KR20200092993A - Hydro power system and control method - Google Patents

Abstract

Even if the output power is properly controlled without performing pre-measurement, and even in the stall state, the load of the generator can be reduced or opened to return to the normal power generation state from the stall state and obtain large power generation power. It provides a hydro power generation system that can prevent hunting. The hydroelectric power system includes a water turbine (1), a generator (3), and a control device (4). The control device 4 performs basic control by MPPT control or the like. The control device 4 determines the stall state of the stall determination means 22 and the aberration 1, and when stalled, reduces the load power of the generator 3 by the load reduction/opening means 23 or Open. For the stall determination, the stall determination curve a, which determines that the stall state is when the difference power is increased and/or when the difference rotation speed is lowered, and the stall state when the difference power is decreased and/or when the difference rotation speed is increased The return determination curve b determined as being set is set, and the curves a and b are defined as stall boundary regions C constituting the hysteresis region.

Description

Hydro power system and control method

This application claims the priority of Japanese Patent Application No. 2017-227737 of November 28, 2017, the entire contents of which are hereby incorporated by reference.

The present invention relates to a hydro power generation system and a control method having a function of determining a stall state of a hydro power generation device and returning it to a normal state.

The hydroelectric power generation device is a system that uses kinetic energy of running water for power generation. The hydroelectric power generation apparatus includes a water wheel that rotates under a flow of water, a generator that is connected to the water turbine and converts rotational energy into electrical energy, and a control device that controls the output and aberration of the generator. It is provided as.

Since the power drawn from the generator is changed by the flow rate, the control device determines the optimum power drawn from the generator by measuring the flow rate, the rotational speed of the aberration, or the generator voltage. The generator is controlled to match the generated power and the optimum value.

To this end, it is necessary to install a hydroelectric generator in a waterway in advance, measure flow velocity, power generation power, and power generation characteristics to set optimum values, and create table characteristics using a control map or the like. Therefore, there is a factor in cost increase, such as measurement work, until the operation of the hydroelectric power system.

In order to eliminate prior measurement and setting of an optimal value, a method of controlling hydroelectric power generation by a maximum power point tracking control called MPPT control by a search algorithm has been proposed (for example, Patent Document 1). MPPT control is also used in wind power generation (for example, Patent Document 2).

Japanese Patent Application Publication No. 2016-185006 Japanese Patent Application Publication No. 2010-200533

However, it is difficult to apply the MPPT control to the hydro power generation control device because the number of revolutions of the aberration may fall and the power generation power may also fall into a stall state.

In Patent Document 2, MPPT control in wind power generation, but control to cope with stall has been proposed. That is, whenever the optimum operating point of the generator is sought by MPPT control, the time derivative of the output voltage or the time derivative of the output current is calculated, and the output power at the operating point and the calculated output power time The stall is judged according to whether the relationship with the differential satisfies the stall boundary condition. When it is determined to be stalled, the load of the generator is opened or reduced.

However, by opening or reducing the load of the generator, when the stall boundary condition is not satisfied, when the load is returned to the original value, the stall limit condition is satisfied again immediately, thereby turning the power limit on or off. ) There may be cases where hunting occurs in a repetitive state.

The present invention is intended to solve the above problems, and its purpose is to control the output power appropriately without performing pre-measurement, and even if it is in the stalled state, from the stalled state to a normal power generation state by reducing or opening the load of the generator. By returning, it is possible to obtain a large power generation power, and to provide a hydro power generation system and control method capable of preventing hunting of power control.

Hereinafter, in order to facilitate understanding for convenience, it will be described with reference to the symbols of the embodiments.

