JP2005278231A - Power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly economic power generation system by utilizing generated power and exhaust heat efficiently even when power consumption or heat demand at a heat consuming section varies significantly while reducing the cost of a system where a power load 13 is born by a plurality of cogeneration facilities A, B and C and a commercial power supply 1. <P>SOLUTION: In the power generation system where a power generation facility including a plurality of cogeneration facilities A, B and C and a commercial power supply 1 are subjected to DC interconnection, its control section 26 determines priority of the plurality of power generation facilities based on a heat demand detected at a heat demand detecting section 22, and operates the power generation facilities sequentially according to the priority when a commercial electric energy monitoring section 29 detects a fact that electric energy W flowing from the commercial power supply 1 into the DC interconnection line exceeded a predetermined level. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a system that supplies power to a power load while adjusting power generated by a power generation facility including a plurality of cogeneration facilities and power from a commercial power source.

  Conventionally, when a power generation company supplies power to a plurality of consumers via a transmission line network, and a part of the plurality of consumers includes a power generation facility, the entire consumer group So-called coincidence in which the total amount of power received from the transmission line network and the total amount of power supplied by the power generation company to the entire transmission line network are matched within a specified period such as 30 minutes. In order to be able to achieve the same amount of principles, systems are known that control each power plant. In this system, a power meter that measures the amount of power received from the transmission line network is placed at each customer, and the output of each power generation facility is adjusted so that the measured amount of received power is maintained at the target amount of power received for each specified period It is the composition to do. When changing the power generation output of each power generation facility, prioritize the power generation cost in ascending order based on the information on power generation cost in addition to the power generation surplus and allowable power output change rate of each power generation facility. Control is performed to increase the power generation output of the power generation facility by preferentially increasing the target power reception amount of the customer having the power generation facility having a higher rank (see, for example, Patent Document 1).

JP 2004-40956 A (page 5-7, FIG. 1)

  However, in the conventional technology as described above, since it is not permitted that the power generated by the power generation facility flows into the transmission line network, that is, the commercial power supply side, it is necessary to provide a system protection device to prevent it, It was a factor of system cost increase.

  When the power generation facility is a cogeneration facility, the exhaust heat generated during power generation is supplied to a heat consuming unit such as a hot water tank and used for increasing the hot water temperature. However, particularly in a household cogeneration facility, there is a case where the heat demand is low even though the power demand is high because the power consumption by the time and the fluctuation of the heat demand in the heat consuming part are large. In that case, part of the exhaust heat must be wasted. Conversely, if the power demand is low despite high heat demand, part of the generated power must be wasted, and even if it is used, a part of the generated power is supplied to the heat consuming part. It can be used for raising the hot water temperature. Therefore, if many such operation states occur, the efficiency as a cogeneration facility is deteriorated and the economy is impaired.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce the cost of the system and reduce power consumption and heat in a system that shares a power load with a plurality of cogeneration facilities and a commercial power source. The present invention is to provide a power generation system with high economic efficiency by making it possible to efficiently use generated power and exhaust heat even when the fluctuation of heat demand in the consumption section is large.

  A first characteristic configuration of a power generation system according to the present invention for achieving the above object includes a power generation facility including a plurality of cogeneration facilities and a commercial power source, and the power generation facility and the commercial power source that output AC power are AC power. Are connected via a converter that converts DC power to DC power, and the power generation facilities that output DC power are directly connected, and these are connected to DC power via an inverter that converts DC power to AC power from the DC power connection line. A power generation system that distributes power to one or more power loads, wherein a heat demand detection unit that detects a heat demand in a heat consumption unit of the plurality of cogeneration facilities, and flows from the commercial power source into the DC interconnection line A commercial power amount monitoring unit that monitors the amount of power; and a control unit that performs operation control of the power generation facility, wherein the control unit is prioritized for each of the plurality of power generation facilities. Based on the heat demand detected by the heat demand detection unit, when the commercial power amount monitoring unit detects that the amount of power from the commercial power source flowing into the DC interconnection line exceeds a predetermined value, It is in the point of operating in order from the power generation equipment with the highest priority.

