Analysis of startup and synchronization process of two-axis steam turbine generator set

200137 Keywords two-axis turbo generator; start; there is no mechanical connection between the two rotors of the synchronous twin-shaft steam turbine generator set, after the turbine is rushed. Since the enthalpy drop and the moment of inertia of the two axes cannot be the same. If there are no special measures. The two-axis transfer will not be the same. How to use the simple method to synchronize the two in the startup, the two-person technical class of the two-person technical class of the Chongming Power Company Power Plant No. 14 is 25 high-temperature high-pressure back pressure The front-mounted unit is sent to the three low-pressure condensing units of the old workshop for power generation. The whole system is very complicated, the thermal efficiency is low, the operation adjustment is difficult, the stability and the safety factor are poor. Therefore, the company carried out technical transformation in 1991992, and installed a specially designed 301 Jia low-pressure cylinder and generator. The original back press combines 55 dual-axis twin-cylinder steam turbine generator sets. This solution takes into account the investment benefits and the operability of the isolated 改造1 transformation, but the heart has brought about the special lessons of how to use the grid and speed control. 1 System Brief Description The structure of the low-pressure cylinder is equivalent to intercepting 50. The value of the soil door threshold cannot be lower than 49.0, because this value is the first set value of the low-frequency load shedding of the net. This value of low Shanghai will cause grid load loss. Considering the frequency drop, there is a process, the threshold value should be greater than 4 to 0. The minimum frequency of the starting frequency of the power station unit is reduced within the frequency tolerance. The difference is seen by 3, the frequency change of the 600 river unit of the platform is 0.080.131. This change is within the allowable range of the frequency. If the two machines are hopped at the same time, the frequency change must exceed the normal allowable range. To reach 0.300.40HZ, because the grid is transported in the two 600MW machines, the situation of jumping is very rare. Therefore, the low-frequency self-starting threshold value of the power station can be used as the alias. It is also recommended to set the margin in the half-person deduction. Pumped storage power station and power market At present, the main part of the operation principle of Tianhuangping Power Station in East China Power Grid belongs to the administrative regulations. With the continuous development of the power market, these principles obviously do not work. The power market requires the factory network to bid separately. Pumped storage power stations, although unique, cannot violate the basic principles of the electricity market unless the state or market participants agree to give preferential policies to new power plants. In the future, various joint venture power plants will be connected to the grid. The method of distribution and use is not effective and it is an important task to actively study the policy of power stations in the future competition of the power market.

4 Conclusion Tianhuangping Power Station has just been connected to the grid. So far, the unit has not been fully invested, and the reservoir has not entered normal operation. Therefore, there are still many questions to be asked about how to optimize the operation of the power station.

At present, reducing the impact on the grid to maintain the operational order of the electrical gateway is a top priority. In the long run, it is an important lesson to optimize the operation of the entire network after the normal operation of the power station.

Class, household 乍 Zhou Jinqi, fully reduce the loss of throttling and part of the intake of steam, etc. This cylinder drive station 30 PCT boundary generator, through the switch and the high-pressure cylinder machine hereinafter referred to as the generator switch outlet of the human machine, and sent to 80%, the start-up of the main transformer 2 twin-shaft unit and the on-grid 2.1 start-up and grid-connected problem. During the joint start-up process, the two cylinders have different enthalpy drops. In the case of small flow, the high-pressure cylinder with complex speed stage The enthalpy is larger than the low pressure cylinder, and the low inertia rotor has a much larger moment of inertia than the high pressure rotor. However, the two shafts have no mechanical connection and cannot transfer mechanical work to each other. If there is no other measure, it will inevitably make the low-pressure rotor, the low-pressure cylinder does not have the main valve and the regulating valve, there is no adjustment means, how to make the low-voltage rotor enter the synchronization and the grid connection is a big question 12 startup and grid-connected scheme in several years of research In the process of argumentation, 5 sets of startup grid-connected cases were considered. Three sets of coexisting before commissioning were started, and a small bypass was set up. The grid-connected scheme was at +63, and the insulated gate valve of the steam guide was closed at both ends. Parallel sleeve small bypass start regulation control system, in fact, is a small-diameter main valve 8 series connection adjustment, but the generator of this scheme must be configured with switches, the principle of the scheme is relatively simple, during the startup process, the isolation gate valve is always It is off and the bypass is on. At this time, the bypass start regulation control system and the low pressure cylinder machine are referred to as the 8-machine closed loop, which is equivalent to a complete low-voltage unit, which can be controlled by the speed, and the original before. The start-up type of the rear unit is not different. During the start-up process of the man-machine, the small-sized door is opened, and the rear-end machine is in the follow-up state. As mentioned above, the low-speed and wide-speed will load. At this time, due to the steam flow, the rear-end opportunity continues to increase. When approaching the rated speed, the small-key door will be closed due to the action of the speed control system, and enter the speed control state, and then it will be connected to the grid as an ordinary unit. After the 8 machines are connected to the grid, open the isolated gate valve of the steam guide tube and exit the system with a small bypass.

