JP2000181547A - Hydraulic power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic power plant capable of detecting the shift to single operation and automatically switching the governor gain at the time of the shift to single operation. SOLUTION: A governor is provided with an integration operating part 5a for cooperative operating mode and an integration operating part 5b for single operating mode and contacts 19a and 19b are switched by a shift-to single operation sensor 20. The shift-to single operation sensor 20 sets the monitoring period from the monitoring signal of either each response signals ε of respective parts of the governor or rotating speed signal N and operates the attenuation degree of the monitoring signal during that period and when the attenuation degree is worse than a prescribed one, it is judged that the operation has been shifted to be in the shift to single operating state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hydroelectric power station having a linked operation mode connected to a large power system and a single operation mode connected to a relatively small power system to bear most or all of the power in the power system. The present invention relates to a power plant, and more particularly to a hydroelectric power plant in which a governor is set to a relatively high-speed response in a linked operation mode and a governor is set to a relatively low-speed response in an isolated operation mode.

[0002]

FIG. 8 is a block diagram of a hydroelectric power plant. Ga is a generator of the hydropower plant, La is a neighboring load connected to the same power system 100 as the hydropower plant,
L1 and L2 are distant loads and 101 to 106 are circuit breakers.

[0003] The breaker 1 during the power generation operation of the hydropower plant Ga
When 01 is opened, the load of the hydropower plant Ga suddenly becomes zero from the set value up to now, the power plant 100 is completely disconnected from the power system 100, and power transmission ends here. That is,
A complete “load shedding” state is achieved. On the other hand, when the circuit breaker 102 is opened during the power generation operation of the hydropower plant Ga, the load of the hydropower plant suddenly becomes only the neighboring load La from the set value up to now. In this case, it is necessary to continue power transmission to the neighboring load La. In such a case, the only plant that adjusts the frequency of the power system is the hydropower plant Ga, and this is called the “single power transmission” state, that is, the “single operation mode”.

On the other hand, when all the circuit breakers 101 to 106 are in, the plants G1 and G2 also participate in the stabilization of the frequency of the power system. Generally, the loads La, L1, L2, and the like often have self-control. For this reason, if the size of the power system becomes infinite, even if the governor of this hydropower plant Ga is set to the quick-response emphasis (setting where stability becomes worse), the frequency stability of the entire power system will not be impaired. Absent. This is called a "linked operation mode".

[0005] Even if the above-mentioned complete power transmission is not achieved, there are countless possibilities of a near power transmission state.
For example, when the circuit breakers 103 to 106 are simultaneously opened even if the circuit breakers 101 and 102 are closed,
Circuit breakers other than 102 and 103 are opened, and power plant G
1 is expected to support frequency stabilization, but this plant does not provide the expected support.

As described above, in a hydroelectric power plant that generates commercial power, it is not always necessary to pursue the stability of the frequency / rotational speed of the plant alone in the linked operation mode connected to the large power system. The governor gain is set relatively high. This is because quick response is emphasized so as to follow a power increase / decrease command from a central power supply station or the like as quickly as possible. On the other hand, in a single operation mode in which the power system is connected to a relatively small power system and bears most or all of the power in the power system, the stability of the frequency / rotational speed of the entire power system is completely or almost completely maintained. Because it depends on the hydro plant, the governor gain of that plant must be set relatively low. This is because if the gain is kept high in the linked operation mode, the stability of the frequency f / rotational speed N cannot be maintained.

[0007]

By the way, in the prior art, there is no method for always accurately detecting when the plant shifts from the linked operation to the isolated operation regardless of the shift condition. If the connection point (breaker) with the power system is specified, the ON / OFF state of the breaker may be detected. However, in reality, the number of connection points with the power system is innumerable and cannot be specified. Therefore, when the plant shifts from the linked operation to the isolated operation, the governor gain cannot be reliably switched. For this reason, conventionally, in a plant where there is a possibility of a transition to an isolated operation, the governor gain is always set to a low value, that is, a stability-oriented setting is used. However, in this case, AFC
However, there is a problem that the governor response speed is too low in response to a power increase / decrease command from a central power supply station or the like.

[0008] An object of the present invention is to determine that the operation has shifted to the islanding operation from the rotation speed N and the governor response waveform corresponding to the rotation speed N.
An object of the present invention is to provide a hydroelectric power plant that reliably detects an islanding operation shift and thereby automatically switches the governor gain during the islanding operation shift.

