A device and method for preventing malfunction of injection-type stator grounding protection of phase regulator

Abstract

The present invention discloses a device for preventing the malfunction of the injection-type stator grounding protection of a phase regulator, comprising an excitation-side relay and a steam-side relay respectively connected to the grounding lead of the excitation-side manifold and the grounding lead of the steam-side manifold through current transformers, and a cooling water-side relay connected to the online monitoring point of the conductivity of cooling water in the DCS system; and also comprising three normally closed contacts connected in parallel to the injection-type stator grounding protection outlet tripping circuit, the three normally closed contacts are also electrically connected to the excitation-side relay, the steam-side relay and the cooling water-side relay respectively. The present invention connects the three normally closed contacts in parallel to the injection-type stator grounding protection outlet tripping circuit and controls them respectively through three relays, so that the injection-type stator grounding protection outlet tripping circuit can be locked only when the three relays are actuated at the same time, thereby improving reliability and preventing false locking caused by faults of the relays themselves.

Description

Technical Field

[0001] The present invention belongs to the technical field of relay protection of double water internally cooled synchronous phase regulator, and specifically relates to a device for preventing malfunction of injection type stator grounding protection of phase regulator. The present invention also relates to a method for preventing malfunction of injection type stator grounding protection of phase regulator. Background Art

[0002] For double water-cooled synchronous condensers, such as Figure 2 As shown in the upper phase modulator body 18 and the left part, its stator winding 19 is water-cooled. Stator winding cooling water (referred to as stator cooling water) generally flows from the outside of the casing into the excitation side manifold 1, and then flows from the excitation side manifold 1 through the branch insulation water pipe 20 into the stator winding 19 to cool the stator winding 19. Then it flows into the steam side manifold 2 and finally flows out of the casing. The excitation side manifold 1 and the steam side manifold 2 are both made of metal and are structurally insulated from the machine base. When the unit is operating normally, the excitation side manifold 1 and the steam side manifold 2 are directly grounded through special leads. The conductivity of stator cooling water is generally controlled in a relatively low range, and its conductivity is generally required to be less than 2.0μS / cm.

[0003] Injection type stator grounding protection is a common type of protection, which is used to issue an alarm or trip command when the stator winding is grounded. The protection uses an external 20Hz AC power supply, that is, a protection device auxiliary power supply 21 with a square wave source, a voltage divider and a bandpass filter, to inject it from the low-voltage side circuit of the neutral point grounding transformer 22 into the stator circuit. The protection device measures the 20Hz AC voltage and current, calculates the grounding resistance value, and thus determines the stator circuit fault state. Its principle is as follows Figure 1 and Figure 2 Shown in the upper, left portion. Figure 1 The transformation ratio of the grounding transformer is n, U S For 20Hz AC power supply, R in is the internal resistance of the power supply; R n is the load resistance on the low voltage side of the grounding transformer, R g is the transition resistance of the stator winding when it is grounded; -jX C The protection device measures the AC voltage U through the load resistor Rn. g0 and the AC current I g0 After digital filtering, we get 20Hz U LF0 and I LF0 , and then the transition resistance value of the ground fault can be calculated using the admittance method, that is:

[0004]

[0005] K R =k×n 2

[0006] Where k is the conversion factor.

[0007] In normal operation, the voltage of the phase-converter stator winding 19 to ground is U. Since the conductivity of the stator cooling water is less than 2.0μS / cm, the grounding current I1 of the excitation side manifold 1 and the grounding current I2 of the steam side manifold 2 are both very small and will not affect the injection type stator grounding protection.

[0008] When the conductivity of the constant cooling water increases abnormally, the grounding current I1 of the excitation side manifold 1 and the grounding current I2 of the steam side manifold 2 will increase significantly, resulting in I g0 The R value measured by the injection type stator grounding protection is significantly increased. g When the value is smaller than the protection setting value, the injection type stator grounding protection will be activated. At this time, there is no real problem with the stator winding insulation, and the injection type stator grounding protection should not be activated. Instead, the staff should be reminded to solve the problem of abnormal increase in stator cooling water conductivity through alarms or other means. Summary of the invention

[0009] The purpose of the present invention is to provide a device to prevent the malfunction of the injection type stator grounding protection of the phase shifter, thereby solving the problem that the existing injection type stator grounding protection is malfunctioned due to the increase of the conductivity of the stator cooling water.

[0010] Another object of the present invention is to provide a method for preventing malfunction of injection-type stator grounding protection of a phase regulator.