The hydroelectric power generation system of the present invention includes an aberration (1) rotating by hydraulic power, a generator (3) that converts the rotational energy of the aberration (1) into electrical energy, and aberration by adjusting the load power of the generator (3) A hydro power system having a control device (4) for controlling the number of revolutions of (1),

The control device (4),

Power past present value detecting means (16) for detecting the output power past value and the output power present value of the generator (3);

Power past present value storage means (17) for storing the detected past value of output power and the present value of output power;

A rotation speed past current value detecting means (18) for detecting a rotation speed past value and a rotation speed present value of the generator (3);

A rotation speed past current value storage means (19) for storing the detected rotation speed past value and the rotation speed present value;

Difference power calculating means (20) for calculating the difference power between the output power past value and the output power present value;

Difference rotation speed calculation means (21) for calculating a difference rotation speed between the output rotation speed past value and the output rotation speed present value;

Stall determination means (22) for determining a stall state or a stall state of the aberration from the difference power and the difference rotation speed;

If it is determined by the stall determination means 22 that it is in the stall state, a load reduction/opening means 23 for reducing or opening the load of the generator 3 is provided,

The stall determination area A for determining that the stall determination means 22 is in the stall state and the stall stall determination area B for determining that the stall determination means 22 is in the stall state are the difference power and the difference rotation speed. It is divided by the determination curves a and b indicating the relationship of, and the determination curves a and b are different from the stall determination curve a for determining that the stall state is in the case where the difference power is increased and/or the difference rotation speed is lowered. And a return determination curve b for determining that it is in a non-stalled state when the power is lowered and/or when the differential rotational speed is increased, and between these curves a and b is a stall boundary region as a hysteresis region. ) C is composed.

According to this configuration, the control device 4 basically controls the number of revolutions of the aberration 1 by monitoring power generation power and the like, and controlling the output power according to a prescribed control rule. In the meantime, the stall determination means 22 determines the stall state or non-stall state of the aberration 1 from the difference power and the difference rotation speed, and if it is determined that the stall state, the load reduction/opening means The load power of the generator 3 is reduced or opened by (load reducing/releasing means) 23. Thus, when the stall of the aberration 1 occurs, the load power is reduced or opened, so that it can be returned from the stall state to a normal power generation state, and it becomes possible to obtain a large power generation power. Since the determination of the stall state is performed based on the difference power and the difference rotational speed between the present and the past, appropriate determination is made. In addition, since the stall boundary area C is provided as the hysteresis area, hunting of power control by stall determination is prevented. The rotation speed is the rotation speed per unit time, in other words, the rotation speed.

The control device 4 is provided with MPPT control means 13 for tracking and controlling the maximum power operation point with respect to the output fluctuation of the generator 3, and every time it goes to find the maximum power operation point, the stall determination The means 22 determines the stall state or the stall state of the aberration 1, and if necessary, the load reduction/opening means 23 may reduce or open the load of the generator 3.

According to the MPPT control that follows-controls the maximum power operating point, it is possible to generate good efficiency even if the pre-measurement of the flow velocity and aberration rotation speed in the field where the aberration 1 is installed is omitted. However, if the MPPT control is applied to the hydroelectric power generation system, it may not be possible to return to the normal state in the case where the rotation speed of the aberration 1 is reduced and the generated power is also reduced by the control alone. On the other hand, according to this hydroelectric power generation system, the stall state is determined and the load power is reduced or stopped in the stall state, so that the return from the stall state is performed, and the power generation reduction due to stall is not large, resulting in MPPT Efficient control by control is performed.

The control method of the hydroelectric power generation system of the present invention includes a water turbine (1) rotating by hydraulic power, a generator (3) converting the rotational energy of the water turbine (1) into electrical energy, and the load power of the generator (3). As a method of controlling a hydroelectric power generation system having a control device (4) to control the number of revolutions of the water turbine (1) by adjusting,

A difference power calculating step (also referred to as a process) (S6) for calculating the difference power between the past value and the current value of the output power of the generator 3,

A difference rotation speed calculating step (S5) of obtaining a difference rotation speed between a past value and a current value of the rotation speed value of the generator 1;

A stall determination step (S6) of determining a stall state or a stall state according to whether the relationship between the difference power and the difference rotation speed satisfies a predetermined stall boundary condition;

In the stall determination step (S6), if it is determined that the stall state, includes a load reduction/opening step (S7) of reducing or opening the load of the generator (3),

These steps are repeated every control cycle of the control device 4,

The stall boundary condition is determined by the determination curves a and b showing the relationship between the difference power and the difference rotational speed, and the stall determination area A determined to be stalled and the stall stall determination area determined to be stalled B is divided by the determination curves a and b, and the determination curve has a difference power from the stall determination curve a which determines that it is in a stall state when the difference power rises and/or when the difference rotation speed decreases. The return determination curve b is determined to be in a stalled state when the time and/or the difference rotation speed rises, and the stall boundary area C is formed as a hysteresis area between the curves a and b.

