CHAPTER 1 1.0 BACKGROUND TO SCADA - Electrical Engineering Portal
CHAPTER 1 1.0 BACKGROUND TO SCADA 1.1 INTRODUCTION. What is SCADA? The acronym SCADA stands for Supervisory Control and Data Acquisition. SCADA is an industrial monitoring measurement and control system. It consists of a central station, field data gathering elements (RTUs) and a collection of standard and/or custom software used to monitor and control remotely located data elements. Contemporarily SCADA system exhibit predominantly open loop control characteristics and utilize predominantly long distance communication. Similar system to SCADA systems are routinely seen in factories, treatment plants etc. These are often referred to as distributed control systems (DCS). They have similar functions to SCADA systems, but the field data gathering or control units are usually located within a more confined area. Communications may be via a local area network (LAN), and will normally be reliable and high speed integrated. A DCS system usually employs significant amounts of closed loop control. SCADA systems on the other hand generally cover larger geographic areas, and rely on a variety of communication systems that are normally less reliable than a LAN. Supervisory refers to the actual seeing and monitoring of the system. Control is the real operation. It involves the sending and receiving of commands. Data acquisition is the most important part of SCADA system. It involves the collection of data. Data collected includes: · Measurements i.e. voltage, frequency, current and reactive power. · Indications i.e. ON or OFF switches, auto or manual transformers, open or closed CBs. · Alarms i.e. for system operation 1 AYISI VALENTINE F17/8244/04 2009
1.2 HOW SCADA WORKS In most SCADA systems, the master unit sequentially scans the remote terminal units (RTUs), by sending a message to each RTU to inquire whether the RTU has anything to report. If it does, the RTU will send a message back to the master, and the data received will be put into the memory of the computer for processing. The scan of all RTUs in the systems will be completed in approximately 2s. However, in the event of trouble at a remote station, a message will be sent from the remote unit to the master. The normal scan will be interrupted long enough for the master to receive the message and provide an alarm so that the master unit can automatically perform predetermined control actions. In any event, in most cases, the status of all stations equipped with RTUs can be monitored every few seconds, providing the operations at the control center with-up-to-date reviews of the system conditions. CENTRAL STATION POWER LINE TRANSFORMER 1 RTU 1 . RTU X TRANSFORMER N RTU 1 RTU Y . FIGURE 1.1 GENERAL SCADA SYSTEMS SCHEMATIC 2 AYISI VALENTINE F17/8244/04 2009
1.3 SCADA ARCHITECTURES SCADA systems have evolved in parallel with the growth and sophistication of modern computing technology. The following sections will provide a description of the following three generations of SCADA systems: First Generation – Monolithic Second Generation – Distributed Third Generation – Networked 1.3.1 Monolithic SCADA Systems When SCADA systems were first developed, the concept of computing in general centered on “mainframe” systems. Networks were generally non-existent, and each centralized system stood alone. As a result, SCADA systems were standalone systems with virtually no connectivity to other systems. The Wide Area Networks (WANs) that were implemented to communicate with remote terminal units (RTUs) were designed with a single purpose in mind–that of communicating with RTUs in the field and nothing else. In addition, WAN protocols in use today were largely unknown at the time. The communication protocols in use on SCADA networks were developed by vendors of RTU equipment and were often proprietary. In addition, these protocols were generally very “lean”, supporting virtually no functionality beyond that required scanning and controlling points within the remote device. Also, it was generally not feasible to inter-mingle other types of data traffic with RTU communications on the network. Connectivity to the SCADA master station itself was very limited by the system vendor. Connections to the master typically were done at the bus level via a proprietary adapter or controller plugged into the Central Processing Unit (CPU) backplane. Redundancy in these first generation systems was accomplished by the use of two identically equipped mainframe systems, a primary and a backup, connected at the bus level. The standby system’s primary function was to monitor the primary and take over in the event of a detected failure. This type of standby operation meant that little or no processing was done on the standby system. Figure 1.2 shows a typical first generation SCADA architecture. 3 AYISI VALENTINE F17/8244/04 2009
1.3.2 Distributed SCADA Systems The next generation of SCADA systems took advantage of developments and improvement in system miniaturization and Local Area Networking (LAN) technology to distribute the processing across multiple systems. Multiple stations, each with a specific function, were connected to a LAN and shared information with each other in real-time. These stations were typically of the mini-computer class, smaller and less expensive than their first generation processors. Figure 1.2 First generation SCADA architecture Some of these distributed stations served as communications processors, primarily communicating with field devices such as RTUs. Some served as operator interfaces, providing 4 AYISI VALENTINE F17/8244/04 2009
