Erfan Mohagheghi

Real-time optimal power flow under wind energy penetration-Part I: Approach

Real-time optimal power flow (RT-OPF) under wind energy penetration is highly desired but extremely difficult to realize. This is basically due to the conflict between the fast changes in wind power generation and the slow response from the optimization computation. This paper (Part I) presents a prediction-updating approach to address this challenge. We consider essential scenarios around forecasted data of wind power that would probably happen during the computation time required for solving a large-scale complex optimal power flow problem. Parallel computing is used to solve the individual OPF problems corresponding to these scenarios. This provides for the forecasted time horizon probable reference operations in the form of a lookup-table. One of these operations will be selected based on the actual wind power and realized to the grid for the current time interval, thus leading to a RT-OPF framework. The proposed approach is implemented in Part II of this paper using a 41-bus medium-voltage distribution network as a case study.

A Study of Uncertain Wind Power in Active-Reactive Optimal Power Flow

Wind power fluctuates with time and it is reasonable to regard it as a random variable. Recently, an active-reactive optimal power flow (A-R-OPF) method in active distribution networks with wind stations has been developed to handle the problem of wind power curtailment (WPC). Since the mentioned method is deterministic, it may fail to handle uncertain wind power (UWP). Therefore, our study in this paper will firstly discuss the issue of UWP and secondly develop a new strategy which can improve the A-R-OPF by considering UWP. The new strategy can be distinguished from the original so that: 1) it considers shorter time intervals, i.e., 15 minutes instead of one hour and 2) it can handle both UWP and WPC simultaneously. The effectiveness of the new strategy is shown by using a real case medium-voltage distribution network. Keywords-active-reactive optimal power flow (A-R-OPF); medium-voltage; uncertain wind power (UWP); wind power curtailment (WPC).

Real-time optimal power flow under wind energy penetration-Part II: Implementation

In this paper (Part II) we implement the prediction-updating approach developed in Part I to address fast changes in wind power generation when solving a complex realtime optimal power flow (RT-OPF) problem. The approach considers essential scenarios around forecasted wind power values in a moving prediction horizon (120 seconds). The individual optimal power flow problems corresponding to these scenarios are solved in parallel using a multi-processor server. Then the operation strategy is updated in a short sampling time (every 20 seconds) considering real wind power values. The RT-OPF problem is formulated considering both technical and economic aspects simultaneously. The RT-OPF is implemented on a 41-bus medium-voltage distribution network with two wind stations. The results show the benefits of the proposed approach and highlight further challenges of RT-OPF.