Optimal Scheduling Method For Cross-Area DC Grid System Based On Fuzzy Opportunity Constraint Planning

With the rapid development of new energy technology,the grid-connected capacity of new energy is also gradually increasing,and DC cross-zone transmission has become an effective means for current new energy power consumption and optimal resource allocation,but the uncertainty of new energy generation brings new challenges to the safe and stable operation of cross-zone DC power network.In order to reasonably utilize the large-scale grid-connected new energy and realize the optimal allocation of power resources at both ends by DC liaison lines,a reasonable and efficient optimal scheduling model for cross-zone DC power networks needs to be established.Based on fuzzy theory and credibility measurement,this paper establishes a cross-area DC network optimal dispatching model applicable to large-scale access of new energy.This paper first analyzes the clustering scenarios of the new energy annual output data of both ends of the grid to obtain its typical scenarios.Combined with fuzzy theory,the prediction errors of wind power and photovoltaic power generation are fuzzily modeled by fuzzy parameters,and the fuzziness of wind power and photovoltaic power generation output in each scenario is expressed by the fuzziness of prediction errors,and its plausibility measures are obtained by plausibility theory.Then,based on the traditional deterministic inter-area DC network model,a fuzzy opportunity constraint-based inter-area DC network optimal dispatching model is established by introducing the plausibility measure and fuzzy opportunity constraint to take into account the uncertainty of new energy output.The fuzziness of new energy forecast error is used to express the fuzziness of new energy output,the credibility measure is used to avoid the confusion of decision making under the traditional affiliation degree,and the confidence level is used to express the risk tolerance of system decision making.The case verification shows that the dispatching method can reflect the impact of new energy output uncertainty on the inter-area DC system,realize the fuzzy chance-constrained dispatching decision under the confidence level,and make a decision plan that can balance economy and safety under the premise of risk control.Finally,a discrete Frechet distance-based day-ahead and intra-day collaborative optimal scheduling method for cross-area DC networks is established to adapt to extreme weather changes.The day-ahead optimal scheduling provides the decision plan of unit start/stop and rotating reserve capacity for the intra-day optimization,the intra-day scheduling obtains the unit output and power transmission plan of DC contact line through rolling optimization,and the extreme weather emergency response model provides the emergency scheduling plan in case of extreme weather.The algorithm shows that this day-ahead-internal day collaborative optimization scheduling method can adapt to sudden changes in new energy output caused by extreme weather and ensure the safe and stable operation of the system.