of a power fluctuation detection device having a protective relay group according to Embodiment 3 of the present invention;

Fig. 6 is a wiring diagram of a power fluctuation detection device according to Embodiment 4 of the present invention;

Fig. 7 is a timing diagram showing the function of Embodiment 4;

Fig. 8 is a wiring diagram of a power fluctuation detection device according to Embodiment 5 of the present invention;

Fig. 9 is a wiring diagram of a power fluctuation detection device according to Embodiment 6 of the present invention;

Fig. 10 is a wiring diagram of a power fluctuation detection device according to Embodiment 7 of the present invention;

Fig. 11 is a timing diagram showing the function of Embodiment 7;

Fig. 12 is a wiring diagram of a prior art power fluctuation detection device with a protective relay group;

Fig. 13 is a working waveform diagram of a mho relay illustrating the function of the prior art;

Figure 14 is a timing diagram illustrating prior art functionality;

Figure 15 is a timing diagram illustrating prior art functionality;

Figure 16 is a timing diagram illustrating prior art functionality; and

Fig. 17 is a timing diagram illustrating prior art functions.

The preferred embodiment of the present invention will be described with reference to Figs. 1 to 11, where the same or corresponding parts as those in the prior art will be marked with the same reference numerals. Embodiment 1 (claim 1)

FIG. 1 is a wiring diagram of a power fluctuation detection device including a power system protection relay group according to Embodiment 1 of the present invention. In Fig. 1, protection relay group 1 includes: 1 zone short-circuit mho relay 3-5, 2 zone short-circuit mho relay 6-8, 3 zone short-circuit mho relay 9-11, "AND" circuit 13-15, generating "OR" circuit 16 for zone 1 output, prohibition circuit 17 for phase 1 zone protection output, "AND" circuit 18-20, "OR" circuit 21 for zone 2 output, or "or" circuit 22 for zone 3 output 2. Zone 2 protection timer 23 constituting the time-limited operation circuit, zone 3 protection timer 24 constituting the time-limited operation circuit, an "AND" circuit 25 for generating zone 2 protection output and an "OR" circuit 26 for tripping. The power fluctuation detection device 2 includes: a short-circuit bias mho relay 12, an "or" circuit 27 for generating 3-zone protection output, a prohibition circuit 28, a power fluctuation detection timer 29 constituting a time-limited operation circuit, constituting a time-limited operation and a time-limited reset Power fluctuation detection and hold timer 30, OR circuit 31 generating power fluctuation detection output, impedance relay 32, fault detection timer 33 and release circuit 34. The impedance relay 32 detects the impedance change rate caused by the current and voltage of the power system, and forms an impedance change rate detection circuit. When the impedance change rate (change width) drops below a certain value, the circuit starts to work. The output of the impedance relay 32 is coupled to the fault detection timer 33, and the release circuit 34 is a prohibition circuit, which receives the output of the fault detection timer 33 as a prohibition input, and also receives the output of the "OR" circuit 31 to generate a power fluctuation detection output . The output of the release circuit 17 is applied to the disable input of the disable circuit 17 of the protective relay group 1 . Impedance relay 32 excitation when satisfying following formula;

|R(t)-R(t-180)|<0.5Ω...(1)

|X(t)-X(t-180)|<0.5Ω... (2) Here R(t) and x(t) represent the resistance and reactance components of the impedance, respectively. R(t-180) and x(t-180) represent the corresponding data half a cycle ago. Therefore, in FIG. 3 , if F ₃ =10 ohms and F ₄ =2 ohms, formula (1) is not true but formula (2) is true. As a result, impedance relay 32 does not energize. If F ₃ =10 ohms and F ₄ =9.6 ohms, both of the above equations hold, impedance relay 32 is energized.