[0009]

In the normal operation mode in which the generator is connected to a large power system, the governor is set to a value that emphasizes the quick response, while the governor is set to a value in the no-load operation or when the generator is connected to the high power system. In a hydropower plant equipped with an automatic set value switching device in the governor so that the stability is emphasized at the time of isolated operation from the large power system, two values selected from the governor response signal and the rotation speed signal If the signal is a first signal and a second signal, either the first signal or a signal obtained by adding a predetermined operation to the first signal, the signal returns to zero or substantially zero in a steady state, and the absolute value in a transient state. A signal that displaces relatively greatly is selected, this is used as a first monitoring signal, and either the second signal or a signal obtained by adding a predetermined operation to the second signal has an absolute value during a transition immediately after the transition to the islanding operation. Relatively large change Select a signal to be monitored, set this as a second monitoring signal, and start monitoring on the condition that the absolute value of either the first monitoring signal or the second monitoring signal has changed by a predetermined value or more, and then the second monitoring signal Monitoring period setting means for ending the monitoring after at least approximately 1.5 times a cycle in which one monitoring signal alternates between the plus side and the minus side with zero interposed therebetween; and a monitoring period set by the monitoring period setting means. Means for calculating the degree of attenuation of the first monitoring signal, and means for determining that the hydropower plant has substantially shifted to the islanding operation state when the degree of attenuation is lower than a predetermined value. This is achieved by providing a sensor.

In the above description, the monitoring may be started on the condition that the first monitoring signal itself has changed by a predetermined value or more without preparing the second monitoring signal. When the islanding shift sensor detects the islanding shift, it operates the set value switching device to automatically switch the governor set value to a setting that emphasizes stability.

In addition, specifically, while the monitoring period setting means is ON, the islanding operation transition sensor separates the plus side of the monitoring target signal> 0 and the minus side of the monitoring target signal <0 separately. The product of the monitoring target signal and the duration, that is, the time integration value of the monitoring signal is calculated, and the respective time integration values on the plus side are timed as the second wave from the first wave and the third wave from the second wave. And the time integration value on the minus side is 2 from the first wave.
It is determined that the state has shifted to the islanding operation state in one or both of the decay tendencies that decay with time as the third wave from the second wave. Here, there is a method of comparing the time integral values of the two waves and determining that the state has shifted to the islanding operation state when the degree of attenuation is lower than a predetermined value.

In the above description, while the monitoring period setting means is ON, the transition to the isolated operation is determined based on the degree of attenuation of the time integrated value of the monitoring target signal. Is ON, the duration of the signal to be monitored is separately measured for the plus side of the signal to be monitored> 0 and the minus side of the signal to be monitored <0, and the duration of the plus side is measured from the first wave. Either the second wave, the third wave from the second wave, shortens (decays) over time, or the duration on the minus side is the second wave from the first wave, the third wave from the second wave, As described above, the transition to the islanding operation may be determined based on the shortening (decay) with the passage of time.

The above means operates as follows. If the operation mode is shifted from the linked operation mode to the isolated operation mode, the fluctuation width of the power system frequency f is widened even if the corresponding machine performs the same output change. In the linked operation mode, the object to be accelerated / decelerated by the output change of the machine is not only the inertial effect of the rotating part of the machine but also the inertia effect of the entire power system, and the inertia effect is greatly increased. If the frequency f increases, the turbine wheel output is reduced, and the generator load is increased to suppress the frequency increase. Conversely, if the frequency f decreases, the turbine wheel output is increased, the generator load is reduced, and the frequency decrease is suppressed. This is because the effect of the so-called self-controllability greatly increases.

Therefore, when the governor set value is not changed in the linked operation mode or the stand-alone operation mode, the loop gain of the turbine control system that loops through f → guide vane opening Y → water turbine output P → f becomes the single operation. In mode.
If P (proportional element), I (integral element),
If the D (differential element) gain is set to be suitable for the linked operation mode, the loop gain becomes excessive in the single operation mode, and the entire turbine control system becomes unstable.
There is no problem if the governor gain is set low enough to be suitable for the stand-alone operation mode, but in this case, the response of the governor is too slow in the linked operation mode, and the response to the power control command from the Too bad. Therefore,
A method of automatically switching the governor P, I, and D gains according to the operation mode is widely used.

The problem is how to determine / detect whether the operation mode is the linked operation mode or the isolated operation mode. As described above, there has been no reliable detection method. In a representative example of the present invention, the governor deviation signal (that is, the input of the P, I, and D calculation units) is used as the first monitoring target signal. Generally, the generator load is large (for example, 50% or more) in the linked operation mode and small (for example, 10 to 30%) in the single power transmission mode, so that the load decreases stepwise when shifting to the single operation mode. For this reason,
The speed increases and the governor responds to this, and the turbine output eventually settles at the load required by the isolated grid. The governor deviation signal, which is normally settled at zero, is largely shaken to the minus side (side to close the guide vane) and then to the plus side (side to open the guide vane). Stable turbine control system including governor (loop gain is small enough)
If so, the swing width of the first monitoring target signal gradually attenuates while repeating such swing. However, if the turbine control system including the governor is unstable (loop gain is excessive), the swing of the first monitoring target signal gradually increases immediately after the shift to the islanding operation. In addition, the expansion of the run-out becomes saturated soon.
Thereafter, the same amplitude is repeated, that is, a so-called limit cycle state. By the way, a steady state exists as long as the turbine control system is stable. In the steady state, the first monitoring target signal returns to zero.

