Motor-boiler electric connection tripping system of generator set

Abstract

The invention discloses a generator-boiler electric tripping system of a generator set, which belongs to the field of generator sets and comprises a steam turbine ETS, a generator protection screen thermotechnical protection signal unit, a generator protection screen reverse power signal unit and a steam turbine main throttle valve closing signal unit. The turbine ETS is in communication connection with the input end of the generator protection screen thermotechnical protection signal unit, and the output end of the generator protection screen thermotechnical protection signal unit is connected with an engine outlet circuit breaker through a thermotechnical protection pressing plate; a generator protection screen reverse power signal is connected with an engine outlet circuit breaker; and non-signals of the turbine ETS, the turbine main throttle valve closing signal unit and the generator protection screen reverse power signal unit are connected with the turbine main throttle valve fault cut-off device. Unit overspeed caused by the time sequence difference of the main throttle valve action and the electric protection action can be avoided. And meanwhile, common major galloping accidents such as inner leakage of a main throttle valve and the like are caused for many times.

Description

Technical Field

[0001] The invention relates to the field of generator sets, in particular to a machine-boiler electric joint trip system of a generator set. Background Art

[0002] Under the background of "dual carbon", the steel industry has a new round of technological upgrades in the energy field. In particular, there has been a leapfrog development in the utilization of waste heat, and a large number of domestically produced high-efficiency subcritical and supercritical gas generators have been put into operation. At the same time as the new high-grade units are put into operation, many risk factors have also appeared in safety protection. The signal generated by the triggering of the ETS protection of the traditional generator turbine is sent to the generator protection screen C through the non-electrical channel. The generator protection device generates a thermal protection signal through logical operation. When the thermal protection hard pressure plate of the generator protection screen is put into operation, it directly sends a disconnection signal to the generator outlet circuit breaker. During the normal shutdown process of the unit, the thermal protection hard pressure plate is manually exited, and the generator outlet circuit breaker is disconnected through the program reverse power trip protection, that is, the main steam valve closing stroke is in place, and the generator outputs a trip signal when reverse power occurs to interlock the generator grid-connected circuit breaker to disconnect. During normal operation, the thermal protection hard pressure plate is put into operation. When the turbine fails, the turbine directly trips the generator outlet circuit breaker through thermal protection while the ETS is in operation. When the automatic main steam valve of the steam turbine is working normally, the action of the steam turbine ETS is driven by the hydraulic device, and the action completion time is about 1s. However, the action completion time of the output circuit breaker of the generator tripped by the thermal protection is within 40ms. Therefore, there is a risk of overspeed for the generator set after disconnection. In the case of internal leakage or jamming of the automatic main steam valve of the steam turbine, the thermal protection signal triggers the electrical disconnection of the generator. The automatic main steam valve of the steam turbine fails to completely cut off the main steam source, and the generator set after disconnection will inevitably run out of speed.

[0003] At present, most power plants use the main steam valve travel position signal as the condition for whether the generator can be disconnected. The above method ensures that the main steam valve of the steam turbine has been actuated before the generator is disconnected. It effectively avoids the overspeed fault caused by the early disconnection of the generator when the main steam is not completely cut off. However, when the unit encounters the following two situations, the risk of overspeed and runaway of the steam turbine generator set cannot be avoided.

[0004] ① Internal leakage of main steam valve

[0005] When ETS is activated, if the main steam valve of the steam turbine leaks internally, the main steam valve travel switch is normal, but the main steam valve with internal leakage cannot effectively disconnect the main steam source. According to the above logic instructions, the unit still has the risk of overspeed and runaway after the generator set is electrically disconnected.

[0006] ②The exhaust check valve leaks or refuses to operate

[0007] After the ETS is activated, the main steam valve of the steam turbine is activated and the main steam valve travel switch is normal. However, the turbine exhaust check valve leaks or refuses to operate, causing a large amount of steam to enter the steam turbine through the exhaust circuit to perform work. At this time, according to the above logic instructions, the unit still has the risk of overspeed and runaway after the generator set is electrically disconnected.

[0008] In summary, using the main steam valve stroke position signal as the condition for whether the generator can be disconnected cannot completely eliminate the hidden dangers of overspeed and runaway of the unit under the main steam valve failure state. Therefore, a safer generator set boiler electrical joint trip system is needed to solve the above problems. Summary of the invention

[0009] In view of the above problems existing in the prior art, the object of the present invention is to provide a boiler-machine electrical trip system for a generator set to solve the problems raised in the above background technology.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A boiler-machine electrical trip system for a generator set, comprising a steam turbine ETS, a thermal protection signal unit of a generator protection screen, a reverse power signal unit of a generator protection screen, and a main steam valve closing signal unit of a steam turbine, wherein the steam turbine ETS is communicatively connected to an input end of the thermal protection signal unit of the generator protection screen, and an output end of the thermal protection signal unit of the generator protection screen is connected to an input end of a first AND gate through a thermal protection pressure plate;