The configuration of the system brings great convenience to the individual debugging of a few. After the installation, the exhaust steam of the back pressure machine is used and the small bypass system is separately activated and debugged by the 8 machine. The principle of the scheme is simple, but it needs to be connected to the grid twice and the two generator outlets need to be equipped with switches. In addition, the small main valve is small and the regulating valve is 0. The most complicated system is similar to the low frequency start of the camera. . Before starting, the generator outlet switch has been closed or directly shorted, and the outlet is the main high-voltage side switch; the isolated gate valve of the steam guide has been opened; the standby exciter is opened, and the excitation mode is switched to the first step. Impulsive man-machine, 8 machines to follow. When the current one is near 10001.1, the two-spindle machine and the valley exciter plus excitation can also be activated by human-machine and excitation. When the difference between the two is small, the excitation is several. The theory of motor excitation knows that the excitation current does not change. On the premise that the stator core is not saturated, the stator voltage is proportional to the rotational speed, so the rotational speed of the timing is much higher than that of the engine. Therefore, the induction potential of the generator stator is much higher than that of the 8-machine. It is allowed in the two-motor coupling system. The generator character. The active power is output and the low-cylinder hair dryer is equivalent to an asynchronous motor, which inputs active power. This electric power and the steam work on the cylinder side jointly drive the rotor to accelerate, so that the rotational speed difference between the two rotors tends to decrease. When the speed of the two machines is close and the slip is very small, the two rotors will be quickly dragged due to the synchronous electromagnetic torque of the motor. At this point, the electromagnetic torque makes the two shafts rigidly connected by the coupling, and will be firmly fixed. Stay in sync. After that, you can ignore the game, only 3 is a single-axis machine. operating. The machine continues to increase speed until the rated speed is connected to the grid. After the grid connection, both motors need to cut the excitation source back to the 1-axis exciter by the standby exciter. The synchronization process of the two hair dryers is equivalent to the non-period parallel process of the secondary non-periodic component. Under normal circumstances, the parallel operation of the motor to the grid is never allowed to use the non-phase 1 side-by-side because this will result in a large inrush current. Therefore, the safety of the power grid and the generator is endangered. However, in this special two-machine system, the excitation voltage can be controlled; in addition, the synchronous speed is lower, and it is always slower than the former Li, 1 and 2 are in the same, 0, 1 Rating.

Obviously, this scheme is much simpler than the separate grid-connected scheme. The only drawback is that the grid must be added before the grid connection and the grid is switched to the main excitation. Net, for units that use static excitation, no coaxial exciter, do not switch the excitation source before and after the network, so the square blower is often reasonable.

Self-excited variable frequency asynchronous start for the shortcomings of the above scheme, progress to explore and demonstrate a more simple method. The idea is to directly use the excitation voltage gradually established by the coaxial exciter during the speed-up process, so that the two generators are pulled into the step. The excitation voltage of the coaxial coaxial excitation exciter is extremely weak at low speed. In order to obtain sufficient synchronous electromagnetic torque, the selected synchronous rotation, the point should be and the speed should be lifted, and the motor resistance is also increased accordingly. To obtain the same electromagnetic torque as the excitation type asynchronous start-up scheme. The higher excitation current 1 23,1 generator measured excitation curve. The operation of this scheme is as follows. Before starting, the generator outlet switch has been directly connected to the spicy short-circuit, and the outlet is also the main high-voltage side switch; The rated position of the no-load of the steam main pipe is not reversed, the main exciter has no output to turn the man-machine, and the 8 machine is allowed to follow the process. The coaxial exciter will gradually change with the regener The excitation card causes the generator to gradually generate an electric potential. at this time. The high-pressure cylinder generator also acts as a generator in the two-motor coupling system, and the output has a merit. The low-voltage cylinder generator is still equivalent to the motor, and the active power is transmitted. This electric power and the cylinder's steam-driven work drive the rotor to accelerate, with the high voltage. As the rotor speed increases, the excitation potential accelerates, the electric power transmission increases, and the slip between the two axes begins to shrink.

