Renewable energy power generation projects started construction in Tibet

On March 19, the construction of a 10-MW photovoltaic power plant and a 1 000-kW new type geothermal power generation project were started by Guodian Longyuan Group in Yanbajing Town, Dangxiong County of Tibet.

A VAE-Bayesian deep learning scheme for solar power generation forecasting based on dimensionality reduction

The advancements in distributed generation(DG)technologies such as solar panels have led to a widespread integration of renewable power generation in modern power systems.However,the intermittent nature of renewable energy poses new challenges to the network operational planning with underlying uncertainties.This paper proposes a novel probabilistic scheme for renewable solar power generation forecasting by addressing data and model parameter uncertainties using Bayesian bidirectional long short-term memory(BiLSTM)neural networks,while handling the high dimensionality in weight parameters using variational auto-encoders(VAE).The forecasting performance of the proposed method is evaluated using various deterministic and probabilistic evaluation metrics such as root-mean square error(RMSE),Pinball loss,etc.Furthermore,reconstruction error and computational time are also monitored to evaluate the dimensionality reduction using the VAE component.When compared with benchmark methods,the proposed method leads to significant improvements in weight reduction,i.e.,from 76,4224 to 2,022 number of weight parameters,quantifying to 97.35%improvement in weight parameters reduction and 37.93%improvement in computational time for 6 months of solar power generation data.

Small-signal Stability Criteria in Power Electronics-dominated Power Systems:A Comparative Review

To tackle emerging power system small-signal stability problems such as wideband oscillations induced by the large-scale integration of renewable energy and power electronics,it is crucial to review and compare existing small-signal stability analysis methods.On this basis,guidance can be provided on determining suitable analysis methods to solve relevant small-signal stability problems in power electronics-dominated power systems(PEDPSs).Various mature methods have been developed to analyze the small-signal stability of PEDPSs,including eigenvalue-based methods,Routh stability criterion,Nyquist/Bode plot based methods,passivity-based methods,positive-net-damping method,lumped impedance-based methods,bifurcation-based methods,etc.In this paper,the application conditions,advantages,and limitations of these criteria in identifying oscillation frequencies and stability margins are reviewed and compared to reveal and explain connections and discrepancies among them.Especially,efforts are devoted to mathematically proving the equivalence between these small-signal stability criteria.Finally,the performance of these criteria is demonstrated and compared in a 4-machine 2-area power system with a wind farm and an IEEE 39-bus power system with 3 wind farms.

Assessment of Sustainable Energy Strategy with Long-Term Global Energy Model Incorporating Nuclear Fuel Cycle

This paper investigates long-term energy strategy compatible with significant reduction of world carbon dioxide （CO2） emissions, employing a long-term global energy model, Dynamic New Earth 21 （called DNE21）. The model seeks the optimal energy mix from 2000 to 2100 that minimizes the world total energy system cost under various kinds of energy and technological constraints, such as energy resource constraints, energy supply and demand balance constraints, and CO2 emissions constraints. This paper discusses the results of primary energy supply, power generation mix, CO2 emission, CCS （carbon capture and storage） and total system costs for six regions including world as a whole. To evaluate viable pathways forward for implementation of sustainable energy strategies, nuclear power generation is a viable source of clean and green energy to mitigate the CO2 emissions. Present research shows simulation results in two cases consisting of no CO2 regulation case （base case） and CO2 REG case （regulation case） which halves the world CO2 emissions by the year 2050. Main findings of this research describe that renewable and nuclear power generation will contribute significantly to mitigate the CO2 emission worldwide.

Impact of the cold surge event in January 2021 on the power system of China

During 6-10 January 2021,a recorded strong cold surge took place in China,with over 800 observational stations reaching their historical extremes.Unlike previous studies that focused on the response of either the power load or generation separately,this study quantitatively revealed the impacts on the balance between the demand and supply sides of the grid.On the demand side,the sensitivity of power load was found to increase substantially higher in southern China(0.533 GW°C^(−1))than in the northern region(0.139 GW°C^(−1))due to the limited municipal heating system.On the supply side,the hourly wind power generation dropped from the highest of 110 GW on 6 January to the lowest of 54 GW on 9 January due to the reduction in wind speed.In addition,a reduction in solar power generation was observed during 8-10 January.Thus,the balance of the power system was influenced by this cold event.As an effective adaptation measure,results further showed that early warning by three weeks ahead can be obtained by an operational climate model.The sensitivity of China's power system to such cold surge events may increase remarkably due to the expected increase in the proportion of wind and solar power generation in future new-type power systems.Thus,close cooperation between climate scientists and power engineers is needed to build the resilience of the power system to the cold extremes.

Analysis and control of wind-driven self-excited induction generators connected to the grid through power converters

The analysis of the wind-driven self-excited induction generators （SEIGs） connected to the grid through power converters has been developed in this paper. For this analysis, a method of representing the grid power as equivalent load resistance in the steady-state equivalent circuit of SEIG has been formulated. The technique of genetic algorithm （GA） has been adopted for making the analysis of the proposed system simple and straightfor- ward. The control of SEIG is attempted by connecting an uncontrolled diode bridge rectifier （DBR） and a line commutated inverter （LCI） between the generator term- inals and three-phase utility grid. A simple control technique for maximum power point tracking （MPPT） in wind energy conversion systems （WECS）, in which the firing angle of the LCI alone needs to be controlled by sensing the rotor speed of the generator has been proposed. The effectiveness of the proposed method of MPPT and method of analysis of this wind-driven SEIG-converter system connected to the grid through power converters has been demonstrated by experiments and simulation. These experimental and simulated results confirm the usefulness and successful working of the proposed system and its analysis.

Dispatchable Region for Active Distribution Networks Using Approximate Second-order Cone Relaxation

Uncertainty in distributed renewable generation threatens the security of power distribution systems.The concept of dispatchable region is developed to assess the ability of power systems to accommodate renewable generation at a given operating point.Although DC and linearized AC power flow equations are typically used to model dispatchable regions for transmission systems,these equations are rarely suitable for distribution networks.To achieve a suitable trade-off between accuracy and efficiency,this paper proposes a dispatchable region formulation for distribution networks using tight convex relaxation.Secondorder cone relaxation is adopted to reformulate AC power flow equations,which are then approximated by a polyhedron to improve tractability.Further,an efficient adaptive constraint generation algorithm is employed to construct the proposed dispatchable region.Case studies on distribution systems of various scales validate the computational efficiency and accuracy of the proposed method.