(1990). ENERGY FUNCTION ANALYSIS FOR POWER SYSTEM STABILITY. Electric Machines & Power Systems: Vol. 18, No. 2, pp. 209-210.

Energy function analysis for power system stability

IEEE Reliability Test System (RTS) of 1996 (Available in Hypersim)

This paper presents a detailed literature review on the issues and technical difficulties encountered in integrating large-scale photovoltaic (PV) systems to the grid and the role of generation dispatch in solving such challenges. It is observed that although there is a widespread adoption of stability (voltage, frequency and angle) strategies in dealing with intermittent nature of PV systems, generation dispatch techniques can equally be employed to overcome the challenges posed by large-scale PV systems. Hydro-electric generators equipped with automatic generation control and combustion turbines coupled to the grid are some of the best options in this regard. It is expected that utilities will not only fulfill their mandate of ensuring continuity of supply, but will also be able to cut costs through optimal generation dispatch. The greatest benefit is the self-reliance in terms of energy supply at all times, including night-time when ordinary photovoltaic systems are considered redundant.

A review of generation dispatch with large-scale photovoltaic systems

Modeling framework for planning and operation of multi-modal energy systems in the case of Germany

Flow tracing as a tool set for the analysis of networked large-scale renewable electricity systems

The formulation of a cohesive, yet solvable optimization program for transmission expansion planning of extended systems is engaging many researchers. Related approaches and achievements are often presented by means of a transmission network model with a single snapshot of generation and demand. Moreover the use of proprietary network data leads to difficulties when benchmarking the different existing approaches and thus identifying possible departures to advance. Derived from the IEEE 118 bus network this paper provides a modified network model in accordance with European standards. Four distinct scenarios are developed defining different mixes of conventional and renewable generation facilities as well as the load. Based on intermitted generation and load time series an appropriate economic dispatch in hourly resolution for a whole year for the conventional generators is calculated. Fulfilled by a set of network expansion options the benchmark case including all data is made publicly available.

A benchmark case for network expansion methods

The structural changes in the European energy system lead to an increase of renewable energy sources that are primarily connected to the distribution grid. Hence the stationary analysis of the transmission grid and the regionalization of generation capacities are strongly influenced by subordinate grid structures. To quantify the impact on the congestion management in the German transmission grid, a 110 kV grid model is derived using publicly available data delivered by Open Street Map and integrated into an existing model of the European transmission grid. Power flow and redispatch simulations are performed for three different regionalization methods and grid configurations. The results show a significant impact of the 110 kV system and prove an overestimation of power flows in the transmission grid when neglecting subordinate grids. Thus, the redispatch volume in Germany to dissolve bottlenecks in case of N-1 contingencies decreases by 38 % when considering the 110 kV grid.

Impact of Considering 110 kV Grid Structures on the Congestion Management in the German Transmission Grid

The transition from conventional towards renewable energy systems requires additional transmission capacities and higher operational flexibility to overcome contingency situations. This study presents a novel transmission expansion planning approach for the simultaneous placement of AC systems and power flow controlling technologies including high voltage direct current, phase shifting transformers (PSTs) and thyristor controlled series compensators (TCSCs). The approach is formulated as a mixed-integer linear programming optimisation problem and the operating point of power flow controlling devices is endogenously determined by minimising expansion costs. Both PSTs and TCSCs are integrated into the optimisation problem by means of new mathematical formulations. PSTs are presented in more detail considering the PST impedance, which is modelled as an equivalent phase shift. The controllable series impedance of TCSCs is also represented as an equivalent phase shift. Exemplary results based on a synthetic 120 bus system show a significant potential of PSTs and TCSCs to reduce expansion costs as well as to lower the requirement for new transmission capacities. The simultaneous employment of these technologies reduces the expansion costs within the test system between 18.7 and 32.4% compared to those costs generated by the sole reinforcement by AC systems.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-gtd.2019.1897

Transmission expansion planning via power flow controlling technologies

This paper presents a network reinforcement method, capable of considering different expansion measures such as voltage upgrade, repowering with High Temperature Low Sag (HTLS) as well as the construction of new parallel lines. The motivation is to exploit the possibility of optimizing the existing network structure before considering the building of new transmission lines. A set of bottleneck indicators based on the N-1 criterion is proposed for the identification of expansion measures as well as for the quantification of the bottleneck situation of the whole network. Exemplary results show the applicability to real-scale grid structures under consideration of a high number of grid snapshots. Furthermore, the suitability of different bottleneck indicators as well as some possible approaches to reduce calculation time are analyzed. Finally, the benefit of HTLS is exemplary quantified.

Hans Barrios

Papers

A benchmark case for network expansion methods

Impact of Considering 110 kV Grid Structures on the Congestion Management in the German Transmission Grid

Transmission expansion planning via power flow controlling technologies

A network reinforcement method based on bottleneck indicators

Co-optimization of multi-stage transmission expansion planning and grid operation