CN110635621A - Method for changing retired generator into self-shunt excitation synchronous phase modulator - Google Patents

Method for changing retired generator into self-shunt excitation synchronous phase modulator Download PDF

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Publication number
CN110635621A
CN110635621A CN201911021992.5A CN201911021992A CN110635621A CN 110635621 A CN110635621 A CN 110635621A CN 201911021992 A CN201911021992 A CN 201911021992A CN 110635621 A CN110635621 A CN 110635621A
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China
Prior art keywords
phase modulator
generator
excitation
synchronous phase
synchronous
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CN201911021992.5A
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Inventor
谭闻
谭江平
陈亮
汪少勇
阳熹
王小虎
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China Energy Engineering Group Guangdong Electric Power Design Institute Co Ltd
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China Energy Engineering Group Guangdong Electric Power Design Institute Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1885—Arrangements for adjusting, eliminating or compensating reactive power in networks using rotating means, e.g. synchronous generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/20—Structural association with auxiliary dynamo-electric machines, e.g. with electric starter motors or exciters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
    • H02P9/38—Self-excitation by current derived from rectification of both output voltage and output current of generator
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Abstract

The invention discloses a method for changing an retired generator into a self-shunt excitation synchronous phase modulator, which comprises the following steps: decoupling the steam turbine and the generator; newly adding a starting device, and connecting the starting device with a generator by using a coupler and a coupling; adding an exciter or transforming a coaxial exciter excitation loop to transform an excitation regulating system so as to meet the excitation current standard of the synchronous phase modulator; the generator body is modified so that the heat dissipation capacity of the rotor winding and the end structural part can meet the preset requirement; a thrust bearing is added so that the mechanical mechanism of the original generator meets the preset operation requirement of the synchronous phase modulator; the method comprises the following steps of modifying a protection device and a monitoring system of an original generator to meet the operation requirement of a preset synchronous phase modulator; and transforming the oil system of the original generator according to the preset requirements of the synchronous phase modulator oil system. The invention can transform the retired synchronous generator into the synchronous phase modulator, thereby effectively utilizing the retired unit and providing reactive support for the power system.

Description

Method for changing retired generator into self-shunt excitation synchronous phase modulator
Technical Field
The invention relates to the technical field of power system transformation, in particular to a method for changing a retired generator into a self-shunt excitation synchronous phase modulator.
Background
With the adjustment of energy structures and the large-scale development of renewable energy sources, the living space of the coal-electric unit is continuously compressed, the supply side reforming task is difficult, and a large number of thermal power generating units face retirement. Therefore, how to properly handle retired thermal power and effectively utilize retired unit equipment and plant sites is a problem that needs to be considered in important terms in energy and power planning.
It is a conceivable solution to transform a decommissioned synchronous generator into a synchronous phase modulator. Firstly, if the synchronous generator can be transformed into a synchronous phase modulator, higher reactive support can be provided for the system. With the continuous expansion of the transmission scale of the power transmitted from the west to the east, the average utilization hours of thermal power generating units in the coastal region of the southeast part are kept at a lower level for a long time. Under the condition of insufficient starting of the thermal power supply, reactive power control of the system may have problems. The reactive power that the unit can provide may not meet the stable operation requirement of the extra-high voltage transmission network.
Secondly, the synchronous generator is transformed into a synchronous phase modulator, a high-level short-circuit current can be maintained for a power grid, a power grid running state with higher stability is maintained, and the system with large short-circuit capacity is the basis for implementing advanced power technologies such as high-voltage direct-current power transmission and clean energy. With the continuous promotion of extra-high voltage direct current engineering construction, the direct current drop points are increased, and the influence of the stable operation of direct current on the stable operation of a system is gradually increased. If a large number of thermal power generating units are retired, the short-circuit capacity of the system is greatly reduced, the direct-current system is prone to phase commutation failure under the condition of facing disturbance of the alternating-current system or various alternating-current and direct-current faults, and the probability of serious faults such as blocking and the like is greatly increased. Generally, when the Short Circuit Ratio (SCR) is equal to or less than 3, difficulties in the operation of the high voltage direct current transmission system will be caused. Meanwhile, a strong power grid is also needed for large-scale grid connection of new energy power generation. One feature of these new energy power generation is that the moment of inertia is almost 0. The retired unit is transformed into a synchronous phase modulator, so that the rotational inertia of the system is maintained, and a stable power grid is maintained.
Meanwhile, with the advance of the electric power market, the flexibility of the operation of the power grid is increasing. The newly added synchronous phase modulator is beneficial to the flexible regulation and control of the trend of nearby high-voltage lines, and provides a certain guarantee for the promotion of the power market. Therefore, the scheme of changing the retired generator into the self-shunt excitation synchronous phase modulator has important research significance.
Disclosure of Invention
The technical problem to be solved by the embodiment of the invention is to provide a method for changing a decommissioned generator into a self-shunt excitation synchronous phase modulator, so that a decommissioned unit can be effectively utilized, and reactive support can be provided for a power system.