On the other hand, the appearance of the waveform of the first monitoring target signal differs greatly as described above immediately after the transition to the islanding operation, depending on the stability of the water turbine control system. In this sense, it is convenient to select the governor deviation signal as the first monitoring target signal. Of course, it is possible to derive a signal equivalent to the governor deviation signal by performing a predetermined operation on any of the f / N and governor state quantities that are inputs to the governor. In the above-mentioned case, the load during the linked operation is large, and the load after the transition to the isolated operation is a staircase-like transition. Since the signal does not fluctuate significantly, the monitoring period setting means is turned on.
Is late. However, since the amplitude of the first signal to be monitored gradually increases, the monitoring period setting means does not turn ON. In order to sufficiently reduce the amplitude expansion during this period, it is necessary to lower the operating point of the monitoring period setting means. It is desirable that the amplitude be much smaller than the amplitude during the limit cycle.

When the limit of the opening speed and the limit of the closing speed given to the water amount adjusting means, which is the final operating end of the governor, are significantly different, it is necessary to pay attention to the waveform analysis of the first signal to be monitored. In particular, in the case of a pump turbine, it is necessary to limit the closing speed extremely lower than the opening speed when the guide vane opening is <60 to 80%. If the governor system including the water flow control means is a linear system, or if there is almost no difference in opening and closing even if there is a speed limit, the next plus The side runout is surely smaller, and monotonically decreases in the following order.

However, when the guide vane opening degree of the pump turbine is <60 to 80%, the negative (closed) response waveform tends to be abnormally large and the positive (open) response waveform tends to be abnormally small. Therefore, it is not appropriate to directly analyze the two. In the present invention, the negative waveform and the positive waveform are separately analyzed. Specifically, 1 on the minus side
The wave and the second wave on the minus side are compared, or the first wave on the plus side and the second wave on the plus side are compared. Therefore, the waveform analysis period determined by the monitoring period setting means is at least 1.
It is necessary to make 5 cycles.

Note that the governor deviation signal is also an input to an arithmetic unit including integration of P, I, D, and the like. If the P and D calculations are ignored, the governor deviation signal corresponds to the differential value of the guide vane opening command signal. Therefore, the time integration of this roughly corresponds to the guide vane opening command signal of the governor, and is significant as an analysis index. Alternatively, the analysis may be performed by comparing the durations of the first and second waves of the negative waveform or the duration of the first and second waves of the positive waveform (confirmed in the simulation analysis example). .

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. 1 is a speed detecting unit, 2 is a speed adjusting unit generally called 65F,
3 is an adder, 4 is a governor proportional calculator (P calculator), 5
a is an integral operation unit (I operation unit) in the linked operation mode, 5b is an integral operation unit (I operation unit) in the independent operation mode, and 6 is a differential operation unit (D operation unit). 7 is an adder, 8 is an adder, 9
Is a guide vane opening / closing speed limit setting unit, 10 is a guide vane hydraulic amplification unit, 11 is an adding unit, 12 is a speed regulation rate setting unit, and 13 is a turbine output setting unit generally called 65P. 14 is a turbine (pump turbine) including the influence of the upstream and downstream waterways
Characterizing section, 15 is an adding section, 16 is a rotating section inertia effect section of a turbine (pump turbine) and a generator (generator / motor), 17a is a self-controlling section of a turbine (pump turbine), and 17b is a self-controlling property of a power system. , 18 is an adder, and 21 is an adder. 2
0 is a single transfer sensor, the governor I of 19a and 19b
Operate the gain switching contact.

L is the base load applied from the power system to the generator, and RL is the power system side to the generator when the rotational speed N (pu) or f (pu) rises from the rated value (1.0). When the load is increased, and conversely, when N decreases, it indicates a load for the self-control function of the power system that acts to reduce the load and suppress the fluctuation of the rotation speed N. That is, normally, the load applied to the generator is L, and the load applied transiently becomes an added output (L + RL). RT decreases the turbine output when the rotation speed N (pu) or f (pu) rises from the rated value (1.0), and conversely, N
Is decreased, the turbine output is increased to increase the rotation speed N
This is the output of the self-controllability of the water turbine acting to suppress the fluctuation of the water turbine. That is, the output of the turbine is normally P, and the output is transiently the added output (P-RT).

