Simulation study on low frequency load shedding strategy of large power grid considering wind power participation in frequency modulation

Under-frequency load shedding (UFLS) prevents a power grid from a blackout when a severe contingency occurs. UFLS schemes can be classified into two categories—event-based and response-driven. A response-driven scheme utilizes 81L relays with pre-determined settings while an event-based scheme develops a pre-specified look-up table. In this work, an event-based UFLS scheme is presented for use in an offshore standalone power grid with renewables to avoid cascading outages due to low frequency protection of wind power generators and photovoltaic arrays. Possible “N-1” and “N-2” forced outages for peak and off-peak load scenarios in summer and winter are investigated. For each forced outage event, the total shed load is minimized and the frequency nadir is maximized using particle swarm optimization (PSO). In order to reduce the computation time, initialization and parallel computing are implemented using MATLAB/Simulink because all forced outage events and all particles in PSO are mutually independent. A standalone 38-bus power grid with two wind turbines of 2 × 2 MW and photovoltaics of 7.563 MW was studied. For each event, the proposed method generally obtains a result with a smaller shed load and a smaller overshoot frequency than the utility and existing methods. These simulation results verify that the proposed method is practically applicable in a standalone power system with penetration of renewables.

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Study on Low Frequency Load-Shedding of Substitute District

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.706-708.2048 ◽

2013 ◽

Vol 706-708 ◽

pp. 2048-2052

Author(s):

Guo Wei Ren

Keyword(s):

Power Supply ◽

Power Grid ◽

Low Frequency ◽

Load Shedding

Based on low frequency load-shedding practice experiments of Xinyang power supply company, work principles as three reports, one examination and a table modification is proposed to improve the management of power grid in substitute district. The methods introduced in the paper is proved to be effective in the practice.

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Analysis of the Influence of Renewable Generator Frequency Endurance Capability on Low-Frequency Load Shedding: A Hunan Case Study

Complexity ◽

10.1155/2020/8899946 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Yang-Wu Shen ◽

Ding Wang ◽

Hao Chen ◽

Jian Zuo ◽

Min Xu ◽

...

Keyword(s):

Power Grid ◽

Rapid Development ◽

Low Frequency ◽

Load Shedding ◽

Response Characteristics ◽

High Penetration ◽

Overshoot Phenomenon ◽

Implementation Effect ◽

Grid Load ◽

Generator Frequency

With the rapid development of renewable generators such as distributed photovoltaic and profound changes of the power structure, this paper analyzes the frequency characteristics of the power system with high penetration of renewable generations in the process of low-frequency load shedding and discusses the influence of the distributed renewable generator frequency endurance capabilities on the implementation effect of low-frequency load shedding in detail. Finally, the influences of the distributed renewable generator frequency endurance capability and the capacities of the distributed renewable generator on frequency response characteristics of an actual Hunan power grid are simulated. The simulation results show that more distributed photovoltaic capacity without frequency endurance capability leads to deeper frequency drops after the disturbance and requires more basic rounds of load shedding. When the penetration rate of distributed photovoltaic is too high, it may cause load shedding, resulting in power grid load losses and, at the same time, leading to an overshoot phenomenon in the process of frequency recovery. Therefore, the influence of distributed photovoltaic on the control of low-frequency load shedding should be considered when designing low-frequency load shedding schemes for the power grid with high penetration of distributed photovoltaic.

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