Referring to Fig. 2, the operation of Embodiment 1 of the present invention will be described below. When a power system fluctuates, the current and voltage changes more slowly than when the system fails, and the impedance follows a trajectory as shown in Figure 2. Corresponding to the impedance locus at the moment of fluctuation, the short-circuit bias mho relay 12 is energized at time t1, followed by the short-circuit mho relay 9-11 being energized at time t2. As in the prior art, if the time difference t1-t2 between the operating moments t1 and t2 exceeds the operating time limit of the power fluctuation detection timer 29, the power system is deemed to have power fluctuations, and the power fluctuation detection device 2 will report to the prohibition circuit 17 The prohibition input terminal of the circuit sends a high level "1" as the output of the power fluctuation detection to prevent unnecessary tripping action of the protection relay group 1. When the impedance locus at the time of fluctuation in FIG. 2 moves from inside the protection range of the short-circuit mho relay 9-11 to outside the protection range of the short-circuit bias mho relay 12, after the time-limited reset period of the fluctuation detection and hold timer 30 , the power fluctuation detection device 2 sends a low level "0" as a power fluctuation detection output to the prohibition input terminal of the prohibition circuit 17, so the protection relay group 1 returns to the state capable of generating a tripping action, which is the same as the prior art of.

At the same time, if a system fault occurs within the protection range of the short-circuit mho relay 9-11 during power fluctuation detection, the slowly changing impedance trace will move to the fault point F1, as shown in FIG. 2 . Because the impedance is a fixed value substantially at the fault point F1 place, the impedance relay 32 just detects the system fault, and after a set time, the detection timer completes a time-limited operation, and the "AND" circuit 34 cancels the "OR" circuit 31, High level "1" sent to protection relay group 1 as power fluctuation detection output. As a result, the OR circuit 26 produces a tripping action after the time-limited operation of the 2-zone protection timer 23 and the 3-zone protection timer 24 or before the time-limited reset of the fluctuation detection and hold timer 30 is completed regardless of the fluctuation detection and hold timing. What is the relationship between the time-limited reset period of the timer 30 and the time-limited operation period of the 2-zone protection timer 23 and the 3-zone protection timer 24.

When the system fault represented by _F1 occurs within the protection section of the short-circuit mho relay 9-11 and occurs after the remote system fault represented by _F2 in Fig. European relays 9-11 are not activated), the impedance relay 32 detects the system fault F ₁ , and the detection timer 33 thus completes a time-limited operation, as described above. After a preset delay time caused by the time-limited operation, the detection timer 33 sends a high level "1" to the prohibition input terminal of the "AND" circuit 34, and the "AND" circuit 34 cancels this high level again. The level is used as a power fluctuation detection output from the OR circuit 31 to the protective relay group 1 . As a result, the OR circuit 25 produces a tripping action just after the time-limited operation of the 2-zone protection timer 23 and the 3-zone protection timer 24 or before the time-limited reset of the fluctuation detection and hold timer 30 occurs regardless of the above-mentioned two kinds of limits. What is the relationship between periods.

Moreover, even if a single-phase ground fault occurs in the protection section of the ground protection device not shown, the short circuit bias mho relay 12 is excited due to the wide protection range, and the power fluctuation detection device 2 sends a signal to the prohibition terminal of the prohibition circuit 17. As a high level "1" output of power fluctuation detection, it can prevent unnecessary tripping action of protective relay group 1. When the above-mentioned single-phase ground fault occurs, and a system fault occurs in two phases or more than two phases, the impedance relay 32 detects the system fault, and the "AND" circuit 34 will cancel the fault from the "OR" circuit 31 and send it to the protection relay. Group 1 disable signal, so that OR circuit 26 produces a tripping action, similar to the situation described above. Embodiment 2 (claim 2)

4 is a wiring diagram of a power fluctuation detection device including a power system protection relay group according to Embodiment 2 of the present invention. In Fig. 4, the feature of the present embodiment 2 is that an "AND" circuit 35 for fixing the system power flux is provided between the impedance relay 32 (indicated by △RX in the figure) and the detection timer 33, and the impedance relay The output of 32 and the output of "OR" circuit 31 are sent to "AND" circuit 35, and the output of "AND" circuit 35 is sent to detection timer 33.

