Research On Operation Reserve Of Power System With Wind Power Integration

The burst of wind power development has become one of important measures of the electric power system to cope with energy crisis and environment deterioration. Although the wind has characteristics of being renewable, clean, having no pollution, low running cost and many other advantages, but the random fluctuation of natural wind has led to high uncertainty of wind power and the difficulty in prediction. When the wind power with high uncertainty has been integrated into the grid, it may bring both the green energy and a lot of adverse effects on power system operation at the same time. Meanwhile reserve which is an effective measure to guarantee the safety and reliability of power grid operation will also be influenced greatly. In order to apply wind power resources economically and efficiently, it is totally imperative to analyze and solve the reserve problems with wind power integration.Based on the theory of power system risk analysis and the mathematical optimization theory, according to the characteristics of wind power and wind power prediction under different time scales, this paper aims to analyze the influences of wind power integrating into grid on different reserves in the system. Furthermore, the problems of the optimized reserve acquisition in the power system containing wind, the joint optimization of determintion and acquisition of the reserve capacity, and the reserve cost allocation will be studied comprehensively and deeply.In order to solve the problem of deficiency and diseconomy of generation side reserve in the system with wind power integration, the use of combination of interruptible load reserve on demand side with the traditional reserve access will be proposed. The analysis of the probability distribution of "equivalent load" prediction error shows that the increased reserve capacity after the high uncertainty wind power integration belongs to the small probability of reserve demand. Based on this characteristic, this paper proposes the strategy that the combination of high compensation interruptible load on demand side with generation side reserve may deal with the increased reserve demand. In the case of wind power output is not large, the strategy can solve the shortage problem of generation side reserve. At the same time, the system economy will be improved. Further analysis shows that, with the increasing of wind power output, the reliance on only generation side reserve and high compensation interruptible load to solve the increased reserve demand will lead to economic benefits decrease, which may definitely lead to the loss of its advantages. Therefore, a kind of reserve acquisition way with the combination of two kinds of interruptible load with low price and high compensation together with generation side reserve is put forward. Based on the principle of risk management, the minimum purchase cost will be regarded as the objective function and the optimal proportion of the three will be set. In the premise of maintaining system reliability, the proposed acquisition way is better in the economy than the way only resorting to generation side reserve.Aiming at the identification problem of reserve capacity under the condition of high wind power output, a joint optimization approach is proposed to determine and acquire the capacity of reserve based on the analysis of the system demand and supply. Through analysis of influence of various uncertain factors on the system reserve requirement, the reserve demand curve with wind power integration is obtained. Because different types of reserve cost have different sensitivity to the reserve called frequencies, this paper proposes to process the reserve demand curve in different segments. Based on the different characteristics of different segments adjusting probability, the reserve suppliers of different segment will experience optimal selection. Thus, based on the method of cost benefit analysis, the optimal way to acquire the reserve is obtained with the determination of the optimal reserve capacity. Theoretical analysis and numerical result show that the proposed joint optimization method can solve the poor economy problem caused by relying only on the generation side reserve with wind power integration. At the same time, since the system reliability is taken as one part of the reserve social cost as a reserve benefit way, the method considers both the reliability and economy of the system, leading to the improvement of both two significantly.As a non-profit organization, Independent System Operator needs to allocate the purchase costs related to the purchase of reserve which occurs for the safety and stability of power grid operation to responsibility parties including the one brings in the reserve and the beneficial owner of the reserve set. Under the condition of wind power being integrated into system, this paper proposes the allocation principle according to the responsibility for reserve cost, and regards wind power as one of the responsibility party that causes the reserve to join cost allocation. Based on different mechanisms for two kinds of cost, the two-step allocation way is put forward.To the reserve capacity cost, because the values of capacity in different positions for risky parties are different, the segmented allocation way of is put forward. To the reserve electricity cost, since the reasons that lead to reserve application tend to be different, it should be allocated to the responsibility party which brings in power unbalance to reflect the fairness. The example analysis shows that the segment allocation mode of reserve capacity cost can be more precise to clarify the responsibility that causes reserve demand, and the allocation mode of the reserve electricity cost also reflects the allocation principle according to responsibility which can avoid the problem being unable to allocate reserve cost due to the non-application of reserve in the traditional allocation way. The proposed allocation methods can bring in encouragement more effectively to reduce the reserve requirement, which can lead to more efficient resource allocation.The above studies show that the reserve acquisition way of interruptible load corporation with generation side reserve can effectively solve the deficiency of traditional reserve and the diseconomy problem after large scale of wind power integration, in the reflecting of economic advantage. The joint optimization method to acquire and determine the capacity of reserve can ensure the system reliability after large scale of wind power integration and achieve the goal to improve economy. The two-step cost allocation way based on responsibility can provide an effective incentive to different parts in the system and achieve the goal to reduce the reserve demand fundamentally. The solution to the above reserve related problems can effectively improve the system ability of acceptance of large-scale of renewable energy and improve the stability and economy of system operation at the same time.