In order to solve the above technical problem, an embodiment of the present invention provides a method for changing an out-of-service generator into a self-shunt excitation synchronous phase modulator, including:
removing a coupling between the steam turbine and the original generator so as to decouple the coaxially installed steam turbine and the original generator;
adding a new starting motor, and connecting the starting motor with the original generator by using a coupler and a coupling;
modifying an excitation adjusting system by adopting a mode of newly adding an exciter or a mode of modifying a coaxial exciter excitation loop so as to enable the excitation adjusting system to meet the excitation current standard of a synchronous phase modulator;
calculating the heat dissipation condition of the rotor winding, determining the range of the sending and absorbing reactive power of the synchronous phase modulator according to the calculation result, and modifying the original generator body according to the range of the sending and absorbing reactive power so that the heat dissipation capacity of the rotor winding and the end structural member meets the preset requirement;
a thrust bearing is additionally arranged so that a mechanical mechanism of the original generator meets the preset operation requirement of a synchronous phase modulator;
transforming a protection device and a monitoring system of the original generator so that the protection device and the monitoring system meet the preset operation requirement of the synchronous phase modulator;
and transforming the oil system of the original generator according to the preset requirements of the oil system of the synchronous phase modulator to obtain the self-shunt excitation synchronous phase modulator transformed by the retired generator.
Further, the newly-added starting motor is connected with the original generator by using a coupler and a coupling, and specifically comprises:
and (3) removing the original steam turbine, adding an asynchronous induction motor, and connecting the starting motor with the original generator by using a coupler and a coupling.
Further, the method of adding an exciter newly or modifying a coaxial exciter excitation loop is adopted to modify the excitation regulation system, so that the excitation regulation system meets the excitation current standard of the synchronous phase modulator, and the method specifically includes:
if the original generator is excited by adopting an exciter, modifying an excitation adjusting system by adopting a mode of newly adding the exciter so as to enable the excitation adjusting system to meet the excitation current standard of the synchronous phase modulator;
if the original generator is a generator adopting a self-shunt excitation alternating current excitation system, the excitation regulating system is modified in a way of modifying a coaxial exciter excitation loop so as to enable the excitation regulating system to meet the excitation current standard of the synchronous phase modulator.
Further, the calculating the heat dissipation condition of the rotor winding specifically includes:
calculating the rotor temperature rise data in the over-excited state;
calculating an end electromagnetic field and a strength field in an underexcited state;
calculating the rotor loss and the heat productivity in the starting process;
and calculating rotor coasting data in the grid connection process.
Further, the method for modifying the original generator body comprises one or more of replacing a cooler, replacing a rotor copper wire and additionally installing an end shield.
Further, the method for changing the retired generator into the self-shunt excitation synchronous phase modulator further comprises the following steps:
and adding a supporting bearing so that the mechanical mechanism of the original generator meets the preset operation requirement of the synchronous phase modulator.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, by means of decoupling the steam turbine and the synchronous generator, increasing the asynchronous motor to realize starting, modifying an excitation system, modifying a motor body, modifying a mechanical structure, modifying a monitoring system, modifying a motor auxiliary system and the like, the retired synchronous generator can be modified into a synchronous phase modulator, so that a retired unit can be effectively utilized, a reactive support can be provided for an electric power system, waste is changed into valuable, and two purposes are achieved.
Drawings
Fig. 1 is a schematic flow chart of a method for changing an out-of-service generator into a self-shunt excitation synchronous phase modulator according to an embodiment of the present invention;
fig. 2 is a diagram of a phase modulator operating vector provided by an embodiment of the present invention;
fig. 3 is a schematic diagram of frequency conversion starting of an SFC according to an embodiment of the present invention;
fig. 4 is a schematic diagram of control logic of a synchronous phase modulator according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Firstly, the present invention explains a part of technical principles:
1. the reversibility principle of synchronous motor operation is as follows:
the operation of the synchronous motor is reversible, namely mechanical energy can be input by the rotor, and is converted into electric energy through electromagnetic action and output from the stator; or the stator inputs electric energy, and the electric energy is converted into mechanical energy through electromagnetic action and is output from the rotor. I.e. the synchronous machine can operate both in generator mode and in motor mode, depending entirely on whether the energy supplied to it is mechanical or electrical.
If the synchronous motor is not driven by prime mover, and has no mechanical load on its shaft, it is connected with power network and is operated in idle load mode, and specially it is used for regulating reactive power of system.
2. Synchronous machines transition from generator to motor:
when the synchronous motor is used as a generator, the magnetic pole axis of the rotor in a delayed state leads the magnetic pole curve delta angle of the air gap synthetic magnetic field along the rotation direction of the rotor, and the driving torque of the prime motor is mainly used for overcoming the braking electromagnetic torque and converting the mechanical energy into electric energy for output.
