JPS63277869A - Hydraulic power generation control system - Google Patents

Abstract

PURPOSE:To prevent a rapid change in an amount of used water by preventing a rapid change in the output load of a generator and to prevent elevating movement of a water level in a surge tank, by providing correcting function to hold control of increase and decrease of a load for a specified time during AFC control. CONSTITUTION:A calculator for control inputs information, e.g. the motion states of the main and the auxiliary machine of a hydraulic generator, frequency of a system, an output of a generator, a water level in a surface tank, and performs output of a command through a remote monitoring control device after an output command value to the generator is calculated by automation or manual. After receipt of the command, an automatic load control device performs feedback control on the generator. In which case, during AFC control, control of increase and decrease of a load is held for a specified time set intrinsically to a system. This constitution enables prevention of the occurrence of resonance phenomenon of a water level in a surge tank due to a rapid change in an output load.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control system for a hydroelectric power plant, and in particular to an AF suitable for suppressing resonance of a surge tank water level during frequency control.
Regarding C command value output method.

[Conventional technology]

Conventionally, the design conditions and precautions for use of surge tanks have been general, as described in the above literature.
No specific measures were taken to address this issue.

[The interlayer point that the invention attempts to solve]

Figure 5 shows a schematic diagram of a hydroelectric power plant consisting of a dam, pressure tunnel, surge tank, and water turbine.

The surge tank absorbs the water hammer effect caused by sudden changes in the amount of water used due to increases and decreases in the turbine load, and prevents it from directly impacting the pressure tunnel, but as a result, the water level in the tank repeatedly rises and falls over time. In this lifting and lowering motion, if load fluctuations such as rapid increases or decreases happen to synchronize with the water surface vibrations of the surge tank, the water surface vibrations will fall into a resonance state and cause abnormally large surging even if the range of load fluctuations is small. be. In this case, the following phenomenon occurs.

(1) Even if the surging becomes abnormally large, if the same control is continued, water may overflow from the tank.

(2) If resonance occurs at a low water level, air may flow into the waterway along with water from the mouth of the surge tank.

(3) The surge tank itself is made of reinforced concrete or steel, but repeated surging causes it to age quickly.

As described above, surging on the water surface of the surge tank causes great damage to the control system including the power generation equipment even if it does not reach a resonance state.

However, in the past, in order to take countermeasures against (1) and (2), only the upper and lower limits of the surge tank water level were monitored as shown in Figure 2. Specifically, the water level is monitored in four stages: upper limit, upper limit, lower limit, and lower limit, and if the water level exceeds the upper or lower limit, an alarm is output and the operator is notified, allowing the operator to set the control command value. The maximum limit shall be on control.

If the lower limit was exceeded, the generator control was automatically locked using the computer or ALR.

However, this method does not suppress the resonance of the surge tank water surface, and does not take into account the fact that it accelerates the aging of the tank itself. Also, there was a lack of consideration in the event of failure of the water level abnormality alarm and detection function for control lock.

An object of the present invention is to suppress the vertical movement of the water surface itself in order to compensate for these drawbacks.

[Means for solving problems]

Before describing the solution to the problem, the mechanism of generator control and the relationship between output load and water level vibration will be explained with reference to FIGS. 3 and 4.

As shown in FIG. 3, commands for hydroelectric power generation are issued from a remote control center or command center. The control center (command center) takes in the frequency of its own system, calculates the command value for the generator in short cycles (approximately 10 to 60 second cycles) to maintain the reference frequency, and generates power via a remote monitoring and control device. Issue an output command to the location. In response to this, automatic load control equipment (A L
R) checks the condition of the generator, and if there is no abnormality, issues an output command to the generator, and continues control until the generator output value matches the command value.

The water level change when the command value is changed in such a short cycle will be explained with reference to FIG. 4. The lower curve in FIG. 4 shows the output load of the generator, and the load is varied for frequency adjustment at a cycle of 10 to 60 seconds.

On the other hand, the water level in the surge tank repeats short periodic oscillations due to fluctuations in the amount of water used due to load fluctuations (the large amplitude part in the diagram corresponds to this).

In the long term, gradual changes in water level may result in repeated large changes in the moment.

Therefore, it is important to suppress water surface vibration, which is a change in water level, and this can be achieved by suppressing sudden changes in output load.

