Enhancing Autonomy Capability in Regional Power Grids:A Strategic Planning Approach with Multiple Autonomous Evaluation Indexes

After the integration of large-scale DistributedGeneration(DG)into the distribution network,the randomness and volatility of its output result in a reduction of spatiotemporal alignment between power generation and demand in the distribution network,exacerbating the phenomenon of wind and solar power wastage.As a novel power system model,the fundamental concept of Regional Autonomous Power Grids(RAPGs)is to achieve localized management and energy autonomy,thereby facilitating the effective consumption of DGs.Therefore,this paper proposes a distributed resource planning strategy that enhances the autonomy capabilities of regional power grids by considering multiple evaluation indexes for autonomy.First,a regional Energy Storage(ES)configuration strategy is proposed.This strategy can select a suitable reference value for the upper limit of ES configuration based on the regional load andDGoutput to maximize the elimination of source load deviations in the region as the upper limit constraint of ES capacity.Then,a control strategy for regional ES is proposed,the charging and discharging reference line of ES is set,and multiple autonomy and economic indexes are used as objective functions to select different proportions of ES to control the distributed resources of the regional power grid and establish evaluation indexes of the internal regional generation and load power ratio,the proportion of power supply matching hours,new energy consumption rate and tie line power imbalance outside the region to evaluate changes in the regional autonomy capabilities.The final simulation results showthat in the real regional grid example,the planning method in the planning year in the region of the overall power supply matching hour ratio and new energy consumption rate increased by 3.9%and 4.8%on average,and the power imbalance of the tie line decreased by 7.8%on average.The proposed planning approach enables the maximization of regional autonomy while effectively smoothing the fluctuation of power exchange between the regional grid and the higher-level grid.This presents a rational and effective planning solution for the regional grid,facilitating the coordinated development between the region and the distribution network.

Evaluation of regional ionospheric grid model over China from dense GPS observations

The current global or regional ionospheric models have been established for monitoring the ionospheric variations. However, the spatial and temporal resolutions are not enough to describe total electron content（TEC） variations in small scales for China. In this paper, a regional ionospheric grid model（RIGM） with high spatial-temporal resolution（0.5 0.5 and 10-min interval） in China and surrounding areas is established based on spherical harmonics expansion from dense GPS measurements provided by Crustal Movement Observation Network of China（CMONOC） and the International GNSS Service（IGS）. The correlation coefficient between the estimated TEC from GPS and the ionosonde measurements is 0.97, and the root mean square（RMS） with respect to Center for Orbit Determination in Europe（CODE） Global Ionosphere Maps（GIMs） is 4.87 TECU. In addition, the impact of different spherical harmonics orders and degrees on TEC estimations are evaluated and the degree/order 6 is better. Moreover, effective ionospheric shell heights from300 km to 700 km are further assessed and the result indicates that 550 km is the most suitable for regional ionospheric modeling in China at solar maximum.

Research on Safety and Stability of Regional Power Grids to the Year 2020

The safety and stability study on Northeast, North, East, Northwest and Central China power grids had been carried out, which provided technical supports to planning design of regional power grids. By analyzing safety and stability under severe faults in regional power grids, revealed weaknesses on power grid configurations and measures for preventing from loss of stability were presented. In comparison of various schemes of power system safety and stability among parts of power grids, more than two recommended schemes can be chosen as reference in planning design for regional power grids. Considering the safety and stability control measures necessary for each power grids, it is believed the trunk networks of all power grids can fulfill the third criteria of Guideline for Power System Safety and Stability, while the weakness and predominated hydropower may deteriorate safety and stability of power grids. The power grid shall be regulated in line with the variation of boundary conditions.

Energy Conservation and Emissions Reduction: Experiences from Three Provincial Power Companies and One Regional Power Grid Company

Power industry is one of the key fields for energy conservation and emissions reduction (ECER) in China. In order to achieve the nation's overall energy consumption target and pollutant emission target set by the 11th Five-Year Plan, to build the resource-conservation and environment-friendly society during the 11th Five-Year Plan period (2006-2010), it is crucial to implement the policy of "Large (units) In and Small (units) Out (LISO)" (i.e., replacing small units with large ones) and accelerate the retirement of small thermal units. According to the statistics, the power industry has made a significant progress in SO2 emission reduction during the first half of 2007. Specifically, with 18.3% growth in power generation, the SO2 emission was reduced by 5.2% compared with the same period in 2006. By the end of July 2007, the retired small units have totaled 6950 MW, 85% of which belongs to the five major power generation groups such as Guodian and Huadian. In this article, the achievements and remaining issues in Henan, Jiangsu, Sichuan Power Companies and East China Grid Company were presented and discussed thoroughly.

