Common-Mode Frequency in Inverter-Penetrated Power Systems: Definition, Analysis, and Quantitative Evaluation

2022 ◽  
Author(s):  
Huisheng Gao ◽  
Huanhai Xin ◽  
Linbin Huang ◽  
Zhiyi Li ◽  
Wei Huang ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Test System ◽  
Mode Frequency ◽  
Rate Of Change ◽  
Synchronous Generators ◽  
Common Mode ◽  
Response Characteristics ◽  
Frequency Drop ◽  
System Frequency

<p>As synchronous generators (SGs) are extensively replaced by inverter-based generators (IBGs), modern power systems are facing complicated frequency stability problems. Conventionally, the frequency nadir and the rate of change of frequency (RoCoF) are the two main factors concerned by power system operators. However, these two factors heavily rely on simulations or experiments, especially in a power system with high-penetration IBGs, which offer limited theoretical insight into how the frequency response characteristics are affected by the devices. This paper aims at filling this gap. Firstly, we derive a formulation of the global frequency for an IBG-penetrated power system, referred to as common-mode frequency (CMF). The derived CMF is demonstrated to be more accurate than existing frequency definitions, e.g., the average system frequency (ASF). Then, a unified transfer function structure (UTFS) is proposed to approximate the frequency responses of different types of devices by focusing on three key parameters<a>, which dramatically reduces the complexity of frequency analysis. </a>On this basis, we introduce two evaluation indices, i.e., frequency drop depth coefficient (FDDC) and frequency drop slope coefficient (FDSC), to theoretically quantify the frequency nadir and the average RoCoF, respectively. Instead of relying on simulations or experiments, our method rigorously links the system’s frequency characteristics to the characteristics of heterogeneous devices, which enables an in-depth understanding regarding how devices affect the system frequency. Finally, the proposed indices are verified through simulations on a modified IEEE 39-bus test system. </p>

scholarly journals Common-Mode Frequency in Inverter-Penetrated Power Systems: Definition, Analysis, and Quantitative Evaluation

2022 ◽  
Author(s):  
Huisheng Gao ◽  
Huanhai Xin ◽  
Linbin Huang ◽  
Zhiyi Li ◽  
Wei Huang ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Test System ◽  
Mode Frequency ◽  
Rate Of Change ◽  
Synchronous Generators ◽  
Common Mode ◽  
Response Characteristics ◽  
Frequency Drop ◽  
System Frequency

<p>As synchronous generators (SGs) are extensively replaced by inverter-based generators (IBGs), modern power systems are facing complicated frequency stability problems. Conventionally, the frequency nadir and the rate of change of frequency (RoCoF) are the two main factors concerned by power system operators. However, these two factors heavily rely on simulations or experiments, especially in a power system with high-penetration IBGs, which offer limited theoretical insight into how the frequency response characteristics are affected by the devices. This paper aims at filling this gap. Firstly, we derive a formulation of the global frequency for an IBG-penetrated power system, referred to as common-mode frequency (CMF). The derived CMF is demonstrated to be more accurate than existing frequency definitions, e.g., the average system frequency (ASF). Then, a unified transfer function structure (UTFS) is proposed to approximate the frequency responses of different types of devices by focusing on three key parameters<a>, which dramatically reduces the complexity of frequency analysis. </a>On this basis, we introduce two evaluation indices, i.e., frequency drop depth coefficient (FDDC) and frequency drop slope coefficient (FDSC), to theoretically quantify the frequency nadir and the average RoCoF, respectively. Instead of relying on simulations or experiments, our method rigorously links the system’s frequency characteristics to the characteristics of heterogeneous devices, which enables an in-depth understanding regarding how devices affect the system frequency. Finally, the proposed indices are verified through simulations on a modified IEEE 39-bus test system. </p>