  According to the first characteristic configuration, since the commercial power source is DC-connected to the power generation facility via the converter, it is possible to prevent a reverse power flow in which electric power flows into the commercial power source side. There is no need to provide a protective device, and the cost of the system can be reduced. In addition, when power demand rises, based on the heat demand in the heat consumption part of the cogeneration facility, it is operated preferentially from the cogeneration facility with high heat demand among the multiple power generation facilities, so exhaust heat is reduced. The system is not thrown away wastefully, and the system can be made highly efficient.

  A second characteristic configuration of a power generation system according to the present invention includes a power generation facility including a plurality of cogeneration facilities and a commercial power source, and the power generation facility that outputs AC power and the commercial power source convert the AC power into DC power. 1 or 2 or more power via an inverter that directly connects and connects these power generators that output DC power, and converts the DC power from the DC interconnection line to AC power. A power generation system that distributes power to a load, wherein the heat demand detecting unit detects heat demand in a heat consuming unit of the plurality of cogeneration facilities, and commercial power that monitors the amount of power flowing from the commercial power source into the DC interconnection line An amount monitoring unit and a control unit that performs operation control of the power generation facility, and the control unit detects a priority order for each of the plurality of power generation facilities by the heat demand detection unit. If the commercial power amount monitoring unit detects that the amount of power from the commercial power source flowing into the DC interconnection line has fallen below a predetermined value, the power generation facility with a low priority is selected. The point is to stop in order.

  According to the second characteristic configuration, since the commercial power source is DC-connected to the power generation facility through the converter, it is possible to prevent a reverse power flow in which electric power flows into the commercial power source side, so that the system can be There is no need to provide a protective device, and the cost of the system can be reduced. In addition, when power demand decreases, based on the heat demand in the heat consumption section of the cogeneration facility, the cogeneration facility with low heat demand is stopped first among the multiple power generation facilities, so waste heat is wasted Therefore, the system can be made highly efficient.

  Here, each of the plurality of cogeneration facilities has a hot water storage tank as a heat consuming section, and the heat demand detection section detects heat demand by detecting one or both of the temperature and amount of hot water in the hot water storage tank. It is possible to make it the structure to do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a power generation system according to the present embodiment. In this embodiment, a case where three cogeneration facilities A, B, and C are provided as power generation facilities will be described. Here, A and B of the three cogeneration facilities A, B, and C are the power generators 27 and the rotary generators 2 and 3, respectively, and the AC generators 4 and 5 that are linked to them, and C is the power generator. The unit 27 is the fuel cell 6. Further, the heat consuming sections 28 of the three cogeneration facilities A, B, C are all hot water tanks 16, 17, 18 connected to the power generating section 27 through heat exchangers 19, 20, 21. .

  The commercial power source 1 and the power generation units 27 of the three cogeneration facilities A, B, and C are interconnected in a DC state on the DC interconnection line 7. At this time, since the commercial power source 1 outputs AC power, it is connected to the DC interconnection line 7 through a converter 8 that converts AC power into DC power. Further, since the AC generators 4 and 5 also output AC power, they are connected to the DC interconnection line 7 via converters 9 and 10 that convert AC power into DC power. On the other hand, since the fuel cell 6 outputs DC power, it is directly connected to the DC interconnection line 7. A smoothing capacitor 11 is connected to the DC interconnection line 7.

  The electric power from the commercial power source 1 and the power generation units 27 of the three cogeneration facilities A, B, and C is supplied from the DC interconnection line 7 to the electric power load 13 through the inverter 12 that converts DC power into AC power. Is done. The power load 13 includes, for example, a group of various electrical devices such as lighting equipment, air conditioning equipment, and machine tools used in general households and business offices. In the present embodiment, the three power loads 13 are connected to each other via the inverter 12, but this shows a case where power is supplied to, for example, a plurality of homes or offices.

