Research On Power Coordinate Optimization Of Offshore Oilfield Power System

Offshore oilfield power system is the independent micro grid which connects neighboring platforms with submarine cables. The platforms were powered alone. Compared with the traditional way, offshore oilfield power system ensures the power safety and efficiency of equipments in the offshore oilfield. So offhsore oilfield power system has been the trend of powering offshore platforms.Recently as the development of wind power and storage technology, China National Offshore Oil Corporation (CNOOC) plans to introduce wind power and storage system into offshore oilfield power system to reduce the gas consumptions and the emission of greenhouse gases such as CO2 through the power generation. However, the conditions of offshore oilfield power system is bad and the engineers lacks the dispatching experience of large power system. After introducing the wind power and storage system, the control variables of offshore oilfield power system increases and so do the difficulties in dispatching and controling the system.To address the issues mentioned above, this thesis proposes the power coordinate optimization of offshore oilfield power system. By coordinating the dimensions of control resources, time and control targets, the complicated dispatching problem with random variables is transformed into the solvable optimization problem with smaller scale. Moreover, the algorithms corresponding different dimensions are put forward.For the dimension of control resources, wind power, storage system and gas turbines are considered. The unit commitment model with state-controllable wind power and the unit commitment model with wind power and storage system are proposed. The former focuses on the circumstance of the weak overload capability of cables and the small number of wind turbines in offshore oilfield power system with small load. Wind turbines are modeled as random power sources with controllable status. The problem is solved by L-shaped algorithm and the coordinate optimization between wind power and gas turbines is achieved. The latter introduces the storage system and large amount of wind power into the unit commitment problem based on the power system with huge load. The unit commitment of wind power, storage system and gas turbines is obtained by solving the problem with Benders decomposition algorithm so the coordinate optimization in control resources dimension is implemented.For the dimension of time, the fore day and realtime comtrol are included in this thesis. Based on the fact that the prediction accuracy of wind power and load increases by the shrink of prediction time, the optimal power flow model is proposed. With the fore day unit commitment, the model could adjust the power output of different resources according to the realtime prediction of wind power and load. So the coordinate optimization between fore day unit commitment and realtime dispatching is achieved.For the dimension of control targets, this thesis divides the targets into safety and efficiency and put forward active and reactive power indexes. These indexes are included in the objective function of optimal power flow model and the model is solved by the mix methed that combines the interior point and the fast branch and bound method, which implements the coordinate optimation of active and reactive power.