JP4623557B2 - Cogeneration system - Google Patents

Description

  The present invention supplies electric power generated by an in-house power generator such as an engine generator or a fuel cell to an in-house load in synchronization with a commercial power source, performs linked operation with the commercial power source, and exhausts heat from the in-house power generator. More particularly, the present invention relates to a cogeneration system provided with surplus power recovery means for recovering surplus power of the private power generation means in the form of heat for preventing reverse power flow.

  A cogeneration system is known in which self-power generation means such as an engine generator or a fuel cell is operated to obtain electric power, and the exhaust heat of the self-power generation means is effectively used as a heat source for hot water supply and air conditioning. Since the cogeneration system literally makes effective use of waste heat that has been discarded, it saves fuel and saves resources and reduces greenhouse gas emissions. In addition, a system combining a cogeneration system with a commercial power source supplied by an electric power company, that is, cogeneration system power and power from a commercial power source are linked to each other. In the case where overload occurs, a system that compensates with the power of the commercial power supply has been proposed. The cogeneration system linked with the commercial power supply is attracting social attention because it has an economic effect of saving electricity costs for users.

  Now, when designing a cogeneration system linked to a commercial power source, the standard load is estimated and the rated output of the private power generation means is determined according to this standard load. Then, since the electric power purchased from a commercial power supply increases, an operating cost rises. For this reason, it is desirable to set the rated output of the private power generation means larger. However, when the rated output is set to be large, when the actual load falls below the rated output, a phenomenon that surplus power is generated and flows backward to the commercial power supply, that is, reverse power flow occurs. Since this reverse power flow adversely affects the quality of power supplied by the commercial power source, the reverse power flow of the cogeneration system linked to the commercial power source is regulated to 5% or less of the power generation capacity. Therefore, in a cogeneration system linked to a commercial power source, it is necessary to recover surplus power and prevent reverse power flow, and various devices have been proposed for that purpose.

  In Patent Document 1, when a reverse power flow is detected, the power supply circuit of the private power generation means is disconnected from the power supply circuit of the commercial power supply, and the surplus power is stored in a capacitor or is provided with a reverse power flow prevention function that consumes the electric heater. A generation system is disclosed.

Patent Document 2 discloses a cogeneration system that includes a plurality of electric heaters and a changeover switch, and connects the electric heaters commensurate with the amount of surplus power to the private power generation means to collect surplus power.
A specific configuration of an electric heater for recovering surplus power is disclosed in Patent Document 3.

  FIG. 4 is a power system diagram of a cogeneration system showing an example of the prior art. In FIG. 4, 1 is a cogeneration system, 2 is a control device of the cogeneration system, 3 is a distribution board, 4 is a self-load such as home appliances, and 5 is a commercial power source.

The cogeneration system 1 includes a private power generation means 11, a surplus power recovery unit 12, and a leakage breaker 13. The surplus power recovery unit 12 includes a heater 121, a heater 122, and a heater 123 connected between the U-phase output line and the N-phase output line of the private power generation means 11, and the V-phase output line of the private power generation means 11. The heater 124, the heater 125, and the heater 126 connected between the N-phase output lines, and a changeover switch 127 for turning the heaters 121 to 126 on and off. The heating values of the heater 121 and the heater 124 are 100 W (watts), the heating values of the heater 122 and the heater 125 are 200 W, and the heating values of the heater 123 and the heater 126 are 300 W. The surplus power recovery unit 12 can set the heat generation amount from 0 to 1200 W in increments of 100 W by turning on and off the changeover switch 127 in response to a command from the control device 2. The heat generated by the heaters 121 to 126 is effectively used as a heat source for a water heater or an air conditioner together with the exhaust heat of the private power generation means 11.

  The control device 2 is a computer that controls the entire cogeneration system 1, receives the output of a reverse power flow detector 36 of the distribution board 3 described later, obtains the amount of surplus power, and matches the amount of surplus power. The selected heater is selected from the heaters 121 to 126, and a signal for turning on / off the changeover switch 127 is output.

  The distribution board 3 includes a limiter 31 and a leakage breaker 32 for determining the maximum power (contract power) input from the commercial power supply 5, safety breakers 33 and 34 for limiting the current flowing through the private load 4, and a cogeneration system. A safety breaker 35 for limiting the current flowing from 1 to the distribution board 3 and a reverse flow detector 36 for detecting reverse flow are provided. The N-phase wire is grounded, the voltage between the N-phase wire and the U-phase wire and between the N-phase wire and the V-phase wire is 100V, and the voltage between the U-phase wire and the V-phase wire is 200V. is there.