the human-machine interface (HMI) for system operators. Still others served as calculation processors or database servers. The distribution of individual SCADA system functions across multiple systems provided more processing power for the system as a whole than would have been available in a single processor. The networks that connected these individual systems were generally based on LAN protocols and were not capable of reaching beyond the limits of the local environment. Figure 1.3 Second Generation SCADA Architecture 5 AYISI VALENTINE F17/8244/04 2009
1.3.3 Networked SCADA Systems The current generation of SCADA master station architecture is closely related to that of the second generation, with the primary difference being that of open system architecture rather than a vendor controlled, proprietary environment. There are still multiple networked systems, sharing master station functions. There are still RTUs utilizing protocols that are vendor-proprietary. The major improvement in the third generation is that of opening the system architecture, utilizing open standards and 13 protocols and making it possible to distribute SCADA functionality across a WAN and not just a LAN. Open standards eliminate a number of the limitations of previous generations of SCADA systems. The utilization of off-the-shelf systems makes it easier for the user to connect third party peripheral devices (such as monitors, printers, disk drives, tape drives, etc.) to the system and/or the network. As they have moved to “open” or “off-the-shelf” systems, SCADA vendors have gradually gotten out of the hardware development business. These vendors have looked to system vendors such as Compaq, Hewlett-Packard, and Sun Microsystems for their expertise in developing the basic computer platforms and operating system software. This allows SCADA vendors to concentrate their development in an area where they can add specific value to the system–that of SCADA master station software. The major improvement in third generation SCADA systems comes from the use of WAN protocols such as the Internet Protocol (IP) for communication between the master station and communications equipment. This allows the portion of the master station that is responsible for communications with the field devices to be separated from the master station “proper” across a WAN. Vendors are now producing RTUs that can communicate with the master station using an Ethernet connection. 6 AYISI VALENTINE F17/8244/04 2009
CHAPTER 2 2.0. TECHNOLOGY BACKGROUND 2.1 SUPERVISORY AND CONTROL FUNCTIONS 2.1.0 INTRODUCTION The SCADA system is a general hardware and software concept providing a flexible set of functions. The actual use of the SCADA system is specified by parameters defined in the database. This brings down system costs, increases system reliability through its well-proven design, and makes project development and implementation safe. It further constitutes a basis for implementing more advanced functions. They provide for further development of the control system once it has been put into operation. This is a basic requirement since it must be possible to add new power system components which are going to be monitored and controlled by the control system. This chapter gives an overview of the SCADA functions available in control systems today. First, the collected and processed data are presented and then the basic monitoring and event handling of these data are described. 2.1.1 Data Acquisition The basic information with regard to the power system is collected by equipment in the various substations and power plants. The distributed control system equipment enables remote data acquisition. Data may also be entered manually or calculated. These data are treated exactly like the automatically collected data. Data acquisition operation is required to: · Read power system measurement data from RTUs into the control computer under program control. · Detect and handle data error conditions due to RTU and communication system malfunctions and noise. 7 AYISI VALENTINE F17/8244/04 2009
· Scale and convert analogue data into binary form directly usable by the computer programs. · Interface with database manager (DBM) that generates data base addresses, and store data in database. · Store only error free data, quality indicators should be set to denote error conditions. · Complete the scan in minimum possible time before the next scan begins. 1. Status indicators The status of CBs, indicators, alarm signals and other signals is represented by means of “status indicators”. These status indications are contact closings connected to digital input boards. Normally there are both single (1-bit) and double (2-bit) status indications. Double indications are normally for circuit breakers, disconnectors and other two-state and the other bit represents the CLOSE-contact and the other bit the OPEN-contact. This facilitates detection of false and intermediate values. 