Therefore, according to the present embodiment 2, since the "AND" circuit 35 of the fixed system power flux is excited by the output of the "OR" circuit 31 and the impedance relay 32, the detection time relay 33 is not excited when the power system has power flux . Therefore, if a power fluctuation occurs in the power system, the power fluctuation detecting device 2 detects the fluctuation immediately in addition to performing the operation of Embodiment 1, and prevents the protective relay group 1 from tripping. In short, in order to maintain the voltage and current substantially constant, power flow generally always flows in the power system, so the impedance relay 32 will operate when the impedance drops below a predetermined value. Therefore, in the absence of the AND circuit 35 to fix the system power flow, the power fluctuation detection output from the drop-in circuit 34 is blocked, and the reset period of the impedance relay 32 may delay the power fluctuation detection output when the power fluctuation occurs. , thus delaying the tripping action to prevent the protection relay group 1 from occurring. Based on the above reasons, in the normal operation of the power system, the "AND" circuit 35 of the fixed system power flux plays a role of not blocking the output of the power fluctuation detection. As a result, the power fluctuation detecting device 2 immediately detects the power fluctuation and prevents the protective relay group 1 from tripping. Embodiment 3 (claim 3)

5 is a wiring diagram of a power fluctuation detection device including a power system protection relay group according to Embodiment 3 of the present invention. In Fig. 5, the present embodiment 3 is characterized in that the "AND" circuit 35 of the power flow of the fixed system of the above-mentioned embodiment 2 is composed of a three-output component, and a fault detection circuit 36 such as an overcurrent detection relay is provided. , and the output of the fault detection circuit 36 is coupled to the additional output of the AND circuit 35.

Therefore, according to the third embodiment, since the fault detection circuit 36 works when the current exceeds the predetermined system fault value or the voltage is lower than the predetermined system fault value, the power fluctuation detection device 2 can not be activated when necessary. When a power fluctuation occurs in the power system, in addition to implementing the operation of Embodiment 2, the power fluctuation detection device 2 immediately detects the power fluctuation and prevents the protective relay group 1 from tripping. Embodiment 4 (claim 4)

Fig. 6 is a wiring diagram of a power fluctuation detection device including a power system protection relay group according to Embodiment 4 of the present invention. FIG. 7 is a timing chart for explaining the operation of Embodiment 4. FIG. In Fig. 6, the characteristic of embodiment 4 is that (1) the impedance relay 32 of embodiment 2 is composed of the first phase-to-ground impedance relay 51 (indicated by △RXG-1 in the figure), the second phase-to-ground impedance relay 52 (represented by △RXG-2 in the figure) and the third phase-to-ground impedance relay 53 (represented by ΔRXG-3 in the figure); (2) the "AND" circuit 35 of the fixed system power flow of the above-mentioned embodiment 2 It consists of a first phase-to-ground "AND" circuit 54, a second phase-to-ground "AND" circuit 55 and a third phase-to-ground "AND" circuit 56, each of these three circuits receives the "OR" circuit 31 output and independently receive the output of the first phase, the second phase, and the third phase grounding impedance relay 51-53; , the second phase-to-ground fault timer 67, and the third phase-to-ground fault timer 68 and the short-circuit detection timer 69; (4) the release circuit 34 described in embodiment 2 is composed of the first phase-to-ground release circuit, The second phase-to-ground release circuit 71, the third phase-to-ground release circuit 72 and the short-circuit release circuit 73 are composed; (5) the device includes: receiving the first phase, the second phase and the third phase to the "AND" circuit 54 -56 output "AND" circuit 57, "AND" circuit 58 receiving the output of the first phase and the second phase ground "AND" circuit 54 and 55, receiving the second phase and the third phase ground "AND" circuit 55 and 56 outputs AND circuit 59, AND circuit 60 receiving the outputs of first and third phase AND circuits 54 and 56, AND circuit 60 receiving the outputs of AND circuits 58-60 Or" circuit 61, receiving the output of "OR" circuit 61 and the prohibition circuit 62 of the output of "AND" circuit 57 as prohibition input, and receiving the output of prohibition circuit 62 as prohibition input and the first phase, the second phase, the second phase The prohibition circuit 63-65 of the output of the three-phase ground "AND" circuit 54-56; (6) the output terminal of the prohibition circuit 63-65 is coupled to the first phase, the second phase and the third phase ground fault detection respectively On the timer 66-68, the output terminal of "or" circuit 61 is coupled to the short circuit detection timer 69, the input terminal of the short circuit detection timer 69 is coupled to the prohibition input terminal of the short circuit release circuit 73, and the short circuit release circuit The input of 73 is coupled to the output of AND circuit 31.

