JPH04331500A - Co-generation system - Google Patents

Abstract

PURPOSE:To enhance efficiency of co-generation system by operating the system while switching the lower of receiving power according to a power demand schedule thereby enhancing the operating rate of the system in night time band where power demand is low. CONSTITUTION:One day is sectioned into low and high demand time bands A and B based on a demand schedule. Furthermore, lower limits of receiving power PSA, PSB are set by means of setters VR1A, VR13 in load machine section. When the system is operated, a timer 6 identifies the time band and a relay control section 7 actuates relays RA, RB to select a lower limit of receiving power to be fed to a control section 4. Consequently, the system can be operated efficiently even during the low demand time band resulting in the enhancement of the operating rate of co-generation system.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined heat and power generation system (co-generation system) for supplying heat by in-house power generation and exhaust heat recovery during power generation.

0002

[Prior Art] A cogeneration system is a system that aims to use energy efficiently and economically by recovering exhaust heat from the prime mover and supplying heat during private power generation. It will be introduced in facilities such as hospitals that have both heat demand and heat demand.

[0003] Generally, when grid-connected operation is performed using a cogeneration system, reverse power flow transmission is not permitted, and even an instantaneous reverse power flow phenomenon must be avoided. For this reason, in the past, a method has been used to operate while maintaining the amount of received power above a certain value (see Japanese Patent Laid-Open No. 58-46900).

FIG. 3 shows an overview of a conventional cogeneration system. The commercial power supply is a commercial transformer MOF
and is supplied to the bus bar 1 via the bus bar connection breaker CB1. On the other hand, the electric power generated by generator G is transferred to generator circuit breaker C.
It is supplied to bus 1 via B2.

[0005] The power detection unit 2 includes a transformer PT1 and a transformer C.
The received power P is detected by taking in the bus voltage V and the received current I by T1. Similarly, the power detection unit 3 is connected to the transformer PT2.
, the bus voltage V from the current transformer CT2, and the generator current IG to detect the generator output PG.

[0006] A received power lower limit value PS is set in the setting device VR1 to avoid reverse power flow. This received power lower limit value PS is determined from the relationship of PS≧ΔPLX, where ΔPLX is the maximum steep power change amount of the power demand within the consumer. On the other hand, a power generation output upper limit value PGS that is determined in consideration of the ratings of the generator G and the prime mover E is set in the setting device VR2.

The control unit 4 controls the prime mover E by constant receiving power control so that the received power P does not fall below the lower limit value of the received power.
As a result, if the generator output PG exceeds the generator output upper limit value PGS, the generator output constant control (PG=PGS) is operated. This situation is shown in Figure 4.
Shown below.

[0008] The above-mentioned switching of the control method is performed based on the result of monitoring the received power P. That is, P≧P
If S, constant received power control is selected, and if P<PS, constant generator output control is selected. During steady operation,
Since the power demand is large and P≧PS, operation is performed by constant received power control.

[0009]

[Problem to be Solved by the Invention] In order for a cogeneration system to operate efficiently, it is necessary to balance the demand for electricity and the demand for heat. However,
For example, in a hospital, large medical equipment is used during the day, so power demand is large, but large medical equipment is usually not used at night, so power demand tends to differ greatly between daytime and nighttime. As described above, the received power lower limit PS is determined in relation to the maximum steep power change amount ΔPLX within the consumer, and is therefore determined based on large medical equipment used during the day. As a result, during the night, the operating rate of the generator decreases, the heat recovery temperature decreases, and it becomes difficult to maintain the heat supply temperature, which hinders the reliability and economic efficiency of the system. there were.

[0010] In view of these problems, the present invention provides a cogeneration system that can efficiently combine heat and power in response to fluctuations in power demand.
The purpose is to provide a generation system.

[0011]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes a generator connected in parallel to a power supply system, a prime mover for driving the generator, and recovery of exhaust heat from the prime mover. A co-generation system equipped with an exhaust heat recovery unit that supplies the heat to the outside, a received power detection unit that detects received power, and a control unit that operates a prime mover so that the received power maintains at least a lower limit value of received power. The system is equipped with the following means.

(1) A time zone setting storage unit that stores a plurality of time zones that are set by dividing the driving time.

(2) A timer that identifies to which time zone the current time belongs.

(3) A received power setting storage unit that stores a plurality of received power lower limit values set corresponding to each of a plurality of time periods.

