JPH0236045Y2 - - Google Patents

Description

[Detailed description of the invention] This invention controls the temporal arrangement of the energization time of electric water heaters that utilize late-night surplus electricity, thereby controlling the time distribution of electric water heaters during late-night power hours at a central electric station, such as a substation. The aim is to equalize the total late-night power demand with the general load.

Currently, electric power companies are installing synchronous motor type time switches on the power supply circuits of consumers who use late-night surplus electricity in order to efficiently utilize late-night surplus electricity.
Electricity is supplied at a lower price than general electricity rates only during late-night hours, such as from 11pm to 7am. However, with the recent spread of electric water heaters that use late-night power, the late-night power period begins at 11 p.m.
Immediately after that, the time switches in each household turn on all at once and start energizing the electric water heaters.
Immediately after that, the peak demand for electricity tends to continue for a while. In addition, the amount of water used in electric water heaters in each household varies depending on the household or season, so even if the power is turned on at the same time, the amount of water remaining in the water heater boils to the specified temperature. There is a lot of variety depending on the situation. Figure 1 shows the relationship in which the distribution of water heater energization times measured by a monitor changes depending on the season, with the horizontal axis representing the energization time H, and the vertical axis representing the number of electric water heaters having this energization time. The rate N is expressed in %. C ₂
is the curve for February, C ₅ is for May, and C ₉ is for September.
As shown in the figure, the average power-on time in summer is 2~
3 hours, and 4 to 5 hours in winter. Depending on this situation, peaks and declines in power demand will occur during late night hours. Figure 2 shows the relationship between the nighttime time t and the power demand P at the central electric power station for the summer. According to this, the general load excluding electric water heaters increases as shown by curve B in the late night time period t ₁ → t ₂ . _However , the electricity demand including the general load and the electric water heater peaks in the first half of the midnight period, as shown in curve E, and conversely It will decline in the second half of the year. In this respect, a decline in power generation efficiency and power transmission efficiency has become a problem.

In order to solve the above-mentioned problems, the present invention uses a mainly electronic time switch device equipped with a function to detect the amount of hot water in an electric water heater instead of the conventional synchronous motor type time switch. The system automatically adjusts the time distribution of electricity to electric water heaters, thereby leveling out late-night electricity demand.

The specific configuration will be explained below with reference to the drawings. First, in the conventional device shown in Fig. 3, the electric water heater power supply wiring 1 is connected to a synchronous motor type time switch 2
Power meter 3 → Electric water heater 9 via safety breaker 4
supply power to Time switch 2 is a synchronous motor 2m
and a contact 2a that opens and closes in connection with it, and the contact 2a is connected to the start time _t1 of the late-night power period, for example, in the afternoon.
Closes at 11 o'clock and ends at the same time t ₂ For example, 7 a.m.
It is set to open at the same time. In the electric water heater 9, the line from the safety breaker 4 is connected to the heater 7 of the hot water storage tank 6 via the earth leakage breaker 5 and the thermostat 8. The thermostat 8 is always closed and the heater 7 heats the water in the tank 6.
When this water turns into hot water and reaches the set boiling temperature _T1 , it opens and heating stops.

According to the above-mentioned conventional device, the start time of the late-night power period at each consumer using the late-night surplus power
Immediately after _t1 , the contacts 2a of the time switches are closed almost all at once, so the power demand P at the central electrical station, such as a substation, increases dramatically at this time. Thereafter, the amount of hot water remaining in the tank differs depending on each customer, and therefore the energization time H of the heater 7 differs, so the power demand P at the central electric power station decreases somewhat slowly. Therefore, the electric power demand obtained by adding the electric water heater to the demand curve B due to the general load described above is the curve E shown in Figure 2.
The value is particularly high in the first half of the late-night power period, and it is not possible to achieve the desired leveling of power demand.