Therefore, according to Embodiment 4, since the first phase, second phase, and third phase ground detection output and short circuit detection output are generated separately, even if the power supply frequency changes during power fluctuations in the power system, in addition to implementing the above implementation In addition to the operation of Example 1, the power fluctuation detection device can prevent unnecessary tripping action of the ground protection relay group. Referring to Fig. 7 (A), 7 (B) and 7 (C), the same label among the figure represents the signal waveform of the same circuit part, wherein label a represents the signal waveform of the first phase ground impedance relay 51, and label b represents the first The signal waveform of the two-phase grounding impedance relay 52, the symbol c represents the signal waveform of the third phase grounding impedance relay 53, the symbol d represents the signal waveform of the "AND" circuit 58 to 60, and the symbol e represents the signal of the "AND" circuit 57 Waveforms, the symbol f represents the signal waveform of the AND circuit 62, the symbol g represents the signal waveform of the prohibition circuit 63, the symbol h represents the signal waveform of the prohibition circuit 64, and the symbol i represents the signal waveform of the prohibition circuit 65. In short, when a ground fault occurs in one phase, as shown in FIG. Phase impedance relay excitation, "and" circuit 57-60, "or" circuit 61 and prohibition circuit 62 are not excited, only one excitation in "and" circuit 63-65. When the two-phase ground fault shown in Figure 7 (B) occurs, in the first phase, second phase and third phase ground impedance relays 51-53, there are two phase faults corresponding to the fault. The impedance relay is activated, the "AND" circuit 58-60 and the "OR" circuit 61 are activated, the "AND" circuit 57 is not activated, the prohibition circuit 62 is activated, and the "AND" circuit 63-65 is not activated. Moreover, when a three-phase fault as shown in Figure 7 (C) occurs, the first phase, the second phase and the third phase grounding impedance relays are all activated, and the "AND" circuit 57-60 and the "OR" circuit 61 are activated , inhibit circuit 62 is not activated, and "AND" circuits 63-65 are activated. As a result, even if the frequency of the power supply varies during power fluctuations in the power system, unnecessary tripping of the ground protection relay group can be prevented. Embodiment 5 (claim 5)

Fig. 8 is a wiring diagram of a power fluctuation detection device including a power system protection relay group according to Embodiment 5 of the present invention. In Fig. 8, the characteristics of Embodiment 5 are that (1) the impedance relay 32 in Embodiment 4 is composed of the first phase, the second phase and the third phase ground impedance relay 51-53, the first phase short circuit impedance relay 81 (indicated by ΔRXS-1 in the figure), the second phase short-circuit impedance relay 82 (indicated by ΔRXS-2 in the figure) and the third phase short-circuit impedance relay 83 (indicated by ΔRXS-3 in the figure); (2 ) The "AND" circuit 35 of the fixed system power flow of the above-mentioned embodiment 4 is made up of the first phase, the second phase and the third phase short-circuit "AND" circuit 84-86; (3) the failure detection timing of the above-mentioned embodiment 4 The device 33 is composed of first phase, second phase and third phase ground fault detection timers 66-68 and first phase, second phase and third phase short circuit detection timers 87-89. In the fifth embodiment, like the above-mentioned embodiment 4, the release circuit 33 is composed of the first phase, the second phase and the third phase ground release circuits 70 - 72 and a short circuit release circuit 73 .

Therefore, according to this Embodiment 5, unlike Embodiment 4, since the impedance relay and the fault detection timer are provided for each phase here, the structure of the logic circuit is simplified, even if the power supply frequency changes during power fluctuations in the power system , It can also prevent unnecessary tripping of the grounding protective relay group. Embodiment 6 (claim 5)

Fig. 9 is a wiring diagram of a power fluctuation detection device including a power system protection relay group according to Embodiment 6 of the present invention. As shown in Figure 9, the feature of this embodiment 6 is that the short-circuit release circuit 73 of the above-mentioned embodiment 5 is composed of the first phase, the second phase and the third phase short-circuit release circuit 91-93, so that the first phase Both can generate short-circuit detection output.