Details will be explained with reference to FIG. As mentioned above, the calculation command value is calculated at a cycle of 10 to 60 seconds, but this is corrected according to the rules below so that when outputting from the computer to the remote monitoring control device, the corrected command value is as shown in Figure 1. do.

<Rule 1) The AFC command value is updated at a cycle of 10 to 60 seconds, but the control direction of increasing or decreasing is maintained for a certain period of time (constant determined for each system). That is, once a command is given in the "up" (or "down") direction, no command value in the opposite direction will be accepted for a certain period of time N minutes.

<Rule 2> After a certain period of time has elapsed, if the direction is the same, the control shall continue, but if the direction is the opposite direction, the response shall be immediate.

<Rule 3> During continuous control in the same direction, a time count of a certain period of time is not performed, but a count of N minutes shall be started from the time the direction changes.

[Effect]

According to the above problem solving means, as can be seen in FIG. 1, in order to keep one frequency constant, the calculation command value changes as the frequency changes. This calculation command value is sent as is ff1
When the power is output to fi, the power generation load changes in a short period, so there is a possibility that the water surface of the surge tank will also vibrate. In Fig. 5, the calculated command value, which initially changed by two degrees in the upward direction, now moves downward, but since it is within a predetermined range of N minutes, the current command value is maintained by the correction function of the present invention. do. If the calculated command value is lower than the correction command value after N minutes have elapsed, the output command value is immediately corrected in a downward direction. Further, if there is no change in the command direction even after N minutes have elapsed, the correction command value is changed in accordance with the calculated command value.

By the above correction, sudden changes in the power generation load are suppressed and changes in the amount of water used are also reduced, making it possible to prevent the resonance state of the surge tank water surface.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 6 and 7.

In the embodiment, the AFC control period is 30 seconds, and the fixed time for maintaining the control direction is 3 minutes. In Figure 6, the calculated command value increases in response to fluctuations in the grid frequency, but the command value output process that receives this command value is dependent on the generator characteristics such as the load change rate of the generator. is determined and output to the remote monitoring and control device. Therefore, the command value for the generator follows a gradual upward curve. The calculated command value decreases after 1.5 minutes have passed after the start of AFC control, but since it is within 3 minutes, the previous command value is maintained. Furthermore, since the calculation command value increases again after 2.5 minutes, the output command value is also increased.

After this, the continuous control period is outside the counting range of 3 minutes until the control changes to the reverse direction (downward), and the timer count starts when the control in the downward direction starts.

In contrast to FIG. 6, FIG. 7 shows a case where the calculation command value is in the opposite direction to the output command value at the end of the 3-minute control period. In this case, at the end of the 3 minutes, the controller immediately responds and issues an output command in the opposite direction.

As described above, according to this embodiment, as can be seen from the figure, the calculation command value (conventional final output value) is increased.

A command value with little downward change can be obtained. Furthermore, the function of maintaining the reference frequency, which is the original purpose of AFC control, is not impaired.

〔Effect of the invention〕

According to the present invention, sudden changes in the output load of the generator can be suppressed, thereby eliminating sudden changes in the amount of water used. As a result,
It becomes possible to suppress the rising and falling movement of the water surface of the surge tank and further eliminate resonance conditions. The effects of this are as follows.

(1) Due to excess water surface vibration of the surge tank. Control locks can be removed.

(2) Eliminate overflow on the water surface due to resonance.

(3) Prevent aging of the surge tank.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a hydroelectric power plant, Figure 2 is a diagram showing the conventional surge tank water level monitoring method, Figure 3 is a diagram of the hydroelectric power generation system configuration, Figure 4 is a diagram of the relationship between output load and water level vibration, Fifth
The figure is a diagram of the command value correction method.

Claims (1)

[Claims] 1. Enter information such as the operating status of the hydroelectric generator, the main engine and auxiliary equipment of this generator, as well as system frequency, generator output, surge tank water level, etc., and automatically or manually set the specified output value to the generator. After calculation, there is a control computer that outputs a command via a remote monitoring control device, and an automatic load control device (ALR) that receives this command value and performs feedback control for the generator.
), and a surge tank to absorb changes in the amount of water used for power generation. During AFC control, in order to suppress the resonance phenomenon of the water level of the surge tank that occurs due to sudden changes in the output load, a certain period of time (system-specific This is a hydroelectric power generation control method characterized by a correction function that maintains load increase (lower) control within the set value).