Control system for high-efficiency operation of generating units in hydroelectric power stations

Abstract: A control system for the high-efficiency operation of two or more large-capacity generating (5, 6) units and at least one small-capacity (7) generating unit provided at a hydroelectric power station which has a necessity ot ensure the discharge of a constant amount of water taken downstream therefrom. This control system is provided with an intake flow amount calculation element (32) that calculates an amount of water flowing into a head tank (4) , and a processing element (34) that uses the results of calculation of this water amount calculation element (32) to distribute water for power generation and that flows from the intake gate and taken is so that performs selection processing to start and stop generating units so that operation is performed to maximize the efficiency of the entire power station with respect to the water that is used for power generation.

Description: The present invention relates to control systems for high-efficiency operation of a plural number of generating units according to the first part of claim 1 (US-A-4 467 216). The invention is especially directed to control systems for hydroelectric power stations that can efficiently operate generating units using the correlation between the amount and capacity of a storage reservoir and the control elements. In hydroelectric power stations that take an inflow amount from upstream via an intake gate and turbines of upstream power stations, the inflow water an occasion for being used as waterworks water and agricultural water taken downstream from the generating units, and a single generating unit of small capacity for utilization water when it is necessary to maintain discharge to ensure a constant amount of water for generating units. In this occasion a plural number of normal capacity generating units are provided . The normal capacity generating units are used to generate power when there is normal operation for a relatively large amount of water, and the small capacity generating units are used in winter and periods of abnormal drought when it is difficult to ensure the discharge of a constant amount of water. It is possible to use the normal capacity generating units to generate power even when there is a small amount of water but when there is operation at light load, there is a remarkable deterioration of the efficiency, there is an increase in the vibration, and continuous operation is not desirable. FIG. 2 shows one example of a water system of such a hydroelectric power station. The water from the water intake 1 has its intake flow adjusted by a gate 2 and is taken in, to flow into a head tank or serge tank 4 via a water channel 3. The water that is stored in the head tank 4 is discharged to the discharge outlet 8 after it has passed through the turbines of the first through third generating units 5, 6 and 7 and been used to generate power, and is then guided to downstream hydroelectric power stations and for direct usage. Here, the first and second generating units 5 and 6 are of regular capacity and the third generating unit 7 is of small capacity. In general, the capacity of the head tank 4 is not large and so there is only response control in which the water level in the head tank 4 is used as the basis to perform start and stop of the generating units 5, 6 and 7. However, with response control, it is difficult to perform start and stop operation and maintain a stable water level and because of this it has been conventional practise to perform response control into which the upstream conditions have been incorporated. FIG. 1 shows a conventional control system for this purpose. This system is basically configured from a calculation unit 9 and control units 21, 25 and 26. The gate degree of opening gauge 10 is for the detection of the degree of opening of a gate 2 provided at the water intake 1, and is provided with a contact 11 that turns on when the gate 2 is in the fully closed status, a contact 12 that turns on when the degree of opening of the gate 2 is more than a rated value A₁ corresponding to the maximum flow amount of the generating unit 7, and a contact 13 that turns on when the degree of opening of the gate 2 is a rated value A₂ corresponding to the maximum flow amount of one of the generating unit 5 and the generating unit 6. Here, the rated value A₂ is greater than the rated value A₁. The signal S₁ from the contact 11 is inverted and applied to one of the input terminals of the AND circuit 14, the signal S₂ from the contact 12 is inverted and applied to the other of the input terminals of the AND circuit 14 and is also applied to one of the input terminals of the AND gate 15. The signal S₃ from the contact 13 is inverted and applied to the other of the input terminals of the AND circuit 15 and in the status where it is not inverted, is also applied to a trigger input terminal of the timer 16. The output signal S₄ from the AND circuit 14 is applied to the trigger input terminal of a timer 17 and the output signal S₅ from the AND circuit 15 is applied to the trigger input terminal of a timer 18. When the signal S₃ is applied to the trigger input terminal, the timer 16 outputs the signal S₆ after a certain amount of time has elapsed from when the degree of opening of the gate 2 changes until the time that the flow amount to the head tank 4 changes. This output signal S₆ is applied to the input terminals of the OR circuits 19 and 20. When the signal S₄ is applied to the trigger input terminal, the timer 17 outputs the signal S₇ after a certain amount of time corresponding to the sum of water arrival/reduction time and the time required to change the degree of opening of the gate 2 from the fully closed position to the rated value A₁, and this output signal S₇ is applied to the start/stop processing means of the control unit 21 so as to control the