By the way, in the linked operation mode in which the generator is connected to the large power system, the gain of the self-controllability of the power system is very large, and a large RL fluctuation occurs with a small N fluctuation. In this case, the self-controllable gain of the water turbine is negligibly small compared to the self-controllable gain of the electric power system. Therefore, even if the turbine output P of the turbine characteristic section 14 increases and the rotational speed N increases, the RL increases before the change of N hardly progresses, thereby canceling the previous increase in P. In other words, the total gain from P to N is extremely small.

On the other hand, in the case of the single operation mode in which power is transmitted to a small electric power system having a significantly smaller inertia effect than the inherent inertia effect of the generator, the turbine of the turbine characteristic section 14 The transfer function from the output P to the rotation speed N is substantially determined by the rotary unit inertia effect of the rotary unit inertia effect unit 16 and the self-controllability of the water turbine itself by the water turbine self-characterizing unit 17a. Naturally, in this case, the behavior at the time of start-up and the behavior after load shedding are performed, and the total gain from P to N is so large as to be incomparable with the value in the above-described linked operation mode.

The change in the rotation speed N is determined by the governor speed detection unit 1.
The N detection signal is compared with the rated rotation speed N0 set by the speed adjustment unit 2 to become a speed deviation signal. The governor receives the speed deviation signal as input and outputs the guide vane opening Y as output. The guide vane opening Y is restored via the speed regulation rate setting unit 12 and is compared with the speed deviation signal by the adding unit 3. More specifically, the restoration signal of the opening Y is compared with the guide vane opening command value Y0 given by the water turbine output setting unit 13 in the adding unit 11 on the way, and only the difference between the two is restored.

Eventually, the difference ε between the speed deviation signal and the restoration signal from the speed regulation rate setting unit 12 is input to the governor as a deviation signal, and this is the input signal for the P, I, and D calculation units. I
There are two operation units 5a and 5b, and in the normal linked operation, the I operation unit 5a in the illustrated state is used, but when the single transfer sensor 20 detects the single operation transfer, the contacts 19a and 19b are used.
At the same time so that the I operation unit 5a is disconnected and connected to the I operation unit 5b. Thus, the outputs of the P, I, and D calculation units are summed up by the addition unit 7, and the combined signal Yx is input to the hydraulic amplification unit 10 described below. Although the hydraulic pressure amplification unit 10 usually has two or three stages, it is simplified here to one stage.

The composite signal Yx is compared with the guide vane opening Y which is a restoration signal of the hydraulic amplification unit 10, and if there is a deviation, this deviation signal is passed through the guide vane opening / closing speed limit setting unit 9 and hydraulically amplified for the guide vane. Input to the unit 10.
Here, the guide vane hydraulic amplification unit 10 is approximated as a simple integral element. That is, since the output of the guide vane hydraulic amplification unit 10 is the guide vane opening Y,
The input of the guide vane hydraulic pressure amplification unit 10 corresponds to dY / dt, that is, the guide vane traveling speed. The guide vane opening / closing speed limit setting unit 9 limits the signal corresponding to dY / dt, and the opening speed limit is limited by θR on the + side,
The closing speed is limited by θL on the negative side.

Here, the speed adjusting unit 2 and the water turbine output setting unit 1
3. The operation of the speed regulation rate setting unit 12 will be described with reference to FIGS. Here, it is assumed that the guide vane opening at no load is 0.2 (pu). The solid line in the lower right of FIG. 2 shows a state immediately before this plant is connected to the power system.
That is, the intersection Z1 between the rated value (synchronous speed) line of N and this solid line indicates the guide vane opening, but is just the no-load opening 0.2. Before the water turbine is started, this solid line is set at a lower position. For example, it is set at the position indicated by the dotted line in FIG. The speed adjuster 2 moves the solid line up and down in parallel below the solid line in FIG. When this solid line is moved up and down in parallel, the no-load opening is 0.
The intersection of the two lines moves up and down, so the name of the speed adjustment unit is given. On the other hand, the operation after the plant is connected to the power system will be described with reference to FIG. In this case, the intersection Z2 between the solid line and the rated speed is Y = 1.0.
That is, it indicates that 100% load operation is being performed. The position of the solid line at the time of no load in FIG. 2 is the position of the dotted line in FIG. Thus, the water turbine output setting unit 13 adjusts the guide vane opening by moving the solid line in parallel. The water turbine output setting unit 13 translates the solid line in the horizontal direction. However, when the turbine is connected to the infinite power system, the rotation speed is practically fixed to 1.0. With N = 1.0
Intersections on the line move from side to side, hence the name.