2. Measured values Measured values of various kind e.g. voltage levels, active and reactive power flows, temperature and tap changer positions are collected by the control system. These values then represent the momentary state of the measuring point. Two types of values are normally collected. · Analog values, transformed via an A/D converter o a binary format- supported without time tag · Digitally coded values- supported without time tag 3. Energy values Energy values are obtained from pulse counters. The pulse counting normally involves two registers: a continuous counter and a time interval register. The pulse counters are frozen locally in the controlled stations at specified point of time i.e. (when the time expires, a transfer is 8 AYISI VALENTINE F17/8244/04 2009
initiated from the counter to the time interval register). The generally accepted time is one hour. Then the counter continues on for the next hour and the register content is collected as part of the normal scanning. The frozen counter values are reported spontaneously. The included time tag is the point of time for the freezing. 4. Commands and clock synchronization Both single and double object commands are supported. Regulating step command is supported. Set point command and bit string commands are also supported. Clock synchronization is initially performed according to the procedure defined. However, if the controlling station does not reply on ‘delay acquisition command’ the controlling station will adapt to that. The clock synchronization is performed according to the user convention. 2.1.3 Man/Human-machine interface (MMI/HMI) Man-machine communication is of utmost importance in modern control systems. Few functions are fully automated, and most require man to interact with the computer system. The design of the man-machine subsystem involves many ergonomic features that are of equal importance to the purely technical ones. MMI is required to provide the following capabilities and facilities: Ø VDU Displays The color VDU is the state-of-the-art medium for presenting information to the operator at a console. The VDU gives the operator an efficient and flexible tool for obtaining as to the state of the power and control systems. All the data in the system database are available for presentation on VDU. The only requirement is the specification of a display. This is easily achieved since it is an inherent function of the modern SCADA system. Displays objects with power information on the operator console monitor e.g. § Online diagrams § Alphanumeric tabular displays 9 AYISI VALENTINE F17/8244/04 2009
§ Lists of various kinds or curve diagrams Figure 2.1 The main SCADA Display 10 AYISI VALENTINE F17/8244/04 2009
Ø Data entry This is via console keyboard. Requirements include: § Initiation of control actions § Manual data entry into the data base § Data entry forms – for passing parameter to a program All data entry operations may be selected by cursor from menu of options. Interrupt is serviced from the console hardware and places the console entries into the data entry input queue. Ø Audible alarms The audible alarm is the system’s way of notifying the operator about an alarm situation. Sometimes one audible alarm is shared by the entire control room but often each console has its own audible alarm, so that activation follows the actual console authority assignment. If the system implements different priority levels for alarms, this can also be reflected in a set of audible alarms. When power system goes into an emergency state an alarm condition occurs. Once it occurs, it must be properly detected and identified. The operator should be notified with a short message displayed on the monitor. This message must contain sufficient information to enable the operator identify the alarm condition, evaluate its threat to security of the power system, and decide on the corrective measure to be taken. An important definition task is to define the alarm condition to be checked and determine where and how to perform alarm condition detection and identification. Ø Printer outputs The operator normally obtains information about the state of the power system via the VDUs of the consoles. For permanent records of the state, various output units are introduced in the system configuration. The documents produced are used for operational follow-ups, documentation purposes and maintenance of the control system database. 11 AYISI VALENTINE F17/8244/04 2009
2.1.4 Performance monitoring Performance monitoring function is required to enhance the operational availability of the SCADA system. Response time is the manifestation of control system performance as seen from the operator’s point of view. Response time is defined as the time from the request of a function until the complete result of the function is ready. The requirements on system response time of showing data to the operators, or of performing control commands, greatly affect the design of the system and need to be looked into deeply. The reason why response time is important is that long delays cause stress and are very annoying to the operator. Stress is caused by disruption of the operator’s thought process. Humans in a problem solving situation use the short term memory of their brains. This short-term memory is characterized by low capacity and high volatility. A basic requirement (and design goal) is that the availability of SCADA system, its communication system and RTUs must be greater than the corresponding availability of the power system network. That is, to be of value, the SCADA system must remain in operation during power system outages, faults, and failures caused by electrical and mechanical malfunctions or hostile environment conditions. Basic philosophy of performance monitoring is that any single fault within the SCADA system shall neither stop the system from operating nor disturb the power system. 12 AYISI VALENTINE F17/8244/04 2009
