J. Energy Power Sources Vol. 2, No. 5, 2015, pp. 189-197 Received: April 2, 2015, Published: May 30, 2015

Journal of Energy and Power Sources www.ethanpublishing.com

Using ZigBee for Wireless Remote Monitoring and Control Ali Ibrahim RASHPETCO (Rashid Petroleum Company), Cairo, Egypt Corresponding author: Ali Ibrahim ([email protected]) Abstract: Wireless sensing technology can collect pressure, temperature, and flow measurements in remote and often unsafe locations that is common in the offshore/on land oil and gas industry without cables and the associated problems. However, the severe offshore conditions make it necessary to develop reliable and cost-effective real-time monitoring structures when building offshore control and monitoring systems. Nowadays, ZigBee RF standard is deployed. This has opened new perspectives for wireless control networks. ZigBee is powerful and easy to install because it was developed in order to be installed in a new or existing sensor network. RASHPETCO has many geographically distributed offshore platforms. Some types of ZigBee radio modules provide a transmission range over 40 km with multi-hop communication capability to extend the coverage. Many oil and gas applications, where ZigBee technology can be deployed, can be overseen. (1) The use of ZigBee to build a redundant wireless controlling/monitoring system for remote installed valves and metering stations; (2) Monitoring pressure/temperature at the well head, i.e., intrinsically safe sensors use ZigBee technology to transmit well head readings from a hazardous area to a safe area. This paper proposes an innovative method for designing remote monitoring and control systems of offshore platforms based on ZigBee wireless sensor networks. The fundamental idea, as studied in this work, is of great value for building reliable and economically affordable real-time monitoring systems for subsea production arrangements (offshore and on land) with enhanced safety and efficiency. Keywords: Offshore, wellhead, ZigBee, wireless.

1. Introduction Oil and gas represents some of the most demanding environments

with

unique

and

challenging

communications needs. Oil and gas companies rely on automation and control technologies to monitor and manage various operational activities including leak detection, cathodic protection, flow measurement, wellhead control and environmental monitoring. Well owners, rig operators, gas producers and exploration companies are using wireless to increase productivity, reduce costs and improve safety [1]. Offshore remote monitoring and control particularly through radio signals, is finding more and more popularity, the need to collect pressure, temperature, and flow measurements

in remote and often unsafe locations is common in the oil and gas industry. As the industry grows and technology advances, the drive to measure, record, and transmit data in real time goes up. Implementing instrumentation into an offshore drilling or wellhead monitoring application involves a variety of systems. Wired sensors and equipment require electrical power, cables, and conduit to reach measurement devices often in remote locations also besides the constraints of running long distances and the possibilities of obstacle electrical power may not be available. This can be costly, inconvenient, and often impossible. One of the biggest concerns is operation in risky and extreme offshore conditions. Traditional monitoring systems for oil and gas industry mostly use fiber Ethernet for

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Using ZigBee for Wireless Remote Monitoring and Control

communication that represents high cost of operation and maintenance. Wireless sensing technology can do this without cables and the associated problems. Wireless sensing systems can eliminate expensive and inconvenient conduit. Measurement data can be collected accurately in real-time for faster response and decision-making with no loss in system integrity and availability. Wireless sensing systems are an affordable option for offshore production platforms. The cost to equip an entire platform with wireless networks fits within the budget of most offshore operations. Oil and gas companies now can afford to integrate sensors at process points unavailable to traditional wired networks. The technology may also offer benefits for temporary setups, during system installation; and in workover operations [2]. Wireless sensor networks are transmitting and receiving information via radio and comprised of Transmitters, Receivers and Gateways and all are network nodes, each sensing node consist of sensing component, Radio Frequency (RF) transceiver module, antenna, analog-to-digital conversion circuitry, and a power supply. Once a wireless sensor collects the specified data, it transmits the measurements to a gateway device (base station) up on request or periodically or at predetermined signal value. Both sensor and base station have a variety of RF transceivers embedded into their design. The transceivers communicate via specific protocols such as ZigBee, Wireless HART, ISA100, and Bluetooth [2]. Fig. 1 displays how the ZigBee wireless market shares. Some technologies like the Bluetooth have been quite a success story, in the areas like computer peripherals, mobile devices, etc., they could not be expanded to the automation arena. This led to the specification of the