According to this control method, it is possible to return to the normal power generation state even when a stall state occurs, as described above for the hydro power generation system, and it becomes possible to obtain large power generation power. In addition, since the stall boundary area C is provided as the hysteresis area, hunting of power control by stall determination is prevented.

The control device 4 is provided with MPPT control means 13 for tracking and controlling the maximum power operating point with respect to the output fluctuation of the generator 3, and whenever the tracking control seeks to find the operating point, the The difference power calculation step (S6), the difference rotation speed calculation step (S5), the stall determination step (S7), and the load reduction/opening step (S8) may be repeated as necessary.

According to the MPPT control, even if the pre-measurement work of the flow velocity and aberration rotation speed in the field is omitted, good efficiency is developed. However, there are cases in which it is impossible to return to the normal state when the stall state is reached by the control alone. On the other hand, according to this method, the stall state is determined, and the load power is reduced or stopped in the stall state, so that the stall state is returned, and the generation power reduction due to stall is not significantly reduced, which is effective by MPPT control. Control is performed.

Any combination of two or more configurations disclosed in the claims and/or specifications and/or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be understood more clearly from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and are not used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numbers in the plurality of drawings indicate the same or equivalent parts.
1 is an explanatory view showing an outline of a hydroelectric power generation system according to an embodiment of the present invention.
FIG. 2 is a block diagram showing the conceptual configuration of the hydroelectric power generation system of FIG. 1.
3 is a stall threshold control graph serving as a reference example of the stall determination area and the non-stall determination area.
4 is a stall threshold control graph showing a stall determination area, a non-stall determination area, and a stall boundary area used by the hydroelectric power generation system of FIG. 1.
5 is a flowchart showing the procedure of a control method executed by the hydroelectric power generation system of FIG. 1.
6 is a schematic explanatory diagram of another example of the hydroelectric generator used by the hydroelectric power generation system of FIG. 1.

One embodiment of the present invention will be described together with the drawings. This hydroelectric power generation system is an example of a horizontal axis (propeller type) hydroelectric generator. The aberration 1 is rotated by the kinetic energy of water flowing through a water channel (not shown), and the main spindle 2 of the aberration 1 rotates the generator 3. The generator 3 is, for example, a three-phase synchronous generator using a permanent magnet, and is coupled to the main shaft 2 by coupling (not shown) or the like. Between the main shaft 2 and the generator 3, a speed increaser 25 may be provided as in the example of FIG.

When a load is connected to the generator 3 and consumes output, torque from the generator 3 is applied to the water turbine 1, and rotation of the water turbine 1 is braked. When the load power is made heavy, the rotational speed of the aberration 1 becomes slow, and when the load power is made light, the rotational speed of the aberration 1 increases. As a load of the generator 3, a load circuit is connected via the control device 4. The control device 4 increases or decreases the torque of the generator 3 according to the flow rate, and controls the aberration to rotate at an optimal rotation speed. For the control device 4, a DC/DC converter, an inverter, or the like is used. The load circuit 5 is an electric device or a load system.

2 shows a specific example of the control device 4. The control device 4 includes a main circuit part 6 that supplies the power generated by the generator 3 to the load circuit 5, and a control circuit part 7 that controls the main circuit part 6, and further generates power. A battery 8 for storing electric power is provided. The main circuit part 6 includes a rectifier 9, a converter 10, an ammeter 11, a voltmeter 24, and switching means interposed between the battery 8 and the generator 3 in sequence. (12) is provided.