In the setting of the solid line in FIG. 3, N = 1.
Although the operation is performed at 0, Y = 1.0, if the frequency of the power system rises by 3% and becomes N = 1.03, Y becomes 0.2. If the increase of the power system frequency is 1.5%, it is confined to Y = 0.6. The speed regulation rate setting unit 12 gives a proportional relationship between the frequency change width and the guide vane closing width as described above. If the gain of the speed regulation rate setting unit 12 is increased, the slope of the solid line in FIG. 3 falling to the right becomes steeper, and the gain of the guide vane opening response width with respect to the frequency change decreases.

FIG. 4 is a typical example showing the closing speed limitation of the pump turbine. In the case of a pump turbine, it is necessary to limit the speed so that the gradient does not become larger than θ1a in the range of guide vane opening Y> Ya, and that the gradient is smaller than θ1a and smaller than θ1b in the range of Y <Ya. In the case of a pump turbine, there is a special characteristic called an S-shaped characteristic in the turbine region, and even if the guide vane is not closed, the flow rate of the turbine tends to decrease naturally as the rotation speed increases. On the other hand, the opening operation of the guide vanes does not have special circumstances as in the closing operation described above. Therefore, also in the pump turbine, generally | θ1a |> | θ2 |> | θ1 regardless of the guide vane opening degree as shown in FIG.
In many cases, the constant value θ2 is set to be b |. Unless there are special circumstances, the original operation of the governor should not be hindered, and care should be taken to minimize the guide vane traveling speed limit. FIG. 5 shows a custom reflecting such circumstances.

Now, while the hydroelectric power plant of FIG. 1 is connected to a large power system and operated at L = L0, P = P0 = L0 + RL0, the connection with the power system is cut off, and the operation shifts completely or substantially to standalone operation. Consider the case. Load L is from L0 to L
Becomes 1. The self-controllability RL of the power system changes from RL0 to zero. As a result, the adder 15 has performed zero (P0−
L0−RL0) expands to P0−L1.
As a result, N starts to rise. With the rise of N, RT
Increases, the deviation P0-L1 becomes P0-L1-RT and decreases.

In the adding section 3, ε = 1.0 (6
5F output) -1.0 (rated N = N0)-[sigma] (here 0.03) * [1.0 (output of 65P) -Y (=
1.0)], but as N increases, ε starts to swing to the minus side. That is, a close signal is started to be issued. This ε is subjected to the PID operation, and the adder 7 outputs the integral operation unit initial value −ε [Kp + (Kia / S) +
(Kd * S / (1 + T1 * S))] is output. Hereinafter, this is referred to as Yx. In addition,
The initial output value of the integration operation unit (Kia / S) is Y = 1.0
(Pu), which corresponds to 1.0, so that the guide vane opening control signal Yx becomes 1.
Start to decrease from zero. Thus, the adding section 8, the guide vane opening / closing speed limit setting section 9, the guide vane hydraulic amplification section 1
The amplifying unit composed of 0 starts closing the guide vane opening Y following the decrease of the guide vane opening control signal Yx. This Y closing operation is restored to the adding unit 3 via the speed adjustment rate setting unit 12. Further, by the closing operation of Y, the water turbine output P decreases. Naturally, the decrease P-L1−
RT also decreases, and the rising speed of N is gradually suppressed.

FIGS. 6 and 7 show how the variables change when the hydropower plant shifts to the islanding operation as described above. FIG. 6 is an explanatory diagram in a case where the I operation unit gain during the linked operation is originally sufficiently low. FIG. 7 shows that the high I operation unit gain in the linked operation and the low I
This indicates a case where the switching to the arithmetic unit gain has not been reliably performed, or a state before the switching has been performed. In the state of FIG. 7, the governor I-operation unit gain remains high despite the increase in gain from P to N due to the fact that the self-controllability RL of the power system does not work, and so N → ε → Yx → Y
→ P → N The loop gain becomes too high and the whole system becomes unstable. FIG. 7 shows a response curve of each part at this time. Note that ΔN = N−N0.

In the representative example of the present invention, the governor deviation signal (ie, the input of the P, I, and D calculation units) ε is used as the first monitoring target signal, and a single transition is determined by this waveform analysis. Since stability is ensured during the continuous operation, ε may be transiently increased, for example, during output adjustment, but ε always decreases. If the governor I-operation unit gain is sufficiently reduced during the linked operation, ε is still attenuated even when the operation shifts to the isolated operation. When shifting to the islanding operation, ε shows a tendency to diverge when the islanding operation is continued with the I operation unit gain during the linked operation. In other words, only when it is necessary to switch the I operation unit gain to a lower value.

