A practical approach to wireless Power A practical approach to wireless Power Quality, Energy and Facilities Monitoring Quality, Energy and Facilities Monitoring System System P.K. Lee 1 and L.L. Lai FIEEE 2 1 2 1 Powerpeg NSI Limited, Hong Kong 2 Energy Systems Group, City University, London, United Kingdom ABSTRACT • In this paper, the authors discuss the way to adopt the cost effective SMS applications to Power Quality, Energy and Facilities Monitoring System. Also, the limited up to 160 characters will be considered during the design which cannot be used on high data volume such as waveform pattern is not preferred but simple message such as voltage dip % is good enough. System Diagram INTRODUCTION • Short Message Service (SMS) • the SMS is very cost effective transmission media in which real-time connection between point-to-point or point-to-multipoint are not required. • GPRS, 3G or 3.5G network are available, it is more convenient for higher speed data transmission services, consumer can enjoy advanced, feature-rich data services such as color Internet browsing, e-mail on the move, etc. However, SMS is still very popular since it can be used for pushing method without on-line connection and the cost is acceptable in some applications. Characteristic of SMS • SMS may be one of the simple, quick and cost- effective strategy when on-line connection is not needed for remote area and pushing method is preferable such as energy profile collection and alarm reporting, voltage dip % etc. SYSTEM DESIGN CONSIDERATION • Operating Cost the reason for the adoption of SMS is the cost. The SMS offer a very competitive price in many countries already. Some of them, the SMS are even free of charge if they are sent or received from the same mobile services provider • Connection/Connectionless: SMS is a connectionless media. It pushes the SMS to single/multi users or receivers without any point-to-point or point-to-multipoint on-line connection - no feedback or acknowledge Data Volume • It has limit with typically 160 characters • good enough in many cases such as voltage dip %/fault/trip alarm reporting in building services facilities. Energy or water flow date collections from properties management or voltage Dip level from fault recorder in Power Utilities, etc are some typical examples. • waveform in power system is not recommended since it needs a large volume. Data Transmission: • Character length per message is recommended to be adjustable • Transmitted message into few messages when they are over the preset limit • Encryption, Decryption, handshaking, missing data, CRC and priority may need is they are sensitive message or critical data. Encryption • Advanced Encryption Standard AES is one of the most popular encryption standards that is acceptable to many Power Utilities already and can be adopted to SMS or GPRS as well. Data compression • The main purpose for this feature is for cost saving. • It should be done from the modem’s firmware before transmission and after received. • Optional selection only System Scale • the system design for 10 remote sites are different from 100 or 500 remote sites. • Multiple com ports or SMS gateway from the sms server may be necessary when a large system is implemented Intelligent firmware inside the modem • An intelligent firmware can be designed and downloaded into the GSM modem • Example : MODBUS Master firmware inside the modem is able to map the register points inside the PLC or energy meters or any device with MODBUS RTU protocol via RS232 or RS485. You need to design a graphical User Interface (GUI) to download the firmware. • Set points can be defined to monitor those register points for monitoring and controls. • Data dump with interval setting can be defined to collect data from energy meters and push to the SMS Server Software periodically after encryption and compression. • Report to the mobile phone of maintenance staff directly with readable messages Graphical User Interface (GUI) example General Setting Data Records Contact list and contact group GUI example • General Setting : to define the communication of the modem speed and some basic setting during the operation of the modem • Data Records : to define what registers should be monitored and what set points to trigger the alarm • Contact list and group : to define who will receive this message during alarm and which group he belongs to. Eg. Group A has 3 people from contact list, Group B has 1 people from contact list. SMS Server Software design consideration – Graphical User Interface (GUI) – Database structure. – Communication structure. – Data logging such as analogue log. – Graphical plot. – Reporting format. – Sequence of Event (SOE). – Human Machine Interface (HMI). – Diagnostic – Protocol Example Adhoc/ Reset to send comma to modem for data dump Modem COM port configuration Status information Global Event Log Analogue Input (AI) Log Change of Status (COS) Log Alarm Log Thank you!
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