Geng Jian

The interior point branch and cut method for optimal power flow

As a complex mixed integer nonlinear programming problem, optimal power flow (OPF) is hardly to be solved by strict polynomial-time algorithm. In this paper, we present an interior point branch and cut method (IPBCM) for decoupled OPF problem. We use the modern interior point algorithm to solve active power suboptimal problem because it is very efficient for nonlinear programming problem. Reactive power suboptimal problem is a mixed integer nonlinear programming problem, we use IPBCM to iteratively solve its linearizations. Compared with simplex cutting plane method, IPBCM is more efficient because of its polynomial-time characteristic. Furthermore, we discuss some important issues in the implementation of IPBCM. Numerical simulations on IEEE 14-57 buses standard test systems have shown that the proposed method is efficient in solving OPT problems for large-scale power systems.

Comparison of block bidding and hourly bidding based on case study

Hourly bidding is the widely used bidding mechanism in present power markets, by which load demand is divided and auctioned hour by hour (or half hour by half hour) to form the spot price. However, this bidding mechanism has some shortcomings, such as uncertainty, randomness of unit commitment and price spikes, because of its inconsistence with the continuity features of electric energy production. Block bidding is a new bidding mechanism in which demand load are divided into multiple blocks with continuous segments and the auction is performed for each block. In this paper, market rules and models for block bidding are introduced. With these rules, it is convenient for power supplies to determine unit operation and make bidding decisions; also, it is convenient for market operating. Based on IEEE-RTS data, hourly bidding and block bidding are compared. Results show that Block Bidding is a suitable and simple bidding mechanism for power auction. Furthermore, as contrast with hourly bidding, block bidding gains a large payment savings and. makes the market more efficient.

New mode to schedule and price hydro power in market environment

A new mode to schedule and price hydro power in a hydrothermal system is presented in this paper. By which hydro energy is optimally scheduled in priority, thermal units bid for remainder load demand and clear the market, and then hydro energy is paid for the price cleared by thermal units. Based on the characteristic of hydro energy, market rules are proposed first in the paper, and a schedule method based on the principles of production simulation is presented to optimize hydro energy. The price paid for hydropower is proved to be equivalent to the equilibrium price when hydro and thermal power bid simultaneously. Numerical simulation and analysis are carried out based on an actual power system. Simulation results show that the proposed mode for hydro power can sufficiently utilize its capacity and energy in market environment, and the payment correctly reflects the hydro contribution to the power system. In power market, it is a simple mode to realize hydro efficiency and comprehensive social benefits; also it is an effective way to avoid hydro plant abusing market power