In the high-voltage rotor speed of 2300 to prevent the generator potential is too high, the inrush current overcurrent torque and steam push work in synchronization, continue to accelerate, and at the same time, its own excitation voltage is correspondingly increased, making asynchronous The torque and speed are accelerated. After a few minutes, when the whistle is close to the speed, the synchronous electromagnetic torque between the two motors will drag the two rotors together. After that, the man-machine is operated to continue to accelerate until the volume is rotated. The foreland magnetic field varistor is placed at the no-load rated position, so the generator outlet voltage at this time is close to the rated value, and can be connected to the grid with a slight adjustment.

It can be seen from the above process that if the scheme is feasible, the 6 machines have no operation during the whole process of rushing to the grid connection, and the operation adjustment is extremely simple. In this process 1; the machine is considered to be + transparent, it seems that in the console single-axis unit 23 program comparison and ask the above three cases, from the perspective of transportation, the third program is obviously optimal, like the technology In terms of degree, the most unsure is that there are 3 obvious questions to be considered. Since the 8 machines are in the process of starting until the synchronization, they are in a free state, and the operator cannot directly control the speed. This is the steam turbine that usually needs the critical speed. It is unfavorable. However, the low-pressure cylinder rotor of this machine is equivalent to 10 stages after the 50 Jia steam turbine. It is thick and short, and the critical speed is far above 30001. Therefore, there is no such worry. During the start-up process, the steam flow is very small, and ç„“The drop is mainly in the high pressure cylinder, and the blast loss of the final stage of the low pressure cylinder will increase sharply. The loss is about proportional to the power of the second speed. However, if the difference between the two revolutions and the fire is only the electromagnetic torque is lower than the rotor speed, if the torque cannot overcome the blast loss that increases sharply with the rotation speed, the two can be dragged into synchronization, or even if they can barely Sync, but time consuming The program will also lose its advantage. At the same time, the generator rotor will be derived and the temperature will rise. Because of the asynchronous start, the 8-machine generator will have a large induced current and generate heat during the speed increase process. This current is not evenly distributed across the full section of the rotor, only through a relatively thin layer, and this layer thickness varies with the frequency of the induced current. Since the rotor coil is placed in the rotor slot of the hidden pole turbine generator, the heat generated by the rotor core loss will directly affect the temperature rise of the rotor coil. Therefore, it must be ensured that it is large during the entire process of reversal. Stop the speed increase, the moment the ship's low pressure can't turn, to answer the last two questions, it is obviously not possible to rely on qualitative analysis alone. As a heavy technical transformation project, it is not allowed to wait until the construction is completed, and then the feasibility of the test plan must be strictly quantitative. 3 Start-up process analysis 3.18 machine force analysis Self-excited frequency conversion asynchronous start process mainly exists in the high-pressure cylinder row The steam directly enters the low-pressure cylinder, drives the turbine rotor to increase speed; the mechanical resistance torque loss small oil pump, the exciter consumes power; the bearing, the turbine blade corpse and the generator fan blast loss; when the high and low voltage rotors are respectively put into the main exciter, During the speed-up process, the generator excitation potential changes according to 2, when there is no synchronization, there