[0012] The generator protection screen reverse power signal unit includes a first generator protection screen reverse power signal unit, a second generator protection screen reverse power signal unit and a third generator protection screen reverse power signal unit;

[0013] The reverse power signal unit of the first generator protection screen is connected to the other input end of the first AND gate; the output end of the first AND gate is connected to the engine outlet circuit breaker through the OR gate;

[0014] The reverse power signal unit of the second generator protection screen is directly connected to the engine outlet circuit breaker through an OR gate;

[0015] The reverse power signal unit of the third generator protection screen and the main steam valve closing signal unit of the steam turbine are both connected to the program reverse power adjustment module, and the program reverse power adjustment module is connected to the engine outlet circuit breaker through an OR gate;

[0016] The steam turbine ETS and the steam turbine main steam valve closing signal unit are connected to the input end of the second AND gate, and the generator protection screen reverse power signal unit is connected to the input end of the second AND gate through the NOT gate;

[0017] The output end of the second AND gate is connected to one end of the fast protection pressure plate, and the other end of the fast protection pressure plate is connected to the main steam valve fault cut-off device of the steam turbine.

[0018] As a further solution of the present invention: the turbine main steam valve fault cut-off device includes a boiler combustion burner cut-off module, a boiler drain valve opening door, a PCV pressure relief valve opening module and a turbine high and low bypass valve opening module.

[0019] As a further solution of the present invention: the steam turbine ETS is connected to the thermal protection signal unit of the generator protection screen via a non-electrical quantity channel.

[0020] As a further solution of the present invention: the first generator protection screen reverse power signal unit is a passive motor protection screen reverse power signal.

[0021] As a further solution of the present invention:

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention can not only avoid the overspeed of the unit caused by the timing difference between the main steam valve action and the electrical protection action, but also prevent the common main steam valve internal leakage and other major runaway accidents that have repeatedly caused major runaway accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic structural diagram of a boiler-machine electrical joint trip system of a generator set disclosed in an embodiment. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", and "connected" should be understood in a broad sense; for example, it can be a fixed connection, a detachable connection, or an integral connection, a mechanical connection, or an electrical connection, a direct connection, or an indirect connection through an intermediate medium, or the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] See also Figure 1, a boiler-machine electrical trip system for a generator set, comprising a steam turbine ETS, a thermal protection signal unit of a generator protection screen, a reverse power signal unit of a generator protection screen, and a main steam valve closing signal unit of a steam turbine, wherein the steam turbine ETS is communicatively connected to an input end of the thermal protection signal unit of the generator protection screen, and an output end of the thermal protection signal unit of the generator protection screen is connected to an input end of a first AND gate through a thermal protection pressure plate;

[0028] The generator protection screen reverse power signal unit includes a first generator protection screen reverse power signal unit, a second generator protection screen reverse power signal unit and a third generator protection screen reverse power signal unit;

[0029] The reverse power signal unit of the first generator protection screen is connected to the other input end of the first AND gate; the output end of the first AND gate is connected to the engine outlet circuit breaker through the OR gate;

[0030] The reverse power signal unit of the second generator protection screen is directly connected to the engine outlet circuit breaker through an OR gate;

[0031] The reverse power signal unit of the third generator protection screen and the main steam valve closing signal unit of the steam turbine are both connected to the program reverse power adjustment module, and the program reverse power adjustment module is connected to the engine outlet circuit breaker through an OR gate;

[0032] The steam turbine ETS and the steam turbine main steam valve closing signal unit are connected to the input end of the second AND gate, and the generator protection screen reverse power signal unit is connected to the input end of the second AND gate through the NOT gate;

[0033] The output end of the second AND gate is connected to one end of the fast protection pressure plate, and the other end of the fast protection pressure plate is connected to the turbine main steam valve fault cut-off device;

[0034] The turbine main steam valve fault cut-off device includes a boiler combustion burner cut-off module, a boiler drain valve opening door, a PCV pressure relief valve opening module and a turbine high and low bypass valve opening module;

[0035] The ETS signal of the steam turbine is sent to the protection device of the generator protection screen through the non-electrical channel. The device generates a thermal protection signal through logical operation, and at the same time connects the passive nodes of the two main steam valve travel switch in place signals of the steam turbine in series to the thermal protection circuit. When the thermal protection appears and the main steam valve of the steam turbine has reached the closed position, a disconnection signal is sent to the generator output circuit breaker.

[0036] The ETS signal of the steam turbine is sent to the generator protection screen C through the non-electrical channel. The protection device generates a thermal protection signal through logical operation. At the same time, a generator reverse power signal passive node is added and connected in series to the thermal protection circuit. When the thermal protection is activated and the generator has reverse power, a disconnection signal is sent to the generator output circuit breaker.

[0037] This solution ensures that the generator is disconnected only after reverse power occurs in the generator. This solution solves the potential risk of overspeed caused by disconnection of the unit.

