Impacts Analysis And Countermeasures Of Dongning Cogeneration Power Plant On Power Grid Security

The grid-connected scheme of the Dongning cogeneration power plant is analyzed in this thesis by reviewing the security of the scheme. Dongning grid, located at the junction of Mudanjiang and Jixi grids, has comparatively weak regional grid structure. The grid integration of the plant will affect the grid power flow, power quality, and even the security of the connected general grid. Therefore, the research on the influence of the integration of Dongning cogeneration power plant on the security of connected grid is of great significance in the engineering field.Analyses have been conducted in this thesis on the status of power grids and the balance of electric power and energy in Mudanjiang and Jixi regions and in the whole province of Heilongjiang. The author has elaborated the significance of constructing the Dongning cogeneration power plant from the prospective of eliminating the regional electric gap and improving the power quality and power supply reliability, and the significance of the power construction has also been expounded by calculating the typical current flow of the connected grid. The grid security under great disturbance has been studied in both static and transient states after Dongning plant is put in operation, and countermeasures have been taken to safeguard the safety and reliability of electric power system.As for the steady-state security of the power grid with the Dongning plant, simulations have been made in the condition of complex troubles including N-1 and N-2, etc. and the weak link of the connected grid security in static state has been found and measures have been devised to solve such problem. The connected grid may be crashed if protective measures were not taken, and such crash may impact the neighboring grid that is connected to it. Counter-measures have been put forward to normalize it by constraining the output of generator units when the regional grid is overloaded. Such measures are simple, but analysis have been conducted to verify that the security need of the power grid can be satisfied. The research can be the basis to handle similar troubles of regional grid in the future.Simulations have been conducted for the transient security of the accessed Dongning cogeneration power plant by taking into account the N-1 and other possible complex troubles such as failures in the main transformer and the lines to analyze the security of the connected grid in transient state, and measures have been suggested. Simulations show that the slight and general troubles can be solved by the excitation regulation of the generator unit, which can guarantee the transient security of the electric power system. As for the contingent severe troubles, the solutions include shutting down the plant or putting the plant in the isolated operation to avoid serious accidents such as overall power failure of the grid chains. The measures proposed above are verified via simulation to guarantee the stable operation of the power grid, which provides reference and basis for troubleshooting similar troubles of the regional power grid.