If the prime mover is removed, the energy required for the synchronous machine to maintain rotation is entirely from the grid. When a mechanical load is applied to the motor shaft, the rotor lags further and the delta angle increases, the electromagnetic torque becomes a driving torque for the rotor, and the motor becomes a synchronous motor with load operation, and the magnetic poles of the rotor are driven to be dragged. The electrical power input by the power grid is converted into mechanical power through electromagnetic power.
3. Analyzing the running state of the self-shunt excitation synchronous phase modulator:
the synchronous motor supplies the active power of the power grid when operating as a generator and absorbs the active power of the power grid when operating as a motor. The reactive power of the transformer can change the value of the value along with the adjustment of the exciting current of the transformer, and can conveniently realize the conversion between the two properties (lag or lead).
The self-shunt excitation synchronous phase modulator can be regarded as a synchronous motor without mechanical load, absorbs a small amount of active power of a power grid to overcome loss of the synchronous motor, and absorbs or sends out reactive power from the power grid by changing excitation regulation for regulating reactive power of the power grid.
Neglecting the stator winding resistance, the potential balance equation of the self shunt phase modulator can be simplified as:
UN＝E0+jINXd
wherein U isNFor phase-modifier terminal voltage, E0To excitation potential, INFor rated current, XdFor direct-axis synchronous reactance, a diagram of the operating vectors for both over-and under-excitation is shown, as shown in figure 2.
As can be seen from the phasor diagram, when the over-excitation runs, it supplies inductive reactive power to the system to play a role of a reactive power supply; during underexcited operation, it absorbs inductive reactive power from the system to act as a reactive load. When the phase modulator is operated, the property and the size of the reactive power of the phase modulator can be changed only by adjusting the exciting current. When the voltage at the machine end is higher than the rated voltage, the exciting current can be reduced, the reactive power emitted by the phase modulator is reduced or the reactive power absorbed by the phase modulator is increased; when the voltage of the machine terminal is lower than the rated voltage, the exciting current of the phase modulator can be increased, the reactive power emitted by the phase modulator can be increased, or the reactive power absorbed by the phase modulator can be reduced. Through the control mode, the reactive power balance of the power system can be realized through the phase modulator, and the voltage of the grid node is maintained.
The synchronous phase modulator with automatic excitation regulator can change the output or absorption of reactive power based on the voltage value at installation site to regulate voltage. Especially, when the forced excitation device is installed, the voltage of the system can be adjusted when the system is in failure, and the stability of the system is improved.
It should be noted that patent No. CN201910266073.8 proposes a method for transforming a coal-fired power generating unit into a phase modulator, and the inventor of the present application finds in practice that the solution of the patent has the following disadvantages:
1) the prime motor part of the coal-fired engine unit is reserved, namely a boiler, a steam turbine, a power generation system, a steam-water circulating system and a peripheral desulfurization and denitrification system are reserved, so that the process system and the control system of the coal-fired engine unit are basically the same as those of a conventional coal-fired unit, the system is relatively complex, and the requirement on the level of operators is high. In addition, the number of the high-pressure heaters and the steam inlet quantity of the high-pressure heaters need to be adjusted according to the operation load during operation, and the control logic is complicated; when the system is operated, coal fuel needs to be purchased and operators such as a coal conveying system, a boiler system, a steam turbine system and the like need to be configured, so that the operation cost is extremely high.
2) The improvement needs to flexibly connect the high-pressure cylinder rotor with the generator rotor and separate the steam inlets and the steam outlets of the medium-pressure cylinder and the low-pressure cylinder of the steam turbine, and the improvement has very high requirements on the improvement design and construction side.
3) At present, an electric power system is not lack of electric energy, and the electric energy of the electric power system can come from clean and environment-friendly energy sources such as water, electricity, wind power and photovoltaic, so that fossil fuel does not need to be wasted as energy sources for maintaining the synchronous phase modulator to generate reactive power. At present, the price of coal is in a high history, and the cost is high and the economic benefit is poor when the coal is used as an energy source of a phase modifier.
4) The phase modulator in the scheme needs a prime motor, and the phase modulators in the current power system are all self-shunt phase modulators, namely the phase modulators have no prime motor and are directly connected to the AC bus of the system. Therefore, the pattern of the phase modulator in the scheme no longer conforms to the mainstream configuration of the power system.
5) The scheme adopts high-pressure cylinder steam to push a high-pressure cylinder rotor, the high-pressure cylinder rotor is connected with a generator rotor to form a prime motor of the phase modifier, the phase-entering working state of the phase modifier is adjusted by adjusting the air input of the high-pressure cylinder, and the response rate is low.
The invention provides a method for changing an retired generator into a self-shunt excitation synchronous phase modulator. In the future, the living space of the coal-electric unit is continuously compressed, and a large number of thermal power generating units face retirement. Meanwhile, with the continuous expansion of the transmission scale of high-voltage direct-current transmission and the large-scale development of renewable energy sources, the power system faces the situation of reactive power shortage. If the retired synchronous generator can be transformed into the synchronous phase modulator, the retired unit can be effectively utilized, reactive support can be provided for a power system, waste is changed into wealth, and the two purposes are achieved.
