JP5213566B2 - System no-voltage generator starting method - Google Patents

Description

  The present invention relates to starting of a generator, and more particularly, to starting of a generator at the time of system no-voltage when the generator is started with a power system connected to the generator being in a non-voltage state.

  A distributed power supply system or a private power generation system has a system interconnection method and a system separation method for a power system that supplies power to the load (hereinafter referred to as an internal power system) (for example, Patent Document 1). . In the grid interconnection method, the internal power system is linked to the commercial power system, and the power supply / demand balance and the maintenance of power quality in the internal power system depend on the commercial power system. On the other hand, in the system separation method, the internal power system is operated in a separated state without being linked to the commercial power system. Such a system separation method is excellent in that it does not require coordination with an electric power company in the operation of a distributed power supply system or a private power generation system, and its future spread is expected.

  By the way, in the system separation method, there may occur a case where the generator needs to be started in a state where no voltage is applied to the internal power system, that is, in a system no-voltage state. For example, in the case of the system separation method, the internal power system is in a non-voltage state when all of its own generators (distributed power sources and generators in private power generation) are stopped. When the own generator is sequentially activated in such a state, the first generator is activated in the system no-voltage state, that is, the generator activation in the system no-voltage state.

  If the system is activated by a general activation method when there is no system voltage, the inrush current (excitation inrush current of the transformer) becomes excessive and reaches the generator protection operation level. However, the inrush current correlates with the capacity ratio between the generator and the transformer, and the generator is started with the capacity of the transformer in the internal power system being sufficiently smaller than the capacity of the generator. . Specifically, if the generator is started with some of the transformers in the internal power system shut off from the generator, the inrush current will reach the generator protection operation level even when the system is not under voltage. Can be prevented from reaching. However, such an activation method has a problem that the control becomes complicated. For this reason, system no-voltage that can effectively suppress excessive inrush current by simpler control, that is, control that can be performed without major changes to the control logic used in general startup. A time generator starting method is desired.

  In addition, as a technique regarding suppression of the inrush current accompanying starting of a generator, the example described in patent document 2 and patent document 3, for example is known.

JP 2001-268799 A JP 2008-61298 A JP 2005-117879 A

  The present invention has been made in response to the above-described demand for starting the system no-voltage generator, and is capable of effectively suppressing the excessive inrush current by simpler control. The issue is to provide a machine start-up method.

  In the present invention, in order to solve the above-mentioned problem, a generator no-voltage generator starting method in which a generator exciter is connected to a generator connected via a field breaker while the connected power system is in a no-voltage state. The step of boosting the generator is performed while performing a field current inching operation that alternately repeats supply and stop of the field current generated by the generator excitation device to the generator.

  According to such a system no-voltage generator starting method, it is possible to effectively suppress an excessive inrush current by simple control. That is, in the field current inching operation in which the supply and stop of the field current are alternately repeated, the power supply is generated by the supply of the field current that is intermittently performed with the stop time interposed therebetween by appropriately setting the supply time and the stop time. While boosting the machine voltage step by step with a small unit voltage, it is possible to absorb the inrush current at each boosting stage in the field current supply stop time, thereby effectively suppressing the inrush current, Moreover, since the field current inching operation can be performed using the manual voltage adjustment mode that the generator control system has as standard, the control can be simplified.

  Further, in the present invention, with respect to the system no-voltage generator starting method as described above, the process of setting the no-voltage starting mode in the generator control system, the process of starting the generator driver after setting the no-voltage starting mode, and Including a step of setting a voltage adjustment mode at the time of no-voltage startup when the rotation speed of the generator drive reaches a mode setting speed, the voltage adjustment mode at the time of no-voltage startup is a rotation speed of the generator drive The process of turning on the field breaker when the field breaker closing speed is reached, when the rotational speed of the generator drive machine reaches the generator breaker turning speed after turning on the field breaker The process of turning on the generator breaker, the process of maintaining the current voltage for a certain period of time when the generator voltage reaches the initial inrush current absorption voltage, and after maintaining the voltage for the certain period of time, the field current inching Power generation by operation Process performs boosting and voltage of the generator step-up in the process is the preferred form to include a process of setting the automatic voltage adjusting mode upon reaching the mode switching voltage.