[0011] The first technical solution adopted by the present invention is: a device for preventing the injection-type stator grounding protection of a phase-converting machine from malfunctioning, comprising an excitation-side relay and a steam-side relay respectively connected to the grounding lead of the excitation-side water collecting pipe and the grounding lead of the steam-side water collecting pipe through current transformers, and a cooling water-side relay connected to the online monitoring point of the conductivity of cooling water in the DCS system; and also comprising a first normally closed contact, a second normally closed contact and a third normally closed contact connected in parallel to the injection-type stator grounding protection outlet tripping circuit, and the first normally closed contact, the second normally closed contact and the third normally closed contact are also electrically connected to the excitation-side relay, the steam-side relay and the cooling water-side relay respectively.

[0012] The first technical solution of the present invention is also characterized in that:

[0013] The excitation side relay, steam side relay and cooling water side relay are commonly connected to an alarm unit, and the connection lines between the excitation side relay, steam side relay and cooling water side relay and the alarm unit are respectively provided with a first normally open contact, a second normally open contact and a third normally open contact connected in parallel with each other.

[0014] The current transformer includes an excitation side current transformer connected to the grounding lead of the excitation side water collecting pipe, and the secondary side of the excitation side current transformer is connected to the excitation side relay; it also includes a steam side current transformer connected to the grounding lead of the steam side water collecting pipe, and the secondary side of the steam side current transformer is connected to the steam side relay.

[0015] The excitation side current transformer and the steam side current transformer are both through-core current transformers.

[0016] The injection type stator grounding protection outlet tripping circuit is connected with the phase regulator stator grounding protection device and the unit tripping system and device.

[0017] The second technical solution adopted by the present invention is: a method for preventing the malfunction of the injection-type stator grounding protection of the phase regulator, comprising the following steps:

[0018] Step 1: Connect the excitation side current transformer and the excitation side relay to the grounding lead of the excitation side water collecting pipe in sequence, connect the steam side current transformer and the steam side relay to the grounding lead of the steam side water collecting pipe in sequence, and connect the cooling water side relay to the online monitoring point of the cooling water conductivity of the DCS system;

[0019] Step 2, connecting the first normally closed contact, the second normally closed contact and the third normally closed contact in parallel to the injection type stator ground protection outlet tripping circuit, and then electrically connecting the first normally closed contact, the second normally closed contact and the third normally closed contact to the excitation side relay, the steam side relay and the stator cooling water side relay respectively;

[0020] Step 3, setting an alarm unit, the input end of the alarm unit is connected to the first normally open contact, the second normally open contact and the third normally open contact connected in parallel, and then the first normally open contact, the second normally open contact and the third normally open contact are electrically connected to the excitation side relay, the steam side relay and the constant cooling water side relay respectively;

[0021] Step 4: Set the action value of the cooling water side relay to γ set When the DCS system coolant water conductivity online monitoring point detects that the coolant water conductivity exceeds the set value γ set When the relay on the cooling water side controls the third normally closed contact to be disconnected, and controls the third normally open contact to be closed; the action value of the relay on the excitation side is set to I set1 When the current I1 on the grounding lead of the excitation side water collector exceeds the set value I set1 When the excitation side relay controls the first normally closed contact to open, and controls the first normally open contact to close; the action value of the steam side relay is set to I set2 When the current I2 on the grounding lead of the steam side water pipe exceeds the set value I set2 When the steam side relay controls the second normally closed contact to open, and controls the second normally open contact to close.

[0022] The beneficial effects of the present invention are as follows: the present invention provides a device and method for preventing the injection-type stator grounding protection of a phase regulator from malfunctioning, by connecting three normally closed contacts in parallel on the injection-type stator grounding protection outlet tripping circuit and controlling them respectively through three relays, so that the three relays can operate simultaneously to lock the injection-type stator grounding protection outlet tripping circuit, thereby improving reliability and preventing malfunction caused by faults of the relay itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the circuit principle of the existing injection type stator grounding protection device;

[0024] Figure 2 The present invention is a schematic structural diagram of a device for preventing malfunction of injection-type stator grounding protection of a phase regulator.

