Analysis Of Dynamic Natural Frequency Response And Ace Time Series

In the operation of interconnected power system, the standard to evaluate the control performance is needed to evaluate and govern the behavior of different control areas. The standard should make the power system operate reliably and benefit from the interconnected power system. At present, the second generation evaluation standard which was built based by the theory of the relationship between ACE(Area Control Error) and frequency bias is adopted both in the domestic and on overseas. It can evaluate the mixed performance of primary and secondary frequency control and produces a well result in the practice.In domestic, secondary frequency control is charged, on the contrary, as the necessary function of generator primary frequency control has to be supplied for free; the second generation evaluation standard is weak in evaluating the ability of primary frequency control and the cost of primary frequency control is also higher than secondary frequency control. The two reasons result in the shutting down of primary frequency control by power plant operators, which causes the decline of primary frequency control ability and the safety of system frequency is also affected. Therefore it is necessary to develop a standard which can evaluate primary frequency control separately.Beginning with the principle of frequency regulating, the paper makes a deep analysis of the procedure of primary frequency control. Dynamic natural response coefficient is proposed for the first time by the paper. It is found that the widely used natural response coefficient which can’t be used in describing the dynamic procedure of primary frequency control is just the steady value of dynamic natural response. By the analysis of dynamic characteristic in time domain, the time series of dynamic natural response coefficient can reflect the primary frequency control ability of the control area.In consideration of the difficulty in acquisition of the time series of the primary frequency control, by a theoretical analysis, the paper investigates the dynamic characteristic of the widely used parameter ACE in interconnected power system and draws a conclusion that the reason of ACE’s dynamic changing is resulted by the dynamic changing of natural response coefficient. In other words, ACE time series is the reflection of the dynamic response procedure of primary frequency control. Because the static natural response coefficient neglects the dynamic procedure and only the static ACE can be calculated, the static ACE can’t be used to evaluate the performance of primary frequency control. The time series of ACE includes the information of dynamic procedure of primary frequency control, and can be used as a way to evaluate the ability of primary frequency control independently. The data of dynamic ACE can be obtained by WAMS, which makes the separate evaluation of primary frequency control feasible by using the dynamic series of ACE.The paper proposes a method of analyze the time series of ACE on the basis of dynamic natural frequency. The method can be used as the theoretical basis and the design idea in building a new evaluation standard for evaluating primary frequency control separately.