The rectifier 9 is a device that rectifies the power of the three-phase alternating current generated by the generator 3 into direct current, and is composed of a half-bridge circuit of a semiconductor switching element. The converter 10 is made of, for example, a step-up chopper. Instead, the converter 10 may be a step-down chopper. The switching means 12 is a means for switching whether or not the rectified DC power is supplied to the battery 8 by turning it on or off. The switching means 12 may be a semiconductor switching element or a contact switch. The switching means 12 can be switched on or off by a control signal output from the gate circuit 15.

The battery 8 and the load circuit 5 are parallel, and can supply power to the load circuit 5 while charging the electric power of the generator 3 to the battery 8. Since the main circuit part 6 connects the battery 8 and the load circuit 5 in parallel to the output side of the generator 3, the output voltage is substantially constant. Therefore, the output power of the generator 3 can be adjusted by adjusting the duty ratio of the output current of the converter 10 by opening and closing of the switching means 12.

The control circuit unit 7 is made of a computer or the like, and in this example, the basic control is performed by the MPPT control means 13 which is the basic control means to control the stall of the aberration 1 by the stall control means 14 To be done. The MPPT control means 13 and the stall corresponding control means 14 both regulate the output power by opening and closing the switching means 12 under the control of the gate circuit 15. In addition, the control circuit unit 7 may perform the basic control by the MPPT control means 13 by basic control means employing other control methods.

The MPPT control means 13 withdraws the maximum output from the generator 3 by changing the operating point of the generator 3 to always follow the maximum output operating point on the control in response to the change in the output power of the generator 3 It is a means to perform control. The maximum output operating point is an operating point at which the output to the load circuit 5 becomes the maximum among the operating points obtained for each sampling by the MPPT control means 13. The power of the operating point is detected from the measured values of the ammeter 11 and the voltmeter 24.

Stall-response control means 14 includes power past present value detection means 16, power past present value storage means 17, rotation speed past present value detection means 18, rotation past past value storage means 19 , Differential power calculation means 20, differential rotation speed calculation means 21, stall determination means 22, and load reduction/opening means 23. The stall-response control means 14 repeats a series of stall determination processes. In this embodiment, whenever the MPPT control goes to find the operating point, stall determination by the stall determination means 22 and processing by the load reduction/opening means 23 are performed as necessary.

The power past present value detecting means 16 detects the output power past value and the output power present value of the generator 3. The output power present value is the output power at the time of sampling immediately after sampling during each of the series of stall determinations, that is, in this example, every time the MPPT control goes to find the operating point. The output power past value is, for example, output power at the time of sampling in one rotation room of the next sampling. The output power past value may be the average value of the output power of recent multiple samplings. The sampled output power is, for example, a value obtained by multiplying the current obtained by the ammeter 11 by the voltage obtained by the voltmeter 24. The output voltage may be a value obtained by multiplying the current obtained by the ammeter 11 by a constant voltage serving as the voltage of the battery 8. The output voltage may be detected by setting a power meter (not shown). The power past current value storage means 16 is means for storing the detected output power past value and output power present value of the generator 3 to be.

The rotation speed past present value detection means 18 is means for detecting the rotation speed past value and the rotation speed present value of the generator 3 from a rotation detector (not shown) provided in the generator 3. The past number of revolutions and the present number of revolutions may be the number of revolutions at the time of sampling immediately next to the previous sampling and the previous sampling, such as the output voltage past and output voltage present. The rotation speed past current value storage means 19 is a means for storing the detected rotation speed past value and the rotation speed present value of the generator 3.

The difference power calculating means 20 is means for calculating the difference power ΔP between the output power past value and the output power present value of the generator 3 stored in the power past present value storage means 17. The difference rotational speed calculating means 13 is a means for calculating the difference rotational speed ΔN between the output rotational speed past value and the output rotational current value of the generator 3 stored in the rotational past current value storage means 19.

The stall determination means 22 is means for determining whether or not the stall state is satisfied according to whether or not the stall boundary condition determined from the difference power ΔP and the difference rotation speed ΔN is satisfied. Specifically, as shown in FIG. 4, the determination curve a showing the relationship between the difference power ΔP and the difference rotational speed ΔN between the stall determination area A determined to be stalled and the stall stall determination area B determined to be stalled , b. The determination curves a and b are not the same determination curve d in the example of FIG. 3. The stall determination curve a is a curve determined to determine that the stall is stalled when the difference power ΔP rises and/or when the difference rotation speed ΔN decreases. The return determination curve b is a curve determined to determine that the difference is not stalled when the difference power ΔP decreases and/or when the difference rotational speed ΔN rises. Both curves a and b are stalled boundary regions C of the simple hysteresis region.

