Modernization of the National Wide Dispatch Centers of CADAFE - Venezuela

1 Modernization of the National Wide Dispatch Centers of CADAFE - Venezuela R. Pirela, R. Pargas, and R. Céspedes, Senior Member, IEEE Abstract-- The Compañía Anónima de Administración y Fomento Eléctrico (CADAFE), is one of the most important utilities of the Venezuelan electric sector given that it is responsible for the supply of electricity in the major part of the national territory. With the aim to improve the service to its millions of end users, CADAFE designed an ambitious plan to renovate its National and Regional Dispatch Centers and the data acquisition system using normalized protocols including the recently standardized IEC 61850 at the level of remote data concentrating units interfacing modern Intelligent Electronic Devices (IEDs). The adopted hierarchical architecture is presented highlighting the changes made with the purpose of obtaining the optimal use of the computer resources, the best use of the more than 6000 Km of optical fiber communications and the integration with the distribution control systems and with the commercial and corporate IT platforms. The SCADA platform is described together with the mechanisms adopted for the centralized data base maintenance and the functionality that supports both the analysis and the power system operation. The paper concludes detailing the expected benefits of the project as part of the general Program of the Integrated CADAFE Management Reinforcement. Private 10% Public 90% Net assets US$25000 Million Index Terms-- SCADA/EMS, Control Centers, Power System Operation, Hierarchical Control Systems, Data Communication. T I. INTRODUCTION HIS document presents the conceptual design of the SCADA and Energy Management Systems at high voltage and Distribution SCADA systems for an integrated operation or the power system under CADAFE s responsibility. To this end a hierarchical architecture is presented incorporating the various levels that are defined for these systems. The design has as main objective to allow CADAFE to warrant the security, quality of supply and economy of the power system operation. To achieve this goal CADAFE is in the process of implementing state-of-the art technologically systems supported by a country wide communication network mainly using fiber optic links in a ring configuration. Fig. 1. CADAFE geographical presence in Venezuela Fig. 1 shows that CADAFE has a main role among the public electrical utilities in Venezuela since it is the company that provides electric energy service in almost 70% of the territory of Venezuela. CADAFE up to now has been operating with 6 subsidiaries but a reorganization process will regroup them in a single legal entity responsible for generation, transmission and distribution of electrical energy. CADAFE has in excess of 5 million users and provides services using a complex network at 400/230/115/34.5/13.8 kv. Complete figures about CADAFE are presented in the company website www.cadafe.gov.ve. Approximate figures used for sizing the SCADA needs in CADAFE are as follows in number of substation and data points: R. Pirela and R. Pargas are with CADAFE, Venezuela and R. Cespedes is Director of KEMA Inc. for Latin America.

2 I II II NIVEL NATIONAL REGIONAL DISTRIBUTION SCADA SIZING POWER SYSTEM SUB- STATIONS DATA POINTS GENERATION AND BULK TRANSMISSION 40 6000 TRANSSMISION (AT 230 kv OR HIGHER) 60 9000 SUBTRANSSMISION (AT 115KV) DISTRIBUTION AT 34.5 OR 13.8kV Fig. 2. Sizing of SCADA needs in CADAFE 100 20000 300 75000 II. CONCEPTUAL SCADA CONFIGURATION According to CADAFE needs a top-down conceptual configuration was developed which is based on five Control System levels as shown in Fig. 3: Fig. 3. Conceptual Configuration Level 0: This level corresponds to the Independent System Operador of Venezuela, Oasis, and to the Corporate Coordination of CADAFE. Venezuela has not yet implemented an open Market structure so that no Market Operador exists in this design. Level I: Nacional Control Center and Backup Control Center at the national level. This last one is supported by one of the regional Level II control centers as explained below. Level II: Central, Occidental and Oriental Regional Dispatching Level III: Distribution Dispatching responsible for the management of the distribution in each one of their zones of jurisdiction. Level IV: Substation equipment including: Data Concentrators, RTUs, IEDs and other similar equipment. This depends on the automation level of each substation. All levels are supported by a comprehensive communication architecture which includes the following media: Fiber Optics mostly in ring configuration Digital Power Line Carrier with bandwidths of typically 64Kbps or higher Microwave with Wi-Fi capability. Given the extensive geographical area served by CADAFE, the major part of the data links uses a combination of data communication media. High availability is by design assured by redundant data communications, where available. The next sections explain in more details the role assigned to the control centers at each one of the designed hierarchical levels. A. Level 0 This level corresponds to the highest hierarchical level in the configuration. In Venezuela the supervision and coordination of the operation at the National Interconnected System SIN is the Oficina de Operación de Sistemas Interconnectados OPSIS which is the national ISO. OPSIS operates based on an agreement of the following electrical entities of Venezuela: CADAFE, EDELCA, EDC and ENELVEN. OPSIS interchanges data with the CADAFE National Control Center using the ICCP, IEC 60870-6 standard protocol on top of a TCP/IP network. At Level 0 the hierarchy includes the CADAFE corporate IT systems where CADAFE management and other CADAFE divisions will have mainly user interfaces to receive information. Also at this level corporate GIS/AM/FM/DMS system may reside. B. Level I The National Control Center of CADAFE is responsible for the supervision and coordination of the operation of the CADAFE power system. This center will orient its tasks to strategic operation planning of the generation and transmission systems including: 1. Generation operations planning in order to optimize the operations of the hydro-thermal resources of CADAFE and also to optimize energy interchanges with other utilities both for normal and emergency conditions in coordination with OPSIS, 2. Economic Dispatch in real-time, 3. Frequency and reserve monitoring in the CADAFE system, 4. Load Forecast for the entire CADAFE system, 5. Coordination of Bulk Energy Metering 6. Maintenance Coordination of Transmission and