(4) A received power lower limit selection section that selects a value corresponding to the current time from among the plurality of received power lower limit values based on a timer output, and outputs the selected value to the control section.

[0016]

[Operation] According to the present invention, a day is divided into, for example, a high power demand time period and a low power demand time period based on fluctuations in power demand within a consumer, and the time period setting section sets these time periods. The lower limit value of received power during high demand power and the lower limit value of received power during low power demand are set in the received power setting storage unit based on the maximum steep power amount in each time period. When the system operates, a timer identifies which time zone it is currently in, a received power lower limit value selection section selects the received power lower limit value corresponding to the current time, and the received power lower limit value is selected based on the selected received power lower limit value. System operation control is performed. As a result, even during times when power demand is low,
This enables efficient system operation.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cogeneration system according to an embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows the main parts of a cogeneration system according to an embodiment. In FIG. 1, the same or corresponding parts as in FIG. 3 are given the same reference numerals. In this system, the day is divided into low demand time period A (more precisely, time period when heavy load equipment is not used) and high demand power time period B (time period when heavy load equipment is used) based on the demand plan of the consumer. I am planning to do so. Setting of each time zone is performed by inputting a switching time using the time setting section 5. Furthermore, time period A,
Calculate the maximum steep power consumption ΔPLXA, ΔPLXB from the ratings of the load equipment groups A and B used in B, and set the lower limit values of received power PSA and PSB for each time period using the setting devices VR1A and VR.
Set it to 1B.

When the system is operated, as described above, the operation is basically carried out under the received power minimum holding control, but the lower limit value of the received power, which is the standard, is such that the relay contacts RA and RB are alternatively closed. It is selected by That is, the timer 6 identifies which time zone the current time belongs to, and based on the result, the relay control unit 7 controls the relays RA,
By selectively operating RB, the lower limit value of the received power input to the control unit 4 is selected.

FIG. 2 shows how this system operates. Since heavy-load equipment is not used in time period A, the received power lower limit value PSA can be set smaller than PSB. For example, if the consumer is a hospital equipped with radiation medical equipment, etc., the PS
It can be set as A=50KW and PSB=200KW. Therefore, as can be seen by comparing Figures 2 and 4,
It has become possible to increase the ratio of the power generation output (B) to the total power demand (A) and improve the system operating rate. Furthermore, by increasing the operating rate at night, it has become possible to reliably maintain the heat recovery temperature, improving the reliability of heat supply.

[0020]

[Effects of the Invention] As explained above, according to the present invention,
Since the system can be operated by switching the lower limit of received power according to the power demand plan, it is possible to increase the system operation rate during times when power demand is low, such as at night, and improve efficiency and efficiency, which are the key points of cogeneration systems. Economic efficiency improves. In addition, by increasing the operating rate during low power demand hours, the reliability of maintaining the heat supply temperature increases, and the reliability of heat supply also improves.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing main parts of a cogeneration system according to an embodiment of the present invention.

FIG. 2 is a graph showing the operation of the system of the embodiment.

FIG. 3 is a block diagram showing the main parts of a conventional cogeneration system.

FIG. 4 is a graph showing the operation of the conventional system.

[Explanation of symbols]

1... Bus bar 2... Power detection section 3 that detects received power... Power detection section 4 that detects generator output... Control section 5... Time setting section 6... Timer 7... Relay control section G... Generator E... Prime mover VR1A... Setter for lower limit value of received power during high demand power hours VR1B...Setter for lower limit value of received power during low demand hours RA, RB...Relay

Claims (1)

[Claims] [Claim 1] A generator connected in parallel to a power supply system;
A prime mover that drives this generator, an exhaust heat recovery unit that recovers the exhaust heat of this prime mover and supplies it to the outside, a received power detection unit that detects received power, and a received power that maintains at least the lower limit value of received power. In the combined heat and power generation system, the combined heat and power generation device includes a control unit that operates the prime mover so as to operate the prime mover, and a time zone setting storage unit that stores a plurality of time zones that are set by dividing the operating time, and a time zone setting storage unit that stores a plurality of time zones that are set by dividing the operating time, and a time zone to which the current time belongs. a received power setting storage unit that stores a plurality of received power lower limit values set corresponding to each of the plurality of time periods; A combined heat and power generation device comprising: a received power lower limit selection section that selects a value corresponding to the current time from among the received power lower limit values and outputs the selected value to the control section.