Fig. 1 ZigBee market share projection on 2012.

wireless low data rate personal area networking technology, ZigBee (IEEE 802.15.4), for the home/industrial automation [3]. ZigBee frequency assignments, throughput and are shown in Table 1. ZigBee is a new wireless communication protocol and most of its applications were oriented to home automation applications, nowadays ZigBee is used in industrial automation and process control applications because it has many useful features: Low energy consumption, Low cost, range and obstruction issues avoidance (self healing), up to 250 Kbps of data transfer rate, AES 128 bits data encryption algorithm, auto-configure for work in a net with support for several topologies and unlimited coverage [4]. That makes it suitable for using in monitoring systems for oil and gas industry. ZigBee offers a practical solution due to its low cost, simple structure, and low energy consumption characteristics for Wireless Sensor Network (WSNs). As a promising technology, ZigBee WSN has been widely applied in a variety of areas such as industrial control, health-care system, agriculture monitoring, and traditional energy exploration. However, to our best knowledge, very few works on applying ZigBee to an offshore drilling or wellhead monitoring application have been reported in the literature although ZigBee can be deployed in many oil & gas and process industries. In this paper, our objective is to present an innovative method for designing remote monitoring system for offshore/on-land oil and gas industry with reliable communication in the harsh environment found on offshore platforms. More specifically, we utilize ZigBee WSN to develop a redundant monitoring system for offshore safety valves position feedback. Each sensing node is based on ZigBee radio wireless modules like: XBee by MaxStream and MRF24J40 by microchip Inc. XBee brand ZigBee radio is used in this paper. The XBee wireless communication module adopting the IEEE 802.15.4/ZigBee standards Series I or Series II and a microcontroller. Fig. 2 shows the main idea. As shown in the topology of the proposed

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191

Table 1 ZigBee frequency assignment. Geographical regions Frequency assignment Number of channels Channel bandwidth Symbol rate Data rate Modulation

Options for frequency assignments Europe Americas 868 to 868.6 MHz 902 to 928 MHz 1 10 600 kHz 2 MHz 20 ksymbols s-1 40 ksymbols s-1 20 kbits s-1 40 kbits s-1 BPSK BPSK

Worldwide 2.4 to 2.4835 GHz 16 5 MHz 62.5 ksymbols s-1 250 kbits s-1 Q-QPSK

Fig. 2 Scheme of the proposed system.

system the overall network consists of a data gateway or coordinator which wirelessly polls the data from the local or remote radio nodes. The incorporation of a microcontroller to each wellhead radio node is necessary to allow some form of local logic because the XBee Module by itself is not intelligent. If the used ZigBee coordinator radio module supports long distance. The coordinator can send collected mentoring control data directly to onshore control centre. In some cases, a hybrid approach may be called for, with ZigBee collected mentoring control data for wide area communications across a GPRS/GSM or Wi-Fi network. In this case, the ZigBee coordinator radio module is working as a ZigBee network gateway.

IEEE 802.15.4 standard and ZigBee wireless network technology are the best solution for the implementation of a wide range of low cost, low power and reliable control and monitoring applications within the private home and industrial environment. In our paper each subsystem node is based on the wireless modules XBee which support the IEEE 802.15.4 and ZigBee protocols.

2. Communication Protocols: ZigBee/IEEE 802.15.4/Digimesh

 ZigBee is a wireless communication protocol which works over IEEE 802.15.4 as in Fig. 3. It defines the PHY and MAC layers in the radio device.

Majority of domain analysis are indicating that the

 IEEE 802.15.4 is a wireless standard protocol oriented to the implementation of wireless sensor network applications. This communication protocol drive the physical (PHY) and Media Access Control MAC layers of the device of radio frequency and as in the most of the wireless communication protocols the MAC layer coordinates the access to one channel of radio share for several wireless devices and modules [4].

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Using ZigBee for Wireless Remote Monitoring and Control

Fig. 3 ZigBee is a set of specs built around the IEEE 802.15.4 wireless protocol.