generating unit 7. When the signal S₅ is applied to the trigger input terminal, the timer 18 outputs a signal S₈ after the lapse of a certain time corresponding to the sum of water arrival/reduction time and the time required to change the degree of opening of the gate 2 from the rated value A₁ to the rated value A₂, and this output signal S₈ is applied to one of the input terminals of the AND circuit 22 and the AND circuit 23. The contact 24 is turned on to generate a signal S₉ and operate generating unit 5 when this generating unit 5 is to be given priority of operation over generating unit 6, and this signal S₉ is inverted and applied to the other of the input terminals of the AND circuit 22. The output signal S₁₀ of the AND circuit 22 is applied to the other of the input terminals of the OR circuit 20, and the output signal S₁₁ of the AND circuit 23 is applied to the other input terminal of the OR circuit 19. The output signal S₁₂ of the OR circuit 19 is applied to the start/stop control means 25a of the control apparatus 25 in order to control the generating unit 5, and the output signal S₁₃ of the OR circuit 20 is applied to the start/stop control means 26a in order to control the generating unit 6. The water level gauge 27 is to detect the water level of the head tank 4, and its detection signal S₁₄ is respectively applied to the water level adjustment control means 21b, 25b, 26b of the control units 21, 25 and 26. In addition, the contact 28 is to turn on when the selection signal S₁₄ is smaller than a rated value, and its signal S₁₅ is respectively applied to the start/stop control means 21a, 25a, 26a of the control units 21, 25 and 26. The head tank water level detection portion 29 is connected to water level gauge 27 by a contact 28. The water level adjustment control means 21b, 25b and 26b judge the head tank water level on the basis of the detection signals S₁₃, and controls the output of the generating units 7, 5 and 6, and those control signals S₁₆, S₁₇ and S₁₈ control the load limit values of the governors 21c, 25c and 26c of the generating units 7, 5 and 6. By the configuration described above, the operation will be described when the gate 2 is opened from the fully closed status to the fully open status. The contact 11 turns ON, and the contacts 12 and 13 turn OFF for the status where the gate 2 is fully closed, and all of the contacts 11, 12 and 13 are OFF when the gate starts to open, contact 12 turns ON when the degree of opening of the gate 2 is a rated value A₁ or more, and the contact 11 turns ON and contacts 12 and 13 turn ON when the degree of opening is the rated value A₂ or more. Accordingly, in the status where the gate 2 is fully closed, the signal S₁ provides ON output and the signals S₂ and S₃ provide OFF output and so the signals S₄ and S₅ output from the AND circuits 14 and 15 are OFF. By this, the signals S₆, S₇ and S₈ are not output from the timers 16, 17 and 18 and so the control apparatus 21, 25 and 26 do not start. When the gate 2 starts to open, then the signals S₁, S₂ and S₃ are all OFF until the time when the degree of opening becomes the rated value A₁, and this causes the signal S₄ to be ON and so this signal is applied to the control apparatus 21 at the point when a time set for the timer 17 has elapsed from the timing of when the signal S₄ rose to ON output. With this, the generating unit 7 is started in phase with the timing at which the gate 2 starts to open, and the water that flows in from the water intake 1 reaches the head tank 4. When the degree of opening of the gate 2 changes from the rated value A₁ to the rated value A₂, the signal S₁ is OFF output and the signals S₂ and S₃ are ON output so that the signal S₅ is made ON output, and the signal S₈ becomes ON output at the time when a set time of the timer 18 has elapsed from the timing at which the signal S₅ became ON output and rose. At this timing, when the contact 24 is ON and the signal S₉ is ON output, the AND circuit 23 is in a status where it can be operated and so the signal S₁₁ is ON output. Accordingly, in this case, the signal S₁₂ is ON output and is applied to the control unit 25. The first generating unit 5 is started by this. When the degree of opening of the gate 2 is the rated value A₂ or greater, then the signal S₁ is OFF output and the signals S₂ and S₃ are ON output so that the signal S₆ turns ON after the elapse of a time set for the timer 16, from the timing of the rise of the signal S₃ to ON output. By this, the signals S₁₂ and S₁₃ are ON output and so the second generating unit 6 is started after starting the first generating unit 5. By this, the generating units 5, 6 and 7 are suitably controlled in accordance with the degree of opening of the gate 2. In addition, after the output of the started generating units 5, 6 and 7 has been included into the power system, the water level adjustment control means 21b, 25b and 26b performs respective load control of the governors 21c, 25c and 26c of the generating units 7, 5 and 6. In addition, when the water drops to lower than the rated value and the contact 28 turns ON and the signal S₁₅ becomes ON output, the start/stop control means 21a, 25a and 26a of the control units 21, 25 and 26 stops the generating units 7, 5 and 6. However, there is the following problem with such a conventional apparatus. Firstly, the flow amount from the gate 2 is regulated by the degree of opening when there is a constant water level and so when the water level at the water intake 1 changes, the actual flow amount and the flow amount anticipated by the degree of opening of the gate are not in agreement, and as a result there occurs overflows and unnecessary change in the water level of the head tank, and there is the unwanted consequence of the trip of the generating unit due to the drop in the water level. Secondly, there is also the unwanted consequence of the operating efficiency of the power station not