[0025] In the figure, 1. excitation side water pipe, 2. steam side water pipe, 3. excitation side relay, 4. steam side relay, 5. DCS system, 6. stator cooling water side relay, 7. first normally closed contact, 8. second normally closed contact, 9. third normally closed contact, 10. alarm unit, 11. first normally open contact, 12. second normally open contact, 13. third normally open contact, 14. excitation side current transformer, 15. steam side current transformer, 16. phase regulator stator grounding protection device, 17. unit tripping system and device, 18. phase regulator body, 19. stator winding, 20. insulated water pipe, 21. auxiliary power supply of protection device, 22. neutral point grounding transformer. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The present invention provides a device for preventing the malfunction of the injection type stator grounding protection of the phase regulator, such as Figure 2As shown, it includes a through-type excitation side current transformer 14 and a through-type steam side current transformer 15 respectively connected to the grounding lead of the excitation side water collector 1 and the grounding lead of the steam side water collector 2, which are respectively used to measure the grounding current I1 of the excitation side water collector 1 and the grounding current I2 of the steam side water collector 2, and the secondary sides of the excitation side current transformer 14 and the steam side current transformer 15 are respectively connected to the excitation side relay 3 and the steam side relay 4; it also includes a cooling water side relay 6 connected to the online monitoring point of the cooling water conductivity of the DCS system 5; it also includes a first normally closed contact 7, a second normally closed contact 8 and a third normally closed contact 9 on the injection type stator grounding protection outlet tripping circuit connected in parallel between the phase regulator stator grounding protection device 16 and the unit tripping system and device 17, and the first normally closed contact 7, the second normally closed contact 8 and the third normally closed contact 9 are also electrically connected to the excitation side relay 3, the steam side relay 4 and the cooling water side relay 6, respectively. The excitation side relay 3, the steam side relay 4 and the cooling water side relay 6 are commonly connected to an alarm unit 10, and the connection lines between the excitation side relay 3, the steam side relay 4 and the cooling water side relay 6 and the alarm unit 10 are respectively provided with a first normally open contact 11, a second normally open contact 12 and a third normally open contact 13 connected in parallel with each other.

[0028] The present invention also provides a method for preventing malfunction of injection-type stator grounding protection of a phase regulator, comprising the following steps:

[0029] Step 1, connect the excitation side current transformer 14 and the excitation side relay 3 to the grounding lead of the excitation side water collecting pipe 1 in sequence, connect the steam side current transformer 15 and the steam side relay 4 to the grounding lead of the steam side water collecting pipe 2 in sequence, and connect the cooling water side relay 6 to the cooling water conductivity online monitoring point of the DCS system 5;

[0030] Step 2, connecting the first normally closed contact 7, the second normally closed contact 8 and the third normally closed contact 9 in parallel to each other on the injection type stator grounding protection outlet tripping circuit, and then electrically connecting the first normally closed contact 7, the second normally closed contact 8 and the third normally closed contact 9 to the excitation side relay 3, the steam side relay 4 and the stator cooling water side relay 6 respectively;

[0031] Step 3, setting an alarm unit 10, the input end of the alarm unit 10 is connected to a first normally open contact 11, a second normally open contact 12 and a third normally open contact 13 which are connected in parallel, and then the first normally open contact 11, the second normally open contact 12 and the third normally open contact 13 are electrically connected to the excitation side relay 3, the steam side relay 4 and the constant cooling water side relay 6 respectively;

[0032] Step 4: Set the action value of the cooling water side relay 6 to γ set , when the DCS system 5 fixed cooling water conductivity online monitoring point detects that the fixed cooling water conductivity exceeds the set value γ setWhen the cold water side relay 6 controls the third normally closed contact 9 to be disconnected, and controls the third normally open contact 13 to be closed; the action value of the excitation side relay 3 is set to I set1 When the current I1 on the grounding lead of the excitation side water collector 1 exceeds the set value I set1 When the excitation side relay 3 controls the first normally closed contact 7 to be disconnected, and at the same time controls the first normally open contact 11 to be closed; the action value of the steam side relay 4 is set to I set2 When the current I2 on the grounding lead of the steam side water pipe 2 exceeds the set value I set2 When the steam-side relay 4 controls the second normally closed contact 8 to open, and controls the second normally open contact 12 to close.

[0033] When the DCS system 5 monitors the conductivity of the cooling water online, it will be greater than the set value γ. set When the grounding current I1 of the excitation side water collector 1 is greater than the set value I set1 When the grounding current I2 of the steam side water conduit 2 is greater than the set value I set2 When the steam-side relay 4 is activated, the second normally closed contact 8 is controlled to be opened, and the second normally open contact 12 is controlled to be closed.

[0034] When the conductivity of the cooling water increases abnormally, I1 and I2 will increase significantly. When the three relays are actuated at the same time, the first normally closed contact 7, the second normally closed contact 8 and the third normally closed contact 9 are all disconnected, which will lock the injection type stator grounding protection outlet tripping circuit. The three normally closed contacts of the first normally closed contact 7, the second normally closed contact 8 and the third normally closed contact 9 are connected in parallel, which improves the reliability and prevents the relay itself from causing false locking. The three normally open contacts of the first normally open contact 11, the second normally open contact 12 and the third normally open contact 13 are connected in parallel. When any of the three relays is actuated, an alarm signal can be issued.