3. XBee Addressing Basics Every XBee radio has a 64-bit serial number address printed on the underside. The beginning or “high” part of the address is 0013A200. The last or “low” part of the address will be different for every radio. It will look something like 40697E8E as shown in Fig. 4. Then there is a shorter 16-bit address that is dynamically assigned to each radio by the coordinator when it sets up a network. This address is unique only within a given network. Generally, each XBee radio can be assigned a short string of text called the node identifier. This allows the radio to be addressed with a more human-friendly name.

4. XBee I/O Features The XBee is capable of directly sending these DIO signals from one module to another without any additional hardware. The XBee has 8 usable DIO lines that can be used to send digital data as shown in Fig. 5. The XBee offers some simple output functions so that basic actuations can also take place without an external microcontroller being present. For example, it is possible to send digital information directly to a standalone XBee radio to have it turn on a light or start up a motor. Each XBee radio has the capability to directly gather sensor data and transmit it without the use of an external microcontroller. This means that we do not always need a microcontroller when building simple sensor nodes with XBee radios. In addition, the XBee offers some simple output functions so that basic actuations can also take place without an external microcontroller being present. For example, it is possible to send digital information directly to a standalone XBee radio to have it turn on

Fig. 4 XBee 64-bit serial number address.

Fig. 5 XBee physical pin numbering.

a light or start up a motor. There are lots of good reasons to use the XBee for direct input or output. By not having an external microcontroller, the overall size of the project is reduced. By using the XBee weight is saved. Also omitting the external microcontroller reduces the power consumption and for sensor networks with hundreds of nodes it can mean saving a lot of money [5]. The XBee Series 2 hardware offers several flexible features for projects that need simple input and output. There are 10 pins that can be configured either as digital inputs for sensing switches and other things that operate like switches, or as digital outputs for controlling LEDs and small motors directly. Larger loads, including ones that run on alternating current, can be operated using these digital outputs via a relay. The first four of these pins can be configured as analog inputs for sensing a huge array of phenomena that scale over a range, like light, temperature, force, acceleration, humidity, gas levels.

5. XBee Communication Modes

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193

Mesh Fig. 6 Basic API frame structure.

XBee module has three communication modes: (1) Transparent mode It is called transparent because the radio simply passes information along exactly as it receives it. This mode is used to send data through the XBee to a remote destination radio. When data is received, it is sent out through the serial port exactly as it was received; (2) Command mode No data are sent, but the local radio is talked to. Transparent mode is used to send data through the XBee to a remote destination radio [5]; (3) API mode API mode is the best mode to choose. It is the most powerful but also the most complicated mode to use. API mode is a frame-based method for sending and receiving data to and from an XBee. API in a set of instructions is divided into four groups as shown in Fig. 6, namely [6]:  Start Delimiter (0X7E) to tell that this is the beginning of the API (1 Byte);  Length is the number of Frame Data Byte (2 Bytes);  Frame Data is specific to each type of message received from the XBee radio;  Checksum is the place to check the accuracy of the data to derive the correct frame size (1 Byte).

6. Network Topologies ZigBee networks can connect together in several different layouts or topologies to give the network its structure. These topologies indicate how the radios are logically connected to each other. Their physical arrangement, of course, may be different. There are three major ZigBee topologies [5], illustrated as in Fig. 7. The types of topologies are: (1) Pair The simplest network is one with just two radios, or nodes. One node must be a coordinator so that the network can be formed. The other can be configured as

Star

Pair

Cluster

Coordinator Router End Device

Fig. 7 ZigBee pair, star, mesh, and cluster tree topologies.

a router or an end device; (2) Star This network arrangement is also fairly simple. A coordinator radio sits at the center of the star topology and connects to a circle of end devices. Every message in the system must pass through the coordinator radio, which routes them as needed between devices. The end devices do not communicate with each other directly; (3) Mesh The mesh configuration employs router nodes in addition to the coordinator radio. These radios can pass messages along to other routers and end devices as needed. The coordinator (really just a special form of router) acts to manage the network. It can also route messages. Various end devices may be attached to any router or to the coordinator. These can generate and receive information, but will need their parent’s help to communicate with the other nodes; (4) Cluster tree This is a network layout where routers form the backbone with end devices clustered around each router. It is not very different from a mesh configuration [5].

