The time-sharing smart electricity meter is a novel single-chip microcomputer-based intelligent electric energy measurement product adapted to the time-sharing charge electricity system. It not only retains the main functions of the original three-phase/single-phase watt-hour meter, but also adds the function of time-sharing calculation of electricity consumption and electricity charges. This method can play a very important role in solving the problem of unbalanced electricity load and giving full play to the existing power generation capacity.
1 Structure principle of smart time-sharing meter
This smart watt-hour meter maintains the current three-phase/single-phase watt-hour meter as the electricity measurement standard, only by making a small photoelectric detection hole on the dial, so that the dial will give a pulse every revolution After the signal is amplified and shaped, the pulse signal is used as the input signal for the external counting pulse of the single-chip microcomputer.
Generally, the smart time-sharing meter can be composed of two parts. The first part is the original three-phase/single-phase watt-hour meter, which can still be used alone as an electricity metering system. That is to say, every time the dial turns through a gear drive, the mechanical counter shows the power consumption. This original function remains unchanged; the second part is the newly added single-chip system, which is mainly to input the signal of the number of turns of the dial from the T0 in the form of counting pulses, and then according to the regulations of the electricity metering system , Properly process this signal, so as to give the user's power consumption for each usage billing period, and then directly calculate the user's electricity bill according to the time-sharing price standard.
Realization of 2 time-share billing
It is very easy to use this kind of smart electricity meter to record the electricity consumption. Its technical difficulty is to separate the electricity consumption according to different billing periods (high, medium and low peak periods), so as to multiply different After the unit price of The key to solving this problem is to have an absolute time standard.
This design uses a programmable timer as the time reference of the smart watt-hour meter. The so-called "absolute time standard" means that even in the event of a power failure, the watt-hour meter does not rotate and no pulse signal is given, the timer must also run as usual. Otherwise, if the power is turned off for a few hours, and the timer stops working for a few hours, the low peak period may be mistaken for the peak period..., thereby disrupting the entire time-sharing billing system. Because power outages occur frequently, a practical time-sharing smart meter must have a backup power source. During the power outage, the processing procedure of the smart watt-hour meter is this: When a power-off signal is detected, the microcontroller can be interrupted by INT1, and the IDL bit of PCON is set in its interrupt service subroutine, so that the microcontroller enters the idle operation state , At the same time access to standby power. Then switch the backup power supply to an external timer so that the timer does not stop working. During the power outage, if the set time has expired, that is, a billing period expires, the timer INT0 will issue an interrupt request signal. Because INT0 is programmed as a high priority interrupt, INT1 is a low priority interrupt, so, and During the interruption period of INT1, it can still respond to the interruption request of INT0, so that the single-chip microcomputer ends the idle operation state, and settles the electricity charges of a certain charging period in the interrupt service subroutine of INT0. Therefore, the use of the idle operating state of the single-chip microcomputer can reduce the consumption of backup power during the power outage; on the other hand, the settlement of electricity bills can also be carried out as usual without being affected by the slightest. After the calculation is completed, the MCU can still be returned to the idle operating state and wait for the recovery of the grid voltage.
In order to distinguish the three different charging periods of high, medium and low peaks, a shiftable flag can be set in the interrupt service subroutine of INT0. Each interrupt is shifted once, 3 times is a cycle, that is, shift 3 After returning to the initial value position. In this way, from the position of the mark, it can determine which billing period the system is in, and then transfer to the corresponding electricity bill settlement subroutine.
3 Main functions of the new smart energy meter
The start and end time of the three billing periods of high, medium and low peaks in a day and the unit price of electricity bills for each period can be input by the power supply department through the keyboard when the smart meter is installed and activated, and then sealed. During the work of the smart meter, the meter should have the following main functions:
(1) The user's cumulative power consumption can be displayed by the original three-phase/single-phase watt-hour meter;
(2) Through the LED display of the single-chip microcomputer system, the cumulative power consumption of each segment, the total cumulative power consumption, the cumulative electricity cost of each segment, and the total cumulative electricity fee can be displayed as required;
(3) Various data can be printed as needed;
(4) You can inquire the electricity consumption and electricity charges in various periods of the day;
(5) has a backup power supply and can be switched automatically.
(6) The above various data can be sent from the serial port as needed, and then transmitted to the central control room of the power supply department through the wired/wireless data transmission machine, so that the power supply department can always understand the electricity consumption and electricity fee settlement of the relevant units Happening;
(7) After the electricity supply department collects electricity bills on a monthly basis, the above amount can be cleared through the reset button and the accumulation starts again;
(8) For power-limiting units, the power supply department can preset the power consumption limit, and it has the function of over-alarm and double-over-billing.
4 Conclusion
According to the time-sharing electricity billing system, and through the single-chip system and absolute time standard, this paper proposes a design method of time-sharing smart electricity meter based on single-chip microcomputer. The realization scheme of time-sharing charging in the system is analyzed in detail.