Ionospheric disturbances following the March 2015 geomagnetic storm from GPS observations in China

When strong solar activities and geomagnetic storms happen, satellite communications and navigation system will be strongly disturbed. It is of great significance to monitor ionospheric disturbances,because empirical models cannot capture ionospheric anomalous disturbances well. Nowadays, dualfrequency GPS(Global Positioning System) observations can be used to estimate the ionospheric total electron content, correct the ionospheric delay and analyze the response of the ionosphere to geomagnetic storms. In this paper, the ionospheric response to the geomagnetic storm occurred in March 2015 is investigated using GPS observations provided by Crustal Movement of Observation Network of China. The result shows that this storm increases the electron density in the ionosphere quickly and disrupts the structure of the northern equatorial anomaly region at the beginning. In the main process stage, compared with that in the quite periods, the VTEC(Vertical Total Electron Content)around the longitude of 120°E decreases by 50% and the amount of depletion is larger in the high latitude region than that in the low latitude region. We also find the height of the peak electron density in F2 layer increases during the geomagnetic storm from the electron density profiles derived from GPS occultation mission.

Problems of Planning for Power Industry in China

On the basis of summing up the development of electric power industry in the 10th Five-Year Plan period, the idea of electric power development planning from 2006 to 2020 is presented. The authors analyzed ten main problems that existed in electric development during the 10th Five-Year Plan period, forecasted the electricity generation from 2006 to 2020, put forward the development strategy of power industry, discussed the component and development program of hydropower, thermal power, nuclear power, natural gas power and renewable power, outlined the present situations of six regional power grids, power transmission from western to eastern regions, UHV AC/DC power transmission and nationwide power grid interconnections, and finally gave out seven suggestions about electric power development in the future.

Optimal redundant placement of PMUs in Indian power grid -- northern, eastern and north-eastern regions

Effective utilization of renewable energy sources and efficient management of electric energy are essential for any developing countries like India. This can be envisioned through the implementation of concepts of smart grid （SG）. One of the key requisites for SG implementation is that the grid should be completely observable. Renovation of conventional Indian power grid to a SG necessitates incorporation of the phasor measure- ment units （PMUs） in the present power grid measurement and monitoring system. Since the cost of PMU is high and any bus containing a PMU makes the neighboring connected buses observable, optimal placement of PMUs is very important for complete observability of the grid. This paper proposes optimal redundant geographical locations in the northern, eastern and north-eastern regions of Indian power grid for PMU placement. The PMUs installed in these geographical locations will make the grid completely observable and maintain the observability under the conditions of failure of some PMUs or branch outages. Integer linear programming has been used for finding the optimal PMU locations. The results proposed in this paper can be a stepping stone for revamping the Indian power grid to a SG ensuring complete observability during different contingency conditions.

Optimal placement of PMUs for the smart grid implementation in Indian power grid A case study

Efficient utilization of energy resources is essential for a developing country like India. The concept of smart grid （SG） can provide a highly reliable power system with optimized utilization of available resources. The present Indian power grid requires revolutionary changes to meet the growing demands and to make the grid smarter and reliable. One of the important requirements for SG is the instantaneous monitoring of the voltage, current and power flows at all buses in the grid. The traditional monitoring system cannot satisfy this requirement since they are based on nonlinear power flow equations. Synchro-phasor-measurement devices like phasor mea- surement units （PMUs） can measure the phasor values of voltages at installed buses. Consequently, the currents passing through all branches connected to that bus can be computed. Since the voltage phasor values at the neighboring buses of a bus containing the PMU can be estimated using Ohm＇s law, it is redundant to install PMUs at all the buses in a power grid for its complete observability. This paper proposes the optimal geographi- cal locations for the PMUs in southern region Indian power grid for the implementation of SG, using Integer Linear Programming. The proposed optimal geographical locations for PMU placement can be a stepping stone for the implementation of SG in India.