Development of Power Signal Distributor for Electronic Power Meters

The Power Signal Distribution Device is a device that distributes the watt pulse (WP) and the End of the interval (EOI) in real time by receiving the power signal from the electronic power meter installed in a building or factory. It is possible to prevent electrical damage of the electronic power meter due to the abnormally applied back electromotive force. And it is possible to construct a redundant system of demand controller and power surveillance system by calculating and analyzing power consumption through power signal provided by the electronic power meter. It is also applicable to demand response monitoring device. Keywords— Demand Controller, Demand Response, Electric Power Management, Maximum Peak Power.


I. INTRODUCTION
Signal d istributor for dig ital power meter d istributes the watt pulse (WP) and the End of the interval (EOI) signals to mu ltiple equip ment such as peak power management devices and demand controllers. It is possible to p revent the electrical damage of the dig ital power meter due to the counter electromotive fo rce applied abnormally in the power management apparatus and to analyze the power use amount through the data provided in the digital power meter and to establish the redundancy of the maximu m power management and power management system. In addition, it is a device capable of provid ing a power signal with a demand response management terminal. The peak power is the maximu m electric power load in a certain period as the base charge of the electricity charge, and is expressed in kW. A lthough there is a d ifference between the method of predict ing the power and the method of controlling the load power according to the technical specifications proposed by KEPCO, the functions of the device for managing the maximu m power are the same. As shown in Fig. 1, when the maximu m power management device receives a signal fro m the meter and calculates the amount of load power in real time. If it is predicted that the used power amount exceeds the target power amount, the connected load device is stepwise blocked, and does not exceed the target amount of power.  Demand Response is a sub-concept of demand management as showed in Fig. 2. It refers to activities to maintain balance of supply and demand through adjustment of electricity rate o r power reduction by instruction of load reduction in case of supply / demand crisis due to peak o f electricity demand. It is a technology that induces the change of electricity usage patterns of electric consumers according to the electricity supply situation such as the peak period through the demand management plan and incentive system.  Because this distributor separates signals fro m meters, we can protect external signal points of meters fro m the falling of a thunderbolt. Moreover, it helps to make duplex configuration of peak power management system, and to provide synchronization information between power data detected fro m SCADA and data fro m KEPCO. Fig. 4 and Fig. 5 show internal module and flowchart of signal distributor for each.

Fig. 4: Internal Configuration of Signal Distributor
Signal distributor consists of signal receiving unit, signal distribution unit, modulation processing unit, and power unit. The signal receiving unit receives kWP signal, and EOI signal fro m d igital power meter. The signal distribution unit distributes the power management signals received at the signal receiv ing unit through a plurality of distribution circuit paths . The modulation processing unit modulates each of the power management signals distributed in the signal distribution unit and generates a distributed power management signal of the signal strength corresponding to the power management signal output from the digital power meter, respectively. The power unit provides power for outputting distribution power management signals generated by modulation processing unit through distribution terminals.

Specification
Specification of signal distributor is showed in Fig. 6 and Table 1.

Interworking method
Input/output terminal of signal distributor has 3 parts: power part, input part from KEPCO meters and output part to distribute signals showed in Fig. 7.

Fig. 7: Input/output Terminals of Signal Distributor
To connect our signal distributor with peak power management device or demand control device, it should be connected as showed in Fig. 6. After signals (EOI, kWP, COM) fro m power meter are connected to input part of signal distributor, it should be connected to output part(7~9 terminal, 10~12 terminal, o r 13~15 terminal) for peak power management device. If an interlocking error occurs, most of all, the terminal connection is often wrong, and then the power calculation in the device received from the output unit is not performed properly.

III. DURABILITY TESTS 1. Voltage Dip / Surge Immunity Test
Signal distributor for this test blin ks kWP LEDs every 2 seconds and EO LEDs every 10 seconds. We use EMS Tester of EM C partner (Model: IMU4000) as measuring equipment, and XBC-DR32H as KEPCO meter signal generator.

Fig. 9: Voltage Dip/ Surge Immunity Tests
Result of voltage dip immunity test and surge resistance test are as showed in Table 2 and Table 3.    IV. CONCLUSION In this paper, we designed and implemented the signal distributor for electronic power meters. And we verify our module as results of voltage dip immunity test, surge resistance test and lightning impu lse test. Our result helps to improve scalability and stability. For the further works, we try to extend it for real-time peak power mon itoring and analysis.