In Figures 6, 8 and 9, the short-circuit and ground-fault protective relay groups are not shown for the sake of clarity. Embodiment 7 (claim 6)

Fig. 10 is a wiring diagram of a power fluctuation detection device including a power system protection relay group according to Embodiment 7 of the present invention. Fig. 11 is a timing chart for explaining the operation of the present embodiment 7. In FIG. 10 , the feature of the present embodiment 7 is that the prohibition circuit 28 of the above-mentioned embodiment 1 is composed of a three-input terminal element including two prohibition input terminals, and the output signal of the single-phase ground detection circuit 47 is added to one of the prohibition input terminals. end. The single-phase grounding detection circuit 47 is composed of the following parts: three-level grounding mho relays 37, 38 and 39 (indicated by 44G-1D, 44G-2D and 44G-3D respectively in the figure), receiving three-level grounding mho relays 37- "OR" circuit 40 for 39 output signals, "AND" circuit 41 for receiving the output of three-level grounding mho relays 37 and 38, "and" circuit 42 for receiving output of three-level grounding mho relays 38 and 39, and receiving three-level grounding The "AND" circuit 43 output by the mho relays 37 and 39, the "OR" circuit 44 that receives the output from the "AND" circuits 41-43, the "AND" circuit 45 that receives the output from the "OR" circuit 44 and the "OR" circuit 40, A time-limited operation circuit is constructed to receive the single-phase ground detection timer 46 output by the AND circuit 45 . A single ground detection timer is coupled to an inhibit input of an inhibit circuit 28 .

Therefore, according to Embodiment 7, since the output of the single-phase ground fault detection circuit 47 is used as a signal for prohibiting the tripping action of the protective relay group 1, even if a single-phase ground fault occurs and a two-phase or more In addition to implementing the operation of Embodiment 1, the power fluctuation detection device 2 does not hinder the tripping action of the protective relay unit. Referring to Fig. 11(A) and Fig. 11(B), the same symbols in the two figures represent the signal waveforms of the same circuit parts, wherein the symbols a, b and c respectively represent the signal waveforms of the three-level grounded mho relays 37, 38 and 39 , d represents the signal waveform of the "OR" circuit 40, the symbol e represents the signal waveform of the "AND" circuits 41 to 43, the symbol f represents the signal waveform of the prohibition circuit 45, and the symbol g represents the signal waveform of the ground detection timer 46. In short, when a single-phase-to-ground fault as shown in Figure 11(A) occurs, one of the three-level grounded mho relays 37-39 corresponding to the fault is activated, and the "or" of the next level is activated. " circuit 40, "AND" circuits 41-43 are not activated, and "AND" circuit 45 is activated, and the single-phase ground detection timer 46 completes the time-limited operation. When a two-phase-to-ground fault as shown in Figure 11 (B) occurs, the two relays in the three-level mho relay 37-39 corresponding to the fault are excited, and the "or" circuit 40 and the "and" circuit 41 are excited. -43, "AND" circuit 45 is not activated, nor is the single-phase ground detection timer activated. As a result, even if a two-phase system fault occurs after a single-phase-to-earth fault, the protection relay group 1 will immediately generate a tripping action regardless of the time-limited reset period of the fluctuation detection and holding timer 30 and the zone 2 protection timer 23 and zone 3 What is the relationship between the time-limited operation periods of the protection timer 24?

According to the first aspect of the present invention, since the release circuit cancels the protection when the impedance change rate detection circuit detects that the impedance change of the power system drops below a predetermined value and the detection operation time of the circuit exceeds the predetermined value in the fault detection timer. The function of the tripping action of the relay group is hindered, so when the remote fault occurs, only the power fluctuation detection relay is excited at this time. If a system fault occurs during the power fluctuation of the power system or the protection section fails, the protection relay unit will immediately generate a tripping action. Regardless of the relationship between the time-limited reset period of the fluctuation detection and protection timer and the time-limited operation period of the zone 2 protection timer and the zone 3 protection timer.