JP 2002-374628 A JP 2004-92458 A Japanese Patent Laid-Open No. 2003-4300

However, since the surplus power recovery unit of the conventional cogeneration system adjusts the heat generation amount in increments of 100 W, there is a problem that the optimum heat generation amount cannot be set according to the amount of surplus power and the efficiency is poor. It was. That is, for example, when the actual surplus power is 651 W, the total heat generation amount of the heater can be set only at 600 W or 700 W. In the setting of 700W, 49W of electric power is converted into heat, so that the amount of electric power is insufficient, and the consumption of commercial power increases and the power generation cost increases. This is because a reverse power flow occurs.
In order to solve this problem, it is conceivable to perform phase control on the current supplied to the heater to periodically turn it on and off to change the power consumption steplessly.・ There is a problem that noise occurs when turned off.

  Therefore, an object of the present invention is to optimize the heat generation amount of the heater for recovering surplus power according to the amount of surplus power, thereby improving the efficiency of the cogeneration system and reducing the generation of noise. It is to realize a highly cogeneration system.

  A first configuration of a cogeneration system according to the present invention includes a power generation device and a surplus power recovery device that recovers surplus power of the power generation device in the form of heat, and uses the power of the power generation device as power of a power system of a power company. In the cogeneration system that supplies the self-load in synchronization with the power supply, the surplus power recovery device includes a plurality of heaters connected between the U phase and the N phase and between the V phase and the N phase of the power generation device, And a switch for individually turning on and off the plurality of heaters, and a device for performing phase control on a current supplied to a heater having the smallest rated heat generation amount among the plurality of heaters.

  According to this configuration, since the heat generation amount of the heater is adjusted steplessly by phase control, it is possible to set an optimal heat generation amount commensurate with the amount of surplus power. As a result, the efficiency of the cogeneration system is improved. Since the phase control is performed on the current flowing through the heater having the smallest rated heat generation, that is, the heater having the largest resistance, the current turned on / off by the phase control is small, and as a result, the noise can be reduced.

  A second configuration of the cogeneration system according to the present invention includes a power generation device and a surplus power recovery device that recovers surplus power of the power generation device in the form of heat, and uses the power of the power generation device as power of a power system of an electric power company. In the cogeneration system that supplies the self-load in synchronization with the power supply, the surplus power recovery device includes a plurality of heaters connected between the U phase and the N phase and between the V phase and the N phase of the power generation device, A switch for individually turning on and off the plurality of heaters, an auxiliary heater connected between the U-phase and the V-phase of the power generator, and a device for performing phase control on the current supplied to the auxiliary heater. Features.

  According to this configuration, since the auxiliary heater is connected between the U phase and the V phase, the same calorific value is compared with the case where the auxiliary heater is connected between the U phase and the N phase or between the V phase and the N phase. The current is halved. Thereby, the noise generated by the phase control can be further reduced.

  A third configuration of the cogeneration system according to the present invention includes a power generation device and a surplus power recovery device that recovers surplus power of the power generation device in the form of heat, and uses the power of the power generation device as power of a power system of an electric power company. In the cogeneration system that supplies the load to the private load in synchronization with each other, the surplus power recovery device individually turns on the plurality of heaters connected between the U phase and the V phase of the power generation device and the plurality of heaters, respectively. A switch for turning off, an auxiliary heater connected between the U phase and the V phase of the power generator, and a device for performing phase control on the current supplied to the auxiliary heater are provided.

  According to this configuration, since the heater and the auxiliary heater are connected between the U phase and the V phase, the same calorific value is connected between the U phase and the N phase or between the V phase and the N phase. The current is halved compared to. Thereby, the noise generated by the phase control can be further reduced.

A fourth configuration of the cogeneration system according to the present invention includes a power generation device and a surplus power recovery device that recovers surplus power of the power generation device in the form of heat, and uses the power of the power generation device as power of the power system of the power company. In the cogeneration system that supplies the self-load in synchronization with each other, the surplus power recovery device includes one heater with a calorific value Q and a calorific value of Q * 2 ⁽ⁿ⁻¹⁾ (where n = 1, 2 ^). , 3,..., N) are connected in parallel to the power generator, and a device for controlling the phase of the current flowing through the one heater of the calorific value Q, and the other A switch for individually turning on / off each of the N heaters is provided.