being very high. For example, if the flow amount from the water intake 1 is made Qi, the maximum flow amount of the large capacity first and second generating units is made Q1m, Q2m (= Q1m) , and the maximum flow of the small capacity third generating unit is made Q3m, then there is the best efficiency when Q1m < Qi ≦ (Q1m + Q3m) either one of the generating units 5 and 6 is operated at its maximum flow Q1m (Q2m) and the generating unit 7 is operated by the flow (Qi-Q1m). However, in this case, in the conventional apparatus described above, the two generating units 5 and 6 are respectively operating at their flow (Qi/2) and so the generating efficiency of the entire power station deteriorates. Finally, when only the generating unit 7 is operating because there is a small flow, the operating life of the generating units 5 and 6 will be reduced because their operating ratio is increased, and the working efficiency of the generating unit 7 will lower and produce the unwanted consequence of a reduced return on the investment. US-4 476 716 discloses a control system for a hydroelectric power station comprising several generating units supplied with water from a flow hydropower source, which comprises means for detecting the individual flow to each generating unit, flow control means for interrupting flow to individual generating units, means for detecting the efficiency of the generating units and control logic means for interrupting flow to generating units operating below the rated efficiency. In the light of the problems described above for the conventional apparatus, the present invention has as object the provision of a control apparatus for a hydroelectric power station which can improve the efficiency of the entire power station, average the operating ratio of each of the generating units, lengthen the life of the equipment, improve the economy and realize stable operation of the water level in a head tank. This object is accomplished by a control system according to claim 1. The present invention is provided with an intake flow calculation means to calculate the flow amount to the water storage reservoir, and a flow distribution means to use the calculation results of the intake flow calculation means to calculate the flow that is to be distributed to each of the generating units so that the total output is maximized. Accordingly, it is possible to accurately detect the flow amount to the water storage reservoir and so it is possible to control oscillation of the water level and overflows in the head tank and at the same time prevent trip. In addition, each of the items of equipment is suitable combined and so the efficiency of the power station becomes more favorable and the life of the generating units and other equipment is lengthened. BRIEF DESCRIPTION OF THE DRAWINGS In the appended drawings: FIG. 1 is a block diagram showing a conventional hydroelectric power station power generating unit operation control system; FIG. 2 is an outline view of a general water intake system in a hydroelectric power plant; FIG. 3 is a block diagram showing a power generating unit high efficiency operation control system for a hydroelectric power station, according to a first embodiment of the present invention; FIG. 4 is a block diagram of a high-efficiency operation selection processing means in a control system of the first embodiment; FIG. 5 is a flowchart for describing the generating unit high-efficiency operation selection processing means in a control system of the first embodiment of the present invention; and FIG. 6 is a block diagram of a generating unit high-efficiency operation selection processing means in a control system of the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a detailed description of preferred embodiments of the present invention, with reference to the appended drawings. FIG. 3 shows a control apparatus for a hydroelectric power station, and according to a first embodiment of the present invention. Moreover, this control apparatus is applied to the hydroelectric power station having the water system shown in FIG. 2 and portions that are the same or equivalent to similar portions in FIG. 1 and FIG. 2 are indicated with the same numerals. The control system of the first embodiment is provided with a water level gauge 31 provided to the water intake 1, a gate degree of opening gauge 33, a flow characteristic calculation means 32 that supplies the measurement values of these instruments 31 and 33, and a water level gauge 27 provided to the head tank 4 in the same manner as the conventional embodiment. The control system is configured from a high-efficiency operation selection processing means 34 that controls the operation of the generating units 5, 6 and 7 on the basis of the signals S₁₄ and S₃₃ output from the water level gauge 27 and the calculation means 32 so that the operation of the generating units 5, 6 and 7 is the most efficient, the automatic control means 35, 36 and 37 that control the generating units 5, 6 and 7, and the objective value calculation means 38, 39 and 40 provided between the automatic control means 35, 36 and 37 and said processing means 34 so as to calculate the power objective values of the generating units 5, 6 and 7. In addition, deviation calculators 41, 42 and 43 are provided between the automatic control means 35, 36 and 37 and the processing means 34. As shown in FIG. 4, the selection processing means is configured from comparators 51, 52, 63, 64 and 65, a water level correction means 53, a high-efficiency distribution calculation processing means 54, timers 55, 56 and 57, switches 58, 60 and 66, and adders 59 and 61, all connected as shown in the figure. The following is a description of the operating procedures for the control system of a first embodiment having the configuration described above, and with reference to FIG. 3 and FIG. 4. The water level gauge 31 is for the detection of the water level