In FIG. 4 showing one embodiment of the present invention, 10
is the entire energization time control device according to the present invention,
Among them, a control power supply 11 receives power from the electric water heater power supply wiring 1 and supplies a control voltage to all of the various elements shown within the dotted line on the right thereof. Auxiliary control power supply 1
Reference numeral 2 denotes a compensator that supplies a control voltage within the dotted line in place of the power supply 11 when there is a power outage or failure. The power switch 13 is turned on at the time determined by the control result and transfers the power from the power supply wiring 1 to the power meter 3 and the safety breaker 4.
The water is supplied to the electric water heater 19 through the. Inside the water heater 19, an earth leakage breaker 5, a hot water storage tank 6, a heater 7 and a thermostat 8 are provided, as in FIG. 3, and a sensor 20 is also bonded to the outside of the tank 6. . This sensor is, for example, a thermistor whose resistance value changes depending on the temperature, and the resistance changes depending on the level from above that hot water is present in the tank 6, and its value, that is, the average temperature T ₂ of the water in the tank. The represented value is sent as a signal to the control device 10.

In the control device 10, an A-D conversion circuit 16
converts the signal from the sensor 20 from an analog signal such as resistance or voltage to a digital signal such as frequency or number of pulses, and sends this to a control processing unit (CPU) 15. The data section 18 contains various necessary data, including the current time, the start time t ₁ of the late-night power period, and its end time t ₂ as well as the set value T ₁ of the boiling temperature of the water in the tank 6, and the capacity V of the tank 6. , the capacity W of the heater 7, etc., and transmits this to the unit 15 at any time. The display section 17 is given various values processed and generated within the unit 15 and displays them.

An electronic timer mechanism is provided within the control processing unit 15, which is started by a start signal from the data section 18, while the other mechanisms are on standby. Starting time of late night power period from data section 18
When the t ₁ signal is input, the required value calculation mechanism starts.
First, the required number of energization hours H _o of the heater 7 is calculated by the following formula.

H _o =V×(T ₁ −T ₂ )/0.95×W×860 Of these, the average temperature T ₂ of the water in the tank 6 is introduced from the sensor 20 via the A-D conversion circuit 16, and other values, that is, the tank The boiling temperature setting value T ₁ of the water in the tank 6 , the capacity V of the tank 6 , and the capacity W of the heater 7 are introduced from the data section 18 . 0.95 is the heating efficiency of the heater 7, and 860 is the conversion coefficient from KW to Kcal.

Next, we move on to calculation of the time t ₃ at which power supply to the heater 7 starts. In the present invention, the temporal position of energization to the heater 7 is centered at the start time t ₁ of the late-night power period.
and the end time t ₂ to coincide with the center time t ₀ . However, this is the case where the general load curve B is at its lowest at the center time _t0 and is symmetrical, as shown in FIG. So within CPU15,
When only the data at times t ₁ and t ₂ come from the data section 18, the average value, ie, the center time t ₀ , is obtained, and then half of the required energization time, ie, H _o /2 is obtained from it.
, that is, a time earlier than time t ₀ by time H _o /2, and set this as t ₃ , and this calculated time t ₃
When the CPU 15 actually arrives, the driver 1
4 to instruct the switch 13 to close. The driver 14 amplifies the power of this input signal and sends it to the switch 13.
is turned on, and energization of the heater 7 is started.

After that, the energization time of the heater 7 is H _o according to the above calculation formula, so the energization end time is a time delayed by the time H _o /2 from the center time t ₀ .
The actual operation of terminating this energization is performed by opening the thermostat 8. If the above-described calculation formula for the required number of energization hours H _o is correct, the above-mentioned calculated value and the actual value of the energization end time should roughly match. Next, when the CPU 15 sends an off signal to the driver 14 at the late-night power period end time t ₂ sent from the data section 18, this signal is power amplified and sent to the switch 13, which opens the circuit. but,
Normally, the energization of the heater 7 is terminated by opening the thermostat 8 before this, so no substantial change occurs at this point. This open state of the switch 13 continues through the daytime of that day until the nighttime power period start time _t1 , and then the same process is repeated.

As mentioned above, by dividing the energization time H _o of the heater 7 into two equal parts before and after the central time t ₀ of the late-night power period, it is possible to Whereas the time curve has a minimum at the center time t ₀ and rises symmetrically before and after that, as shown in curve B shown in Fig. 2,
On the contrary, the load vs. time curve for an electric water heater is highest at the center time t ₀ and decreases symmetrically before and after that, so when both loads are added, the total becomes curve F in Figure 5. By comparing this with the conventional total load curve E that reproduces the second diagram, it can be seen that the leveling of late-night power demand P has been effectively achieved. In addition, as shown in Figure 1, the energization time H of an electric water heater differs depending on the season or each customer, but the load versus time curve at the substation, which is the sum of these times, is centered at the center time t ₀ and then Since there is no difference in that the shapes decrease symmetrically, there is no fundamental difference in the effect of the late-night power demand leveling described above.