  According to this configuration, since the heat generation amount of the heater is set in a geometric sequence with a common ratio of 2, a surplus power recovery device can be configured with the minimum number of heaters.

  As described above, according to the cogeneration system according to the present invention, the amount of heat generated by the heater of the surplus power recovery device can be adjusted steplessly, so that necessary and sufficient heat generation commensurate with the amount of surplus power is achieved. You can set the amount. Therefore, the occurrence of reverse power flow can be prevented, and consumption of power generated by the private power generation means and power purchased from a commercial power source can be minimized. As a result, the power generation cost by the cogeneration system can be minimized.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a wiring diagram of a surplus power recovery unit of the cogeneration system according to the first embodiment of the present invention. In addition, a present Example demonstrates the thing of the electric power generation amount 1kW type currently spread | diffused as a general household use.

In FIG. 1, 6 is a surplus power recovery unit. The surplus power recovery unit 6 is a surplus power recovery device attached to the cogeneration system 1 instead of the surplus power recovery unit 12 of the cogeneration system 1 shown in FIG. In the following description, components of the cogeneration system 1 (not shown in FIG. 1) will be described with reference to the reference numerals attached to FIG.

  Reference numerals 61, 62, 63 denote heaters (resistors) connected between the U-phase line and the N-phase line of the private power generation means 11. Reference numerals 64, 65 and 66 denote heaters (resistors) connected between the V-phase line and the N-phase line of the private power generation means 11. The heating values of the heaters 61 to 66 are 50 W, 100 W, 400 W, 50 W, 200 W, and 400 W, respectively. Reference numeral 611 denotes a phase control device that controls the phase of the current supplied to the heater 61. Here, the phase control refers to adjusting the temporal relationship between the alternating voltage and the current to control the power that is the product thereof. That is, the electric power is changed by cutting the current in a certain range of the AC waveform. The phase control device 611 can change the heat generation amount (power consumption) of the heater 61 steplessly from 0 to 50 W in response to a command from the control device 2 of the cogeneration system 1. Reference numerals 621, 631, 641, 651, and 661 are changeover switches that turn the heaters 62 to 66 on and off, and operate according to commands from the control device 2 of the cogeneration system 1. For convenience of explanation, the changeover switches 621 to 661 are shown as mechanical switches having mechanical contacts, but are not limited to mechanical switches, and may be switches using a semiconductor such as a triac, for example. .

  Since the surplus power recovery unit 6 has the heaters 61 to 66 arranged in parallel, a maximum surplus power of 1200 W can be recovered. The control device 2 obtains surplus power based on the reverse flow power detected by the reverse flow detector 36, and selects a combination of heaters 61 to 66 corresponding to the magnitude. For example, if the surplus power is less than 50 W, the amount of heat generated by the heater 61 is adjusted between 0 to 50 W by the phase control device 611 and the changeover switches 621 to 661 are turned off so that the surplus power and surplus power recovery unit 6 Balance calorific value. Further, when the surplus power is 50 W or more and less than 100 W, the heater 61 and the heater 64 are used, and if the other heaters are turned off, the surplus power and the heat generation amount of the surplus power recovery unit 6 can be balanced. Similarly, if the surplus power is 100 W or more and less than 150 W, the heater 61 and the heater 62 are used. If the surplus power is 150 W or more and less than 200 W, the heater 61, the heater 62, and the heater 64 are used. If the surplus power is 1150 W or more and less than 1200, all the heaters from the heater 61 to the heater 66 are used. As described above, the surplus power recovery unit 6 uses the phase control device 611 to adjust the heat generation amount of the heater 61 between 0 to 50 W and to turn the heaters 62 to 66 on and off to reduce the heat generation amount from 0 to 1200 W. Can be set freely in a stepless manner. Therefore, the surplus power recovery unit 6 can recover surplus power without excess or deficiency, and can prevent the occurrence of reverse power flow without converting excessive power into heat.