  The AC generators 4 and 5 are linked to the rotary prime movers 2 and 3, respectively, and are driven by the rotation of the output shafts 14 and 15 of the rotary prime movers 2 and 3 to generate power. As the rotary prime movers 2 and 3, various known prime movers such as a gas engine, a diesel engine, a gas turbine, or a Stirling engine can be used. The fuel cell 6 includes a reformer (not shown) and is configured to generate power using hydrogen obtained by reforming city gas, LPG, kerosene, or the like. And the heat consumption part 28 of these three cogeneration facilities A, B, and C becomes a structure which can receive the supply of the waste heat produced in the electric power generation part 27 at the time of electric power generation, and can use the heat | fever. That is, the exhaust heat generated during power generation from the rotary prime movers 2 and 3 and the fuel cell 6 is exhausted as heat of a heat transport medium such as exhaust or cooling water, and is heat-exchanged in the heat exchangers 19, 20, and 21. It is configured to be sent to the hot water storage tanks 16, 17, and 18 that are the heat consuming unit 28 for recovery. The hot water storage tanks 16, 17, and 18 store hot water in the interior by using the heat from the power generation unit 27 supplied via the heat exchangers 19, 20, and 21 to increase the temperature of the water. It is configured to supply hot water stored in the

  Further, the heat demand in the heat consuming unit 28 of the cogeneration facilities A, B, and C is detected by the heat demand detecting unit 22. In this embodiment, the heat demand detection part 22 has the hot water temperature sensors 23, 24, 25 which detect the temperature of the hot water stored in the hot water storage tanks 16, 17, 18 as the heat consumption part 28. It is configured. That is, as a result of detection by the hot water temperature sensors 23, 24, 25, if the temperature of the hot water in any one of the hot water tanks 16, 17, 18 is low, the hot water temperature needs to be raised. , 17, 18 can be judged to have a high heat demand, and conversely, if the temperature of hot water in any of the hot water tanks 16, 17, 18 is high, there is no need to raise the temperature of the hot water, so that hot water tank 16 17 and 18 can be judged to be low. And the detection result by such a hot water temperature sensor 24 is sent to the control part 26, and the level of heat demand is judged. The object to be detected by the hot water temperature sensors 23, 24, 25 differs depending on the structure of the hot water tanks 16, 17, 18, and detects the amount of hot water above a certain temperature stored in the hot water tanks 16, 17, 18. Alternatively, there may be a configuration in which both the temperature and amount of hot water are detected.

  The amount of power W flowing from the commercial power source 1 into the DC interconnection line 7 via the converter 8 is monitored by the commercial power amount monitoring unit 29. In the present embodiment, the commercial power amount monitoring unit 29 is configured to include a wattmeter 30 disposed on the direct current side of the converter 8 of the commercial power source 1. The wattmeter 30 detects the DC power amount W flowing from the commercial power source 1 into the DC interconnection line 7 at regular or regular time intervals, and sends the information to the control unit 26.

  The control unit 26 controls the operation of the power generation units 27 of the cogeneration facilities A, B, and C. At that time, the control unit 26 determines the priority order for each of the cogeneration facilities A, B, and C based on the heat demand detected by the heat demand detection unit 22 and from the commercial power source 1 that flows into the DC interconnection line 7. When the commercial power amount monitoring unit 29 detects that the power amount W has exceeded a predetermined value, the power generation unit 27 is operated in order from the priority order cogeneration facilities A, B, and C. When the commercial power amount monitoring unit 29 detects that the power amount W from the commercial power source 1 flowing into the DC interconnection line 7 is lower than a predetermined value, the cogeneration facilities A, B, The power generation unit 27 is stopped in order from C.

  In the present embodiment, specifically, the priority order is determined based on the temperature of hot water stored in the hot water storage tanks 16, 17 and 18 of the cogeneration facilities A, B and C. Rankings are given as “first,” “second,” and “third,” assuming that the heat demand is higher in order from cogeneration facilities A, B, and C, where the temperature of hot water is lower. At this time, when there are a plurality of hot water storage tanks 16, 17, and 18 having the same hot water temperature, their ranks are determined based on the predetermined ranks of the respective cogeneration facilities A, B, and C. Alternatively, it can be determined at random. In determining the specific rank of each cogeneration facility A, B, C, it is preferable to determine based on the heat recovery efficiency, power generation efficiency, etc. of the power generation unit 27 of each cogeneration facility A, B, C.

