East China Power Grid Research Articles

Short-term peak shaving operation for multiple power grids with pumped storage power plants

Abstract The East China Power Grid (ECPG) is the biggest regional power grid in China. It has the biggest installed capacity of pumped storage power plants (PSPPs) and is responsible to coordinate the operation of its five provincial power grids. A recent challenge of coordinating operations is using PSPPs to absorb surplus energy during off-peak periods and generate power during peak periods. Differing from the traditional operations of single power grids, however, the PSPPs are required to respond to load demands from multiple provincial power grids simultaneously. This paper develops a three-step hybrid algorithm for the day-ahead quarter-hourly schedules of PSPPs to meet load demands of multiple provincial power grids. A normalization method is first proposed to reconstruct a total load curve to deal with the load differences of multiple provincial power grids, and to reflect the effect of specified electricity contract ratio on multiple provincial power grids. Secondly, a heuristic search method is presented to determine the generating and pumping powers of PSPP. Thirdly, a combination optimization method is used to allocate the determined generating and pumping powers among multiple provincial power grids to smooth the individual remaining load curve for their thermal systems. Two case studies with greatly different load demands are used to test the proposed algorithm. The simulation results show that the presented method can effectively achieve the goal of shaving the peak load and filling the off-peak load for multiple provincial power grids.

A Fast Contingency Screening Technique for Generation System Reliability Evaluation

In most existing reliability evaluation techniques, the stopping rules applied for contingency enumeration are either a given number of states with the highest probabilities or the states up to a specified failure order. However, the probability of a high order outage state may be larger than that of a low order outage state due to different reliabilities of the failed components. On the other hand, a low probability state with high outage capacity may have larger impact on system reliability than a high probability state with low outage capacity. These effects have not been considered in the existing techniques for contingency filtering or screening. A fast contingency screening technique (FCST) for generation system reliability evaluation is proposed in this paper. In this technique, contingency states are searched and ranked based on the severity coefficients determined by both state probabilities and outage capacities of the failed units. Several severity coefficients for a unit are defined and examined based on reliability and capacity factors. The replaceable neighboring states of a state and the minimum set of the neighboring states are defined to further reduce computation time. The merits of the proposed techniques and severity coefficients are validated by evaluating the East-China Power Grid.

Emergency Control Strategy Study on Multi-Send HVDC Project from Central China to East China Power Grid

In the summer peak load operation mode of the interconnected power grid which is integrated with HVDC transmission lines from Central China power grid to East China power grid, security and stability emergency control strategies based on generator shedding and EDCPS (Emergency DC Power Support) are studied to cope with system instability caused by Tuanlin-Fengjing DC line unipolar block fault. Simulation results show that interconnected system cannot maintain the transient stability effectively by using EDCPS only. A coordinated control strategy which combines generator shedding with EDCPS is proposed to reduce the number of generators to be shed and ensure the transient stability. Through optimizing EDCPS which two or more HVDC lines participate in, an optimal coordinated control strategy is proposed. Simulation results present that the strategy which combines GC shedding with Longzheng DC bipolar supporting is the optimal strategy.

The Research about the Trans-provincial Centralized Bidding Trading Market of East China Power Grid --II：Model Analysis

In this paper a novel cost function based on the relationship between operation cost of unit and generation load rate is employed in an agent-based model of Trans-provincial Centralized Bidding Trading Market of East China Grid. Simulation results are compared to real data to prove that the model is correct. Further analysis on simulation results point out the way to achieve an all-win game for power market members: generation companies improve their average load rates of the units by selling their electricity in the market, which makes units' cost drop and settlement price stay lower than benchmark price. Consequently electricity-demand provinces saved expenses, and units increase their profits. In conclusion, the trans-provincial electricity market of East China Power Grid is a successive case which improves the efficiency of the electricity industry by market-oriented measures.

Analysis of ACCC Applied in the Capacity Expansion Reformation of Electric Transmission Lines in East China Power Grid

Aluminum conductor composite core (ACCC) is a new type of conductors with great advantages in electrical and mechanical performances. It’s demonstrated through the technical and economic analysis of ACCC that application of ACCC for the capacity expansion reformation of electric transmission lines can save construction cost, but it may increase operation cost. In east China, the great performances of ACCC are helpful for solving some specific issues about transmission in some specific circumstances.

The Application of Ucosφ Out of Step Criterion to the East China Power Grid

This paper analysis the characteristics of two-machine equivalent system in out of step state. According to variation in the out of step state, study the out of step criterion of .Use change area to determine whether the system is out of step, The criterion is simple and clear, and the concept is clear. It can distinguish the acceleration step and deceleration of step, and automatically adapt to system changes in the structure and Operation mode. The minimum voltage amplitude of the device installed is used for capture the oscillation center .The 2012 East China Power Grid, region A fleet out of step mode is simulated analyzed, It is verify that the criterion of accuracy and adaptability in the East China Power Grid.

Special Issue on Restructuring and Sustainable Development for China’s Electric Power Industry

Special Issue on Restructuring and Sustainable Development for China’s Electric Power Industry

Mode shape estimation and mode checking for IAO using correlation analysis technique

This paper presents a novel algorithm for rapid estimating mode shape and checking the corresponding mode for inter-area oscillation (IAO) using correlation analysis (CA). It firstly extracts the weak damping components strongly associated with the objective IAO mode from the tie-line active power signals came from wide area measurement system (WAMS), through a low-pass or band-pass filter which is designed by the priori knowledge of modal frequency obtained from off-line calculation. Then their self-correlation and cross-correlation coefficients resulted from the CA technique are used to determine the IAO mode shape for tie-line power deviation or equivalent speed deviation, which is always able to correspond to an IAO mode. Finally, the results are checked with their corresponding items in the modal form (MF) obtained by off-line calculation and on-line correction in order to confirm the dominant IAO mode and its mode shape at current state. Two pairs of stationary and non-stationary synthetic signals are utilized to verify the applicability of CA. The case studies have been carried out on a 4-area and 9-bus system and a planning case in East China Power Grid (ECPG). The results show that the proposed algorithm is efficient and effective, and also indicate its potential practicability for WAMS of bulk power system.

The stability of AGC systems with commensurate delays

AbstractWith communication signal delays, a power system control can actually excite sustained oscillations. This paper proposes a method to analyze the stability of such delayed systems and the like. The stability is estimated using delay margins. The main result is nicely based on a sufficient and necessary condition. Simulation results of the Automatic Generation Control (AGC) system of the real‐world East China Power Grid (ECPG) system are reported to validate the methodology. Copyright © 2007 John Wiley & Sons, Ltd.