  Here, since the phase control device 611 periodically turns on and off the current flowing through the heater 61, the generation of noise becomes a problem. However, since the heating value of the heater 61 is 50 W, the current flowing through the heater 61 is only 0.5 A. Therefore, the noise is small. If the noise needs to be further reduced, the amount of heat generated by the heater for phase control may be reduced. For example, the combination of the heat generation amounts of the heaters may be 25 W, 25 W, 50 W, 100 W, 200 W, 400 W, and 400 W, and the phase control may be performed for one of the 25 W heaters. The reason why the surplus power recovery amount is set to 1200 W with respect to the power generation amount of 1 kW is that a margin is provided in anticipation of a decrease in power recovery capability due to a voltage drop.

  FIG. 2 is a wiring diagram of a surplus power recovery unit of the cogeneration system according to the second embodiment of the present invention.

  In FIG. 2, 7 is a surplus power recovery unit. The surplus power recovery unit 7 is also a surplus power recovery device attached to the cogeneration system 1 in place of the surplus power recovery unit 12 of the cogeneration system 1 shown in FIG.

  Reference numerals 71 and 72 denote heaters (resistors) connected between the U-phase line and the N-phase line of the private power generation means 11. Reference numerals 73, 74, and 75 denote heaters (resistors) connected between the V-phase line and the N-phase line of the private power generation means 11. The heating values of the heaters 71 to 75 are 100 W, 400 W, 50 W, 200 W and 400 W, respectively. 711 to 751 are changeover switches for turning the heaters 71 to 75 on and off, and operate according to a command from the control device 2 of the cogeneration system 1. Reference numeral 76 denotes an auxiliary heater having a calorific value of 50 W connected between the U-phase line and the V-phase line of the private power generation means 11, which is phase-controlled by the phase control device 761, and in a stepless manner between 0 and 50 W. Can be adjusted.

Similar to the above-described surplus power recovery unit 6, the surplus power recovery unit 7 uses the phase control device 761 to adjust the amount of heat generated by the auxiliary heater 76 between 0 to 50 W and to turn the heaters 71 to 75 on and off. Thus, the calorific value can be freely set in a stepless manner between 0 and 1200 W.

  The amount of heat generated by the auxiliary heater 76 is 50 W, similar to that of the heater 61 of the first embodiment, but the voltage applied to the auxiliary heater 76 is 200 V because it is connected between the U phase and the V phase of the private power generation means 11. Therefore, the current flowing through the auxiliary heater 76 is 0.25 A, which is half that of the heater 61, so that the noise generated when phase control is applied to the current flowing through the auxiliary heater 76 is even smaller.

  FIG. 3 is a wiring diagram of the surplus power recovery unit of the cogeneration system according to the third embodiment of the present invention.

  In FIG. 3, 8 is a surplus power recovery unit. The surplus power recovery unit 8 is also a surplus power recovery device attached to the cogeneration system 1 in place of the surplus power recovery unit 12 of the cogeneration system 1 shown in FIG.

  Reference numerals 81, 82, 83, 84, and 85 denote heaters (resistors) connected between the U-phase line and the V-phase line of the private power generation means 11, and the heat generation amounts are 50 W, 100 W, 200 W, 400 W, and 400 W, respectively. It is. 811 to 851 are changeover switches for turning the heaters 81 to 85 on and off, and operate according to a command from the control device 2 of the cogeneration system 1. 86 is an auxiliary heater with a calorific value of 50 W connected between the U-phase line and the V-phase line of the private power generation means 11, and is phase-controlled by the phase control device 861 so that the calorific value is stepless between 0 and 50 W. Can be adjusted.

Similar to the surplus power recovery units 6 and 7 described above, the surplus power recovery unit 8 uses the phase control device 861 to adjust the heat generation amount of the auxiliary heater 86 between 0 to 50 W, and to turn on the heaters 81 to 85. By turning off, the calorific value can be freely set in a stepless manner between 0 and 1200W.

The calorific values of the auxiliary heater 86 and the heaters 81 to 85 may be appropriately determined according to the design requirements, but can be generally determined by the following procedure.
If the heating value of the heaters 81 to 85 is QW (Watt), 2QW, 4QW, 8QW, and 16QW, the heating value is gradually increased from 0W to 31QW in increments of QW by combining on / off of the heaters 81 to 85. Can change. Further, if the heat generation amount of the auxiliary heater 86 is QW (watt) and phase controlled, the heat generation amount can be changed in a stepless manner from 0 W to QW. Therefore, by combining the heaters 81 to 85 and the auxiliary heater 86, from 0 W to 32 QW The calorific value can be changed steplessly.

