Abstract
The time equivalent availability of maximum power for photovoltaics (PVs) is approximately 1500 h per year, and for the wind power plants (WPPs) it is about 3000 h per year. The maximum power generation of PVs and WPPs will occur in several hours per day depending on the season, and for the rest of the day the power will be lower or zero. As a result, the transmission and distribution lines will be highly loaded or overloaded for the previously mentioned specific hours, while during the rest of the year the loading will be lower. In order to overcome the problem of unnecessary reinforcement of lines, this paper proposes less costly operational measures using load and generation flexibility based on electrical distance. According to the Zbus matrix allocation method, the complex power flow of each branch j-k can be expressed as a function of the voltage at node j and the current injections at each node. The electrical distance coefficient matrix represents the electrical distance of the bus i from the branch j-k and it measures the impact of the bus injection on the branch j-k complex power flow. Namely, higher value of electrical distance coefficient means higher impact of the bus i injection on the power flow. The proposed algorithm in this paper uses the electrical distance and load flexibility or generation re-dispatch for solving the overloads in the network. Firstly, power flow is solved, which enables to detect the overloads in the network. After that, the Zbus matrix and the electrical coefficients matrix are calculated. We are observing the row of electrical distance coefficient matrix that corresponds to the overloaded branch(es). The maximum electrical coefficient is detected in that row and load or generator in the corresponding bus is scaled (+ or −) appropriately to solve the overloading(s). The proposed methodology will be tested on distribution and transmission network. The results will be presented and discussed.