[0035] Through the above-mentioned manner, the present invention provides a device and method for preventing the condenser injection type stator grounding protection from malfunctioning. By connecting three normally closed contacts in parallel to the injection type stator grounding protection outlet tripping circuit and controlling them respectively through three relays, the three relays can be actuated simultaneously to lock the injection type stator grounding protection outlet tripping circuit, thereby improving reliability and preventing the relay itself from causing malfunctioning. In addition, by controlling three normally open contacts respectively through three relays and connecting the alarm unit 10, an alarm signal can be issued when any one of the three relays is actuated.

Claims

1. A device for preventing malfunction of injection-type stator grounding protection of a phase regulator, characterized in that: The invention comprises an excitation-side current transformer (14) and a steam-side current transformer (15) respectively connected to the grounding lead of an excitation-side water collecting pipe (1) and the grounding lead of a steam-side water collecting pipe (2), the secondary sides of the excitation-side current transformer (14) and the steam-side current transformer (15) respectively being connected to an excitation-side relay (3) and a steam-side relay (4), and a cooling water-side relay (6) connected to an online monitoring point of cooling water conductivity of a DCS system (5); and further comprises a first normally closed contact (7), a second normally closed contact (8) and a third normally closed contact (9) on an injection-type stator grounding protection outlet tripping circuit connected in parallel between a phase-converting machine stator grounding protection device (16) and a unit tripping system and device (17), the first normally closed contact (7), the second normally closed contact (8) and the third normally closed contact (9) being further electrically connected to the excitation-side relay (3), the steam-side relay (4) and the cooling water-side relay (6), respectively.

2. A device for preventing malfunction of injection-type stator grounding protection of phase regulator according to claim 1, characterized in that: It also includes an alarm unit (10), wherein an input end of the alarm unit (10) is connected to a first normally open contact (11), a second normally open contact (12), and a third normally open contact (13) which are connected in parallel to each other, and the first normally open contact (11), the second normally open contact (12), and the third normally open contact (13) are also electrically connected to an excitation-side relay (3), a steam-side relay (4), and a constant-cooling-water-side relay (6), respectively.

3. A device for preventing malfunction of injection-type stator grounding protection of phase regulator according to claim 1, characterized in that: The excitation-side current transformer (14) and the steam-side current transformer (15) are both through-hole current transformers.

4. A method for preventing malfunction of injection-type stator grounding protection of a phase regulator, characterized in that: The following steps are involved: Step 1, connecting an excitation side current transformer (14) to the ground lead of the excitation side water collecting pipe (1), and connecting an excitation side relay (3) to the secondary side of the excitation side current transformer (14); connecting a steam side current transformer (15) to the ground lead of the steam side water collecting pipe (2), and connecting a steam side relay (4) to the secondary side of the steam side current transformer (15); and connecting a cooling water side relay (6) to the cooling water conductivity online monitoring point of the DCS system (5); Step 2, connecting a first normally closed contact (7), a second normally closed contact (8) and a third normally closed contact (9) connected in parallel to each other on the injection-type stator grounding protection outlet tripping circuit between the phase-converting machine stator grounding protection device (16) and the unit tripping system and device (17), and then electrically connecting the first normally closed contact (7), the second normally closed contact (8) and the third normally closed contact (9) to the excitation side relay (3), the steam side relay (4) and the stator cooling water side relay (6) respectively; Step 3, setting an alarm unit (10), wherein an input end of the alarm unit (10) is connected to a first normally open contact (11), a second normally open contact (12), and a third normally open contact (13) which are connected in parallel with each other, and then the first normally open contact (11), the second normally open contact (12), and the third normally open contact (13) are electrically connected to an excitation side relay (3), a steam side relay (4), and a constant cooling water side relay (6), respectively; Step 4: Set the action value of the cooling water side relay (6) to γ set , when the DCS system (5) detects that the cooling water conductivity exceeds the set value γ set When the relay (6) on the cooling water side controls the third normally closed contact (9) to be disconnected, and controls the third normally open contact (13) to be closed; the action value of the relay (3) on the excitation side is set to I set1 , when the current I1 on the ground lead of the excitation side water collector (1) exceeds the set value I set1 When the excitation side relay (3) controls the first normally closed contact (7) to open, and controls the first normally open contact (11) to close; the action value of the steam side relay (4) is set to I set2 , when the current I2 on the ground lead of the steam side water collector (2) exceeds the set value I set2 When the steam-side relay (4) controls the second normally closed contact (8) to open, and controls the second normally open contact (12) to close.

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