at the water intake 1, and the detection signal S₃₁ is supplied to the flow characteristic calculation means 32. The gate degree of opening gauge 33 is to detect a degree of opening of the gate 2, and the detection signals S₃₂ (analog signals) are supplied to the flow characteristic calculation means 32. The flow characteristic calculation means 32 calculates the water quantity Qa that flows through the gate 2 on the basis of equation (1) and the detection signal S₃₁ and detection signal S₃₂, and the results of calculation are supplied to the high-efficiency operation selection means 34 as flow intake amount signals S₃₃. Qa = f (Ha, Ga) (1) Here, Ha expresses the water level of the water intake 1, and Ga expresses the degree of opening of the gate 2. In this manner, the water quantity Qa is expressed as a function of the water level of the water intake and the degree of opening of the gate. On the basis of the flow amount signals S₃₃ input from the flow characteristic calculation means 32, the detection signals S₁₄ input from the water level gauge 27 of the head tank 4, and the failure signals S₃₄, S₃₅ and S₃₆ input from the automatic control means 35, 36 and 37 that automatically operate the generating units 5, 6 and 7, the high-efficiency operation selection means 34 calculates the flow to be distributed to the generating units 5, 6 and 7 and these calculation results are respectively output as flow amount objective value signals S₃₇, S₃₈ and S₃₉ to the calculation means 38, 39 and 40. In addition to this, the high-efficiency operation selection means 34 forms start command signals S₄₀, S₄₁ and S₄₂ for the generating units 5, 6 and 7, and respectively outputs them to the automatic control means 35, 36 and 37. On the basis of the respective flow objective value signals S₃₇, S₃₈ and S₃₉, the calculation means 38, 39 and 40 calculates the power objective value of the generating units 5, 6 and 7 and those calculation results are applied to the deviation calculators 41, 42 and 43 as power objective value signals S₄₃, S₄₄ and S₄₅. The actual output signals S₄₆, S₄₇ and S₄₈ of the generating units 5, 6 and 7 and output from the automatic control means 35, 36 and 37 are applied to the deviation calculators 41, 42 and 43 which calculate the respective deviations between the actual output signals S₄₆, S₄₇ and S₄₈, and the power objective value signals S₄₃, S₄₄ and S₄₅, and these calculation results are output as output deviation signals S₄₉, S₅₀ and S₅₁ to the automatic control means 35, 36 and 37. When the start command signals S₄₀, S₄₁ and S₄₂ are applied to the automatic control means 35, 36 and 37, the operation of the generating units 5, 6 and 7 starts and the load of the generating units 5, 6 and 7 is controlled so that the output deviation signals S₄₉, S₅₀ and S₅₁ tend towards zero. The signals S₄₉, S₅₀ and S₅₁ are obtained by outputting actual output signals S₄₆, S₄₇ and S₄₈ corresponding to the actual output of the generating units 5, 6 and 7 to the deviation calculation means 41, 42 and 43. In addition, if some abnormality has occurred in the generating units 5, 6 and 7, then the failure signals S₃₄, S₃₅ and S₃₆ are output to the high efficiency operation selection means 34. FIG. 4 shows an example of a high-efficiency operation selection means 34. The detection signals S₁₄ of the water level gauge 27 are applied to the comparators 51 and 52 and to the water level correction means 53. The comparator 51 detects that the detection signal S₁₄ is lower than the lower limit reference value corresponding to the lower limit value for the water level of the head tank 4, and those detection signals are applied to the high-efficiency distribution calculation means 54 as start lock signals S₅₅. The comparator 52 detects that the detection signals S₁₄ are greater than the upper limit reference value corresponding to the upper limit of the water level of the head tank 4, and those detection signals S₅₆ are applied to the timers 55, 56 and 57. The water level correction means 53 corrects for changes in the correlation between the intake amount and the head tank water level that occur over the years, and those correction signals S₅₇ are applied to one of the input terminals of the adder 59 via the contact 58a of the switch 58, and are also applied to one of the input terminals of the adder 61 via the contact 60a of the switch 60. On the basis of the intake flow quantity Qa from the water intake 1 and corresponding to the flow amount signals S₃₃, the high-efficiency distribution calculation means 54 calculates the flow amounts Q1, Q2 and Q3 to be given to the respective generating units so that the total sum P of the output of the generating units 5, 6 and 7 is maximized, and the calculation results are output as the distribution flow amount signals S₅₈, S₅₉ and S₆₀. The distribution flow amount signals S₅₈, are applied to the comparator 63 and to the other input terminal of the adder 59 via the contact 58b of the switch 58. The distribution flow amount signals S₅₉, are applied to the comparator 64 and to the other input terminal of the adder 61 via the contact 60b of the switch 60. The distribution flow amount signals S₆₀, are applied to the comparator 65 and are also output as flow amount objective value signals S₃₉ via the contact 66a of the switch 66. Here, the high-efficiency distribution calculation means 54 executes the calculations of the following equations (2) and (3) Qa = Q₁ + Q2 +Q3 (2) P = P1 + P2 + P3 (3) The combination of the flow amounts Q1, Q2 and Q3 that maximizes the total sum P is then calculated. Then, P1, P2 and P3 are the respective outputs of the generating units 5, 6 and 7 and these are expressed in the following manner by equations (4) through (6). P1 = K1 (Q1) (4) P2 = K2 (Q2) (5) P3 = K3 (Q3) (6) where, Kn (Qn) expresses the flow-output characteristic of the respective generating units. Also, when the start lock signal S₅₅ is applied, the