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Coordinated siting and sizing for energy stations and supply networks in urban integrated energy system (UIES) is significant for economic improvement and carbon emissions reduction. A station-network cooperative planning method of UIES based on energy flow model is proposed. First, an operation model of heat network based on energy flow theory is proposed, which solves the problem that the temperature mixing equation in the traditional operation model cannot be applied to heat network planning. On this basis, a bi-level model for station-network cooperative planning of UIES is constructed, in which the upper level optimizes the siting and sizing of the energy station and the topology of the supply network, and the lower level optimizes the operation of the UIES and feeds back the operation cost of the UIES to the upper level. Finally, a solution method of cooperative planning based on the Karush-Kuhn-Tucher condition is proposed, to transform the bi-level nonlinear optimization model into a single-level linear optimization model for efficient solution. Case studies on the 55-node and 77-road urban topology show that the proposed method can perform an effective planning on energy supply network topology and rationally configure the capacity of various devices in the energy station. [ABSTRACT FROM AUTHOR]

This study introduces a strategy for the pre‐allocation and dispatch of mobile power sources (MPSs) within a power‐transportation coupled network, targeting efficient distribution network fault recovery under extreme weather conditions. The strategy incorporates the Dijkstra algorithm and blind number theory to analyse the MPS driving path and generate fault scenarios respectively, considering the effects of extreme weather on traffic capacity and distribution network fault rate. The MPS pre‐allocation model, formulated to minimize the load outage loss, MPS investment, and driving fuel cost, provides a foundation for optimization of the dispatch process. The dispatch optimization model adapts to dynamic information from the power‐transportation coupled network to make decisions on load restoration sequencing and MPS driving path. The effectiveness of the proposed strategy is demonstrated through an application to the IEEE 33‐node distribution system and a corresponding 33‐node transportation network. [ABSTRACT FROM AUTHOR]

The increasing proportion of distributed energy in the distribution network poses a significant challenge to effectively absorbing distributed generation (DG). On this premise, the DG hosting capacity (HC) assessment in the future distribution network based on the secure operation boundary of the power grid is necessary. In this paper, an improved holomorphic embedding load flow method (HELM) is employed to construct the relationship between the photovoltaic HC (PVHC) and each constraint to determine the upper limit of the comprehensive PVHC. Furthermore, a screening method of PV locations in the distribution network is constructed to screen the alternative PV locations with strong voltage regulation ability and reduce the alternative multi-point schemes, paving the way for simplifying the PVHC assessment based on a stochastic scenario simulation. Finally, a PVHC assessment based on the stochastic scenario simulation is proposed to expand the applicability of the assessment based on improved HELM. The negative impact of PV uncertainty is quantified by generating stochastic load flow scenarios based on the upper limit of the PVHC from improved HELM. The PVHC assessment in the high-voltage distribution network IEEE30 is analyzed to prove the efficiency and comprehensiveness of PVHC assessment in the distribution network. [ABSTRACT FROM AUTHOR]

In order to satisfy the requirements of modern online security assessment of power systems with continuously increasing complexity in terms of structure and scale, it is desirable to develop a power system dynamic security region (DSR) analysis. However, data-driven methods suffer from expensive model training costs and overfitting when determining DSR boundaries with high-dimensional grid features. Given this problem, a distributed feature selection method based on grid partition and fuzzy-rough sets is proposed in this paper. The method first employs the Louvain algorithm to partition the power grid and divide the original feature set so that high-dimensional features can be allocated to multiple computational units for distributed screening. At this point, the connections between features of different computational units are minimized to a relatively low level, thereby avoiding large errors in the distributed results. Then, an incremental search algorithm based on the fuzzy-rough set theory (FRST) is used for feature selection at each computational unit, which can effectively take into account the intrinsic connections between features. Finally, the results of all computational units are integrated in the coordination unit to complete the overall feature selection. The experimental results based on the IEEE-39 bus system show that the proposed method can help simplify the power system DSR analysis with high-dimensional features by screening the critical features. And compared with other commonly used filter methods, it has higher screening accuracy and lower time costs. [ABSTRACT FROM AUTHOR]