2.2 Components of SCADA system 2.2.0 Introduction. In order for the aforementioned functions to be achieved a clear understanding of the following factors that relates to the components becomes critical: I. Components capabilities and limitations II. Functional and design features (definition and evaluation) III. Environmental and functional requirements IV. Operational timeline and resource utilization V. Future functional expandability requirement Generally there are three basic components of a SCADA system; they are:2.2.1 Remote terminal unit (RTU) The remote terminal units (RTUs) read status and information from the power system process, report changes and information to the central system and execute commands received from the central system. They have developed in steps from pure hardware units to flexible microprocessor based units. The basic feature which has made it possible to realize a remote terminal unit is storage of data. The collected data may then be processed in different ways leading to advanced RTUs in terms of functional content. The RTU may serve as a filter performing functions which refine data aimed for the central system. The acquisition and control normally found are: · Collection of: indications, analog values and digital values · Collection and accumulation of energy counting pulses · Output of: On/Off controls, Increase/decrease controls, set point values By using the basic features, data storage and data queuing more advanced functions can be realized. 13 AYISI VALENTINE F17/8244/04 2009
More autonomous RTUs and those having a large functional content have more software, and software which can be changed, giving the RTU a certain functional content or adapting the RTU to various environments. The remote terminal unit (RTU) with power supply, meter sensors, actuators, controlling electronics and communication interface are directly interfaced to the power line through a PLM. Features ü Has a modular and streamlined architecture which simplifies both trouble-shooting and expansion in the field. ü They generate analogue and digital signals that will be monitored by the central station. ü They are normally installed in the meter box and store data in a non volatile memory. Version for both single and three phases are available. ü In a place where meters are nucleated multi-meter interface unit (MMIU) is used. This is an interface that can manage up-to 16 electric meters each with dedicated line, and all with a shared earth. ü They are intelligent devices, which collect, process and record power consumption data from electric meter y picking up the meter-pulse output, converting it to suitable digital format for data processing. They have relay capability in that they resume normal operation when power returns after a failure. ü They have alarm to warn of an impending power interruption. RTU architecture The RTU hardware consists of the following main units: · Central processing unit (CPU) · Memory · I/O interface · Communication interface · Power supply 14 AYISI VALENTINE F17/8244/04 2009
These units or hardware elements can be configured in various structures. The final structure depends on the size of the RTU, as well as the requirements and functions implemented, i.e. the actual use of the RTU. Functional adaptability can be achieved as the functional content generally is determined only by the software. Some RTU functions may require additional hardware, but a modularized concept will support such configuration changes. All intelligent logic and communication functions are included in a single integrated processor card. Field wiring is controlled directly to terminal block monitored on primary types; status, input control, analogue input panel, analogue output panel and control output panel. The I/O panel has a bus address and occupies a single daisy-chained ribbon cable bus to the central processor. Expansion of the RTU requires only the addition I/O panel and re-trapping the central processor panel to define the new print count, no firmware changes are required in the remote central processor. Communication I/O Program memory Micro-processor Power line network Data memory Data control I/O Figure 2.2 RTU architecture 15 AYISI VALENTINE F17/8244/04 2009
Figure 2.3 Typical SCADA system The kernel of flexible SCADA is to provide a flexible and effective platform of data exchange and function coordination. “Flexible” means than the SCADA system is not a point-to-point communication of fixed path, but a communication that can take place between (among) any random two (or more) points at any time. The main functions can be described as follows: a) providing data exchange and data share among independent system b) providing function coordination and result interaction among independent system c) providing data exchange and data share in different locations in distributed system 16 AYISI VALENTINE F17/8244/04 2009