The load reduction/opening means 23 is means for reducing or opening the load power of the generator 3 when it is determined that the stall is determined by the stall determination means 22. The load reduction/opening means 23 specifically reduces the duty of the converter 10 by opening and closing the switching means 12 through the gate circuit 15, or by continuously opening the switching means 12 , Reduce or open the load power.

Referring to Fig. 5, the flow of stall-response control in the hydroelectric power generation system of the above configuration will be described. The figure shows the flow of the control process performed by the stall corresponding control means 14 in FIG. 2. The control process in the figure is repeated every time the MPPT control goes to find the operating point.

First, in the speed detection step (S1), the past speed and the current speed of the generator 3 are detected, and in the power detection step (S2), the output power past value and the output power present value of the generator 3 are detected. Detection is performed. The detected rotation speed past value (previous value N0) and rotation speed present value N1, and output power past value (previous value P0) and output power present value P1 are rotation speed storage step S3 and power, respectively. In the storage step S4, the rotation speed past present value storage means 19 and the power past present value storage means 17 are stored. The memory contents are updated for each control cycle.

The difference rotational speed ΔN between the stored rotational speed past value (previous value N0) and the rotational speed current value N1 is calculated by the difference rotational speed calculation step S5. That is, ΔN=N0-N1 is calculated. The difference power calculation step (S6) calculates the difference power ΔP between the stored output power past value (previous value P0) and the output power present value P1. That is, ΔP=P0-P1 is calculated.

In the stall determination step S7, the stall determination means 22 determines whether the calculated difference rotational speed ΔN and the difference power Δ are stalled according to whether or not a predetermined stall boundary condition is satisfied.

When it is determined that there is no stall, the control process is ended. When it is determined to be stalled, in the load reducing/opening step (S8), the time for opening the switching means 12 through the gate circuit 15 by the load reducing/opening means 23 is lengthened, or By continuing to open, the load power of the generator 3 is reduced or opened.

Since the MPPT control by the control device 4 is followed by the hydroelectric power generation system to follow the maximum power point, the aberration 1 may fall into a stalled state, resulting in a significant decrease in power generation. On the other hand, as described above, the stall state is determined by the control device 4, and the load power is reduced or opened, whereby a normal power generation state can be achieved. Thereby, it becomes possible to obtain large electric power generation.

When determining the stall state as described above, if the stall determination area A and the stall determination area B, which is determined to be stalled, are separated from one determination curve d, as shown in Fig. 3, it is determined to be stall and load power is determined. After reducing or opening the valve, and after being brought into a non-stalled state, the flow rate of the water flow and the like do not change significantly, and there is a case where the stalling occurs again, and there may be a hunting in which the stall determination is turned on or off.

On the other hand, in this embodiment, as the stall boundary condition, as shown in Fig. 4, the stall determination area A determined to be stalled and the stall stall determination area B determined to be stalled differ from the difference power and the difference rotational speed. It is divided by two judgment curves a and b showing the relationship. That is, the determination curve is not stalled when the difference power is lowered and/or when the difference power is increased and the stall determination curve a that is determined to be stalled when the difference power is increased and/or when the difference rotation number is lowered. And a return determination curve b for determining that it is in a state. Between these curves, a stall boundary region C is formed as a hysteresis region.

Whether it is determined by the stall determination curve a or by the return determination curve b, a flag or the like is used to determine whether it was in a stalled state or a stalled state in the previous determination (last control cycle). It is memorized using it, and when the previous time was in the non-stalled state, it is determined using the stall determination curve a, and when the previous time was in the stalled state, it is determined using the return determination curve b.