are two asynchronous torques, which can be regarded as low-voltage rotor without excitation and high-voltage rotor excitation. At this time, the human-machine is a synchronous generator, and the output is Power and reactive power; 1; The machine is an asynchronous motor, the input power and the power of the power are used in the case where the middle moving wheel is magnetic and the driven wheel is pure iron. When the driving wheel 5 is turned, it also pulls the driven wheel by magnetic force. Obviously, the rotating speed of the driven wheel will be lower than that of the driving wheel. M can be regarded as high-voltage rotor without excitation and low-voltage rotor with excitation. At this time; the machine is synchronized. Motor, power transmission and output of reactive power, the system's enthalpy is mainly in the high-pressure cylinder efficiency 3, the rate range is very wide, and the low-cylinder pressure level is extremely low and high in the speed range, when the lower Such unfavorable conditions, the last few stages or even 1 in the state of blasting power consumption, it seems that it is difficult to know the ratio of the high and low pressure cylinders. It is assumed that the steam pressure drop of the low pressure is only the high pressure. The division of the cylinder, because the flow rate of the two is the same, so the 8 machine steam drive work 5; wide. 2. If the mechanical loss of the machine is neglected, it can be obtained according to the equation of motion of the rotor. The steam drive torque of several engines is small for the eight machines except for the blast loss, which is within the scope of the research. It can be neglected that the last stage blade is longer, at a small flow rate, and the blast loss in the higher speed range is not ignored. In view of the fact that the value is about 1 part of the rated speed, the loss and the rotational speed are the power of the unit. It is proportional, so the rate can be described. The machine is an asynchronous generator, and the input of reactive power and output of the work power can be regarded as the fact that the middle drive wheel is pure iron and the driven wheel is magnetic. The driving wheel is dragged by the driven wheel with a magnetic force when the small moving wheel rotates. The driven wheel will also follow the turn but the driven wheel will also be lower than the driving wheel. The above two kinds of torques are independently treated. For the low-turn transfer, both can make the 4 electromagnetic synchronization. When both moments are excited by the two machines, the two machines are equivalent to the magnetic flux at the same speed in the two wheels. Because the magnetic attraction and repulsive force are due to the inertia, when the rotational speed difference between the two is large, The average value of this force is zero. However, when the speed difference or slip is 5 bottles, the magnetic attraction will pull the two wheels into synchronization. When there is power transmission between the two, the magnetic vector angle of the driving wheel will be ahead of the driven wheel 3.2 Basic equation ç“®Pn rated power ki1 machine Actual angular speed; ki rated angular speed 2 asynchronous torque Considering that the human-machine is a synchronous generator and the disc is used as an asynchronous motor working condition, the equivalent circuit is used as the cabinet 4 according to the motor theory, when the hidden-pole generator is used for asynchronous operation. When ignoring the asymmetry of the 4-axis and the 9-axis, the torque equation and the form of the asynchronous motor complete the pressure cylinder generator low-pressure cylinder generator A, the human-machine excitation potential; and the human-machine stator electric group; the XA machine synchronous reactance; The stator resistance of the gamma-plated disc; the leakage resistance of the stator winding of the jrBl machine; the leakage resistance of the rotor of the machine to the stator side; the effective resistance of the B2 rotor to the stator side; the actual reactance of the A-reacted reactance is known.