The invention provides a method for changing a decommissioned generator into a self-shunt excitation synchronous phase modulator, namely, the decommissioned synchronous generator is not dragged by a prime motor, does not have any mechanical load on a shaft, is connected with a power grid for no-load running, and is specially used for adjusting the reactive power of a system. The method is characterized in that a steam turbine and a synchronous generator are decoupled, and a power grid is changed to provide all energy required by the synchronous generator to maintain rotation, so that an out-of-service generator is converted into a synchronous phase modulator.
Referring to fig. 1, an embodiment of the present invention provides a method for changing an out-of-service generator into a self-shunt synchronous phase modulator, including the steps of:
s1, removing a coupling between the steam turbine and the original generator so as to decouple the coaxially installed steam turbine and the original generator.
And step S1, removing the coupling between the steam turbine and the generator, and decoupling the coaxially installed steam turbine and generator.
And S2, adding a new starting motor, and connecting the starting motor with the original generator by using a coupler and a coupling.
Further, step S2 is specifically:
and (3) removing the original steam turbine, adding an asynchronous induction motor, and connecting the starting motor with the original generator by using a coupler and a coupling.
In the embodiment of the present invention, step S2 is to add an asynchronous induction motor, and add a coupler and a coupler to connect the asynchronous induction motor and the synchronous phase modulator at the turbine end of the rotor shaft of the original synchronous generator or at the turbine side.
In order to enable grid connection, the synchronous phase modulator needs to be accelerated to a rated rotation speed after being started. Since the steam turbine, which is originally the prime mover, is now decoupled from the phase modulator, a device is required as a starting device. If an asynchronous induction motor is used as rotating equipment to drag a synchronous phase modulator to a rated rotating speed, an original steam turbine must be dismantled.
In step S2, a Static Frequency Converter (SFC) may be used as a starting device of the synchronous phase modulator.
When a Static Frequency Converter (SFC) is adopted as a starting device of the synchronous phase modulator, the starting schematic diagram is shown in figure 3, and when the phase modulator is started, a rotor magnetic field is established by excitation. The starting power supply is led from an external power grid, rectified and frequency-converted by SFC frequency conversion starting equipment after special isolation transformation, output to a stator of the phase modifier through an isolation switch, drag the whole unit to increase the speed to 105 percent of rated speed, disconnect a switch of a frequency converter, and enable a rotor to enter an idling mode. Before the rotating speed is reduced to 3000rpm, excitation is added to raise the voltage of the phase modulator to the rated value, and the phase modulator is connected with the system in a grid mode after meeting the synchronous condition to finish starting.
If the SFC is adopted as the starting device, the bearing capacity of the rotor damping system in the variable-frequency starting process needs to be checked because the harmonic wave of the variable-frequency device in the starting process is large. In addition, when the motor body is transformed, the motor rotor also needs to be transformed so as to meet the requirement of variable frequency starting (needing static excitation matching).
The scheme of adopting the SFC as the starting device also has the advantages of small occupied area, no need of dismantling steam turbine equipment and no need of additionally arranging a motor, and can further reduce the investment of reconstruction. This solution can also be adapted in the future if the synchronous phase modifier needs to be reduced to a synchronous generator. In addition, the scheme has no motor, simplifies the design of the whole unit, simplifies the transient characteristics of the unit, and eliminates the possible problems of synchronization failure and the like caused by the motor from the source.
And S3, modifying the excitation regulating system by adopting a mode of adding an exciter or a mode of modifying a coaxial exciter excitation loop so as to enable the excitation regulating system to meet the excitation current standard of the synchronous phase modulator.
Further, step S3 specifically includes:
if the original generator is excited by adopting an exciter, modifying an excitation adjusting system by adopting a mode of newly adding the exciter so as to enable the excitation adjusting system to meet the excitation current standard of the synchronous phase modulator;
if the original generator is a generator adopting a self-shunt excitation alternating current excitation system, the excitation regulating system is modified in a way of modifying a coaxial exciter excitation loop so as to enable the excitation regulating system to meet the excitation current standard of the synchronous phase modulator.
In the embodiment of the present invention, it should be noted that, since the phase modulator needs a larger excitation current when fully outputting the reactive power, the excitation adjusting system needs to be modified to adapt to the situation. The excitation system is used as a core control system when the phase modulator is in grid-connected operation, the operation condition of the phase modulator is controlled in real time, the requirement on dynamic reactive power support of the phase modulator is greatly higher than that of a generator, and the phase modulator still has the support capability of 2 times of reactive power under 0.8 times of rated voltage.
For the generator excited by the exciter, the effect of increasing the exciting current can be achieved by adding a larger-capacity exciter.
For the generator adopting the self-shunt excitation AC excitation system, the exciting current of the AC exciter can be increased by controlling the control angle of the silicon controlled rectifier element in the controllable rectifier, so that the exciting current of the generator is increased.