d) providing function coordination and result interaction in different locations in distributed system Figure 2.4 Structure of flexible SCADA system 17 AYISI VALENTINE F17/8244/04 2009
2.2.2 Communication network The communications network is intended to provide the means by which data can be transferred between the central host computer servers and the field-based RTUs. The Communication Network refers to the equipment needed to transfer data to and from different sites. The medium used can either be cable, telephone or radio. The use of cable is usually implemented in a factory. This is not practical for systems covering large geographical areas because of the high cost of the cables, conduits and the extensive labor in installing them. The use of telephone lines (i.e., leased or dial-up) is a more economical solution for systems with large coverage. The leased line is used for systems requiring on-line connection with the remote stations. This is expensive since one telephone line will be needed per site. Dial-up lines can be used on systems requiring updates at regular intervals (e.g., hourly updates). Here ordinary telephone lines can be used. The host can dial a particular number of a remote site to get the readings and send commands. Remote sites are usually not accessible by telephone lines. The use of radio offers an economical solution. Radio modems are used to connect the remote sites to the host. An on-line operation can also be implemented on the radio system. For locations where a direct radio link cannot be established, a radio repeater is used to link these sites. Historically, SCADA networks have been dedicated networks; however, with the increased deployment of office LANs and WANs as a solution for interoffice computer networking, there exists the possibility to integrate SCADA LANs into everyday office computer networks. The foremost advantage of this arrangement is that there is no need to invest in a separate computer network for SCADA operator terminals. In addition, there is an easy path to integrating SCADA data with existing office applications, such as spreadsheets, work management systems, data history databases, Geographic Information System (GIS) systems, and water distribution modeling systems. 18 AYISI VALENTINE F17/8244/04 2009
2.3 SCADA Protocols In a SCADA system, the RTU accepts commands to operate control points, sets analog output levels, and responds to requests. It provides status, analog and accumulated data to the SCADA master station. The data representations sent are not identified in any fashion other than by unique addressing. The addressing is designed to correlate with the SCADA master station database. The RTU has no knowledge of which unique parameters it is monitoring in the real world. It simply monitors certain points and stores the information in a local addressing scheme. The SCADA master station is the part of the system that should “know” that the first status point of RTU number 27 is the status of a certain circuit breaker of a given substation. This represents the predominant SCADA systems and protocols in use in the utility industry today. Each protocol consists of two message sets or pairs. One set forms the master protocol, containing the valid statements for master station initiation or response, and the other set is the RTU protocol, containing the valid statements an RTU can initiate and respond to. In most but not all cases, these pairs can be considered a poll or request for information or action and a confirming response. The SCADA protocol between master and RTU forms a viable model for RTU-to- Intelligent Electronic Device (IED) communications. Currently, in industry, there are several different protocols in use. The most popular are International Electro-technical Commission (IEC) 608705 series, specifically IEC 60870-5-101 (commonly referred to as 101) and Distributed Network Protocol version 3 (DNP3). 2.3.1 IEC 60870-5-101 IEC 60870-5 specifies a number of frame formats and services that may be provided at different layers. IEC 60870-5 is based on a three-layer Enhanced Performance Architecture (EPA) reference model (see Figure 4.1) for efficient implementation within RTUs, meters, relays, and other Intelligent Electronic Devices (IEDs). Additionally, IEC 60870-5 defines basic application functionality for a user layer, which is situated between the Open System Interconnection (OSI) application layer and the application program. This user layer adds interoperability for such functions as clock synchronization and file transfers. The following descriptions provide the basic scope of each of the five documents in the base IEC 60870-5 tele-control transmission protocol specification set. 19 AYISI VALENTINE F17/8244/04 2009
