Solutions of Electrical Control and Management System for thermal power plant based on IEC61850

As an integrated control system of the whole boiler-turbine and its electrical system, the Distributed Control System (DCS) has been widely used in thermal power plants. However, due to the large amount of microprocessor-based protection and monitoring devices in the auxiliary power system, some operation information in the devices can not be detected by the DCS. The devices provides a large number of the protection action Sequence of Events(SOE), measurement, alarm, fault wave record function and so on. To handle the problem, the Electrical Control and Management System(ECMS) which integrates all the electrical devices is widely used in China. The system can achieve the functions such as SOE information collection, measurement, power supply unit control, fault wave recording, auxiliary power consumption rate analysis, energy management, etc., bringing conveniences for the operation and maintenance of power plants. The paper introduces the scheme of ECMS based on IEC61850 for thermal power plants in details, including the ECMS that includes only auxiliary power system of power plant and the integrated ECMS includes the entire electrical system of power plant. For the step-up substation of power plant, primary equipment is placed far away from protection and control devices and bay control units. Using electronic CTs/VTs and intelligent control units can save the amount of cables on site, reduce substation occupied area and solve the insulation, saturation and resonance problems caused by conventional transformers. For the auxiliary power system of plants, protection, control and monitoring devices are installed in the switchgear cabinet that are close to primary equipment. Compared with electronic CTs/VTs, conventional CTs/VTs have more competitive price. Therefore the auxiliary power system inside plants adopts analog sampling method. Protection relay, control and monitoring devices are communicated via GOOSE network to achieve protection functions that can not be- implemented by normal auxiliary power relay devices, such as busbar protection, breaker failure protection, high speed transfer and interlocking functions. The interlocking functions realized by motor protection devices through GOOSE network can be standby or backup of Distributed Control System (DCS). So far, the ECMS schemes discussed in the paper have been applied to many large capacity generators and put into service successfully, including the digital ECMS based on IEC61850 for 1000MW generator units in thermal power plants, the integrated ECMS for 1000MW generator units, and motor interlocking functions based on GOOSE network for a 600MW power plant. With the promotion of the IEC61850 technology in thermal power plants, some new protection and control methods will be necessarily applied, and with the IEC61850 modeling of thermal equipment in the future, IEC61850 technology will get more applications in power plants.