Increasing penetration of distributed energy resources in the distribution network (DN) is threatening safe operation of the DN, which necessitates setup of the ancillary service market in the DN. In the ancillary service market, distribution system operator (DSO) is responsible for safety of the DN by procuring available capacities of aggregators. Unlike existing studies, this paper proposes a novel market mechanism composed of two parts: choice rule and payment rule. The proposed choice rule simultaneously considers social welfare and fairness, encouraging risk-averse aggregators to participate in the ancillary service market. It is then formulated as a linear programming problem, and a distributed solution using the multi-cut Benders decomposition is presented. Moreover, successful implementation of the choice rule depends on each aggregator’s truthful adoption of private parameters. Therefore, a payment rule is also designed, which is proved to possess two properties: incentive compatibility and individual rationality. Simulation results demonstrate effectiveness of the proposed choice rule on improving fairness and verify properties of the payment rule.

To further improve the utilization level of distributed photovoltaics (PV) and realize low-carbon travel, a novel optimization cooperative model that considers multi-stakeholders including integrated prosumers (IP), power to hydrogen (P2H), and grid company (GC) is proposed, based on the Nash bargaining theory. Electricity trading among the three and hydrogen trading between IP and P2H is considered in the model to maximize their own interests. Specifically, IP focus on distributed PV integration and low carbon travels, P2H strives to improve cost competitiveness of hydrogen, and electricity-hydrogen trading prices and quantities are optimized between them. Also, GC obtains profits by charging grid fees considering power flow constraints. The cooperation game model is transformed into a mixed-integer linear programming problem through linearization methods. Case studies show that electricity-hydrogen trading among the three has apparent advantages over pure electricity coupling or non-cooperation. With future reduction of investment prices of PV and P2H and maturity of the carbon trading market, the profit margin of this cooperation model can be further enhanced.

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

As a type of energy system with bright application prospects, the integrated energy system (IES) is environmentally friendly and can improve overall energy efficiency. Tight coupling between heat and electricity outputs of combined heat and power (CHP) units limits IES operational flexibility significantly. To resolve this problem, in this paper, we integrate operating mode optimization of the natural gas combined cycle CHP unit (NGCC-CHP) into dispatch of the IES to improve flexibility of the IES. First, we analyze operational modes of the CHP units from the perspectives of thermal processes and physical mechanisms, including the adjustable extraction mode, back-pressure mode, and switching mode. Next, we propose an explicit mathematical model for full-mode operation of the CHP units, in which the heat-electricity feasible region, switching constraints, and switching costs are all formulated in detail. Finally, a novel economic dispatch model is proposed for a heat and electricity IES, which uses the full-mode operation of CHP units to improve operational flexibility. The Fortuny-Amat transformation is used to convert the economic dispatch model into a mixed-integer quadratic programming model, which can then be solved using commercial solvers. Case studies demonstrate the proposed method can reduce operational costs and obviously promotes wind power utilization.

Distributed secondary control, depending on the sparse communication topology, excels for its flexibility and expandability in microgrids. The communication network plays an important role in microgrid control, but it is vulnerable to cyber-attacks. In this paper, the mathematical model for false data injection (FDI) attacks in AC microgrids is established, and the corresponding detection mechanism based on the morphological gradient is designed for the location of cyber-attacks in communication topology. Then, we propose a median-based resilient consensus voltage control strategy to mitigate the negative effects caused by malicious cyber-attacks and ensure the safe operation of the microgrid. Combining the detection method and resilient consensus control, a novel event-driven mitigation scheme is derived to improve the resilience of microgrids under cyber-attacks. Finally, a tested microgrid model composed of five different distributed generation (DG) units is simulated in the MATLAB/Simulink environment. The feasibility and effectiveness of the presented detection mechanism and resilient consensus strategy are verified by simulation results applying different scenarios.

In contemporary power grids or microgrids, harmonic distortion has emerged as one of the critical power quality issues for utility power grids, which has escalated especially due to the high penetration of power-electronic-converter-interfaced distributed generation (DG). This paper first illustrates the prevalent dispute revolving around the harmonic power sharing and distortion restraint, and subsequently proposes a consensus-based framework that facilitates an accurate sharing of harmonics among multi-DGs connected in parallel, with an effective suppression of the output voltage distortion. Compared with the majority of existing studies addressing the issue of voltage harmonics at the point of common coupling (PCC), our method primarily emphasizes on the output voltage distortion since the power quality requirement for certain local critical loads is often known to be high. With the help of adaptive regulation, the overall distortion produced at the output terminals of DGs can be retained within an acceptable range. The working principle of the proposed control method, which is not only easy to implement but also independent of model parameters, is further described in detail. Employing the small-signal dynamic model, the system stability and robustness are analyzed. The hardware-in-the-loop (HIL) simulations aid in determining the outcome of the proposed strategy in microgrid control.

Dynamic simulation plays a fundamental role in security evaluation of distribution networks (DNs). However, the strong stiffness and non-linearity of distributed generation (DG) models in DNs bring about burdensome computation and noteworthy instability on traditional methods which hampers the rapid response of simulation tool. Thus, a novel L-stable approximate analytical method with high accuracy is proposed to handle these problems. The method referred to as multi-stage discontinuous Galerkin method (MDGM), first derives approximate analytical solutions (AASs) of state variables which are explicit symbolic expressions concerning system states. Then, in each time window, it substitutes values for symbolic variables and trajectories of state variables are obtained subsequently. This paper applies MDGM to DG models to derive AASs. Local-truncation-error-based variable step size strategy is also developed to further improve simulation efficiency. In addition, this paper establishes detailed MDGM-based dynamic simulation procedure. From case studies on a numerical problem, a modified 33-bus system and a practical large-scale DN, it can be seen that proposed method demonstrates fast and dependable performance compared with the traditional trapezoidal method.