The System Reliability Assessment Of Multi-link Power Grid

According to the principle of "Unified dispatching and management at different levels",the power grid can be divided into the provincial power grid, regional power grid anddistribution network. The network structure of the power system, primary electric equipment,secondary system, operation characteristics and control behaviors directly influence the powersupply and its quality. System reliability is transferred from the power supply to the load bythe provincial power grid, regional power grid and medium voltage distribution network, andrepresented by the power supply reliability index. Assessing multi-link power systemreliability objectively and quantitatively can not only help deeply digging the mechanismbetween transmission and distribution network, but also overall quantize the effects oftransmission system reliability level and its related service measures to the distributionnetwork reliability. Besides, it can help grasping the operation state of whole system forrealizing safe, stable and reliable operating target. The main work is as follows:1) Based on the traditional theory of adequacy evaluation, a new algorithm andcomputing technology to ensure the calculation accuracy and improve the evaluation speedwas presented. Expected state set was constructed by the smallest unit based on the loop. Andthe chimney sorting algorithm to further reduce the system states was proposed. Aim at thegenerator rescheduling problems in the case of generator breakdown, a proportional economicscheme was proposed, which ensure other generators to be on the output range. The model ofcorrection measures use an optimal load shedding model based on AC power flow. On thisbasis and making full use of current computer information processing technology, the steadyadequacy evaluation of large grid software was developed. The numerical results of IEEERTS-79demonstrated the approach is efficacious.2) A reliability assessment method of multi-link power system based on principle ofnetwork equivalent was presented. The method puts transmission network and distributionnetwork as an organic whole from the view of mapping, and transfers the load index oftransmission system to distribution network as input parameters based on load-powerequivalent principle. To realize the efficient and scientific assessment of distribution system, itwas adopted network reachability of directed graph and Warshall algorithm. The numerical results of IEEE RTS-79and RBTS-BUS6complete power grid demonstrated the approach isof the practicability and maneuverability, and generalize an practical conclusion to providefast and effective decision guidance for the operation or planning staff.3) A method for sensitivity analysis on reliability assessment of multi-link system basedon differential transfer principle was presented. The reliability index function was establishedfirstly. By use of composite function derivative rule for differential transfer, the sensitivity oftarget distribution system reliability indexes to reliability parameters of transmissioncomponent and distribution component was derived. The numerical results of IEEE RTS-79and improved RBTS-BUS6complete power grid demonstrated the approach is efficacious,which can effectively explore the weakness of system. Besides, that can provide theoreticalsupport and guidance for formulating and perfecting the power grid reliability controlmeasures, and making scientific planning scheme.This dissertation is supported by national science and technology support plan–“comprehensive interactive characters for smart grid comprehensive demonstrationproject”(2013BAA01B02).