Vietnamese Power System Research Articles

Incorporating externalities when optimising power system expansion plans

Power system expansion planning has traditionally been conducted in two phases: optimisation of the future generation system to satisfy forecast demands, followed by that of a complementary transmission system. However, it is now computationally realistic to optimise both aspects simultaneously, even for large and complex systems. At the same time, the range of candidate generation plant types to be considered has widened considerably, with the technical and economic characteristics of wind, solar and biomass plants now having to be compared with those of conventional thermal and hydro plants. It is also becoming increasingly important to take explicit account, within the planning process, of the so-called ‘externalities’ such as emission limits, budget constraints and demand-management measures, in addition to the environmental costs and secondary benefits associated with individual projects. This paper describes the results of a study to demonstrate the feasibility of explicitly considering a range of externalities when mathematically optimising integrated generation and transmission system expansion plans, using the Vietnamese power system as an example.

Improving transmission network using renewable resources efficiency by integrating pumped-storage hydroelectricity

Due to the increasing load demand, integrating renewable energy into the power system to satisfy the electrical consumption is the trend to develop the modern power system. However, the uncertainty of renewable energy sources affects the energy transmission efficiency and the reliability of power systems. To get this under control, connecting storage systems such as pump-storage hydroelectricity is seen to be an efficient solution. In this paper, Python language is used to describe input data and model the Vietnamese power system. The results show the feasibility of the hydro-storage model in improving the power system performance when renewable energy sources are involved.

Subsynchronous Resonance and FACTS-Novel Control Strategy for Its Mitigation

The subsynchronous resonance (SSR) is an important problem in the power system, and especially the series compensated transmission lines may cause SSR in the turbine generators, such that it leads to the electrical instability at subsynchronous frequencies and potential turbine-generator shaft failures. Taking the Vietnamese Vungang thermal plants as an example, a shaft failure of Vungang I thermal power unit has occurred on November 24, 2015, due to SSR. The main cause for this failure is a resonance caused by the series capacitors on the 500 kV grid. This paper analyzes the SSR based on the location of shaft cracks and turbine generator mode shape for Vungang I and II thermal power plants. On the basis of that, it develops a novel control strategy for each Flexible AC Transmission system (FACTS) device as the thyristor controlled series compensator (TCSC), static VAR compensator (SVC), and static synchronous compensator (STATCOM). Then they are comparable to one another in order to choose a feasible solution for mitigating the SSR. The effectiveness of the proposed control strategy is verified via time domain simulation of the Vietnamese 500/220 kV transmission system using EMTP-RV and PSS/E programs. The obtained results show that the proposed strategy for SVC can be applied to immediately solve the difficulties encountering in the Vietnamese power system.

Large-Scale Integration of Renewable Power Sources into the Vietnamese Power System

The Vietnamese Power system is expected to expand considerably in upcoming decades. However, pathways towards higher shares of renewables ought to be investigated. In this work, we investigate a highly renewable Vietnamese power system by jointly optimising the expansion of renewable generation facilities and the transmission grid. We show that in the cost-optimal case, highest amounts of wind capacities are installed in southern Vietnam and solar photovoltaics (PV) in central Vietnam. In addition, we show that transmission has the potential to reduce levelised cost of electricity by approximately 10%.

Improving Power System Stability with Gramian Matrix-Based Optimal Setting of a Single Series FACTS Device: Feasibility Study in Vietnamese Power System

The Vietnamese power system has experienced instabilities due to the effect of increase in peak load demand or contingency grid faults; hence, using flexible alternating-current transmission systems (FACTS) devices is a best choice for improving the stability margins. Among the FACTS devices, the thyristor-controlled series capacitor (TCSC) is a series connected FACTS device widely used in power systems. However, in practice, its influence and ability depend on setting. For solving the problem, this paper proposes a relevant method for optimal setting of a single TCSC for the purpose of damping the power system oscillations. This proposed method is developed from the combination between the energy method and Hankel-norm approximation approach based on the controllability Gramian matrix considering the Lyapunov equation to search for a number of feasible locations on the small-signal stability analysis. The transient stability analysis is used to compare and determine appropriate settings through various simulation cases. The effectiveness of the proposed method is confirmed by the simulation results based on the power system simulation engineering (PSS/E) and MATLAB programs. The obtained results show that the proposed method can apply to immediately solve the difficulties encountering in the Vietnamese power system.

A Quantitative Method to Determine ICT Delay Requirements for Wide-Area Power System Damping Controllers

This paper presents a quantitative method to determine delay requirements of the information and communication technology (ICT) system supporting wide-area power oscillation damping (WAPOD) controllers. An allowable time delay for the ICT infrastructure named “equivalent time delay (ETD)” is defined. The ETD is calculated by numerically comparing the damping behavior of the system when local input signals (LI) and remote input signals (RI) are used in the damping controller. The use of a WAPOD is only justified when its response outperforms that of a controller using local inputs. Therefore, the total time delay in the control loop must be below the calculated ETD. As such, the ETD serves as a design criteria to determine ICT latency requirements. The selection of an effective RI signal can be carried out by considering the maximum delays (ETDs) of different wide-area measurements. A damping improvement $ {\rm ETD}^{x~\%}$ has been proposed using the same methodology indicating a minimum outperformance of the remote signals. The proposed method is demonstrated using the well-known Klein-Rogers-Kundur multi-machine power system and the Vietnamese power system model.