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This study proposes a hybrid energy trading scheme for peer-to-peer (P2P) energy trading in transactive energy markets. Market players can participate in different markets, including local markets, trading with neighbourhood areas, and traditional trading with the grid. In each local market, a community manager (CM) facilitates energy trading and negotiates with other CMs for neighbourhood trading. Based on the heterogeneous preferences of players of each community, each local market has a different price, which is different from market price for neighbourhood trading and trading with the grid. A distributed market clearing mechanism is presented that incorporates coordination among different markets. Also, a network utilisation charge function is defined to apply price signals to the market players to reflect network constraints in energy trading. These price signals are calculated based on the technical constraints in each market and are applied to the corresponding players based on their contribution to network constraints violation. Performance of the proposed trading scheme is evaluated against different market structures and through several case studies. [ABSTRACT FROM AUTHOR]

This study presents a newly developed modular system for control of power electronic amplifiers in high-power, high-frequency power hardware in the loop experiments. The proposed design comprises computational nodes connected via multi-gigabit fibre-optic links. Nodes are modular and reconfigurable, allowing interfacing with a range of sensors and actuators, typically voltage and current sensors, and switching converters. The system has been designed for scalability to permit arbitrarily high power ratings and fidelity to be achieved through paralleling and interleaving of multiple power converter modules, targeting an ultimate sample and control rate of 1 MHz. Experimental validation is presented using a two-node configuration to facilitate a power electronic experiment operating at 120 Vrms and 10 Arms, with a fundamental frequency of 50 Hz and frequency content up to the 11th harmonic. [ABSTRACT FROM AUTHOR]

This study presents a field-programmable gate array implementation of an advanced pulse-width modulator which combines a first-order hold (FOH) with phase accumulator carrier pulse-width modulation (PACPWM) for significantly reduced phase delay, and bandwidth extension in multi-level applications. The FOH block supports arbitrary resampling rates and operates in a single clock cycle for simple integration into multi-rate or asynchronous systems. The proposed modulator is validated experimentally, with performance matching that predicted for both FOH and a zero-order hold (ZOH). For PWM with 8 kHz carrier frequency and 50.4 kHz resampling frequency, a 15 degree phase delay advantage is demonstrated for FOH compared with ZOH across the 5–10 kHz modulation band. [ABSTRACT FROM AUTHOR]

This paper presents a topological exploration and evaluation of modularised battery systems with integrated non-isolated DC–DC converters (battery-integrated-converters). Converter requirements for battery operation in charging/discharging, charge balance, bypass, and pass-through modes have been considered. Topological variations have been derived to permit all battery operation modes. Design considerations and equations for each topology have been presented. The topological requirements have been summarised in tabular form with a 380 V bus storage system case study presented to demonstrate application of the design consideration discusses to a typical battery system specification. The comparison shows the buck, boost, and non-inverting buck-boost-based converters are all similarly suitable, and other performance metrics are likely to determine the best choice for a given set of circumstances. [ABSTRACT FROM AUTHOR]

In a bulk power system, generators can be divided into groups based on the variation of their swing curves after disturbance occurrence. In this regard, generators that have the same variations are placed in the same group and are called 'coherent'. Identifying coherent generators is an important step in creating a reduced model of bulk power systems for dynamic wide‐area analysis. The aim of this study is to provide a comprehensive and up‐to‐date bibliographic review of the literature related to coherency detection and power system partitioning after disturbance occurrence. In this study, coherency detection methods are classified into model‐based and measurement‐based categories. Furthermore, existing methods for power system partitioning based on coherency concept are also reviewed and categorised using two different criteria. Finally, the future trend toward coherency and coherent areas detection is discussed. [ABSTRACT FROM AUTHOR]

In this study, the post‐disturbance coherency of buses is added to the conventional phasor measurement unit (PMU) placement problem to find the minimum number of PMUs at different depths of unobservability. To do that, different scenarios are defined based on probabilistic parameters. Then, in each scenario, central buses are determined based on the similarity of post‐disturbance variations using subtractive clustering algorithm. The central bus in each area is the bus that its post‐disturbance variations are similar to the highest number of buses in the area. The PMU placement problem is then solved considering the number of scenarios where each bus has been selected as a central bus. The resulted placement scheme is more suitable for monitoring the power system dynamics compared to the conventional method. In order to reduce the number of PMUs, the placement problem is solved for higher depths of unobservability. In each depth, the voltage phasor of unobservable buses is obtained using state estimation methods. The results of applying the proposed methodology on 68‐bus, 16‐machine system show its better performance compared to the conventional method. [ABSTRACT FROM AUTHOR]