If the shape of the load vs. time curve for general loads other than electric water heaters is not symmetrical as shown in curve B in Figure 2, but is biased to one side, for example, during the first half of the late-night power hours, In the case where a large factory is installed that operates during certain hours of the day, the load vs. time curve of the electric water heater to compensate for this shift will also be in the opposite direction to the above deviation, that is, in the above example, during the late night power hours. It has to be shifted somewhat to the second half of . Therefore, instead of the center time t ₀ for the general load with respect to the curve B, assume the average center time t ₄ of the load, which means that the time integral value of the load before this time is equal to the same value of the load after this time. The center time t ₀
An appropriate corresponding time t ₅ on the opposite side of the above time t ₄ is selected based on , and the temporal position of the load is shifted so that this time becomes the center of the load versus time curve of the electric water heater. Therefore, in this case, as shown in Figure 4
In the CPU 15, half of the required energization time H _o of the heater 7 is subtracted from the above time t ₅ , that is, the time t ₅ .
A time _t6 that is earlier than that is calculated and a closing command signal for the switch 13 is given to the driver 14 at this time. Note that the above-mentioned corresponding time t ₅ does not necessarily mean that the deviation between t ₅ and t ₀ is equal to the deviation between t ₄ and t ₀ , but is appropriately determined in consideration of various circumstances. This time _t5 may be given directly to the data section 18. Furthermore, if time t ₅ is after time t ₀ , it is conceivable that the energization end time when the thermostat 8 of the heater 7 is opened is later than the end time when the switch 13 is opened at time t ₂ . Care must be taken to prevent this from occurring by appropriately selecting time _t5 .

According to the present invention, by appropriately selecting the temporal position of the energization time of the electric water heater, it is possible to equalize late-night power demand at the central electric station and improve power generation efficiency and power transmission efficiency.

[Brief explanation of drawings]

Figure 1 is a curve diagram showing the relationship between the energization time of electric water heaters for each consumer and the number rate of electric water heaters for various seasons, as compiled by the Central Electricity Station, and Figure 2 is a curve diagram showing the relationship between the energization time of electric water heaters for each customer and the number rate of electric water heaters corresponding to that, calculated at the Central Electricity Station, and Figure 2 shows the relationship between midnight time and the center 3 is a circuit diagram of a conventional electric water heater that uses late-night power; FIG. 4 is a circuit diagram of an electric water heater that uses late-night power according to the present invention; FIG. 5 is a curve diagram showing a situation in which late-night power demand is leveled by the present invention in comparison with a conventional example. 1: Power supply wiring, 4: Safety breaker, 5: Earth leakage breaker, 6: Hot water storage tank, 7: Heater, 8: Thermostat, 9, 19: Electric water heater, 11: Control power supply, 10: Energization time control device, 12 : Auxiliary control power supply, 13: Power switch, 15: Control processing unit, 16: A-D conversion circuit, 18: Data section,
20: Temperature sensor.

Claims (1)

[Claim for Utility Model Registration] A-D conversion that converts an analog signal from a sensor 20 that is glued to the outside of a hot water storage tank 6 of an electric water heater and detects the average temperature _T2 of water in the tank 6 into a digital signal. circuit 16, the set value T ₁ of the boiling temperature of the water in the tank 6, and the central time t ₀ during the late-night power period (t ₁ → t ₂ ) or the general load at the central electric station based on this time. A data unit 18 that transmits each signal regarding the corresponding time t ₅ on the opposite side to the average central time, and a data unit 18 that receives each output signal of the conversion circuit 16 and data unit 18 and is connected in series to the power supply circuit to the heater 7 of the electric water heater. The control processing unit 15 transmits an output signal for controlling the closing of the switch 13, and this unit 15 converts the heater 7 from the output signal of the conversion circuit 16 and the output signal regarding the boiling temperature set value _T1 of the data section 18. A circuit that calculates the required energization time H _o and the above time obtained from the output signal of the data section 18.
The circuit is equipped with a circuit that calculates a time t ₃ or t ₆ that is earlier than _{t 0} or t ₅ by half of the required energization time H _o , respectively, and the switch 13 is closed at this time t ₃ or t ₆ . Electric water heater energization time control device.