According to the second aspect of the present invention, the system power flux fixing circuit which receives the output of the impedance change rate detection circuit from the ground activates the fault detection timer only when necessary in response to the power fluctuation detection output, so it is possible to prevent the failure detection timer from being triggered by the power system. The power fluctuation detection device malfunction caused by the rate flux.

According to the third aspect of the present invention, since the system power energy fixing circuit receiving the output of the impedance change rate detecting circuit is activated only when necessary in response to the detected output of power fluctuation in the power system or the overcurrent protection output when a fault occurs The fault detection timer, so the power fluctuation detection device does not need to be unenergized, and can effectively prevent the malfunction of the device caused by the power flow in the power system.

According to the fourth aspect of the present invention, since the impedance change rate detection circuit is provided on each phase, and the power fluctuation detection means generates a ground detection output and a short circuit detection output for each phase, even if the power frequency fluctuates when the power fluctuates The change also prevents unwanted tripping of the earth-fault relay bank.

According to the fifth aspect of the present invention, since the impedance change rate detection circuit is provided on each line segment and each phase of the power system, and the power fluctuation detection device generates a ground detection output and a short circuit output on each phase, so even in Variations in mains frequency during power fluctuations also prevent unwanted tripping of the ground protection relay bank.

According to the sixth aspect of the present invention, after a single-phase ground fault occurs, two-phase or more than two-phase system faults occur, since a single-phase ground detection circuit is provided, and the output of the power fluctuation detection relay for detecting power system power fluctuations is inhibited, so the protective relay group trips immediately regardless of the relationship between the time-limited reset period of the fluctuation detection and hold timer and the time-limited operation period of the zone 2 protection timer and the zone 3 protection timer.

Claims (6)

1. A power fluctuation detection device of a power system, which can issue a disconnection order according to the power fluctuation detection output suppression protection relay group used for protecting the power system. The power fluctuation detection device has a short-circuit bias mho relay for detecting each Power fluctuations in a single phase of a line segment; a three-level output "OR" circuit for receiving the output of a three-level short-circuit mho relay, thereby implementing three-level protection for each line segment of the power system; a prohibition circuit for prohibiting receiving the tertiary output of the tertiary output "or" circuit and receiving the output of the short-circuit bias mho relay; a power fluctuation detection timer, as a time-limited operation circuit, for receiving the output of the prohibition circuit; a power A fluctuation detection and hold timer, which is used as a time-limited operation and time-limited reset circuit, is used to receive the output of the prohibition circuit; and an "or" circuit, which receives the output of the power fluctuation detection and hold timer and the power fluctuation detecting the output of the timer for generating a power fluctuation detection output, It is characterized in that the power fluctuation detection device also includes: A detection circuit for the rate of impedance change used to detect the rate of change of impedance in the power system; a fault detection timer activated by the output of the impedance change rate detection circuit; and A release circuit for eliminating tripping hindrance to the protection relay group based on the logical product of the output of the fault detection timer and the output of the power fluctuation detection. 2. The power fluctuation detection device of an electric power system according to claim 1, wherein the system power flow fixing circuit for receiving the power fluctuation detection output interconnects the output of the impedance change rate detection circuit with the input of the failure detection timer . 3. The power fluctuation detection device of an electric power system according to claim 2, wherein the system power flux fixing circuit is composed of a logic circuit, and the logic circuit is used to receive the output of the impedance change rate detection circuit, the power fluctuation detection output and the output of the power fluctuation detection circuit. The output of the fault detection circuit to detect overcurrent in the power system. 4. The power fluctuation detection device of an electric power system according to claim 1, wherein an impedance change rate detection circuit, a fault detection timer and a release circuit are equipped for each phase of the electric power system. 5. The power fluctuation detection device of an electric power system according to claim 4, wherein an impedance change rate detection circuit is equipped for each line segment and each phase of the electric power system. 6. The power fluctuation detection device according to claim 1, comprising a single-phase ground fault detection circuit for detecting a single-phase ground fault in the power system and suppressing the output of the power fluctuation detection relay based on the detection output thereof.

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