Massive deployment of distributed energy resources (DERs) along with innovations in information and communication technologies have changed the power system from a hierarchical structure to a more deregulated model by introducing new generations at lower levels. This change raises operational and market challenges. Local energy trading provides opportunities to manage these DERs by encouraging localised trading. The concept of local energy trading at the distribution level is widely broadcasted for implementation in the power system. In the design of electricity markets for local energy trading, a clear definition of market participants, their objective, and purpose of market clearing should be established. This design depends on the changing needs of the power system and can be performed from different viewpoints. Classification and organisation of the literature on potential designs for local energy trading can help researchers to develop their future steps properly. This study presents a comprehensive review on this topic and provides a systematic classification of the market players, market clearing objectives, and approaches. Several research works are analysed against different criteria, including scalability, overheads requirements, and network constraints management. [ABSTRACT FROM AUTHOR]

The integration of stochastic wind power has accentuated a challenge for power system stability assessment. Since the power system is a time‐variant system under wind generation fluctuations, pure time‐domain simulations are difficult to provide real‐time stability assessment. As a result, the worst‐case scenario is simulated to give a very conservative assessment of system transient stability. In this study, a probabilistic contingency analysis through a stability measure method is proposed to provide a less conservative contingency analysis which covers 5‐min wind fluctuations and a successive fault. This probabilistic approach would estimate the transfer limit of a critical line for a given fault with stochastic wind generation and active control devices in a multi‐machine system. This approach achieves a lower computation cost and improved accuracy using a new stability measure and polynomial interpolation, and is feasible for online contingency analysis. [ABSTRACT FROM AUTHOR]

In this study, a non‐linear excitation controller using inverse filtering is proposed to damp inter‐area oscillations. The proposed controller is based on determining generator flux value for the next sampling time which is obtained by maximising reduction rate of kinetic energy of the system after the fault. The desired flux for the next time interval is obtained using wide‐area measurements and the equivalent area rotor angles and velocities are predicted using a non‐linear Kalman filter. A supplementary control input for the excitation system, using inverse filtering approach, to track the desired flux is implemented. The inverse filtering approach ensures that the non‐linearity introduced because of saturation is well compensated. The efficacy of the proposed controller with and without communication time delay is evaluated on different IEEE benchmark systems including Kundur's two area, Western System Coordinating Council three‐area and 16‐machine, 68‐bus test systems. [ABSTRACT FROM AUTHOR]

This study proposes a new method for stabilising disturbed power systems using wide‐area measurement and controllable devices. A new control algorithm based on kinetic energy is proposed to be applied on the controllers to improve the first swing stability of power systems following large disturbances while also damping the subsequent inter‐area oscillations. The wide‐area controller is implemented by using the Kalman filter estimation of the area‐based model of the system, to stabilise the inter‐area dynamic and improve the stability margin of the system. The proposed approach is simulated on several test systems and the results show significant improvement in the first swing and damping stability of the test systems. [ABSTRACT FROM AUTHOR]

Frequency domain spectroscopy (FDS) is being used to assess the insulation condition of oil–paper power transformers. However, it has to date only been implemented on de‐energised transformers, which requires the transformers to be shut down for an extended period and may cause significant costs. To solve this issue, a newly improved monitoring method based on the FDS principle is proposed to implement the dielectric measurement on energised transformers. Moreover, a chirp waveform excitation and its novel processing method are introduced. Compared with the conventional FDS results, dielectric results from the energised insulation system have higher tanδ values because of the increased losses. To further understand the insulation ageing process, the effects of the geometric capacitance are removed from the measured imaginary admittance of the insulation system to enhance the ageing signature. The resulting imaginary admittance is then shown to correlate well with the central time constant in return voltage measurements results. The proposed methods address the issues on techniques used on energised transformers and provide a clue for on‐line FDS diagnostic application. [ABSTRACT FROM AUTHOR]