Standard profiles are necessary for uniform application of the IEC 60870-5 standards. A profile is a set of parameters defining the way a device acts. Such profiles have been and are being created. The 101 profile is described in detail following the description of the applicable standards. · IEC 60870-5-1 (1990-02) specifies the basic requirements for services to be provided by the data link and physical layers for tele-control applications. In particular, it specifies standards on coding, formatting, and synchronizing data frames of variable and fixed lengths that meet specified data integrity requirements. · IEC-60870-5-2 (1992-04) offers a selection of link transmission procedures using a control field and optional address field; the address field is optional because some pointto-point topologies do not require either source or destination addressing. · IEC 60870-5-3 (1992-09) specifies rules for structuring application data units in transmission frames of tele-control systems. IEC 870-5-101 Application Layer (OSI Later 7) IEC 870-5-102 IEC 870-5-103 IEC 870-5-5 Link Interface Link Layer (OSI Layer 2) IEC LLC- Lake Layer MAC- Lake Layer Physical Interface EC 870-5-1 IEC 870-5-1 Physical Layer (OSI Layer 1) Figure 2.5 Enhanced Performance Architecture 20 AYISI VALENTINE F17/8244/04 2009
These rules are presented as generic standards that may be used to support a great variety of present and future tele-control applications. This section of IEC 60870-5 describes the general structure of17 application data and basic rules to specify application data units without specifying details about information fields and their contents. · IEC 60870-5-4 (1993-08) provides rules for defining information data elements and a common set of information elements, particularly digital and analog process variables that are frequently used in tele-control applications. · IEC 60870-5-5 (1995-06) defines basic application functions that perform standard procedures for tele-control systems, which are procedures that reside beyond layer 7 (application layer) of the ISO reference model. These utilize standard services of the application layer. The specifications in IEC 60870-5-5 (1995-06) serve as basic standards for application profiles that are then created in detail for specific tele-control tasks. Each application profile will use a specific selection of the defined functions. Any basic application functions not found in a standards document but necessary for defining certain telecontrol applications should be specified within the profile. Examples of such Tele-control functions include station initialization, cyclic data transmission, and data acquisition by polling, clock synchronization, and station configuration. The Standard 101 Profile provides structures that are also directly applicable to the interface between RTUs and IEDs. It contains all the elements of a protocol necessary to provide an unambiguous profile definition so vendors may create products that interoperate fully. 2.3.2 DNP3 Protocols define the rules by which devices talk with each other, and DNP3 is a protocol for transmission of data from point A to point B using serial communications. It has been 20 used primarily by utilities like the electric companies, but it operates suitably in other areas. The DNP3 is specifically developed for inter-device communication involving SCADA RTUs, and provides for both RTU-to-IED and master-to-RTU/IED. It is based on the three-layer enhanced performance architecture (EPA) model contained in the IEC 60870- 5 standards, with some alterations to meet
1.0 BACKGROUND TO SCADA 1.1 INTRODUCTION. What is SCADA? The acronym SCADA stands for Supervisory Control and Data Acquisition. SCADA is an industrial monitoring measurement and control system. It consists of a central station, field data gathering elements (RTUs) and a collection of standard and/or custom software .
Part One: Heir of Ash Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26 Chapter 27 Chapter 28 Chapter 29 Chapter 30 .
TO KILL A MOCKINGBIRD. Contents Dedication Epigraph Part One Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Part Two Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18. Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 Chapter 24 Chapter 25 Chapter 26
DEDICATION PART ONE Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 PART TWO Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 Chapter 21 Chapter 22 Chapter 23 .
About the husband’s secret. Dedication Epigraph Pandora Monday Chapter One Chapter Two Chapter Three Chapter Four Chapter Five Tuesday Chapter Six Chapter Seven. Chapter Eight Chapter Nine Chapter Ten Chapter Eleven Chapter Twelve Chapter Thirteen Chapter Fourteen Chapter Fifteen Chapter Sixteen Chapter Seventeen Chapter Eighteen
18.4 35 18.5 35 I Solutions to Applying the Concepts Questions II Answers to End-of-chapter Conceptual Questions Chapter 1 37 Chapter 2 38 Chapter 3 39 Chapter 4 40 Chapter 5 43 Chapter 6 45 Chapter 7 46 Chapter 8 47 Chapter 9 50 Chapter 10 52 Chapter 11 55 Chapter 12 56 Chapter 13 57 Chapter 14 61 Chapter 15 62 Chapter 16 63 Chapter 17 65 .
HUNTER. Special thanks to Kate Cary. Contents Cover Title Page Prologue Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter
Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Chapter 20 . Within was a room as familiar to her as her home back in Oparium. A large desk was situated i
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