Models And Methods On Optimal Allocation For Supply/Demand Side Reserve Considering Power Network Constraints

With rapid growth of power flows and increase of power system uncertainty, risks of transmission congestion continuously rise and their influence on reserve deliverability becomes more severe. Therefore, coordination between reserve and transmission capacity should be taken into consideration in reserve allocation. On the other hand, along with the development of smart grid, many demand side management (DSM) tools emerge to make demand side capacity become an important type of reserve. Therefore, cooperation of supply and demand side reserve should also be considered in reserve allocation. By studying the coordination mechanism of reserve and transmission capacity, and improving the cooperation level of supply and demand side reserve, the operation capability on both security and economy, and the operation reliability of power systems can be reinforced.The paper focuses on the optimal allocation of spinning contingency reserve, aiming to establish models and algorithms of optimal reserve allocation considering power network constraints and demand side reserve. Firstly, based on reserve cost and value analysis, the principle of optimal reserve allocation is clarified. Secondly, with simplified demand side reserve model, the reserve allocation methodology based on cost-value decomposition is developed. Thirdly, with characteristics of demand side reserve highlighted, the cooperative optimization methodology of supply/demand reserve is proposed, in addition, the cooperative allocation model of supply/network/demand reserve is established to analyze the cooperation mechanism of network/demand reserve.The reliability and economy of power systems must be balanced in reserve allocation, the essence of which is the coordination of reserve cost and value. The valuation architecture for reserve cost and value, and the clarification of the optimal condition of reserve allocation constitute the basis of optimal reserve allocation. The paper analyzes reserve cost and its components, reserve value and its influence factors. Based on marginal analysis, the reserve supply model and demand model is established. In supply model, the opportunity cost resulted from energy and reserve coupling is considered, and in demand model, power network constraints, contingency probability and involuntary load curtailment are considered. From both economic and mathematical aspects, supply-demand equilibrium is proved the necessary condition of optimal allocation. Based on supply-demand equilibrium, the dynamic ranking method is designed and applied in economic dispatch (ED), to verify the theoretical derivation and lay the foundation for cost-value decomposition.Correction control simulation of massive contingency states is needed in reserve allocation, which results in large computation burden. In order to balance accuracy and efficiency, the reserve allocation methodology is proposed based on cost-value decomposition under ED. Models based on optimization and on deterministic criteria are both developed by considering power network constraints to coordinate reserve and transmission capacity, simplifying demand side reserve as negative generation and employing mixed integer programming (MIP) to linearize objective function. The reserve allocation structure based on cost-value decomposition is constructed, based on which the Benders decomposition method for optimization model and the value distinguishing method for deterministic model are designed to coordinate reliability and economy in a decomposition way, where each system state is decoupled from each other and can be solved independently to effectively balance accuracy and efficiency.Other than supply side reserve, load recovery interval follows demand reduction considering the non-interruption requirement and the aggregation control strategy of demand side reserve, which must be considered in supply-demand reserve cooperation. Under dynamic economic dispatch (DED), a method for cooperative allocation of supply/demand side reserve is proposed based on deterministic model. MIP is employed to model load recovery effect and the algorithm is developed by extending the value distinguishing method which doesn’t introduce Lagrange multipliers and can address load recovery easily, so that the method can avoid memory bottleneck and shorten computation time. Based on the cooperative allocation model for supply/demand reserve, the cooperative allocation model for supply/network/demand reserve is established by modeling transmission capacity as network side reserve, which is applied to analyze the cooperative mechanism of network/demand side reserve.