high-efficiency distribution calculation means 54 sets the value for the distribution flow amount signals S₅₈, S₅₉ and S₆₀ at zero. Furthermore, the calculation processing described above is executed when the failure signals S₃₄, S₃₅ and S₃₆ are input, and the corresponding flow amounts Q1, Q2 and Q3 are in the status where they have been set to zero beforehand. The comparators 63, 64 and 65 are for detecting that the respective flow distribution signals S₅₈, S₅₉ and S₆₀ are above the non-load flow amount for the generating units 5, 6 and 7, and those detection signals S₆₁, S₆₂ and S₆₃ are applied to the trigger input terminal of the timers 55, 56 and 57. The timers 55, 56 and 57 are so that there is no unnecessary start/stop during gate operation and so that the influence of water arrival/reduction is removed, and respectively output the signals S₆₄, S₆₅ and S₆₆ when respective set times have elapsed from when the detection signals S₆₁, S₆₂ and S₆₃ have been applied to the trigger input terminal. Furthermore, when signals S₅₆ from the comparator 52 are applied, the respective set times are switched to the set time that shortens the water arrival time. Also, these detection signals S₆₄, S₆₅ and S₆₆ are respectively output as the start command signals S₄₀, S₄₁ and S₄₂ and the switches 58, 60 and 66 are turned on. The adder 59 is to add the distribution flow amount signal S₅₈ and the correction signal S₅₇ and the results of addition are output as the flow amount objective value signals S₃₇. In addition, the adder 61 is for adding the distribution flow amount signals S₅₉ and the correction signals S₅₇ and the results of addition are output as the flow amount objective value signals S₃₈, while the output signals of the switch 66 are output as flow amount objective value signals S₃₉. In the configuration described above, accompanying the gradual opening of the gate 2, flow amount signals S₃₃ corresponding to the flow quantity Qa from the flow characteristic calculation means 32 are applied to the high-efficiency operation selection means 34 and as has been described above, the high-efficiency distribution calculation means 54 calculates the intake flow amounts Q1, Q2 and Q3 that are to be distributed to the generating units 5, 6 and 7, and outputs corresponding distribution flow amount signals S₅₈, S₅₉ and S₆₀. When these distribution flow amount signals S₅₈, S₅₉ and S₆₀ are output at above the non-load flow amount of the respective generating units 5, 6 and 7, the signals S₆₁, S₆₂ and S₆₃ are output from the comparators 63, 64 and 65 to trigger the timers 55, 56 and 57. By this, the signals S₆₄, S₆₅ and S₆₆ are output from the timers 55, 56 and 57 upon the elapse of respective times set for the timers 55, 56 and 57 after the signals S₆₁, S₆₂ and S₆₃ have been output, and this starts the start processing for the automatic control means 35, 36 and 37 to start the generating units 5, 6 and 7. In addition, when the signals S₆₄, S₆₅ and S₆₆ are output, the switches 58, 60 and 66 are turned on, so that the signal S₅₈ and the signal S₅₇ is input to the adder 59, and the addition results are output to the calculation means 38 as the flow amount objective value signals S₃₇, the signal S₅₉ and the signal S₅₇ are input to the adder 61 and the addition result is output to the calculation means 39 as the flow amount objective value signal S₃₈, and the signal S₆₀ is output to the calculation means 40 as the flow amount objective value signal S₃₉. By this, the power objective value signals S₄₃, S₄₄ and S₄₅ corresponding to the flow amount objective values at that time are output from the calculation means 38, 39 and 40, and output deviation signals S₄₉, S₅₀ and S₅₁ corresponding to the deviation between those power objective values and the actual output, are output from the deviation calculators 41, 42 and 43 to the automatic control means 35, 36 and 37. By this, the generating units 5, 6 and 7 are controlled so that their output becomes the objective value and as a result, the total sum of the output of the hydroelectric power station is controlled so as to be maximum. FIG. 5 is a flow chart indicating an outline of the operation described above. In the figure, the water level of the water intake 1 and the degree of opening of the gate 2 are used as the basis for the flow characteristic calculation means 32 to calculate the intake flow amount to the head tank 4 (step ST1). The signals S₁₄ from the water level gauge 27 that detects the water level of the head tank 4 are output to the flow characteristic calculation means 32 along with the signals S₃₃ (step ST2). In the flow characteristic calculation means 32, there is practically simultaneous processing for the operation for from step ST3 to ST13 but for the sake of convenience of description, they will be described as successive processing operations. On the basis of the previous equations (2) through (6) and considering the output P1 through P3 of the first generating unit 5, the second generating unit 6 and the third generating unit 7, the calculated water amount Qa is judged to correlate with the necessary water amounts Q1 through Q3. For example, a judgment is made for whether or not the calculated water amount Qa is greater than the total sum "Q1 + Q2 + Q3" of each of the necessary water amounts Q1, Q2 and Q3 (step ST3). If the water amount Qa is greater than the total sum, then it is determined that the 1st through 3rd generating units are operating efficiently (step ST14) and continuous operation of the generating units 5, 6 and 7 is performed in the mode selected via each of the automatic control means 35, 36 and 37. When it has been judged in step ST3 that the water amount Qa does not exceed the total sum "Q1 + Q2 + Q3" , then the processing skips to step ST5, and a judgment is made for whether the water amount Qa exceeds the sum "Q1 + Q2" of the water amount Q1 and Q2 necessary for efficient operation of the 