3 Generation facilities 7. Supervision and Operation Coordination of the Main 400kV and 230 kv transmission network. A full redundant back-up system using the Multisite functionality explained herein below complements Level I control centers. The backup function will be assigned to the Occidente Region given the similar equipment being implemented for this control center. For this purpose a large overlap of the main and backup control centers database will be implemented. C. Level II Due to the complexity and size of the power system to be controlled by CADAFE, three geographic zones for the operation have been defined, these are: Central, Occidental and Oriental. Each one of these systems will have an independent and autonomous SCADA/EMS system supported by the multisite functionality. These systems will perform substation data acquisition, information processing and control functions. Additionally, they will carry out the coordination with the distribution dispatches located at Level III. At this level it is also important to identify the Web services. These will allow sharing information among the regional dispatches with the corporate information system of CADAFE through Internet. D. Level III This level corresponds to the distribution dispatches which will be located in diverse areas of the Central, Occidental and Oriental dispatches (to be defined according to criteria in discussion at CADAFE). These systems could be designed with different functionality depending on the area of assigned responsibility and be installed with three different approaches: Local Distribution Dispatch: It will be located at the same site of a regional dispatch and will use the same infrastructure of hardware and software of the associated regional dispatch. It will have an assigned area of specific responsibility for distribution management; for example, the distribution system of Valera (site where the Regional Occidente Dispatch is located) could be supervised and managed by a local distribution dispatch located in the same building with a minimum additional investment. Satellite Distribution Dispatch: It will be located at a remote site but it will be associated to a regional dispatch and will use its hardware and software infrastructure. This system will have an assigned area of specific responsibility for the distribution management; for example, the distribution electric system of Mérida could be supervised and controlled by a Satellite Distribution Dispatch associated to the system of the Occidental regional dispatch, but located in a different site. Communication support of suitable and reliable bandwidth is required to implant a satellite dispatch. Autonomous Distribution Dispatch: It will have its own SCADA system with its own platform of hardware and software, and therefore it will not be associated to any regional dispatch but will exchange information with the regional dispatch. This approach will be required for complex distribution system that may need local operation. The criteria to define which independent SCADA systems will be implemented are in the definition process. For the information exchange between the autonomous distribution dispatch and the regional dispatch center of its zone, the ICCP protocol over TCP/IP would be used over the optical fiber network. It is important to note that the distribution dispatches will count with local user interfaces of the DMS/GIS functionality. E. Level IV This level encompasses all substation equipment related to control, metering and protection, conventional and automated, including: data concentrators, remote terminal units and IEDs. All information gathering processes as well as the supervisory control execution processes will be made at this level. There are some possible configurations depending on the substation voltage level and its location. Conventional substations will have a Remote Terminal Unit (RTU): this include those that do not require a high level of automation. They will support data gathering of status and analog values, and the execution of commands using conventional technology. Automated substations in which it is convenient to integrate protection, control and metering by means of a data concentrator. The data concentrator allows connecting IEDs and conventional inputs/outputs simultaneously, providing some processing capacity and the ability to locally handle automated functions and data processing. This concentrator will be connected to a substation LAN, with IEDs connected directly to the LAN or to the data concentrator. The integration will take place using network protocols such as IEC 61850, DNP 3i or IEC 60870-5-104. Some existing IEDs could be connected via serial DNP 3.0 and Modbus protocols. Automated distribution substations: this type of configuration will be similar to the previous one, but will additionally count with communications via Wi-Fi. Generation plant stations, which must report data from power units typically above 10 MW capacity to the CADAFE National Dispatch. These will be of a special nature, since the implementation of generation management functions will require substation level equipment to read generation plant data and to execute adequate commands. The design should involve the integration of existing and projected plant controls. III. TECHNICAL OVERVIEW A. Hardware Configuration CADAFE is in the process to implement modern open industry standard SCADA/EMS systems for all the control centers of Level I and II. Fig. 4 presents the main components of one of the Control Center Systems of Level II.