  According to the present invention as described above, it is possible to effectively suppress an excessive increase of the inrush current by simpler control for the generator start-up at the time of no system voltage.

  Hereinafter, modes for carrying out the present invention will be described. FIG. 1 shows a configuration example of a power system using a distributed power supply system or a private power generation system to which the system no-voltage generator starting method according to an embodiment is applied.

  The power system 1 includes a generator 2 and also includes a generator control device 3 as a generator control system that controls the start-up of the generator 2 and the power generation state. The generator 2 is a gas turbine system to which a gas turbine 4 is connected as a generator driver. The generator 2 is connected to a generator excitation device 6 for supplying a field current to the field winding 5 via a field breaker 7. The generator excitation device 6 has a thyristor 8 as a field current control means, and controls the magnitude of the field current supplied from the field current power source 9 to the field winding 5 by controlling the gate current of the thyristor 8. It can be controlled.

  Such a generator 2 is connected to a power system 11 via a generator breaker 10. The power system 11 includes a transformer 12, a transformer 13, a load machine breaker 14, and the like, and a load 15 is connected via the load machine breaker 14 and the transformer 13. Here, the power grid 11 is an internal power grid that is separated from the commercial power grid. That is, the power system 1 is a system separation system. The power system 1 normally includes several generators in addition to the generator 2, but the illustration of these generators is omitted in FIG. 1.

  The generator control device 3 relates to the control at the time of starting the generator 2, and a voltage is loaded on the normal start mode used for starting the generator 2 in a state where the voltage is loaded on the power system 11 and the power system 11. There is a no-voltage start mode used for starting the generator 2 in a non-system no-voltage state, and a normal start mode button 16 and a no-voltage start mode button 17 are provided so that these can be selectively set. It has been. The generator control device 3 includes an automatic voltage adjustment mode (AVR mode) in the case of performing automatic generator voltage control based on a control logic incorporated in advance as a basic control mode related to generator voltage control. At the time of no-voltage startup, which has a manual voltage adjustment mode (FVR mode) when the generator voltage control is performed manually by an operator, and is used when the generator 2 is started in a state where the power system 11 is at no voltage It has a voltage adjustment mode.

  Below, the system | strain no-voltage generator start-up of the generator 2 made in the electric power system 1 is demonstrated. FIG. 2 shows a flow of processing in starting the system no-voltage generator, and FIG. 3 shows the turbine speed (rotational speed of the gas turbine 4) and generator voltage (the voltage of the generator 2) in starting the system no-voltage generator. ) Is shown.

  The generator control device 3 is basically in a state where the AVR mode is set. First, in this state, a no-voltage startup mode is set in the generator control device 3 (step S1). Specifically, the no-voltage start mode button 17 in the generator control device 3 is pressed to set the no-voltage start mode. Next, the gas turbine 4 is started (step S2). When the gas turbine 4 is activated, it is determined whether the preset mode switching speed has been reached while measuring the turbine speed (step S3). When the turbine speed reaches the mode switching speed, the no-voltage startup voltage adjustment mode is set (step S4). Specifically, the mode in the generator control device 3 is switched from the AVR mode to the FVR mode, and the no-voltage start-up voltage adjustment mode is set under the FVR mode. Here, it is preferable to use about 44% of the rated speed as the mode switching speed.

  In the no-voltage start-up voltage adjustment mode, the processes in and after step S5 are performed based on the control logic incorporated in advance for controlling the generator voltage during no-voltage start-up. First, while measuring the turbine speed, it is determined whether or not a preset field breaker closing speed has been reached (step S5). When the turbine speed reaches the field breaker closing speed, the field breaker 7 is turned on ( Step S6). Next, while measuring the turbine speed, it is determined whether or not a preset generator breaker closing speed has been reached (step S7). When the generator breaker closing speed is reached, the generator breaker 10 is turned on (step S8). ). Here, it is preferable to use those generally used in the AVR mode for the field breaker closing speed and the generator breaker closing speed. Specifically, 95% of the rated speed is used as the field breaker closing speed, and 97.5% of the rated speed is used as the generator breaker closing speed.