Generally, the generator load in the linked operation mode is large (for example, 50% or more), and the generator load in the isolated operation mode is small (for example, 10 to 30%). . Therefore, as described above, the rotation speed increases, and the governor responds to the rotation speed. The governor deviation signal ε, which is settled at zero at normal times, is first largely shaken to the minus side (side to close the guide vane) and then to the plus side (side to open the guide vane). At this time, if the governor I operation unit gain remains at a suitable setting during the linked operation, the loop gain becomes excessive, and after the transition to the isolated operation,
The swing width of the first monitored signal ε gradually shows a diverging tendency at least for a while.

If the governor system including the water volume adjusting means is a linear system, the waveform analysis of the first monitored signal ε is relatively simple.

This is because the next plus-side swing is surely smaller than the minus-side swing of the first monitored signal ε immediately after the transition to the islanding operation, and monotonically decreases in the following order. However, as shown in FIG. 4, when the guide vane opening degree <Ya, the waveform of ε is significantly distorted because the degree of guide vane speed limitation is large. As a result, the swing width on the minus side (closed side) becomes abnormally large, and the swing width on the plus side (open side) becomes abnormally small. However, in the case of a pump-turbine, there is almost no exception, and in many cases, the pump-turbine is operated independently at the guide vane opening degree Ya or less, and the above-described extreme waveform distortion cannot be avoided.

Based on this background, the present invention provides:
The negative waveform and the positive waveform are separately analyzed. Specifically, the first wave on the minus side is compared with the second wave on the minus side, or the first wave on the plus side is compared with the second wave on the plus side.
Therefore, the waveform analysis is continued for at least 1.5 cycles.

Therefore, the condition for starting the above-mentioned waveform analysis becomes a problem. In the first plan, it is assumed that there is a generator load (not completely disconnected from the power system) and ε has reached a predetermined value or more. A large change in ε during the linked operation is limited only to an output adjustment command during the linked operation or to a transition from the linked operation to the isolated operation. In the former case, the command signal is 6
Given from 5P, 65P generally takes P to 0 in tens of seconds.
→ It is changed by 1.0 (pu), and the command is input relatively slowly, so that the transient change width of ε is not large.
On the other hand, at the time of the single shift, the change in load generally accompanies a change in the rotational speed, so that the temporary change width of ε becomes large.
The predetermined value of ε may be determined in consideration of these.

The second condition for starting the waveform analysis is a condition that the rotation speed N is apart from the rated N0 by a predetermined value or more. During the linked operation, since the self-controllability of the power system and the frequency control of the power system such as the AFC are effective, the rotation speed N hardly varies. The reason that N can fluctuate is that it can occur only after the transition to the islanding operation. In this case, N is a second monitoring target signal, and | (N−N0) |> predetermined value is a waveform analysis start condition.

In the above description, the description has been made on the assumption that the load is large in the continuous operation, and the load after the transition to the independent operation is the stair-like transition. The single transfer sensor is effective. Certainly, immediately after the single transition, the first monitored signal ε does not fluctuate greatly, but since it gradually expands with time, even if the detection of the first proposal for the waveform analysis start condition is slightly delayed, it should not be detected. There is no. In order to sufficiently reduce the amplitude expansion during this period, the predetermined value of ε is reduced as much as possible. In the case of the above-mentioned horizontal shift, the second alternative for the waveform analysis start condition also does not operate immediately after the single shift, but will operate soon because the fluctuation range of N gradually increases.

Here, a method of analyzing the waveform of the first signal to be monitored will be described. The first alternative is how much the time integration ε | ε | dt of the second wave on the minus side (plus side) || ε | dt, compared to the time integration ε | ε | dt of the first wave on the minus side (plus side). This is a method of determining whether or not attenuation occurs. The governor deviation signal ε is also an input of an arithmetic unit including integration of P, I, D, and the like. If the P and D calculations are ignored, the governor deviation signal ε corresponds to the differential value of the guide vane opening command signal. Therefore, the time integral of this roughly corresponds to the guide vane opening command signal of the governor, and is significant as the waveform analysis index.

In the above-mentioned waveform analysis, each time integrated value on the minus side attenuates as time elapses from the first wave to the second wave and from the second wave to the third wave, and each time integrated value on the plus side becomes It attenuates with time as the second wave from the first wave and the third wave from the second wave, and at least 3
The transition to the islanding operation can be determined based on one or both of the decay tendency of each of the time integrals of the three waves with time and the decay of each of the time integrals of the at least three positive waves with time. .

The second alternative of the waveform analysis method is to judge by the decay (reduction) of the duration of the first and second waveforms on the minus side (plus side). It is reasonable to evaluate the attenuation rates (degrees of shortening) of the first wave and the second wave based on the relationship with the stability required during single operation.

In the above-described waveform analysis, the durations of the minus side and plus side monitoring signals are separately measured, and the durations of at least three minus side waves tend to attenuate (shorten) over time. The transition to the islanding operation can be determined based on one or both of the durations of the at least three waves on the plus side and the decay (shortening) over time.

