Interconnected Power System Real Power Balancing Control And Its Performance Assessment

Control performance standards are needed to equally divide frequency control responsibility and to qualify area’s control during real power balancing of interconnected power system. And each area should design its control strategy to meet the standards as well as to reduce the cost of the control. Real power balancing standards in China power grids are based on standards in North America. Because differences in many aspects such as area management, area structure etc. are exist between China and North America, there are problems during standard execution in China. The cause of these problems is essentially about a few unsolved theories. Meanwhile, an accurate and easy-to-use simulation scheme is essential on power system researches. The existing simulation schemes are aiming at transient state or steady state simulation. They are not efficient for real power balancing and its relevant researches.On steady state control performance standards, standard comparisons and analyses between North America and China are presented. The results point out that standards of North America are lack of short period assessment, and standard modifications of China aim at assessing short period control performance but the goal is not attained. Furthermore the logic of the standards are destroyed and the minimum control performance line is lost. Penalty redistribution rules are added in China assessment. These rules make standards more complex and harder to be implemented. These analyses construct the base of area control strategy research. On disturbance state control performance, a new standard is presented which uses multiple application conditions including large frequency deviation, large load disturbance, DC-line failure etc. These changes improve frequency safety and make the standards more applicable in China power grids which have lower reserve level, high percent of large capacity units, high wind power penetration level and ultra-high voltage level characteristics.On AGC regulation power decision of area control strategy, an AGC control philosophy using frequency sign prediction is presented based on results of observation that the frequency average sign during long time period can be predicted with high probability. Control strategy using this philosophy can meet the control performance standards while significantly reduce unit movements. On AGC regulation power dispatch phase, a dispatch algorithm using unit model prediction is presented. By using unit model, unit responses are calculated before optimization to avoid non-linear restriction. With curve tracing technique, the complex non-linear programming problem is transformed into simple quadratic programming problem. The dispatch algorithm is easy to resolve and realizes unit power change rate reservation not only to the current time but also to the future. The summation power curve is cut to present the curve trend which reduces regulation reversal between units. The presented algorithm can simplify model solution, improve control efficiency and dispatch results.On simulation research, a new simulation scheme using energy conservation law and rotational energy equation of rigid body as its core algorithm is presented. Because the presented scheme uses external characteristic parameters of models, models are constructed by fewer parameters and linear equation. The presented scheme achieves the accurate needed by real power balancing researches while reducing quantity of parameters and improving simulation speed. The advantages of the presented scheme make it preferable in long-term balancing research or relevant studies of large interconnected power systems.