Especially considering that the 8 machine is a synchronous motor and the man-machine is used as an asynchronous motor working condition, the equivalent circuit has the same form as 4, except that the symbol interchange is due to the man-machine speed of 8 at this time, the slip 51 is less than 0, according to the formula. 2 Fu is less than, the power is negative, the power is negative, the machine gets the power, so the reference model 3 can get the torque of the 6 machine in this case. The synchronous torque of the synchronous motor is 3, the power angle is time. From the above formula, before the two machines are not synchronized, since 1 is greater than, it will continue and increase, so the direction of the synchronous torque will continue to change according to the material. The rotor that rotates the rigid body as a fixed axis. The equation of motion with the equation of motion is 1. According to the known parameters and initial conditions, equation 7 can be solved. However, the equation is very complicated and the test is multi-level nested. Even for the integral clothing style, it can only be solved by computer, limited by space, not expanded here.

4 The calculation simulation of the starting process and the actual rise and fall are both single-valued functions of the transition or angular speed. The large starting process is a rising process. Therefore, the rising curve is used according to the measured value and the minimum multiplication is used to obtain the 77th polynomial as 3 Synchronous torque can be known from the theory of motor science. In the two-machine system where the synchronous motor is supplied by another generator, if both machines are hidden pole roots, the above formula and the process of the asynchronous excitation process are very high. It is planned to set the speed of the engine to 30, 1. and reach 2,300 baht. The other parameters remain unchanged after the actual value. The initial condition of the two machines is that the state of the disk is turned 5; the machine is 45171 ± 1 The initial power angle is the random machine calculation result 5 from 5, after the human machine reaches 2 30, 1.1 stays about 65, 8 machines can Enter the sync. In order to ensure reliability, it is also checked for more unfavorable working conditions. It is assumed that the driving power of steam is only calculated by the high-pressure cylinder of 13, and the same rate of ascending, and staying at 2 30, 1. heart 1 can also be smoothly Pulling in the Synchronized Denver Residency Program is a viable case for the first joint start of the other two programs as a backup, resulting in a sub-success. During the start-up process, when the speed of the man-machine reaches the speed of the resistance control, the speed is slightly shifted. Then, the speed of the 8 machine speeds up, and the 5th and 8th machines are pulled in the same time. Since the voltage at the time of synchronization is only 13 of the rated voltage, the synchronous current, the rush current is also the rated current of the self-excited inverter asynchronous 1! The success of the operation has simplified the system and operation of the original two generators. It has also obtained two additional benefits. Firstly, it completely eliminates the occurrence of a single false jump, and the generator turns off its overspeed; The situation is that the harmful volume of several is much higher than that of the man-machine, so the speeding energy will be much higher than the machine. In this case, although the pyromagnetic opening of the generator has been actuated, the attenuation of the excitation current also has a process of about several hundred depending on the excitation potential during the attenuation process so that the two axes are kept synchronized, so that the disk can speed it up. The energy transfer part to the human machine is equivalent to increasing the moment of inertia of the eight machines, thereby suppressing the overspeed of the machine;

5 During the start-up process, the temperature rise operation of the rotor surface and the synchronous generator of the asynchronous working condition, such as the surface cooling type, the control criterion of the temperature rise of the cadaver surface is calculated in the calculation of the startup process, and also checked. Household, the result of the anvil, the large value + the excess of the external force of the unit is far away. This is the starting plan, which can ensure the safety of the rotor after the unit has been put into production for nearly 8 years, and experienced 3 major overhauls in the middle. Signs of fever. It is feasible to use the variable frequency asynchronous start of the two-axis turbo generator. The system is simple and reliable, and the operation is the simplest. The only synchronous operation required with the single-axis machine is to stay at the fixed speed for a few minutes. The excitation before the grid connection proves that the scheme is mature and reliable, and the actual drop of the cylinder that is safe for the rotor is indeed relatively low. In fact, after the entire start-up, the low-pressure cylinders were in a state of corpse. Therefore, if there is a leak point in the system of the high pressure cylinder exhaust port to the low pressure cylinder, although there will only be outward leakage during normal operation, the vacuum will be destroyed at this time, resulting in the lowering of the low pressure 1 and the efficiency improvement. The decline and the blast loss have risen sharply. In severe cases, even the net mechanical power may be touched by 1 pair. The shaft machine is smashed to increase the steam volume. The above question will not affect the grid connection.

It seems that the shaft machine can be rushed to the full selection with a smaller flow. When the self-excited frequency asynchronous start is used, the electromagnetic power transmission is limited. If the mechanical net power of the low pressure cylinder is small, even the negative value of the dragon appears. Will extend the synchronization process, and even cause the same can not be completed, the juice calculation simulation is also a positive 31 this is completed! Dynamic simulation of the dynamic process, according to the above, can be used for various frequency conversions and various conditions to consider the analysis and simulation. Through simulation and comparison, it is found that the operation of the self-excited variable frequency asynchronous starting scheme is the simplest, like its magnetic rotation. Moments are also small in all scenarios. The reason is that the machine will start, the rotor of the machine will pass, the rotor coil will pass, and the magnetic machine will be closed. In fact, the average rotor resistance of the rotor is greatly reduced. By Equation 3, this will significantly reduce the asynchronous torque and 8 machines. If you do not invest in the beginning. Then the rotor coil is closed by the de-excitation resistor. When the 8 machine speed is close to the human machine, the self-excitation is put into the machine. As a result, this will significantly shorten the synchronization process.

In fact, this is equivalent to greatly increasing the rotor's folded muscle and asynchronous torque through simulation. Even if the steam drive power is zero, the step can be completed in the arrival of 230, 131. The program needs to be close to 8 After the machine speed is put into the 8 machine excitation, plus the operation operation, so from the makeup using this square

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