With large‐scale wind farms connected to AC/DC network, the transient stability assessment (TSA) of the power system becomes more and more difficult. Among them, estimating the region of attraction (ROA) of the equilibrium point is a traditional but still challenging problem. Based on the Lyapunov stability theory, this paper proposes a new approach to obtain the enlarged estimation of the ROA. The optimization and updating strategy of shape function in the sum of squares (SOS) optimization problem are studied to reduce the conservatism of estimation result. In the proposed method, the gravitational search algorithm (GSA) is employed to optimize the coefficients of initial shape function to improve estimation performance. Based on the time‐domain simulation (TDS) of expected faults, the fitness value for shape function optimization is calculated using the values of state variables at the fault clearing time and the system stability information. Furthermore, the optimal Lyapunov function is computed by introducing the update condition of shape function and adjusting the iteration strategy of the ROA estimation algorithm. Finally, the proposed method is applied to a two‐machine‐infinite‐bus system and a more complex nine‐bus AC/DC system with wind power. And the effectiveness of the proposed method is verified by comparing with the existing ROA estimation methods. [ABSTRACT FROM AUTHOR]

With the interconnection of large power networks, transient voltage stability of AC/DC power systems has been paid more attention in recent years. To investigate main influence of generating facility, high-voltage direct current (HVDC) and motor load for transient voltage stability, from the perspective of the generalised branch potential energy, the new indexes, and analysis method is proposed here. First, an energy function for AC/DC system is constructed with major dynamic components, namely classical HVDC control systems and motors in third-order model. Accordingly, the influence effects of the above major dynamic elements are investigated based on indexes from the corresponding generalised branch potential energy. With the rule of change in transient potential energy distribution in the network and information in stability margins, an evaluating procedure is established. Here, the judgment of transient voltage stability employs a heuristic energy function method. Finally, simulation tests on three-machine system with a HVDC transmission line are conducted in PSAT package, and the obtained results demonstrate the feasibility and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

High‐voltage direct current (HVDC) can speed up the recovery of a power system. However, both rectifier and inverter sides of HVDC are weak systems during a black start. To coordinate frequency characteristics of both sides within the frequency deviation constraint, a frequency regulation strategy based on variable‐parameter frequency limit control (FLC) during a black start is proposed. First, the mathematical models of asynchronous interconnected AC–DC system are established, and the optimal FLC parameters leading to minimum frequency deviation of both sides are obtained. Subsequently, based on the characteristics of the optimal FLC parameters with the parameters of the equivalent generator and the capacity of the AC system, a frequency regulation strategy is proposed to adapt to the continuously changing parameters and configurations of the AC power system during a black start. Finally, the simulation model is established using PSCAD/EMTDC software to verify the control strategy and the correctness of the optimal FLC parameters. [ABSTRACT FROM AUTHOR]

Dynamic voltage restorer (DVR) is a compensation device that can effectively improve power quality, and it is widely used to compensate the voltage sag on sensitive loads. However, DVR will affect the operation of the sensitive loads in parallel at the same busbar (such parallel are defined as adjacent loads) in the process of improving sensitive load voltage quality. With the externality theory, this paper proposes a solution to clarify the influence of DVR on the adjacent load and handle the possible controversy. This paper first establishes a simple system that consists of a DVR, sensitive loads, and adjacent loads. Based on the equivalent network, the influence of the DVR on the adjacent load is analyzed in terms of voltage change and power consumed. The externality boundaries are clearly defined when considering network parameters in order to fairly deal with the interaction of multi entities. Afterwards, an optimization compensation strategy that is based on externality theory is proposed. Finally, the simulation on compensation strategy is tested on the MATLAB/Simulink platform to demonstrate the feasibility and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract: In order to study long-term frequency and voltage dynamics of interconnected power systems under cascading events, the paper has developed a proper mathematical model and simulation algorithm for it with network structure preserved. Similar to the traditional dynamic power flow, the proposed model assumes that the system has survived in the transient stability and has enough damping torque. Therefore, the relative swings among generator rotors in one area will be neglected in long-term dynamics; and each control area is assumed to have a uniform frequency, represented by its area center of inertia (COI). Fast decoupled method has been extended to solve the structure-preserved multi-area network equations. Computer test results from a modified IEEE30-bus power system demonstrate the validity and effectiveness of the proposed model and algorithm. The work establishes a simulation platform for future study on long-term frequency and voltage stability control strategy and coordination of interconnected power systems. [Copyright &y& Elsevier]