  At the time of determination in the control unit 26 that determines the priority order, in this embodiment, the amount of power W from the commercial power source 1 flowing into the DC interconnection line 7 has exceeded a predetermined value (hereinafter referred to as “power generation start value W1”). Is detected by the commercial power amount monitoring unit 29, and when the commercial power amount monitoring unit 29 detects that the power amount W has fallen below a predetermined value (hereinafter referred to as “power generation stop value W2”). Each time, the control unit 26 determines the priority order at that time, and controls the start and stop of the operation of the power generation unit 27 of each cogeneration facility A, B, C according to the priority order. Here, as shown in FIG. 2, for the power amount W detected by the commercial power amount monitoring unit 29, a predetermined value (referred to as “power generation start value W <b> 1”) of the power amount W that triggers the operation start of the power generation unit 27. )) And a predetermined value (referred to as “power generation stop value W2”) of the electric energy W that triggers the power generation unit 27 to stop, it is preferable to provide a hysteresis δ. That is, the amount of power W flowing from the commercial power source 1 into the DC interconnection line 7 varies frequently depending on the state of the power load 13 and the operating state of the cogeneration facilities A, B, C. This is because if the hysteresis δ in consideration of the fluctuation is not provided, the operation of the power generation unit 27 is frequently started and stopped, and the efficiency of the system is deteriorated. In addition, when determining the priority order in the control unit 26, it is added when the power amount W detected by the commercial power amount monitoring unit 29 in this way exceeds the power generation start value W1 or lower than the power generation stop value W2. Thus, it is possible to determine the priority order even at a predetermined time interval. In that case, when the power generation unit 27 of one cogeneration facility (for example, A) is operating and the power generation unit 27 of the cogeneration facility (for example, B) whose priority is stopped is replaced, It is also possible to perform control for stopping the power generation unit 27 of the generation facility (A) and newly starting the operation of the power generation unit 27 of the cogeneration facility (B) whose priority has been raised.

  Hereinafter, the operation control by the control unit 26 of the power generation system according to the present embodiment will be described based on the flowchart shown in FIG. 3. As shown in this figure, first, it is determined whether or not the power amount W from the commercial power source 1 detected by the commercial power amount monitoring unit 29 exceeds the power generation start value W1 (step # 01). If the amount of power W from the commercial power source 1 does not exceed the power generation start value W1 (step # 01: NO), the process proceeds to step # 04. On the other hand, when the amount of power W from the commercial power source 1 exceeds the power generation start value W1 (step # 01: YES), each code is then based on the heat demand detected by the heat demand detector 22 as described above. The control unit 26 determines to determine the priority order for each of the generation facilities A, B, and C (step # 02). Thereafter, the operation of the power generation unit 27 of one cogeneration facility A, B or C having a higher priority is started (step # 03). At this time, if the power generation unit 27 of the cogeneration facility A, B or C with the highest priority is already operating, the operation of the power generation unit 27 of the cogeneration facility A, B or C with the next highest priority If all the power generation units 27 of the cogeneration facilities A, B, and C are already operating, this processing step # 03 is not performed.

  Next, it is determined whether or not the power amount W from the commercial power source 1 detected by the commercial power amount monitoring unit 29 has dropped below the power generation stop value W2 (step # 04). If the amount of power W from the commercial power source 1 is not lower than the power generation stop value W2 (step # 04: NO), the process returns to step # 01. On the other hand, when the amount of power W from the commercial power source 1 falls below the power generation stop value W2 (step # 04: YES), each code is then based on the heat demand detected by the heat demand detector 22 as described above. The control unit 26 determines to determine the priority order for each of the generation facilities A, B, and C (step # 05). Thereafter, the power generation unit 27 of one cogeneration facility A, B, or C having a low priority is stopped (step # 06). At this time, if the power generation unit 27 of the cogeneration facility A, B or C with the lowest priority has already stopped, the power generation unit 27 of the cogeneration facility A, B or C with the next lowest priority is stopped. If all the power generation units 27 of the cogeneration facilities A, B, and C are already stopped, this step # 06 is not performed. Thereafter, the process returns to step # 01. In addition, when the electric energy W from the commercial power source 1 is between the power generation start value W1 and the power generation stop value W2, neither the operation start or stop of the power generation unit 27 of the cogeneration facilities A, B, C is performed. The state as it is is maintained.