7. Components of the Proposed System As a kind of wireless communication technology, ZigBee has broad application prospects. This paper proposes a redundant offshore monitoring system based on ZigBee mesh network. In this system, XBee

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Using ZigBee for Wireless Remote Monitoring and Control

Modules and microchip microcontrollers in addition to the Rabbit SBC BL4S100 Series Single-Board Computer (as gatway) are used to realize the hardware platform and the like C- languages (MikroC, Dynamic C) will be used to construct and realize the software function of the system. And to guarantee the reliability of the system operation, hierarchical networks topology based on mesh will be designed. Fig. 8 shows a general overview of the considered system. The following are the system main components of the considered system. The main components are:  Rabbit SBC BL4S100 Series Single-Board Computer;  The XBee modules;  The XBee USB Adapter;  PIC Microcontrollers;

Fig. 8 General overview of the considered system.

 The application software. (1) Rabbit SBC BL4S100 Series Single-Board Computer It provides Web server functionality. The board shown in Fig. 9 contains the Coordinator XBee Module which easily implements a ZigBee enabled Ethernet gateway suitable for remote monitoring and control. It is an integrated hardware and software platform to easily implement a ZigBee enabled Ethernet gateway ideal for monitoring and control. The series is designed to support the rapidly-increasing use of ZigBee connectivity for applications looking to deploy wireless networking. This board builds feature-rich web pages that allow control and monitoring of ZigBee enabled networks by using ZigBee AT and API command libraries. With two available RS-232 ports, eight analog

Using ZigBe ee for Wireless s Remote Monitoring and Control C

195

Fig. 9 Rabbitt SBC BL4S1000 series single-b board computerr.

inputs and 200 Digital I/O lines, the BL L4S100 is weell suited to handdle a wide rannge of applicaations requirinng ZigBee conneectivity [7]. (2) The XB Bee module The modulle comes in sseveral version ns but all havve similar pin outs o as show wn in Fig. 10. Differencees between XBee versions include the power outpuut, antenna stylee, operating frequency an nd networkinng abilities. The XBee is avaiilable in two major versionns and variants of o those versioons [8]. As in Fig. 11, Devices tthat have a UART U interfacce can connect directly d to the pins of the RF R module. (3) The XB Bee USB adaapter The beneffit of this aadaptor is to facilitate thhe connection off the Base Moodule XBee to o the computeer, whether to uppdate the firm mware or even n to collect datta or control throough the remoote modules. Fig. F 12 shows a sample of XB Bee USB adappter board. X--CTU softwarre allows configguring the XB Bee registers in n a very simplle and intuitive way. The X X-CTU appliccation has thhe resources to update u the firm mware and diaagnostics of thhe XBee/XBee-P Pro modules. (4) The PIIC microcontrroller The PIC188F452 microccontroller hass 16K of codde space, 34 I/O O pins and manny other featu ures in a 40-piin DIP package.. The PIC18F452 features a “C” compileer friendly devvelopment ennvironment, 256 bytes oof EEPROM, Self-programminng, an ICD, 2 caapture/comparre/

PRSM

Chip Wire

U.FL

Fig. 10 Different typees of XBee radiios.

Fig. 111 UART inteerface between n microcontrolllers and XBee modules. m

Fig. 12 XBee USB ad dapter.

PWM functions, 8 ch hannels of 10-bit Analog-too-Digital (A/D) converter, th he synchronouus serial port can be configuured as eitherr 3-wire Seriaal Peripheral IInterface (SPI™ ™) or the 2-wirre Inter-Integgrated Circuit (I²C™)

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Using ZigBee for Wireless Remote Monitoring and Control

Master Valve

Fig. 13 PIC18F452 actual shap and pinout diagram.

bus and Addressable Universal Asynchronous Receiver Transmitter (AUSART). All of these features make it ideal for manufacturing equipment, instrumentation and monitoring, data acquisition, power conditioning, environmental monitoring, telecom and consumer audio/video applications [9], Fig. 13 shows actual shap and pinout diagram for PIC18F452. (5) Application software The development tools that will be used in this project are as follows:  MikroC the mikroC for PIC compiler contains many libraries to create the program that will make it possible to control and monitor devices and process;  Dynamic C will be used for Rabbit SBC BL4S100 board developing; it is designed for use with Rabbit controllers and other controllers based on the Rabbit microprocessor;  X-CTU allows configuring the XBee registers in a very simple and intuitive way.