1st and 2nd generating units that have a large generation capacity. In step ST5, if it is judged that the water amount Qa is less than the total sum "Q1 + Q2 + Q3" and greater than the sum "Q1 + Q2" of the water amount Q1 and Q2 necessary for efficient operation of the large-capacity 1st and 2nd generating units, that is, when "Q1 + Q2" ≦ Qa < Q1 + Q2 + Q3 , then the processing skips to step ST6 and a decision is made to stop the generating unit 7 and perform efficient simultaneous operation for the generating units 5 and 6 only. In step ST5, if it is judged that "Qa < Q1 + Q2" then, the processing skips to the judgment block of step ST7, and a judgment is made for whether simultaneous efficient operation is possible for the one of the large-capacity generating units 5 and 6, and the small-capacity generating unit 7, that is if "Q1 (or Q2) + Q3 ≦ Qa" . If "Q1 (or Q2) + Q3 ≦ Qa" in step ST7, then a decision is made (in step ST8) for the simultaneous efficient operation of one of the large-capacity generating units 5 and 6, and the small-capacity generating unit 7. In addition, if it is judged in step ST7 that "Qa < Q1 (Q2) + Q3" then the processing skips to step ST9 and a judgment is made for whether "Q1 (Q2) ≦ Qa < Q1 (Q2) + Q3" . If it is judged that "Q1 (Q2) ≦ Qa" in ST9, then in step 10, a command is output to the automatic control means 35 or 36 so that there is efficient operation of one of the generating units 5 or 6. As in the previously described step ST8, the determination of the control command in this step ST10 is to operate either of the plural number of generating units with priority and so the operation continues until steps ST8 and ST10, and a decision is made as to which is to be given priority operation in step ST11. The detailed configuration for performing this priority control is described below for the second embodiment, with reference to FIG. 6. In the previously described ST9, when it is judged that "Qa < Q1 (or Q2)", the control process proceeds to step 12 where a judgment is made for whether or not "Q3 ≦ Qa". If it is judged in step ST12 that "Q3 ≦ Qa" then, the operation of one of the large-capacity generating units 5 and 6 is stopped and efficient operation is preformed using only the small-capacity generating unit 7. In the previously described step ST14, a command is given to each of the automatic control means 35, 36 and 37 so that the three generating units 5, 6 and 7 are all operated so that the total efficiency is greatest for the selected mode whether that be the case for step 4, or the case for steps ST6, ST11 and ST13. In step ST12, when it is judged that "Qa < Q3", the operation proceeds to step ST15 and the operation of all generating units 5, 6 and 7 is stopped. In this case, maintenance discharge is performed so as to ensure the necessary water amount in the ancillary facilities downstream. In this manner, in the first embodiment of the present invention, the water level of the water intake 1 and the degree of opening of the gate 2 are used as the basis for suitably calculating the flow amount from the gate 2 and this calculated flow amount is distributed between the generating units 5 and 6 including the small-capacity generating unit 7 so that the total output Pa of the power station is maximized, thereby increasing the power generation efficiency. In addition, it is also possible to prevent unnecessary changing or overflow of the water level of the head tank 4 and therefore prevent the occurrence of trip of the generating units due to a drop in the water level. Each generating unit is also operated uniformly so that the operating ratio of each of the generating units is averaged and it is therefore possible to improve the equipment investment. In FIG. 5 that shows a flowchart for describing the operation, the priority control of the large-capacity generating units 5 and 6 was described as being performed in step ST11. The following will be a description of a specific configuration of a second embodiment that performs priority control, with reference to FIG. 6. In FIG. 6, elements of the configuration that are the same as or equivalent to elements of the configuration of FIG. 4 are represented by the same numerals, and the corresponding descriptions of them are omitted. The configuration of the high-efficiency operation selection means 34 in FIG. 6 is exactly the same as that of the first embodiment. However, in addition to the signal S₃₃ from the flow characteristic calculation means 32, the feedback signals S₃₄, S₃₅ and S₃₆ from the automatic control means 35, 36 and 37, and the signal S₅₅ from the comparator 51, the high-efficiency distribution calculation means 54 is also configured so that the priority operation signal S₇₅ for the first large-capacity generating unit 5 and the priority operation signal S₇₆ for the second large-capacity generating unit 6 are supplied from the priority operation control means 70. The priority operation control means 70 is configured from AND circuits 71 and 72, integration means 73 and 74, a timer 75 that supplies time signals S₆₉ and S₇₀ which are inverted at a constant cycle, to the integration means 73 and 74. The time signal S₇₀ output from the timer 75 switches at a long cycle of from half a year to one year and so when there is priority operation for either of the generating units, then for example, either the signal S₆₉ or the signal S₇₀ is made "high" and the other signal S₇₀ or S₆₉ made "low" so that the first generating unit 5 is operated from January through June, and the second generating unit 6 is operated from July through December. The AND circuit 71 of the control means 70 inputs an inverted signals for the parallel operation signal S₇₁ of the first generating unit 5 and parallel operation signal S₇₂ for the second generating unit 6, and outputs the first generating unit priority signal S₇₃, and the AND circuit 72 inputs an inverted signal. for the signal