  In addition, in the said embodiment, although the case where all the power generation facilities were cogeneration facilities was demonstrated, this invention can also be applied to the power generation system containing the normal power generation facility which does not utilize exhaust heat. In that case, since such a normal power generation facility has no heat demand, the control unit 26 sets the priority to be the lowest. Further, in a power generation system including a plurality of such normal power generation facilities, the priority order between the normal power generation facilities is determined based on a predetermined order of each power generation facility or is determined randomly. It is possible. In determining the unique rank of each power generation facility, it is preferable to determine based on the power generation efficiency of the power generation unit 27 of each cogeneration facility A, B, C.

  INDUSTRIAL APPLICABILITY The present invention is suitable for a power generation system that supplies power load while adjusting power generated by a power generation facility including a plurality of cogeneration facilities installed in a plurality of general households or business establishments and power from a commercial power source. Can be used.

The figure which shows schematic structure of the electric power generation system which concerns on this embodiment. The graph which shows an example of the relationship between the fluctuation | variation of the electric energy detected by the commercial electric energy monitoring part of the electric power generation system which concerns on this embodiment, and a power generation starting value and a power generation stop value. The flowchart which shows the operation control by the control part of the electric power generation system which concerns on this embodiment.

Explanation of symbols

A, B, C Cogeneration facility 1 Commercial power source 2, 3 Rotating motor 4, 5 AC generator 6 Fuel cell 7 DC interconnection lines 8, 9, 10 Converter 12 Inverter 13 Electric load 16, 17, 18 Hot water tank 19 , 20, 21 Heat exchanger 22 Heat demand detection unit 23, 24, 25 Hot water temperature sensor 26 Control unit 27 Power generation unit 28 Heat consumption unit 29 Commercial power amount monitoring unit 30 Wattmeter W Power amount detected by commercial power amount monitoring unit W1 Power generation start value W2 Power generation stop value

Claims (3)

A power generating facility including a plurality of cogeneration facilities and a commercial power source, and a power generating facility that outputs alternating current power and a commercial power source are connected via a converter that converts the alternating current power into direct current power, and the power generating facility that outputs direct current power Is a power generation system that connects directly to each other and DC-connects them, and distributes them to one or more power loads via an inverter that converts DC power from the DC-connected lines into AC power,
A heat demand detection unit that detects heat demand in a heat consumption unit of the plurality of cogeneration facilities, a commercial power amount monitoring unit that monitors the amount of power flowing from the commercial power source to the DC interconnection line, and an operation of the power generation facility A control unit for controlling,
The control unit determines priority for each of the plurality of power generation facilities based on heat demand detected by the heat demand detection unit, and an amount of power from a commercial power source flowing into the DC interconnection line exceeds a predetermined value. When this is detected by the commercial power amount monitoring unit, a power generation system that operates in order from the power generation facility with the highest priority. A power generating facility including a plurality of cogeneration facilities and a commercial power source, and a power generating facility that outputs alternating current power and a commercial power source are connected via a converter that converts the alternating current power into direct current power, and the power generating facility that outputs direct current power Is a power generation system that connects directly to each other and DC-connects them, and distributes them to one or more power loads via an inverter that converts DC power from the DC-connected lines into AC power,
A heat demand detection unit that detects heat demand in a heat consumption unit of the plurality of cogeneration facilities, a commercial power amount monitoring unit that monitors the amount of power flowing from the commercial power source to the DC interconnection line, and an operation of the power generation facility A control unit for controlling,
The control unit determines a priority order for each of the plurality of power generation facilities based on heat demand detected by the heat demand detection unit, and an amount of power from a commercial power source flowing into the DC interconnection line falls below a predetermined value. When the commercial power amount monitoring unit detects that the power generation system, the power generation system is configured to stop in order from the power generation facility with the lowest priority.   The plurality of cogeneration facilities each have a hot water storage tank as a heat consuming section, and the heat demand detection section detects heat demand by detecting one or both of the temperature and amount of hot water in the hot water storage tank. The power generation system according to 1 or 2.

Images