The larger excitation current can bring more serious heating of the rotor winding and the end group components thereof, so that the heat dissipation conditions of the rotor winding and the end structural components of the excitation system need to be enhanced, such as increasing the number of coolers, replacing the rotor copper wires with better conductivity, adding end shields to reduce the heating influence of the end structural components of the rotor, and the like. If necessary, the cooling mode of the excitation system can be changed from air cooling to air-water cooling or water cooling, so as to improve the heat dissipation level of the excitation system.
S4, calculating the heat dissipation condition of the rotor winding, determining the range of the sending and absorbing reactive power of the synchronous phase modulator according to the calculation result, and modifying the original generator body according to the range of the sending and absorbing reactive power so that the heat dissipation capacity of the rotor winding and the end structural part can meet the preset requirement.
In the embodiment of the present invention, further, the calculating the heat dissipation condition of the rotor winding specifically includes:
calculating the rotor temperature rise data in the over-excited state;
calculating an end electromagnetic field and a strength field in an underexcited state;
calculating the rotor loss and the heat productivity in the starting process;
and calculating rotor coasting data in the grid connection process.
In the embodiment of the present invention, further, the method for modifying the original generator body includes one or more of replacing a cooler, replacing a rotor copper wire, and installing an end shield.
It should be noted that, when the phase modulator absorbs active power from the power system, it only needs to overcome its own mechanical loss, its power angle is very small, the armature reaction potential and the excitation potential are basically coincident, when the over-excitation is running, the armature should play a pure demagnetization role, the rotor excitation current is increased, so it needs to account for the heat dissipation of the rotor winding.
When the phase modulator is in underexcitation operation, the end leakage flux is increased, the end loss is increased, and the heating of the end structural part is increased, so that the calculation of an electromagnetic field and a temperature field at the end part of the motor is required.
The phase modulator is dragged to a high rotating speed and then idles for grid connection in the grid connection process, and the grid connection process of the phase modulator needs to be checked again to determine a phase modulator grid connection synchronization window.
From the above analysis, the modification of the motor body includes the following:
1) carrying out temperature rise calculation of the rotor in an over-excited state, calculation and analysis of an electromagnetic field and an intensity field at the end part of the under-excited state, analysis and calculation of rotor loss and heat productivity in a starting process and calculation and analysis of rotor coasting in a grid-connected process;
2) and determining the range of the reactive power emitted and absorbed when the generator is transformed into a phase modulator according to the result of calculation and analysis, and improving the heat dissipation capacity of a rotor winding and an end structural part of the generator according to the requirement, wherein the heat dissipation capacity comprises the steps of replacing a cooler, replacing a rotor copper wire, additionally installing an end shield and the like.
S5, adding a thrust bearing to enable the mechanical mechanism of the original generator to meet the preset operation requirement of the synchronous phase modulator.
Further, the method for changing the retired generator into the self-shunt excitation synchronous phase modulator further comprises the following steps:
and adding a supporting bearing so that the mechanical mechanism of the original generator meets the preset operation requirement of the synchronous phase modulator.
The mechanical structure of the original machine set can not meet the operation requirement of the synchronous phase modulator, so mechanical transformation is needed. The mechanical structure modification range comprises a thrust bearing and a support bearing. On the original synchronous generator, the steam turbine acts as a thrust bearing. Since the turbine is now decoupled from the rotor shaft of the generator, a new thrust bearing is required.
If the dynamic characteristics of the synchronous phase modifier do not meet the requirements, a support bearing is also required to be installed to prevent the long shaft from swinging and the like. A vibration detection device can be arranged on a shaft and a bearing of the synchronous phase modulator, and an alarm is given out when the amplitude exceeds a certain limit so as to indicate that the dynamic characteristic of the synchronous phase modulator does not meet the requirement. At this time, a support bearing is required to be installed to prevent the long shaft from swinging.
S6, transforming the protection device and the monitoring system of the original generator to enable the protection device and the monitoring system to meet the preset operation requirement of the synchronous phase modulator.
It should be noted that, the modification of the retired generator into the synchronous phase modulator also requires the modification of the generator protection device and the monitoring system.
Firstly, the operation mode and the starting mode of the phase modulator are different from those of the generator, so that the protection function configuration, the protection constant value setting and the excitation system limiting function constant value setting in the original generator protection device need to be changed:
1) the differential protection, stator grounding protection, rotor grounding protection, overload protection, composite voltage overcurrent protection, over-excitation protection, overvoltage protection and the like of the phase modulator can continue to use the protection configuration in the conventional generator-transformer set protection.
2) Because the machine end impedance track of the phase modulator during loss of field is in the second quadrant and the third quadrant, the convergence of the impedance track is poor, and the distinction degree between the loss of field and the normal state is not enough, the loss of field protection is not suitable to be realized by using the impedance principle in generator protection and adopting the combination criteria of inverse reactive power, machine end voltage, bus voltage, rotor voltage and the like.
3) Because the phase modifier has no mechanical prime power input, the active power is approximately 0, and the possibility of step-out with a power grid does not exist, the step-out protection does not need to be configured.
4) In order to prevent the condition that a phase modulator is not synchronously connected with a network after a line is reclosed after a total station loses power, low-voltage disconnection protection which is not available in a new generator transformer protection configuration is required.
