pf.py 文件源码

def find_tree(sub_network, weight='x_pu'):
    """Get the spanning tree of the graph, choose the node with the
    highest degree as a central "tree slack" and then see for each
    branch which paths from the slack to each node go through the
    branch.

    """

    branches_bus0 = sub_network.branches()["bus0"]
    branches_i = branches_bus0.index
    buses_i = sub_network.buses_i()

    graph = sub_network.graph(weight=weight)
    sub_network.tree = nx.minimum_spanning_tree(graph)

    #find bus with highest degree to use as slack
    tree_slack_bus, slack_degree = max(degree(sub_network.tree), key=itemgetter(1))
    logger.info("Tree slack bus is %s with degree %d.", tree_slack_bus, slack_degree)

    #determine which buses are supplied in tree through branch from slack

    #matrix to store tree structure
    sub_network.T = dok_matrix((len(branches_i),len(buses_i)))

    for j,bus in enumerate(buses_i):
        path = nx.shortest_path(sub_network.tree,bus,tree_slack_bus)
        for i in range(len(path)-1):
            branch = next(iterkeys(graph[path[i]][path[i+1]]))
            branch_i = branches_i.get_loc(branch)
            sign = +1 if branches_bus0.iat[branch_i] == path[i] else -1
            sub_network.T[branch_i,j] = sign