  When the field breaker is turned on, a field current is supplied from the generator exciter 6 to the field winding 5 of the generator 2 to start boosting the generator voltage. Therefore, while measuring the generator voltage, It is determined whether or not a preset initial inrush current absorption voltage has been reached (step S9). When the initial inrush current absorption voltage is reached, the voltage at that time, that is, the initial inrush current absorption voltage is maintained for a certain period of time. Is reduced (step S10). Here, the initial inrush current absorption voltage is usually set to the lowest voltage in the FVR mode, specifically 20% of the rated voltage of the generator 2. The maintenance time of the initial inrush current absorption voltage is usually about 10 seconds.

  When the initial inrush current absorption process in step S10 is completed, inching boosting is started (step S11). In the inching boost, the generator voltage is boosted while performing the field current inching operation IO. Specifically, as shown in FIG. 4, the field current to the field winding 5 is repeatedly supplied and stopped at regular time intervals, and the field current is sequentially increased in the repetition. The generator voltage is boosted while performing the current inching operation. Here, it is preferable that the field current supply time in the field current inching operation is 1 second and the stop time is 0.5 seconds.

  When inching boosting is started, the generator voltage is measured and it is determined whether the preset mode switching voltage has been reached (step S12). When the mode switching voltage is reached, the mode is switched from the FVR mode to the automatic voltage adjustment mode. The setting is completed (step S13), and the process ends. Here, the mode switching voltage is usually set to 98% of the rated voltage of the generator 2.

  The system no-voltage generator starting method as described above effectively suppresses an inrush current excessively, and enables it with a simple control structure. For this purpose, with respect to the suppression of inrush current, the generator voltage is increased stepwise by inching boost, more specifically, the field current is intermittently supplied across the stop time to increase the voltage. The inching boost boosts the generator voltage step by step with a small unit voltage, and the inrush current at each boost step can be absorbed in the field current supply stop time. This greatly contributes to the initial inrush current absorption. The initial inrush current absorption process by maintaining the voltage for a certain period of time also contributes auxiliaryly. On the other hand, regarding the simplification of control, the inching boosting and the initial inrush current absorption processing that work to suppress the inrush current greatly contribute to the processing that can be performed under the FVR mode that is a standard mode in the generator control device 3. In addition, it contributes that the standard control logic in the generator control device 3 can be used as much as possible by setting the AVR mode until the gas turbine 4 reaches the mode switching speed.

  As mentioned above, although the form for implementing this invention was demonstrated, this is only a representative example and this invention can be implemented with various forms in the range which does not deviate from the meaning.

It is a figure which shows the structural example of the electric power system used as the application object of the generator starting method at the time of a system | strain no voltage by one Embodiment. It is a figure which shows the flow of the process in a system no voltage time generator starting. It is a figure which shows the time chart regarding the turbine speed and generator voltage in the system starting at the time of a system no voltage. It is a figure explaining field current inching operation.

Explanation of symbols

2 Generator 3 Generator control device (generator control system)
4 Gas turbine (generator drive)
6 Generator Exciter 7 Field Breaker 10 Generator Breaker 11 Power System

Claims (1)

When a generator connected to a generator exciter via a field breaker is started in a state where the connected power system is in a non-voltage state, the field current generated by the generator exciter is supplied to the generator. A system no-voltage generator starting method including a process of boosting the generator while performing a field current inching operation that alternately repeats a stop,
In the process of setting the no-voltage start mode in the generator control system, the process of starting the generator drive after setting the no-voltage start mode, and when the rotational speed of the generator drive reaches the mode set speed, Including a step of setting a voltage adjustment mode at the time of no-voltage start-up, wherein the voltage adjustment mode at the time of no-voltage start-up includes the step of turning off the field breaker when the rotational speed of the generator driver reaches the field breaker closing speed. The process of turning on the generator breaker when the rotation speed of the generator drive machine reaches the generator breaker closing speed after turning on the field breaker, the generator voltage is the initial inrush current absorption voltage In the process of maintaining the current voltage for a certain period of time, the process of boosting the generator by the field current inching operation after maintaining the voltage for a certain period of time, and the boosting in the process The generator voltage is Features and to that system Mitsurumu voltage at the generator startup method that includes the step of setting the automatic voltage adjusting mode upon reaching the de switching voltage.

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