S₇₁, and the signal S₇₂ and outputs the signal S₇₄. The integration means 73 inputs the signal S₇₃ and the time signal S₆₉ and outputs a priority operation signal S₇₅ to the processing means 54 when the 1st generating unit priority signal S₇₃ is a significant "1" and when the time signal S₆₉ is also a significant "1". In addition, the signal S₇₄ output from the AND circuit 72 is supplied to the integration means 74 along with the signal S₇₀ output from the timer 75, and when the signal S₇₄ is a significant "1" and the time signal S₇₀ is also a significant "1", the priority usage time for the second generating unit 6 is integrated with the 2nd generating unit 6 being for priority usage. The integration means 73 and 74 alternately output signals S₇₅ and S₇₆, and signals S₇₇ and S₇₈ that are at the same level, to the other integration means 74 and 73, and these signals S₇₇ and S₇₈ clear both priority usage rights when either of the generating units 5 or 6 is used with priority for the set time portions prior to the time set by the timer 75. The provision of a priority operation control means having the configuration and function as described above, a high-efficiency operation control system for a generating unit and according to a second embodiment enables prevents exceedingly long-term use of either of the generating units when there is provided a plural number of generating units which are used for solitary operation and with priority use, and thus enables uniform use over an averaged time, and thus enables the life of the equipment to be extended. Moreover, the above described first and second embodiments have a gate provided at an upstream water intake but the present invention is also applicable when there is a power station upstream. In addition, in the above described first and second embodiments, there are provided three generating units but it is also possible to apply the present invention in the same manner when the hydroelectric power station has more than this number of generating units. In addition, the start command and the stop command can be separately detected and output to an automatic control means.

Claims: Control system for operating a plural number of generating units (5, 6, 7) in a hydroelectric power station with high efficiency, wherein said hydroelectric power station furthermore comprises a head tank for storing intake water supplied from upstream via a gate (2) at a water intake opening, characterized by: tank level detection means (27) for detecting the water level of the head tank, intake level detection means (31) for detecting the water level at the water intake opening and opening degree detection means (33) for detecting the degree of opening of the gate (2), flow amount calculation means (32) receiving the output signals of the intake level detection means (31) and the opening degree detection means (33) for calculating the amount of water flowing into said head tank (4) on the basis of the detected intake water level and the detected degree of opening of the gate and delivering an output signal indicating the result of said calculation, processing means (34) receiving the output of the flow calculation means (32) and of the tank level detection means (27) and outputting flow amount objective value signals, for determining flow amount objective values for each generating unit on the basis of the calculated water flow into the head tank and the detected water level in the head tank, said flow amount objective values representing a distribution of water flow on the individual generating units so that each generating unit can generate power most efficiently and the total power generation output is maximised, a plurality of power objective value calculation means (38, 39, 40) receiving the flow amount objective value signals, wherein each power objective value calculation means (38, 39, 40) is associated to a corresponding generating unit (5, 6, 7), is designed for calculating the power that is most efficiently generated by the respective generating unit (5, 6, 7) on the basis of the flow amount objective values calculated by the operation control means (34), and provides a power objective value signal as output, a plurality of deviation calculation means (41, 42, 43), each being associated with a corresponding generating unit (5, 6, 7), having as one input the power objective value signal of the corresponding power calculation means (38, 39, 40) and as second input an actual output signal from the corresponding generating unit (5, 6, 7) for calculating the deviation of the power objective value from the actual output value and outputting signals indicating the power deviation (S49, S50, S51) as control signals for the corresponding generating unit. The control system according to claim 1, characterized by a plurality of automatic control means (35, 36, 37), which are provided to each of said plurality of generating units (5, 6, 7), respectively, for starting operation of the corresponding generating unit (5, 6, 7) on the basis of start command signals (S40, S41, S42) output from said processing means (34) and for stopping operation of the corresponding generating unit (5, 6, 7) on the basis of the power deviation signals (S49, S50, S51) resulting from the calculation of said deviation calculation means (41, 42, 43). Control system according to claim 2, characterized in that said plurality of automatic control means (35, 36, 37) respectively output and feedback failure signals (S34, S35, S36) to the processing means (34) when an abnormality has occured in one of the generating units (5, 6, 7,). The control system of claim 1, wherein at least one of the plural number of generating units provided at said hydroelectric power station is a small-capacity generating unit (7) that generates a small capacity of power corresponding to a water amount ensuring the discharge of a constant of water supplied to amount of water for a demand