4 Fig. 4. Hardware Configuration The main characteristics of the configuration are as follows: Fully redundant LAN configuration, Full redundancy at the server levels for main applications including Data Base (SDM), Historical Information (HIS), Inter-control Center Protocol (ICCP), Network Applications (NA) and Front End for serial communications, Communications with substations data concentrators using high speed data links, typically 2 MB, with the standard IEC protocol. In addition, the systems will support the DNP 3.0 protocol operating on TCP/IP for this purpose, Serial communications will support the DNP3.0 level 2 protocol to communicate with some existing Remote Terminal Units (RTU). The integration of existing CDC remote terminal units that will remain as part of the control center implementation will use protocol converters to one of the supported protocols depending on the available communication media, WEB server to provide access to selected data for light users that will employ a commercial browser for data access. This may include bulk power consumers in the future, Video Display of latest technology for the presentation of overview data for the dispatchers. B. Software A complete suite of SCADA/EMS is at the base of the control systems software for Levels I and II control centers. The following describes the Multisite functionality allowing the implementation of the conceptual system design explained above. The Multisite function allows connecting all the Level I and II control systems of CADAFE to a Multisite network. The connected control centers register simultaneously process information and fulfill operation control tasks in the geographical areas assigned to them, that is Centro, Occidente and Oriente. In addition the Centro Control System is backed up by the Occidente System using the Multisite functionality. Each control center is autonomous and independent in the Multisite network. A very large data volume will be distributed by means of Multisite over all Level I and II control centers to reduce server loading. The control centers will have similar hardware but different data. However, the functionality may allow to implement Control Centers with different hardware and different responsibilities in case for instance the Multisite functionality is extended to the Level III control centers. The Multisite functionality adopted by CADAFE will run in an environment with the following characteristics: a) Communication between Control Centers All control centers of Levels I and II will be connected via WAN links supporting 100 Mbps in order to allow almost local operation for any operator login into a remote server of another control center. The control centers will communicate with each other using the TCP/IP protocol. The physical connection between the control centers will be redundant using the ring configurations implemented by the Fiber Optics projects of CADAFE using OPGW conductors. b) Control Center Redundancy Multisite features will enable the implementation of a full backup of the National Control Center in the Occidente control center. Besides, the backup of any of the regional control center will be implemented by having all systems sharing a common set of data. In this form operators of any of the regional control centers may perform tasks of another region providing full support between Level II control systems. In this case the areas of information of the control centers will be defined with an appropriate large overlapping allowing two control centers sharing the operation control tasks for the same area. Via Multisite means a control center will be defined with backup functionality for another control center (main system). The main system and the backup system are two autonomous and independent control centers which have identical data model and the same data volume. Identical information areas are assigned to both control centers. The operation control tasks are assigned to the main system. Main system and backup system are master systems for the same data points. The main system always has the data responsibility. The main system is configured as data master system. c) Data Maintenance The data maintenance will be made centrally assigning one of the centers to be responsible for data dissemination. All data model modifications are entered at the data model master and distributed from there to the remaining control centers. For central data maintenance all control centers will have a common data model with identical addressing schemes. The data model modifications are stored intermediately at each control center. After a connection failure or system runup all intermediately queued up data model modifications are requested from an appropriate control center and updated in the data maintenance dependent control center. All control centers have the complete data model with formal identical content of information. The physical data model of the single control centers is known to all other control centers.