Furthermore, if generalized, one heater with a calorific value QW (Watt) and ^N heaters with n = 1 to N, where the calorific value is represented by Q * 2 ^(n-1) W (Watt), respectively. As shown in the first to third embodiments, a heater is connected in parallel to the private power generation means 11 to perform phase control for one heater with a calorific value QW (Watt), and the other N heaters are turned on. be carried out off control, it can change the amount of heat generated in a non-stage from 0W to Q * 2 N ^W. Q and N may be appropriately selected according to a required amount of heat generation and a limit on the size and weight of the surplus power recovery unit 8.

  The self-power generation means used in the cogeneration system of the present invention is generally an engine generator powered by a diesel engine, a gas turbine engine, or the like, or a fuel cell, but is not limited thereto. Any other type of power generation device can be selected as long as it is a power generation device that generates exhaust heat during power generation.

It is a wiring diagram of the surplus electric power collection | recovery part of the cogeneration system which concerns on Example 1 of this invention. It is a wiring diagram of the surplus electric power collection | recovery part of the cogeneration system which concerns on Example 2 of this invention. It is a wiring diagram of the surplus electric power collection | recovery part of the cogeneration system which concerns on Example 3 of this invention. It is an electric power system diagram of a cogeneration system which shows an example of conventional technology.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cogeneration system 11 Private power generation means 12 Surplus power recovery part 121-126 Heater (resistor)
127 selector switch 13 earth leakage breaker 2 control device 3 distribution board 31 limiter 32 earth leakage breaker 33 to 35 safety breaker 36 reverse power detector 4 private load 5 commercial power source 6 surplus power recovery unit 61 to 66 heater 611 phase controller 621 to 661 Changeover switch 7 Surplus power recovery unit 71 to 75 Heater 76 Auxiliary heater 711 to 751 Changeover switch 761 Phase control device 8 Surplus power recovery unit 81 to 85 Heater 86 Auxiliary heater 811 to 851 Changeover switch 861 Phase control device

Claims (4)

In a cogeneration system comprising a power generator and a surplus power recovery device that recovers surplus power of the power generator in the form of heat, and supplying the power of the power generator to a self-load in synchronization with the power of the power system of the power company,
The surplus power recovery device includes a plurality of heaters connected between the U-phase and the N-phase and between the V-phase and the N-phase of the power generation device, and switches for individually turning on and off the plurality of heaters, A cogeneration system comprising: a device for performing phase control on a current to be supplied to a heater having the smallest rated calorific value among the plurality of heaters. In a cogeneration system comprising a power generator and a surplus power recovery device that recovers surplus power of the power generator in the form of heat, and supplying the power of the power generator to a self-load in synchronization with the power of the power system of the power company,
The surplus power recovery device includes a plurality of heaters connected between the U-phase and the N-phase and between the V-phase and the N-phase of the power generation device, and switches for individually turning on and off the plurality of heaters, A cogeneration system comprising: an auxiliary heater connected between a U phase and a V phase of the power generation device; and a device that performs phase control on a current to be supplied to the auxiliary heater. In a cogeneration system comprising a power generator and a surplus power recovery device that recovers surplus power of the power generator in the form of heat, and supplying the power of the power generator to a self-load in synchronization with the power of the power system of the power company,
The surplus power recovery device includes a plurality of heaters connected between the U phase and the V phase of the power generation device, a switch for individually turning on and off the plurality of heaters, and the U phase and V of the power generation device. A cogeneration system comprising: an auxiliary heater connected between phases; and a device for performing phase control on a current supplied to the auxiliary heater. In a cogeneration system comprising a power generator and a surplus power recovery device that recovers surplus power of the power generator in the form of heat, and supplying the power of the power generator to a self-load in synchronization with the power of the power system of the power company,
The surplus power recovery device includes one heater having a calorific value Q, and the calorific value is represented by Q * 2 ⁽ⁿ⁻¹⁾ (where n = 1, 2, 3,..., N). A device that connects the two heaters in parallel to the power generation device and controls the phase of the current that flows through the one heater having a calorific value Q, and a switch that individually turns on and off the other N heaters. Cogeneration system characterized by comprising.

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