If it enters the stall determination area A in excess of the stall determination curve a and is judged to be stalled once, the stall determination state is maintained even if the stall power is reduced or opened again to enter the stall boundary area C again exceeding the stall determination curve a Then, if it exceeds the return determination curve b and enters the non-stall determination area B, it is determined that it is in the non-stall state. Therefore, hunting of stall determination is prevented, and control is stable.

As described above, preferred embodiments have been described with reference to the drawings, but various additions, changes or deletions are possible without departing from the spirit of the present invention. Therefore, such things are also included within the scope of the present invention.

1: aberration
3: generator
4: control device
16: Power past present value detection means
17: Means for storing the past power present value
18: means for detecting the present value of the past speed
19: Revolution speed past present value storage means
20: difference power calculation means
21: difference rotation speed calculation means
22: stall determination means
23: Load reduction/opening means

Claims (4)

A water wheel rotating by hydraulic power;
A generator that converts the rotational energy of the aberration into electrical energy; And
A control device that controls the number of revolutions of the aberration by adjusting the load power of the generator;
A hydro power generation system comprising:
The control device,
Power past present value detecting means for detecting an output power past value and an output power present value of the generator;
Power past present value storage means for storing the detected past output power value and the present output power present value;
A rotation speed past current value detecting means for detecting a rotation speed past value and a rotation speed present value of the generator;
A rotation speed past current value storage means for storing the detected rotation speed past value and the rotation speed present value;
Difference power calculation means for calculating a difference power between the output power past value and the output power present value;
Difference rotation speed calculation means for calculating a difference rotation speed between the output rotation speed past value and the output rotation speed present value;
Stall determination means for determining a stall state or a stall state of the aberration from the difference power and the difference rotation speed; And
And a load reducing/releasing means for reducing or opening the load of the generator when it is determined that the stalling state is performed by the stall determining means.
The stall determination area for determining that the stall determination means is in a stall state and the stall stall determination area for determining that the stall determination means is in the stall state are determined by a determination curve showing the relationship between the difference power and the difference rotational speed. Separated, the determination curve includes a stalling determination curve for determining that the difference is in a stalled state when the power rises and a recovery determination curve for determining that the difference power is in a stalled state when the difference power is decreased. curve, and between these curves, a stall boundary region is formed as a hysteresis region.
Hydro power system. According to claim 1,
The control device includes MPPT control means for tracking and controlling the maximum power operating point with respect to the output fluctuation of the generator, and each time the going to find the maximum power operating point, the stall determining means stalls or stalls the aberration. A hydroelectric power generation system that determines a condition and, if necessary, the load reduction/opening means reduces or opens the load of the generator. Aberration rotating by hydraulic force;
A generator that converts the rotational energy of the aberration into electrical energy; And
A control device for controlling the number of revolutions of the aberration by adjusting the load power of the generator;
A method of controlling a hydro power generation system comprising:
A difference power calculation step (process) of obtaining a difference power between a past value and a current value of the output power of the generator;
A difference rotation speed calculating step of obtaining a difference rotation speed between a past value and a current value of the rotation speed value of the generator;
A stall determination step of determining whether the relationship between the difference power and the difference rotational speed satisfies a predetermined stall boundary condition or a stall state; And
A load reduction/opening step of reducing or opening the load of the generator if it is determined in the stalling step in the stalling state;
Including,
These steps are repeated every control cycle of the control device,
The stall boundary condition is determined by a determination curve indicating the relationship between the difference power and the difference rotational speed, and the stall determination area determined to be stalled and the stall stall determination area determined to be stalled are the determination Separated by a curve, the determination curve includes a stall determination curve that determines that it is in a stall state when the difference power rises and a return determination curve that determines that it is in a non- stall state when the difference power decreases, and between these curves The stall boundary area is formed as a hysteresis area.
Method of control of a hydroelectric power system. According to claim 3,
The control device includes MPPT control means for tracking and controlling the maximum power operating point with respect to the output variation of the generator, and whenever the tracking control seeks the operating point, the difference power calculation step and the difference rotation number A control method of a hydro-electric power generation system wherein the calculation step, the stall determination step, and the load reduction/opening step are repeated as necessary.

Images