5 d) Delegation of Operation Control Task The operation control task will be flexible to move responsibilities between the control centers at the request of the operation supervisor. This will allow operating a control center even unmanned during periods when management requirements are low, which could be the case of future control centers for electrical energy distribution. The Multisite network functionality will allow the control center authority for operation control be defined globally and with overlapping, if necessary. The user authority and the console authority are defined locally as required by the local national or regional operation procedures. e) Data Transmission Local data (captured by the local SCADA functions) and locally calculated values will be made available to other control centers in the Multisite network. Remote control can be done by other control centers, in case the authority for operation control is assigned to that control center. Manual inputs like process substituted values, updating and tagging can be entered by the operator with global or local scope. A local input is only valid for the respective control center. A global input is effective in the whole Multisite network. In case the connection between two control centers fails, then each control center remains in proper autonomous operation condition with the restriction, that in this case only a part of the values may be available, that is, data acquired by another center with failed communication will not be received by the others. However the system robustness allows that after restoration of the connection between the control centers or after system run-up, the data which are necessary for a defined initial status are automatically requested and transmitted. Remote control via the multisite manager is possible at all control centers, if the operation control task is assigned to the respective control center. The commands and setpoints are transmitted to the control center with data responsibility and executed there. The controlling system as well as the system to be controlled make all checks (rights, interlocking conditions, run-time monitoring). As acknowledgment the controlling system gets the status change from the controlled system. In case of no execution because of interlocking conditions, the controlling system receives an error. Detailed diagnostic report is not transmitted from the controlled system. If the connection to the data responsible control center has failed, commands can not be transferred to this control center. In this case a diagnostic report is immediately built at the controlling system. The connection failure to the data responsible control center after sending a command, will be realized by the local time monitoring. Switching procedures are created locally and transmitted via supervisory control in form of single steps, because several control centers may be concerned. Local switching procedures are transmitted in form of single steps. IV. HIERACHICAL CONCEPTUAL CONFIGURATION Figure 5 shows the planned detailed configuration for the implementation of the control centers at the various levels. This configuration includes the different control centers explained above and identifies substation controls for the various voltage levels. The following remarks provide some additional details: 1. The equipment highlighted in blue is part of the implementation of the transmission SCADA systems. They will provide for the operation of all transmission and subtransmission substations. These centers will provide the support of distribution through local and remote user interfaces where needed. 2. A number, yet in the process of being defined, of satellite SCADA systems will complement the previous control centers in order to provide local SCADA functionality for the operation of the distribution networks. 3. Data Concentrators will be implemented in all transmission and subtransmission stations requiring the RTU upgrade allowing collecting data that is presently available through RTUs and also providing for the integration of local Intelligent Electronic Devices, IEDs thus supporting the implementation of substation automation scheme. 4. The IEDs implementation and the implementation of SCADA at the distribution substations is part of a different project that is also being implemented by CADAFE. 5. The boxes in Red are related to the protection relays management which is a future projected function of the regional dispatch. The management of relays will allow the remote change of relays settings including for instance tripping parameters according to the actual network topology. This management is considered important to provide for saving time and resources. V. CONCLUSIONS This paper presented an overview of the control center design of CADAFE. The major components of such design are described in detail. On purpose traditional functionality of SCADA/EMS systems explained in the technical literature are omitted. The main benefits expected form the implementation of these control centers are as follows: 1) Rationalize the expenses of CADAFE in SCADA technology by utilizing at the maximum possible extend the projects already at the development stage and the related communication infrastructure, 2) Provide a solid platform for implementing a National Control center with the functionality directed to support the CADAFE strategies for generation, supply of the demand and selling/purchasing of energy. 3) Support adequately the distribution operation which until now has been mainly coordinated manually without the support of real-time data.

6 Fig.5. Detailed Control Center Configuration of CADAFE The presented design provides for a good support of the CADAFE reorganization and takes advantage of the planned investments on related projects. VI. ACKNOWLEDGMENT The authors thank all CADAFE employees that have provided information that made possible to complete the description of the projects that are addressed in this document. Some of the implementation issues in particular at the distribution level are at the moment of writing still at the design level and thus have to be taken as a preliminary approach and are thus subject to change. VIII. BIOGRAPHIES Raul Pirela is from Venezuela and is presently Transmission Vicepresident of CADAFE. Raul Pirela is Electrical Engineer and has made previously a complete career with ENELVEN the utility of Zulia state where he has held various positions including Vice-president. Ramón Pargas is from Venezuela and is presently the head of the Occidente Dispatch center of CADAFE. He is project manager for the implementation of the new transmission SCADA/EMS platform. Mr. Pargas holds an electrical engineer diploma and has been with CADAFE at various positions in the operations divisions. Renato Cespedes (M76, SM86) is Colombian. He graduated as Electrical Engineer (1972) at the University of the Andes (Colombia). He obtained a Ph.D. in Engineering from the National Polytechnique Institute of Grenoble, France. He is Director Latin America with KEMA Inc.and associate professor at the National University of Colombia, Bogota. VII. REFERENCES [1] CADAFE, Modernization of the Central and Occidente Control Center Systems Specification, 2004. [2] CADAFE, Distribution SCADA/DMS Automation Project description, and terms of references, 2005. [3] SIEMENS A.G. Functional specifications of the CADAFE control center systems implementation.