Next, a method of switching the governor gain when the independent transfer sensor detects the transfer of the isolated operation will be described. In FIG. 1, two types of I operation units are prepared and switched for linked operation and independent operation. In the case of the integral operation unit, the output does not jump even if the two types of integral operation units having different set values are instantaneously switched. It is also possible to switch between the two types of operation units P and I. In this case, unlike the case of FIG. 1, there is a possibility that the output jumps due to the switching of the P operation unit gain. As a countermeasure, for example, a method described in Japanese Patent No. 1951283 may be used.

In the above description, the case where ε is selected as the first signal to be monitored has been described. Instead, an equivalent signal (a signal which is settled at or near zero in a steady state and largely swings in a transient state) is input to the governor. It is possible to perform a predetermined calculation on any of the state quantities of a certain f / N or governor and to extract it.

As described above, according to the present invention, the installation of the single transfer sensor and the automatic switching of the governor set value can be achieved by partially modifying the governor, and the cost is extremely low.

[0049]

As described above, according to the present invention, it is possible to reliably and inexpensively detect the transition to the islanding operation regardless of the separation from the power system, and as a result, the governor gain can be reliably switched at the time of the transition to the islanding operation. become. For this reason, in the linked operation mode, it is possible to securely pursue a setting that places importance on quick response.

[Brief description of the drawings]

FIG. 1 is a block diagram of a hydroelectric power plant according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a setting method of a water turbine output setting device (65P) when there is no load.

FIG. 3 is an explanatory diagram showing a setting method of a water turbine output setting device (65P) at a full load.

FIG. 4 is a diagram showing an example of limiting the closing speed of a pump turbine.

FIG. 5 is a diagram showing an example of limiting the opening speed of a pump turbine.

FIG. 6 is a waveform chart showing the operation of the embodiment of the present invention shown in FIG. 1;

FIG. 7 is a waveform chart showing the operation of the embodiment of the present invention shown in FIG. 1;

FIG. 8 is a block diagram showing a hydraulic plant to which the related art is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Speed detection part, 2 ... Speed adjustment part, 3 ... Addition part, 4 ... Proportional calculation part, (P calculation part), 5a ... Integration calculation part (I calculation part) of linked operation mode, 5b ... Single operation mode Integral calculator (I calculator), 6 Differential calculator (D calculator), 7 Adder, 8 Adder, 9 Guide vane opening / closing speed limit setting unit, 10 Guide vane hydraulic amplifying unit, 11 … Addition unit,
12: speed adjustment rate setting unit, 13: water turbine output setting unit, 14
... Hydro turbine (pump turbine) characteristic section, 15... Addition section, 16... Rotating section and inertia effect section of the turbine and generator, 17a... Water turbine self-controllability section, 17b. , 19a, 19b ... governor I gain switching contact,
20 ... Single operation shift sensor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Yumoto 3-1-1, Sakaimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant (72) Inventor Hiroto Nakagawa 3-chome Nakanoshima, Kita-ku, Osaka-shi No. 22 Kansai Electric Power Co., Inc. (72) Inventor Sosuke Fukaya 3-2-2 Nakanoshima, Kita-ku, Osaka F Kansai Electric Power Co., Inc. F term (reference) 3H073 AA12 BB13 BB25 CC12 CC20 CC26 CD03 CE06 CE09 FF03 5G066 HA11 HB02 5H004 GA05 GA08 GA12 GA28 GB04 HA14 HA16 HB08 HB14 JA01 JA03 JA23 JB09 KA53 KA54 KA69 KB02 KB04 KB06 KB39 KC39 LB02 LB08 LB09 5H307 AA03 BB06 EE02 EE16 GG20 HH04

Claims (8)

