This paper observes the boundary of distribution system security region (DSSR). DSSR is defined as a set of all the operating points satisfying N-1 security constraints. First, the basic concepts of N-1 security are introduced for distribution system under smart grid background. Then, the dividing phenomenon of operating points security is reported, which indicates that DSSR boundary of a given distribution network exists. Moreover, an approximation method based on N-1 simulation is proposed in order to find DSSR boundary. Then, the observation results of the DSSR boundary are presented for the expanded reliability Busbar test system BUS4 case. The topological characteristics of DSSR boundary are further summarized, which show that the DSSR is a dense set and its boundary is approximately linear. This paper indicates the existence of DSSR and gives a method to observe it. Finally, the benefit of DSSR is illustrated by its typical applications.

In the face of the dual crisis of energy shortages and global warming, the vigorous development of renewable energy represented by wind-solar energy is a significant approach towards achieving energy transition, carbon peaking, and carbon neutrality goals. Targeting the park-level integrated energy system (PIES) with high penetration of wind-solar energy, we propose a day-ahead dispatching strategy that takes into account the flexible supply and the reward-punishment ladder-type carbon trading mechanism (RPLTCTM). Firstly, RPLTCTM and carbon capture equipment (CCE) are considered in the dispatching model, and the mechanism of coordinated operation of CCE and RPLTCTM is explored to further improve the system’s ability to restrain carbon emissions. Secondly, power-based flexibility indicators (PFIs) are adopted to quantitatively evaluate the flexibility supply, and based on the load demand response characteristics, the dispatchable resources on the load side are guided to improve the system’s operation flexibility. On this basis, a multi-objective optimal dispatching model that takes into account the carbon emission cost, energy cost, and flexibility supply are constructed, and the original problem is transformed into a mixed-integer single-objective linear problem through mathematical equivalence and flexibility cost. Finally, simulation examples validate that the economy, flexibility, and low-carbon level of the dispatching plan can be synergistically improved by the proposed strategy.

Efficiency pursuit of the distribution system operation should be on the premise of security. This study proposes the network reconfiguration (NR) approach comprehensively considering N −1 security and network loss. A new approach called distribution system security region (DSSR) is first applied in NR problem. The DSSR is the feasible operation space of a system within N −1 security criterion and can quantify the N −1 security margin. Then, the NR is formulated by using the minimum network loss as objective function and the N −1 security margin, which is provided by the DSSR, as constraints. Moreover, the security margin constraints can be customised for each feeder individually, yielding proper compromises between security‐related and efficient concerns. Different NR results for multiple security and efficiency requirements are presented on an extended IEEE‐RBTS test system. Compared with the traditional minimum‐loss NR, the proposed approach reduces the network loss as much as possible with desired security margin, well balancing the security and efficiency of NR.

As an important tool of transmission system dispatching, the region-based method has just been introduced into distribution area with the ongoing smart distribution grid initiatives. First, a more accurate distribution system security region (DSSR) model is proposed. The proposed model is based on detailed feeder-interconnected topology, and both substation transformer and feeder N-1 contingencies are considered. Second, generic characteristics of DSSR are discussed and mathematically proved. That is, DSSR is a dense set of which boundary has no suspension and can be expressed by several union subsurfaces. Finally, the results from both a test case and a practical case demonstrate the effectiveness of the proposed modeling approach; the shape of DSSR is also illustrated by means of 2- and 3-dimensional visualization. Moreover, the DSSR-based assessment and control are preliminary illustrated to show the application of DSSR. The researches in this paper are fundamental work to develop new security region theory for future distribution systems.

In this paper, a new Distribution Management System (DMS) framework based on security region is proposed. First, the concept of Distribution System Security Region (DSSR) is introduced. DSSR is capable to describe the N − 1 security boundary of the whole distribution network, including the secure output range of DGs. This new theoretic tool provides a chance for the implementation of real-time security analysis and active controls in DMS. Second, this paper proposes and describes five security states for distribution system. Third, an upgraded DMS enhanced with DSSR is proposed, which consists of advanced security functions such as preventive and predictive control of the trajectory of operating points. Finally, a practical case is presented to simulate the proposed DSSR-enhanced DMS, in which both the security region of network and the output range of DGs are calculated. Typical security functions are also demonstrated. In conclusion, the new DMS framework aims to help operate the system closed to its security boundary in order to improve the efficiency significantly within same security standard. This work is beneficial for future low carbon distribution systems with high penetration rate of DGs.