8. Application Example We conducted our application example by building a model that simulates the real world that allowed us to observe the effect of the environment on the system behavior. Using wireless connectivity to gather necessary data from a remotely located Oil/Gas wells and send it to the data gathering station (Onshore CCR or process platform) to ensure data consolidation at the central control room. As a result, operators can respond with actions that will reduce or eliminate well downtime and reduce the delay in decision making via online monitoring of the critical parameters. Our application example will be the developing of a redundant monitoring

Shutdown Valve Surface Safety Valve Wellhead Control Panel

Down Hole Safety Valve

Fig. 14 Wellhead major valves with control panel.

Fig. 15

Sample of a router node (wellhead node).

system for offshore valves open/close status shown in Fig. 14 that proved to be applicable and efficient. The monitoring system of the platform valves will be developed such that each wellhead control cabinet will contain a preconfigured wireless radio module (Router) shown in Fig. 15 without any modification in the pre-existing system. In this paper an efficient wireless monitoring system based on ZigBee technology and microchip PIC microcontrollers has been established, which is characterized by low cost, good scalability, long range and easy deployment compared to wired installation. Fig. 16 shows the layout of the proposed simulator of three electronic cards that will be integrated into the wellhead control panel (WHCP) and each contains a XBee radio module (router) with coverage signal range of 1.6 km (outdoor) taking into account that by using XBee-PRO radio modules with a dipole antenna we can reach 40 km. By using a high gain antenna we should get a signal up to 80 km. Each wellhead microcontroller is coded using mikroC environment. The microcontroller is responsible for gathering of the wellhead safety valves position feedback. The auxiliary

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197

for each wellhead simulator.

9. Conclusions  There are a lot of field applications where ZigBee technology is viable. The power of ZigBee came from that it can be easily and cheaply developed not only for the new system but also for the existing ones;  The combination of low-cost hardware, very good radio performance makes ZigBee a competitive choice Fig. 16 Front view of the PIC and XBee circuit for each wellhead.

on the wireless market;  Applying WSN in offshore instrumentation will allow quick reaction to any loss of well pressure and maximizing throughput from the well.

References [1]

[2] Fig. 17 A brief overview of the input output circuit of each microcontroller.

hardware circuit attached to each microcontroller in its simplified form is as in Fig. 16. The first part is to transmit the contacts status of the valve to be monitored (open/close status) to the PIC microcontroller input port. The second part is to transmit the open/close commands from the PIC microcontroller output port to the power and control circuits through the buffer circuit. Each XBee module is configured with a broadcaste address and a mesh network of XBee modules will be established. Fig. 17 displays the interconnection circuit between the PIC Microcontroller and the XBee Module

[3] [4]

[5] [6] [7] [8] [9]

http://www.cooperindustries.com/content/dam/public/bus smann/Wireless/Resources/Brochures/bus-wir-br-10125oil-gas.pdf. http://www.offshore-mag.com/articles/print/volume-70/is sue-9/production-operations/how-wireless-sensing-can-be nefit-offshore.html. V.P. Rao, D. Marandin, Adaptive channel access mechanism for ZigBee (IEEE 802.15). G.C. Ayala, H.C. Meza, Wireless distributed I/O system based on ZigBee: Design and implementation, in: First International Congress Instrumentation and Applied Science, Mexico, Oct. 2010. R. Faludi, Building Wireless Sensor Networks, O’Reilly Media, 2010. http://www.thaieasyelec.com/Embedded-Electronics-App lication/XBee-API-Mode-Tutorial-and-LAB.html. Rabbit SBC BL4S100 Series Brochure, http://www.digi.com. M. Hebel, G. Bricker, Getting Started with XBee RF Modules, Version 1.0 (Web release 2). http://www.futurebots.com/fpga.html.