This study presents a general approach to identify dominant oscillation modes in bulk power system by using wide‐area measurement system. To automatically identify the dominant modes without artificial participation, spectral characteristic of power system oscillation mode is applied to distinguish electromechanical oscillation modes which are calculated by stochastic subspace method, and a proposed mode matching pursuit is adopted to discriminate the dominant modes from the trivial modes, then stepwise‐refinement scheme is developed to remove outliers of the dominant modes and the highly accurate dominant modes of identification are obtained. The method is implemented on the dominant modes of China Southern Power Grid which is one of the largest AC/DC paralleling grids in the world. Simulation data and field‐measurement data are used to demonstrate high accuracy and better robustness of the dominant modes identification approach. [ABSTRACT FROM AUTHOR]

The usual practice to study a large power system is through digital computer simulation. However, the impact of large scale use of small distributed generators on a power network cannot be evaluated strictly by simulation since many of these components cannot be accurately modelled. Moreover, the network complexity makes the task of practical testing on a physical network nearly impossible. This study discusses the paradigm of interfacing a real-time simulation of a power system to real-life hardware devices. This type of splitting a network into two parts and running a real-time simulation with a physical system in parallel is usually termed as power-hardware-in-the-loop (PHIL) simulation. The hardware part is driven by a voltage source converter that amplifies the signals of the simulator. In this paper, the effects of suitable control strategy on the performance of PHIL and the associated stability aspects are analysed in detail. The analyses are validated through several experimental tests using an real-time digital simulator. [ABSTRACT FROM AUTHOR]

A new approach is proposed for obtaining a non‐linear area‐based equivalent model of power systems to express the inter‐area oscillations using synchronised phasor measurements. The generators that remain coherent for inter‐area disturbances over a wide range of operating conditions define the areas, and the reduced model is obtained by representing each area by an equivalent machine. The parameters of the reduced system are identified by processing the obtained measurements, and a non‐linear Kalman estimator is then designed for the estimation of equivalent area angles and frequencies. The simulation of the approach on a two‐area system shows substantial reduction of non‐inter‐area modes in the estimated angles. The proposed methods are also applied to a ten‐machine system to illustrate the feasibility of the approach on larger and meshed networks. [ABSTRACT FROM AUTHOR]

Network reconfiguration after complete blackout of a power system is an essential step for power system restoration. A new node importance evaluation method is presented based on the concept of regret, and maximisation of the average importance of a path is employed as the objective of finding the optimal restoration path. Then, a two‐stage method is presented to optimise the network reconfiguration strategy. Specifically, the restoration sequence of generating units is first optimised so as to maximise the restored generation capacity, then the optimal restoration path is selected to restore the generating nodes concerned and the issues of selecting a serial or parallel restoration mode and the reconnecting failure of a transmission line are next considered. Both the restoration path selection and skeleton‐network determination are implemented together in the proposed method, which overcomes the shortcoming of separate decision‐making in the existing methods. Finally, the New England 10‐unit 39‐bus power system and the Guangzhou power system in South China are employed to demonstrate the basic features of the proposed method. [ABSTRACT FROM AUTHOR]

As the first stage of power system restoration after a blackout, an optimal black‐start scheme is very important for speeding up the whole restoration procedure. Up to now, much research work has been done on generating or selecting an optimal black‐start scheme by a single round of decision‐making. However, less attention has been paid for improving the final decision‐making results through a multiple‐round decision‐making procedure. In the group decision‐making environment, decision‐making results evaluated by different black‐start experts may differ significantly with each other. Thus, the consistency of black‐start decision‐making results could be deemed as an important indicator in assessing the black‐start group decision‐making results. Given this background, an intuitionistic fuzzy distance‐based method is presented to analyse the consistency of black‐start group decision‐making results. Moreover, the weights of black‐start indices as well as the weights of decision‐making experts are modified in order to optimise the consistency of black‐start group decision‐making results. Finally, an actual example is served for demonstrating the proposed method. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports published within the issue which include energy storage, wind energy storage, and renewable energy resources.