5) The phase modulator SFC has long frequency conversion starting time, and needs to be added with low-frequency differential, low-frequency overcurrent and low-frequency zero-sequence voltage protection functions to improve the protection performance in the low-frequency process
6) The excitation reactive power underexcitation limitation of the phase modulator mainly acts near zero active power and is matched with the loss-of-excitation protection of the phase modulator.
7) The multiple of the excitation voltage of the excitation system of the conventional generator is about 2 times, the multiple of the excitation voltage of the phase modulator is 3.5 times, and correspondingly, the setting value of the maximum load excitation current also needs to be improved to 2.5 times of the rated excitation current.
Secondly, as the protection function configuration of the phase modulator is changed, the measuring point in the corresponding phase modulator monitoring system is also changed. Meanwhile, because the phase modulator has a forced excitation operation mode and a variable frequency starting mode, which are obviously different from the generator, the internal logic of the phase modulator monitoring system also needs to be modified:
1) the starting sequence operation logic in the monitoring system is changed into:
when the phase modulator is started, the main excitation loop is not put into use, the rotor of the phase modulator is dragged to 1.05 times of rated rotation speed in a short time through the SFC and the separate excitation loop, then the SFC system exits, the main excitation loop is put into use after the SFC system exits, rated machine end voltage is established through controlling the excitation system, and then the synchronous point capturing and closing tasks are completed by utilizing an automatic quasi-synchronous device in the inertia speed reduction process of the phase modulator.
2) The wiring and internal logic of the quasi-synchronous devices also need to be modified:
when the unit is a generator, a generator-end circuit breaker GCB and a main transformer high-voltage side circuit breaker can be arranged at a synchronization point, and a synchronization device is provided with a line selector and exchanges information with a unit Distribution Control System (DCS) and a steam turbine control system (DEH or TCS); when the unit is changed into a phase modulator, an FCB working condition of island operation does not exist, so that two synchronization points are not needed any more, one of a GCB (gas circuit breaker) at the generator end or a main transformer high circuit breaker is selected as the synchronization point, a line selector is not needed any more, and information exchange with a steam turbine control system (DEH or TCS) is not needed any more due to the fact that a steam turbine is disconnected. It is therefore necessary to modify the wiring of the quasi-contemporaneous devices and the internal logic of the corresponding quasi-contemporaneous devices.
Through the modification, the phase modulator monitoring system finally realizes the coordination control of the start sequence operation, the excitation system and the synchronous grid connection of the synchronous phase modulator, and monitors the running states of a new phase modulator protection system, an auxiliary system and the phase modulator.
S7, transforming the oil system of the original generator according to the preset requirements of the oil system of the synchronous phase modulator to obtain the self-shunt excitation synchronous phase modulator transformed by the retired generator.
After the generator is changed into the self-shunt excitation synchronous phase modulator, the energy of the rotation of the motor rotor is taken from a power grid, once a power loss accident of a whole plant occurs, the motor rotor loses electromagnetic torque and idles under the action of resistance torque, and the rotor idling process needs a lubricating oil system to continuously provide lubricating oil for a bearing under the power loss condition, so that the oil system needs to be modified, and a high-level oil tank and a direct-current oil pump are additionally arranged.
In one embodiment, the method for changing the retired generator into the self-shunt excitation synchronous phase modulator of the invention can be mainly realized by the following steps:
1. the design of the accounting generator body can meet the requirements of a synchronous phase modulator;
2. decoupling a wave coupling between the synchronous generator and the steam turbine and dismantling a low pressure cylinder of the steam turbine;
3. a starting motor is newly added;
4. modifying the shafting parameters of the synchronous generator to meet the requirements of a synchronous phase modulator;
5. a thrust bearing and a supporting bearing are improved or newly added;
6. adding an exciter or transforming a coaxial exciter excitation loop;
7. an oil system is reformed, a high-level oil tank is arranged, and a direct-current oil pump is arranged;
8. reforming a generator protection device;
9. transforming a synchronous closing device;
10. and modifying the measuring point and the control logic of the control system.
In the implementation of the present invention, it should be noted that the control logic of the synchronous phase modulator based on the modification of the retired generator of the present invention is as follows:
1. by adjusting the excitation current, the excitation potential E is varied0And determining whether the synchronous phase modulator emits reactive power or absorbs reactive power.
When the exciting current is large, E0When the phase modulator is in an over-excitation state, the phase modulator supplies inductive reactive power to a system to play a role of a reactive power supply;
when the exciting current is small, E0And when the phase modulator is in underexcitation, the phase modulator absorbs inductive reactive power from a system to play a role of reactive load.
Therefore, in operation, only the exciting current needs to be increased/decreased to change the reactive power property of the phase modulator.
