Grid Code - A Way to Guarantee System Security

摘要

Power system security requires that the integrated operation of power plants and network comply with the plans in all operational circumstances, including disturbances. It is essential that power plants remain synchronized in the network and perform as planned in case disturbances occur. Otherwise disturbances may lead to brownout or blackout, making the restoration process more difficult and taking a considerably longer time.Grid codes are a phenomenon resulting from separation of plant and grid ownership and control. In historical integrated ownership structures, the internal practices, precedents and common engineering organization made the management of the plant-to-grid interface a natural and essentially invisible function. There was no question as to the common interests of plant and grid elements. Each one recognized inherently that his economics and reliability depended on the other. Under dissociated ownership, it's been necessary to create commercial, administrative and legal definitions of obligations at the interfaces. The technical facts are essentially unaltered by changes in commerce and administration at the interfaces; only the way costs and responsibilities are assigned has changed.It is very necessary to ensure that actions taken in the interest of efficient administration processes do not inadvertently compromise the many technical aspects of plant design, plant or grid operation. It is equally desirable to ensure that the design of new plants, particularly in their control room aspects, is well suited to the dissociated operational responsibilities mandated by the grid codes. As many electric power systems move toward deregulation, there has been much focus on the economic issues associated with the new competitive operating environment; details of energy trading and pricing have been put in the forefront. However, the system must have ability to operate in such an environment, with an acceptable and adequate degree of security and reliability.In the new environment, power systems comprise corporate entities having diverse roles, equipment and business interests. There may be independent generating entities, transmission entities, distribution entities and brokering entities. However, the physical functioning of the integrated power system remains the same as before. Therefore, the responsibility for stability and control should be vested with the Independent System Operator (ISO). Otherwise, system security and economy would be sacrificed, defeating the very purpose of reestructuring the industry.The evolving process of connection requirements and Grid Codes for traditional and distributed generators will be discussed in the paper, in order to check the best paths to follow aiming power system security and the integrity of generators units. Current demanded minimum requirements in Brazil will be shown, making a comparison with the demanded requirements in other countries.