from a downstream power station, and the remaining large-capacity generating units (5, 6) generate a large-capacity power when a supplied water amount is sufficient. The control system of claim 4, wherein said plural number of large-capacity generating units (5, 6) comprises a first generating unit (5) and a second generating unit (6). The control system of claim 4, wherein said selection processing means (34) is configured from a first comparison means (51) that uses detection signals (S₁₄) of a water level detector (27) that detects a water level of said head tank (4) as the basis for comparing a lower limit reference value indicating a lower limit water level of said head tank (4) and said detection signals (S₁₄); a second comparator (52) that compares an upper limit reference value that indicates an upper water level of said head tank (4) with said detection signals (S₁₄); a water level correction means (53) that corrects detection signals (S₁₄) by adding the degree of change when the head tank (4) water level indicated by said detection signals (S₁₄) has changed over the years to a water level different from that initially; a high-efficiency distribution water amount calculation processing means (54) to which are input flow amount signals supplied from said flow characteristic calculation means (34) and that indicated the flow amount from said water intake, a plural number of failure diagnosis signals supplied from said automatic control means, and comparison result signals of said first comparator (51), and which outputs distribution flow signals for each generating unit; third, fourth and fifth comparators (63, 64, 65) that compare whether or not distribution water amount signals for the generating units are greater than non-load flow amounts for the generating units; first, second and third timers (55, 56, 57) to which are input the detection signals indicating that the head tank water level exceeds an upper limit value as the result of comparison by said second comparator (52), and distribution water amount signals for each generating unit and which are output by said third, fourth and fifth comparators (63, 64 65), and which output start command signals to each automatic control means (35, 36 37) of each generating unit after the elapse of a set time; first, second and third switches (58, 60, 66) that switch on when there is correction of the water level on the basis of correction water level signals from said water level correction means and distribution flow amount signals for each said generating unit; and first and second adders (59, 61) that output said flow amount objective value signals to each automatic control means (35, 36) of the first and second generating units (5, 6) when said switches are on. The control system of claim 1; further comprising a priority operation control means (70) that successively switches a generating unit (5, or 6) that is in solitary operation when a certain time is reached, so that there is not excessive operation of one particular generating unit (5, or 6) when there is solitary operation of one generating unit (5 or 6) out of said plural number of generating units (5, or 6). The control system of claim 7; wherein said priority operation control means (70) is provided inside a high efficiency operation control system for a hydroelectric power station which is provided with at least one small-capacity generating unit (7) that generates a small capacity of power corresponding to a water amount ensuringthe discharge of a constant amount of water and a plural number of large-capacity generating units (5, 6). The control system of claim 8, wherein said plural number of large-capacity generating units (5, 6) comprises a first generating unit (5) and a second generating unit (6). The control system of claim 9, wherein said priority operation control means (70) is configured from a first AND circuit (71) to which are input first generating unit (5) parallel signals indicating that there is parallel operation of a first generating unit (5), inverted signals of second generating unit (6) parallel signals that indicate that there is parallel operation of a second generating unit (6), and to which are output first generating unit (5) solitary operation signals when only a first generating unit (5) is operating; a second AND circuit (72) to which are input second generating unit (6) parallel signals indicating that there is parallel operation of a second generating unit (6), inverted signals of first generating unit (5) parallel signals that indicate that there is parallel operation of a first generating unit (5), and to which are output second generating unit (6) solitary operation signals when only a second generating unit (6) is operating; a timer (75) that counts the time until the output of a switching signal at a constant cycle of at least half a year; a first integration means (73) that, on the basis of said switching signals from said timer (75) and said first generating unit (5) solitary operation signals, integrates the time that said first generating unit (5) has been in solitary operation; and a second integration means (74) that, on the basis of said switching signals from said timer (75) and said second generating unit solitary operation signals, integrates the time that said second generating unit has been in solitary operation. The control system of claim 10, wherein said first and second integration means (73, 74) have a function so that even when the time (75) of said constant cycle set by said timer has still not been counter, the input of clear signals that indicate that the solitary operation time of that generating unit has exceeded the switching necessary time switches a generating unit on the other side and that is to have solitary operation.

Inventors: NOGUCHI TETSUYA, NOGUCHI, TETSUYA
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1990
Main classification: F03B15
IPC codes: H02P9, F03B15