**1. Introduction**

230 Electrical Generation and Distribution Systems and Power Quality Disturbances

Xu, B., C. Y. Evrenosoglu, A. Abur and E. Akleman, Interactive evaluation of ATC using a

Zhang, X. P., C. Rehtanz and B. Pal, Flexible ac transmission systems: Modeling and control,

graphical user interface,

*Springer-Verlag Berlin Heidelberg* 2006.

The problems about power quality have increasingly caused a failure or a malfunction of the end user equipment for the past few years up to now. The problems have concerned with either voltage or current frequency deviation. To have the power quality monitoring done flowingly and completely, the measurement takes an important role on voltage, current, frequency, harmonic distortion and waveforms. Many researchers have used methods of power quality measurement (Dugan et al., 2002; Baggini, 2008) while other researchers have used various protocols to control the system (Auler & d'Amore, 2002). Others have presented the data acquisition based on PC (Batista et al., 2003) or Power Line Communication (Hong et al., 2005) or TMS320CV5416 DSP Processor (Rahim bin Abdullah & Zuri bin Sha'ameri, 2005). Another researcher has applied ARM and DSP processor (Yang & Wen, 2006) or has only applied DSP processor (Salem et al., 2006) to monitoring power quality in real time. In the meantime, the detecting fault signals of power fluctuation in real time and a power quality monitoring for real-time fault detection using real-time operating system (RTOS) are proposed (Yingkayun & Premrudeepreechacharn, 2008,2009) and the low cost power quality monitoring system is suggested (So et al., 2000; Auler & d'Amore, 2009), for example.

This chapter has developed the idea of power quality monitoring system via the Ethernet network based on the embedded system with the two selected ARM7 microcontrollers: ADUC7024 and LPC2368. On account of ADUC7024, it has a function of sampling waveforms and of writing the sampling signals to the external memory. Meanwhile, LPC2368 can execute the main tasks: detecting the fault signals; storing fault data in SD-CARD up to 2 GB; and communicating with PC or laptop via the Ethernet network. The power quality monitoring on the embedded system suggested can acquire the voltage, the status and the frequency. It can send them via network at real time, can operate as stand alone equipment and can display the fault signals in real time of power fluctuation. But anyhow, when being absent, we can download the fault data from the site place, depending on the program configuration. In this case the fault signals can be displayed on the screen of the PC or laptop at real time or can be done after as desired. Moreover, there can be a single

A Power Quality Monitoring System

**2.1 Signal conditioning modules (HCPL-788J)** 

signal conditioning circuit is shown in Fig. 2.

Fig. 2. The circuit of the signal conditioning module

**2.3 Microcontroller boards (ADUC7024 and LPC2368)**

shown in Fig. 3.

are shown in Fig. 4 and Fig. 5.

**2.2 The voltage and frequency measurement and fault detection board (ADE7758)**  This board is the key part of monitoring system of fault detection which refers to sags and overvoltages. In this chapter, ADE7758 integrated circuit has been chosen to operate because of its suitable qualification to detect the fault signals in time. The circuit of the board is

As it is known that the embedded system with the two selected ARM7 microcontrollers which are ADUC7024 and LPC2368 are the developed microcontroller boards, using in this chapter. The first board is used for sampling waveforms and for writing the sampling signals to the external memory and the latter is used for various purposes: (1) reading voltage, frequency and fault detection from ADE7758; (2) storing fault data in SD-CARD up to 2 GB, for communicating with PC or laptop via the Ethernet Network and; (3) controlling the sampling process of the ADUC7024 board. The picture of the two microcontroller boards

Via the Ethernet Network Based on the Embedded System 233

There are actually 3 signal conditioning modules with 3 HCPL-788J integrated circuits for measuring the voltage of the three-phase AC lines in order to send the attenuated AC voltage to the waveform sampling board which the ADUC7024 microcontroller is embedded in. The 3 signal conditioning modules have used the same electronic circuit. The

phase or a 3-phase voltage measurement supported by the power quality monitoring hardware. When working in different places, we can establish the network in various sites and connect via the Ethernet network from a single PC or laptop. The network has the capability to send from the board site to the PC or laptop with high speed up to 100 megabit per second (Mb/s). Nevertheless, it is easy to monitor the power quality monitoring system via the Ethernet network from PC or laptop.

This chapter is organized as follow: Section 2 is the architecture of the power quality monitoring being composed of 2 sets of ARM7 microcontroller boards, 3 signal conditioning modules, external memory board and energy measurement board. Section 3 is the embedded software design with the details of sampling concept, power quality monitoring concept, data frames, configuration data and Ethernet packet structures. Section 4 is the application software to interface the power quality monitoring hardware. Section 5 is the experimental results which are displaying the fault signals from AC lines while being on operation or being done after. Section 6 is the conclusion from the research with the future work suggestion.