2. When the phase modulator is in an over-excitation state, the reactive power emitted by the phase modulator can be reduced by reducing the exciting current;
when the phase modulator is in an underexcited state, the reactive power absorbed by the phase modulator can be increased by reducing the exciting current;
3. when the phase modulator is in an over-excitation state, the reactive power emitted by the phase modulator can be increased by increasing the exciting current;
when the phase modulator is in an underexcited state, the reactive power absorbed by the phase modulator can be reduced by increasing the exciting current.
The specific control logic diagram is shown in fig. 4. Through the above mode, the operation state of the phase modulator can be adjusted to emit reactive power or absorb reactive power by adjusting the exciting current, and the emitted/absorbed reactive power is increased or reduced.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
1) the invention provides a scheme for converting an retired generator into a self-shunt excitation synchronous phase modulator. Because the generator and the synchronous phase modifier are both synchronous motors, the decommissioned generator can be converted into the synchronous phase modifier by removing the steam turbine and providing all energy required by the synchronous motor to maintain rotation by the power grid. The decommissioned generator is converted into the phase modulator, the decommissioned generator equipment can be effectively utilized, the decommissioned generator is effectively reused, a large number of peripheral places (such as a coal yard, a desulfurization absorption tower and the like) of an original unit are vacated, and the traditional thermal power optimization and upgrading are promoted.
2) Converting an out-of-service generator into a phase modulator has three benefits to the power system: the method can solve the problem of lack of reactive power and rotational inertia caused by long-distance high-voltage direct current power transmission and large-scale clean energy grid connection of the current power system, maintain a high-level short-circuit current for the power grid, keep a more stable power grid running state, facilitate flexible regulation and control of nearby high-voltage line tide, and achieve three purposes at one stroke.
3) The invention is not limited by the energy form of the original generator set, and the coal-fired generator set, the gas generator set, the diesel generator set and even the generator set such as methane and the like can be modified according to the scheme, thus the invention has wide application.
4) The synchronous phase modulator in the scheme is a self-shunt phase modulator, namely, a prime motor is not provided, and the phase modulator is directly hung on an alternating current bus, so that the condition of the phase modulator in the current power system is met. The self-shunt excitation synchronous phase modulator absorbs active power from a power grid, emits/absorbs reactive power according to system requirements, does not need to additionally burn fossil fuel, and is energy-saving and environment-friendly.
5) The scheme adopts the mode that the connection between the generator and the steam turbine is directly disassembled, and the newly-added asynchronous induction motor and the coupler are used for dragging the phase modulator to be connected to the grid. For an original unit, only an oil system needs to be reserved, and a boiler, a steam turbine, a steam-water circulating system, a peripheral coal conveying system, a peripheral desulfurization system and a peripheral denitration system are not needed any more. Therefore, a large amount of land can be saved, equipment is saved, the system is simplified, and environmental pollution can not be caused. The reduction of the system also reduces the maintenance of equipment and the number of operators, saves the cost and creates more economic benefits.
6) The scheme adopts the self-shunt excitation synchronous phase modulator, and when the voltage at the machine end is higher than the rated voltage, the reactive power emitted by the phase modulator can be reduced or the reactive power absorbed by the phase modulator can be increased by reducing the exciting current; when the voltage of the machine terminal is lower than the rated voltage, the reactive power emitted by the phase modulator can be increased or the reactive power absorbed by the phase modulator can be reduced by increasing the exciting current of the phase modulator. Compared with a synchronous phase modulator driven by a steam turbine, the scheme can adjust the working condition of the synchronous phase modulator by only changing the voltage and current of the excitation system, is simple to operate and extremely high in response speed, and can quickly provide stepless continuously adjusted capacitive or inductive reactive power for a power grid.
7) The scheme has small transformation difficulty and low transformation cost. After the transformation is successful, a large amount of operating manpower can be saved and a large amount of land used can be released.
It should be noted that the above method or flow embodiment is described as a series of acts or combinations for simplicity, but those skilled in the art should understand that the present invention is not limited by the described acts or sequences, as some steps may be performed in other sequences or simultaneously according to the present invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are exemplary embodiments and that no single embodiment is necessarily required by the inventive embodiments.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (6)

1. A method for changing an retired generator into a self-shunt excitation synchronous phase modulator is characterized by comprising the following steps:
removing a coupling between the steam turbine and the original generator so as to decouple the coaxially installed steam turbine and the original generator;
adding a new starting motor, and connecting the starting motor with the original generator by using a coupler and a coupling;
modifying an excitation adjusting system by adopting a mode of newly adding an exciter or a mode of modifying a coaxial exciter excitation loop so as to enable the excitation adjusting system to meet the excitation current standard of a synchronous phase modulator;
calculating the heat dissipation condition of the rotor winding, determining the range of the sending and absorbing reactive power of the synchronous phase modulator according to the calculation result, and modifying the original generator body according to the range of the sending and absorbing reactive power so that the heat dissipation capacity of the rotor winding and the end structural member meets the preset requirement;
a thrust bearing is additionally arranged so that a mechanical mechanism of the original generator meets the preset operation requirement of a synchronous phase modulator;
transforming a protection device and a monitoring system of the original generator so that the protection device and the monitoring system meet the preset operation requirement of the synchronous phase modulator;
and transforming the oil system of the original generator according to the preset requirements of the oil system of the synchronous phase modulator to obtain the self-shunt excitation synchronous phase modulator transformed by the retired generator.
