The development of electric power systems has become more complex. Consequently, electric power systems are operating closer to their limits and are more susceptible to instability when a disturbance occurs. Transient stability problems are especially prevalent. In addition, the identification of transient stability is difficult to achieve in real time using the current measurement data. This research focuses on developing a convolutional neural network—long short-term memory (CNN-LSTM) model using historical data events to detect transient stability considering time-series measurement data. The model was developed by considering noise, delay, and loss in measurement data, line outage and variable renewable energy (VRE) integration scenarios. The model requires PMU measurements to provide high sampling rate time-series information. In addition, the effects of different numbers of PMUs were also simulated. The CNN-LSTM method was trained using a synthetic dataset produced using the DigSILENT PowerFactory simulation to represent the PMU measurement data. The IEEE 39 bus test system was used to simulate the model under different loading conditions. On the basis of the research results, the proposed CNN-LSTM model is able to detect stable and unstable conditions of transient stability only from the magnitude and angle of the bus voltage, without considering system parameter information on the network. The accuracy of transient stability detection reached above 99% in all scenarios. The CNN-LSTM method also required less computation time compared to CNN and conventional LSTM with the average computation times of 190.4, 4001.8 and 229.8 s, respectively.

HVDC has experienced substantial growth in utilization globally, attributable to its superior capacity for transmitting large amounts of power relative to its HVAC counterpart and its increasingly competitive pricing. Voltage source converter technology, a variant of HVDC, is particularly well suited for transferring bulk offshore power, whether in point-to-point or multiterminal configurations. Most existing HVDC connections function as interconnections between strong AC grids or between strong and weak/islanded AC grids. However, with the expanding use of distant offshore generation, the establishment of energy islands, and the electrical interconnection of archipelagic nations such as Indonesia, the potential arises for HVDC to link two weak AC grids or even a weak and very weak AC grid. This paper provides a comprehensive review of various HVDC technologies appropriate for such connections, focusing on converters, cables, and circuit breakers. It also offers a technological and methodological assessment of HVDC reinforcement for interconnecting weak AC grids. Furthermore, the paper examines HVDC applications concerning control strategies optimized for weak grid interconnections. Finally, it presents case studies of HVDC implementations for weak grid interconnections in Indonesia.

In this paper, technical challenges for realizing offshore multi-terminal HVDC (MTDC) transmission system in Europe is evaluated. An offshore MTDC topology is projected by interconnecting point-to-point HVDC links with the same voltage level and technology found in south-eastern part of North Sea. Availability analysis is done to evaluate the feasibility of the proposed offshore MTDC topology. As compared to point-to-point (PtP) HVDC link, MTDC operation gives a more secure and reliable system. This paper shows that the proposed MTDC topology can operate 98.36% of the time.

In order to meet the growth in demand and the renewable energy integration target, the Sulawesi Electricity System (SES) should be expanded. Currently, the SES is divided into two systems, namely South and North Sulawesi. These two systems have different characteristics, such as the system size, reliability and operational cost. North Sulawesi is smaller, weaker and more expensive than the South System. In order to improve the system reliability, generation and transmission expansion planning should be executed simultaneously to meet the economical investment cost and satisfy the reliability standard. For this purpose, the necessity of a backbone system with a higher voltage level than the existing 150 kV system should be considered, including the interconnection option between the two existing systems in Sulawesi. A methodology based on economic and technical criteria was developed to determine the backbone voltage level. Two voltage level options were considered, namely 275 and 500 kV. Several criteria were considered in order to determine the backbone voltage level, including the economic voltage, the line-loading limit, N-1 contingency, short circuiting, transient stability, voltage stability and small signal stability. The backbone voltage candidates should fulfil all of the criteria. The simulation was conducted in base- and high-demand scenarios, considering the fluctuation of future economic growth. The load flow and the dynamic analysis were simulated in a DIgSILENT Power Factory environment. The results showed that the 275 kV backbone, which was built in 2022, would violate three criteria: the economic voltage, N-1 contingency and voltage stability. On the other hand, the 500 kV backbone voltage level fulfills all of the criteria. The result of this research was considered in the electricity planning documents in Sulawesi. From a technical and economical perspective, the 500 kV backbone was chosen for the SES.