[Claims] 1. A water turbine provided with a water amount adjusting means whose opening degree is adjustable, and at least in a part of the opening degree adjustable range, an opening operation speed limit and a closing operation speed limit are set differently. A driven generator, a rotation speed detector for detecting a rotation speed of the water wheel, an opening degree detector for detecting an opening degree or an equivalent signal of the water amount adjusting means, and a rotation detected by the rotation speed detector. A governor for controlling the water flow rate adjusting means in accordance with a speed signal and an opening degree restoration signal of the water flow rate adjusting means detected by the opening degree detector; and a governor in a linked operation mode in which the generator is connected to a large power system. While setting the setting value for quick response,
In a hydroelectric power plant including the governor set value switching device that sets a value that emphasizes stability during no-load operation or in the isolated operation mode separated from the large power system, a response signal of each section of the governor and the rotation If two signals selected from the speed signal are a first signal and a second signal,
One of the first signal or the signal obtained by adding a predetermined operation to the first signal, the signal returns to zero or substantially zero in a steady state, and a signal whose absolute value is relatively largely displaced in a transient state is selected. As the first monitoring signal, a signal whose absolute value is relatively largely displaced during the transition immediately after the shift to the isolated operation is selected from either the second signal or a signal obtained by adding a predetermined calculation to the second signal, and As a second monitoring signal, start monitoring on the condition that the absolute value of any of the first monitoring signal or the second monitoring signal has changed by a predetermined value or more, and then the first monitoring signal is sandwiched by zero Monitoring period setting means for ending the monitoring after at least approximately 1.5 cycles of alternately repeating the plus side and the negative side are completed, and attenuation of the first monitoring signal during the monitoring period set by the monitoring period setting means Means to calculate the degree Hydroelectric power plant attenuation degree, characterized in that the hydraulic plant with more consisting isolated operation proceeds sensor and means for determining that it has substantially shifted to islanding state in the worse case than a predetermined value. 2. A water turbine provided with a water amount adjusting means whose opening is adjustable and at least a part of the opening adjustment range is set so that the opening operation speed limit and the closing operation speed limit are different from each other. A driven generator, a rotation speed detector for detecting a rotation speed of the water wheel, an opening degree detector for detecting an opening degree or an equivalent signal of the water amount adjusting means, and a rotation detected by the rotation speed detector. A governor that controls the water flow rate adjusting means in response to a speed signal and an opening degree restoration signal of the water flow rate adjusting means detected by the opening degree detector; and a governor in a linked operation mode in which the generator is connected to a large power system. While setting the setting value for quick response,
In a hydropower plant having the governor set value switching device that sets a value that emphasizes stability in a no-load operation or in an isolated operation mode separated from the high power system, a response signal of each part of the governor or the rotation speed is provided. Select one of the signals or a signal that has undergone a derivative or an operation similar to the derivative, and returns a signal that returns to zero or nearly zero in a steady state, and that has a relatively large displacement in the transient state. Is a monitoring signal, the monitoring is started on condition that the absolute value of the monitoring signal has changed by a predetermined value or more, and thereafter, a cycle in which the monitoring signal alternately repeats on the plus side and the minus side across zero at least approximately 1. Monitoring period setting means for ending monitoring after five times, means for calculating the degree of attenuation of the monitoring signal during the monitoring period set by the monitoring period setting means, Hydroelectric power plant if is characterized in that the hydraulic plant with more consisting isolated operation proceeds sensor and means for determining that it has substantially shifted to islanding state in the worse case than a predetermined value. 3. The system according to claim 1, wherein the isolated operation transition sensor has means for operating the governor set value switching device to automatically switch the governor set value to a setting that emphasizes stability when the isolated operation transition is detected. The hydroelectric power plant according to claim 1 or 2, wherein: 4. The hydroelectric power plant according to claim 1, wherein the governor set value switching device switches an governor integral operation unit. 5. The single-operation shift sensor separates a monitoring signal between a plus side of the monitoring signal> 0 and a minus side of the monitoring signal <0 during the monitoring period set by the monitoring period setting unit. The integrated value obtained by time integration is calculated according to the following formula, and the determination means determines, by the determination means, the decay tendency of the at least three waves on the plus side with the lapse of time, and the respective times of the at least three waves on the minus side. 3. The hydroelectric power plant according to claim 1, wherein the transition to the islanding operation state is determined based on one or both of the attenuation tendencies of the integral value over time. 6. The arithmetic operation means separately monitors the monitoring signal of the monitoring signal> 0 and the monitoring signal of the monitoring signal <0 during the monitoring period set by the monitoring period setting means. Calculating an integrated value obtained by time integration according to the above, and determining the shift to the islanding operation state based on the degree of attenuation obtained by comparing the respective time integrated values of at least two waves on the plus side or the minus side by the determination means. The hydroelectric power plant according to claim 1 or 2, wherein: 7. The arithmetic operation unit separately monitors the monitoring signal of the monitoring signal> 0 and the monitoring signal of the monitoring signal <0 during the monitoring period set by the monitoring period setting unit. The decay tendency of the at least three waves on the plus side with the lapse of time for each of the durations, and the time of the durations of the at least three waves on the minus side are determined by the determination means. 3. The hydroelectric power plant according to claim 1, wherein the transition to the islanding operation state is determined based on one or both of the attenuation tendencies with the lapse of time. 8. The single-operation shift sensor separately calculates a monitoring signal of a plus side of the monitoring signal> 0 and a monitoring signal of a minus side of the monitoring signal <0 during the monitoring period set by the monitoring period setting unit. And measuring the duration of the at least two waves on the plus side or the minus side based on the degree of attenuation by comparing the durations of the at least two waves on the plus side or the minus side. The hydroelectric power plant according to claim 1 or 2, wherein: