Terrestrial Energy Management System A terrestrial energy management system contains components with the following functions: supervisory control and data acquisition, automatic generation control, load forecasting, unit commitment, transaction evaluation, optimal power flow, state estimation, contingency assessment, security dispatching and reactive power management-voltage scheduling [1-5, 7]. We assume that the operator assistance functions will be part of the terrestrial ground coordination system. The operator assistance functions are: load forecasting (experiment load demands), unit commitment (equipment scheduling), optimal power flow (power system assessment) and contingency assessment (failure analysis). Only the appropriate automatic functions are discussed within this paper: supervisory control and data acquisition, automatic generation control and state estimation. Contingency assessment and security dispatch are functions to support manual operation and are not proposed for the PMS. A few terrestrial EMSs have an additional control system for relay arming systems [6]. Since a spacecraft power system will be reconfigured for experiments, it is proposed that a computer relay arming system be included. Since the maintenance of the spacecraft power system will be restricted, it is proposed that errors due to instrumentation aging should be corrected by software [8] and maintained only when necessary. The load and generation management (LGM) control system for a spacecraft power system will be capable of commanding load and generation changes. The corresponding controllers for terrestrial power systems are automatic generation control and load management. An automatic generation control (AGC) system controls the generation to follow the load demand. A load management system (LMS) controls the load equipment on the power system to balance the load demand with the power resources. Basic Structure The basic structure of the proposed power management system is shown in Fig. 1. The major functions include: supervisory control and data acquisition (SCADA) [2], state estimation and bad meter detection (SEBMD) [3], system dispatch [4] and parameter update [5] (SDPU), relay setting control system (RSCS) [6], configuration monitor [7] and instrumentation model and parameter update (IMPU) [8], Complete descriptions of these functions may be found in the references cited. The supervisory control and data acquisition (SCADA) function provides control of the communications system for acquiring data and for sending control commands to equipment. The subfunctions of the SCADA function are shown in Fig. 2. The subfunctions include: load and generation management (LGM), system monitoring and alarm processing (SMAP), mode identification (MI) and observability identification (OI). The LGM subfunction balances the dynamic load demands with the generation resources, the dissipation system, the power losses and the power damping systems. The SMAP subfunction updates the database and routes the data to the appropriate subfunction(s). Any required manual intervention would primarily occur through this subfunction. The mode identification (MI) subfunction determines the state of the power system and the status of all pieces of equipment. The observability identification (OI) subfunction determines what the state estimation function can accomplish, if anything.
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