[0038] We also need to face the equipment safety issue of the turbine main steam valve failure state. Under normal circumstances, the ETS actuates the turbine interlock to automatically close the main steam valve. If the valve can effectively cut off the main steam, the generator will have reverse power and complete the decoupling. If the main steam valve is actuated but fails to effectively cut off the main steam, the generator does not meet the decoupling conditions when there is positive active power. At this time, forcibly decoupling the generator will cause the turbine to overspeed. However, if the generator set is not decoupled quickly and its speed is reduced, other safety risks will also be brought.

[0039] Based on the potential problems mentioned above, an important issue that needs to be urgently addressed before the generator is disconnected is to reduce the main steam flow rate flowing through the main steam valve into the steam turbine to perform work.

[0040] When the main steam valve leaks normally, it is only necessary to quickly reduce the main steam pressure, and the valve leakage will be greatly improved. Therefore, in order to solve the above problem, the following logic is added to the DCS system. When the turbine trips and the main steam valve closing signal appears, if the generator reverse power signal is not received, the system determines that the main steam valve is leaking or the exhaust check valve is faulty. At this time, the DCS cuts off the gas burner of the boiler, and at the same time interlocks to open the boiler electric drain valve and PCV valve to discharge the main steam pressure, and interlocks to open the high and low bypass valves of the turbine to further release the pressure. Quickly reduce the active output of the steam turbine generator to zero, and complete the unit decoupling after the generator load reaches zero.

[0041] This solution can not only avoid the overspeed of the unit caused by the timing difference between the main steam valve action and the electrical protection action, but also prevent the common main steam valve internal leakage and other major runaway accidents that have repeatedly caused major runaway accidents.

[0042] After process optimization and improvement:

[0043] 1. When the unit is operating normally, the "thermal protection pressure plate" is put into operation. When the turbine fails and the generator protection screen triggers the thermal protection action signal, the unit begins to prepare for disconnection. When the unit load drops to the point where the generator has reverse power (1%, 0S), the unit is disconnected;

[0044] 2. The unit is in normal operation and put into "fast unloading pressure plate". When the turbine is in thermal protection but the load of the unit is not zero (no reverse power), in order to quickly reduce the load of the unit to zero as soon as possible to ensure that the unit can be successfully de-energized, the boiler combustion nozzle is interlocked, various boiler drain valves are opened to release pressure, and high and low pressure steam bypass filters are opened to release pressure;

[0045] 3. When the generator set is shut down under normal dispatching instructions, the thermal protection pressure plate is manually withdrawn. After the operator reduces the turbine load until the main steam valve is closed and the generator has reverse power (1%, 1..5s), the unit is disconnected.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive from any point of view. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention, and any reference numerals in the claims should not be considered as limiting the claims involved.

[0047] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A boiler-machine electric trip system for a generator set, characterized in that: It includes a steam turbine ETS, a thermal protection signal unit of a generator protection screen, a reverse power signal unit of a generator protection screen, and a main steam valve closing signal unit of a steam turbine. The steam turbine ETS is communicatively connected to the input end of the thermal protection signal unit of the generator protection screen, and the output end of the thermal protection signal unit of the generator protection screen is connected to an input end of the first AND gate through a thermal protection pressure plate; The generator protection screen reverse power signal unit includes a first generator protection screen reverse power signal unit, a second generator protection screen reverse power signal unit and a third generator protection screen reverse power signal unit; The reverse power signal unit of the first generator protection screen is connected to the other input end of the first AND gate; the output end of the first AND gate is connected to the engine outlet circuit breaker through the OR gate; The reverse power signal unit of the second generator protection screen is directly connected to the engine outlet circuit breaker through an OR gate; The reverse power signal unit of the third generator protection screen and the main steam valve closing signal unit of the steam turbine are both connected to the program reverse power adjustment module, and the program reverse power adjustment module is connected to the engine outlet circuit breaker through an OR gate; The steam turbine ETS and the steam turbine main steam valve closing signal unit are connected to the input end of the second AND gate, and the generator protection screen reverse power signal unit is connected to the input end of the second AND gate through the NOT gate; The output end of the second AND gate is connected to one end of the fast protection pressure plate, and the other end of the fast protection pressure plate is connected to the main steam valve fault cut-off device of the steam turbine.

2. The boiler-machine electrical trip system of a generator set according to claim 1, characterized in that: The steam turbine main steam valve fault cut-off device comprises a boiler combustion burner cut-off module, a boiler drain valve opening door, a PCV pressure relief valve opening module and a turbine high and low bypass valve opening module.

3. The boiler-machine electrical trip system of a generator set according to claim 1, characterized in that: The steam turbine ETS is connected to the thermal protection signal unit of the generator protection screen via a non-electrical quantity channel.

4. The boiler-machine electrical trip system of a generator set according to claim 1, characterized in that: The first generator protection screen reverse power signal unit is a passive motor protection screen reverse power signal.

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