2. The method of changing an out-of-service generator to a self-shunt excitation synchronous phase modulator according to claim 1, wherein the new starting motor is added, and the starting motor is connected to the original generator by using a coupler and a coupling, specifically:
and (3) removing the original steam turbine, adding an asynchronous induction motor, and connecting the starting motor with the original generator by using a coupler and a coupling.
3. The method of changing an out-of-service generator into a self-shunt excitation synchronous phase modulator according to claim 1, wherein the modifying the excitation regulation system by adding an exciter or modifying a coaxial exciter excitation loop is performed to make the excitation regulation system meet the excitation current standard of the synchronous phase modulator, and specifically comprises:
if the original generator is excited by adopting an exciter, modifying an excitation adjusting system by adopting a mode of newly adding the exciter so as to enable the excitation adjusting system to meet the excitation current standard of the synchronous phase modulator;
if the original generator is a generator adopting a self-shunt excitation alternating current excitation system, the excitation regulating system is modified in a way of modifying a coaxial exciter excitation loop so as to enable the excitation regulating system to meet the excitation current standard of the synchronous phase modulator.
4. The method for changing an out-of-service generator into a self-shunt excitation synchronous phase modulator according to claim 1, wherein the calculating of the heat dissipation of the rotor winding specifically comprises:
calculating the rotor temperature rise data in the over-excited state;
calculating an end electromagnetic field and a strength field in an underexcited state;
calculating the rotor loss and the heat productivity in the starting process;
and calculating rotor coasting data in the grid connection process.
5. The method of changing an out-of-service generator to a self-shunt excitation synchronous phase modulator as claimed in claim 1, wherein the modifying of the original generator body comprises one or more of replacing a cooler, replacing rotor copper wires, and adding an end shield.
6. The method of changing an out-of-service generator to a self-shunt excitation synchronous phase modulator as claimed in claim 1, further comprising:
and adding a supporting bearing so that the mechanical mechanism of the original generator meets the preset operation requirement of the synchronous phase modulator.
CN201911021992.5A 2019-10-24 2019-10-24 Method for changing retired generator into self-shunt excitation synchronous phase modulator Pending CN110635621A (en)

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CN111835018A (en) * 2020-04-30 2020-10-27 南京理工大学 Synchronous phase modulator starting grid-connected circuit based on time sequence hybrid excitation control and control method
CN112683543A (en) * 2020-12-21 2021-04-20 国网上海市电力公司 Gas-steam combined cycle unit phase-feed capacity cooperative test method and device
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CN113097973A (en) * 2021-04-08 2021-07-09 中国电力科学研究院有限公司 Phase modulator magnetic loss protection method and system based on maximum phase advance capability
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CN113555880A (en) * 2021-07-23 2021-10-26 国网甘肃省电力公司经济技术研究院 Reactive compensation access point screening method based on retired synchronous generator set

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CN111162544A (en) * 2020-01-06 2020-05-15 长沙而道新能源科技有限公司 New energy power generation control system
CN111162544B (en) * 2020-01-06 2021-08-10 河北点击新能源科技有限公司 New energy power generation control system
CN111835018A (en) * 2020-04-30 2020-10-27 南京理工大学 Synchronous phase modulator starting grid-connected circuit based on time sequence hybrid excitation control and control method
CN112683543A (en) * 2020-12-21 2021-04-20 国网上海市电力公司 Gas-steam combined cycle unit phase-feed capacity cooperative test method and device
CN112683543B (en) * 2020-12-21 2022-10-11 国网上海市电力公司 Gas-steam combined cycle unit phase advance capability cooperative test method and device
CN112751512A (en) * 2020-12-30 2021-05-04 华中科技大学 Self-shunt excitation brushless excitation system of generator and application thereof
CN113158422A (en) * 2021-03-15 2021-07-23 国网陕西省电力公司电力科学研究院 Synchronous phase modulator site selection method for improving stability of large new energy base
CN113097973A (en) * 2021-04-08 2021-07-09 中国电力科学研究院有限公司 Phase modulator magnetic loss protection method and system based on maximum phase advance capability
CN113097973B (en) * 2021-04-08 2023-10-27 中国电力科学研究院有限公司 Maximum phase advance capability-based loss of magnetic protection method and system for camera
CN113555880A (en) * 2021-07-23 2021-10-26 国网甘肃省电力公司经济技术研究院 Reactive compensation access point screening method based on retired synchronous generator set
CN113555880B (en) * 2021-07-23 2022-07-29 国网甘肃省电力公司经济技术研究院 Reactive compensation access point screening method based on retired synchronous generator set
CN113410847A (en) * 2021-08-04 2021-09-17 国网黑龙江省电力有限公司电力科学研究院 Excitation control method of asynchronous phase modulator

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Application publication date: 20191231