Under Frequency Load Shedding Techniques for Future Smart Power Systems

2019 ◽  
pp. 188-202
Author(s):  
H. H. Alhelou
Keyword(s):  
Power Systems ◽  
Power System ◽  
Active Power ◽  
Load Shedding ◽  
System Stability ◽  
Special Focus ◽  
Power Demand ◽  
Synchronous Generators ◽  
Smart Power ◽  
System Frequency

It is critical for today's power system to remain in a state of equilibrium under normal conditions and severe disturbances. Power imbalance between the load and the generation can severely affect system stability. Therefore, it is necessary that these imbalance conditions be addressed in the minimum time possible. It is well known that power system frequency is directly proportional to the speed of rotation of synchronous machines and is also a function of the active power demand. As a consequence, when active power demand is greater than the generation, synchronous generators tends to slow down and the frequency decreases to even below threshold if not quickly addressed. One of the most common methods of restoring frequency is the use of under frequency load shedding (UFLS) techniques. In this chapter, load shedding techniques are presented in general but with special focus on UFLS.

scholarly journals A Methodology for Provision of Frequency Stability in Operation Planning of Low Inertia Power Systems

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 737
Author(s):  
Michał Kosmecki ◽  
Robert Rink ◽  
Anna Wakszyńska ◽  
Roberto Ciavarella ◽  
Marialaura Di Somma ◽  
...  
Keyword(s):  
Power Systems ◽  
Power System ◽  
Power Flow ◽  
Storage System ◽  
Rate Of Change ◽  
System Level ◽  
Operation Planning ◽  
Planning Period ◽  
Power Sources ◽  
Real Time Digital Simulator

Along with the increasing share of non-synchronous power sources, the inertia of power systems is being reduced, which can give rise to frequency containment problems should an outage of a generator or a power infeed happen. Low system inertia is eventually unavoidable, thus power system operators need to be prepared for this condition. This paper addresses the problem of low inertia in the power system from two different perspectives. At a system level, it proposes an operation planning methodology, which utilises a combination of power flow and dynamic simulation for calculation of existing inertia and, if need be, synthetic inertia (SI) to fulfil the security criterion of adequate rate of change of frequency (RoCoF). On a device level, it introduces a new concept for active power controller, which can be applied virtually to any power source with sufficient response time to create synthetic inertia. The methodology is demonstrated for a 24 h planning period, for which it proves to be effective. The performance of SI controller activated in a battery energy storage system (BESS) is positively validated using a real-time digital simulator (RTDS). Both proposals can effectively contribute to facilitating the operation of low inertia power systems.

scholarly journals Voltage Coordination via Communication in Large-Scale Multi-Area Power Systems. Part II: Simulation Results

2012 ◽  
Vol 433-440 ◽  
pp. 7183-7189
Author(s):  
Mohammad Moradzadeh ◽  
René Boel
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electricity Market ◽  
Large Scale ◽  
Test System ◽  
Distributed Model ◽  
Future Evolution ◽  
Distributed Model Predictive Control ◽  
Control Actions ◽  
Simulation Results

This two-part paper deals with the coordination of the control actions in a network of many interacting components, where each component is controlled by independent control agents. As a case study we consider voltage control in large electric power systems where ever-increasing pressures from the liberalization and globalization of the electricity market has led to partitioning the power system into multiple areas each operated by an independent Transmission System Operator (TSO). Coordination of local control actions taken by those TSOs is a very challenging problem as poorly coordinated operation of TSOs may endanger the power system security by increasing the risk of blackouts. This second part of the paper presents simulation results on a 12-bus 3-area test system, using the distributed model predictive control paradigm in order to design a coordinating model-based feedback controller. Coordination requires that each agent has some information on what the future evolution of its power flows to and from its neighbors will be. It will be shown that how the communication between agents can avoid voltage collapse in circumstances where classical uncoordinated controllers fail.

Effect of Large-Scale Wind Power Integration on Inter-Area Oscillation of Power System

2014 ◽  
Vol 672-674 ◽  
pp. 227-232
Author(s):  
Xu Zhi Luo ◽  
Hai Feng Li ◽  
Hua Dong Sun ◽  
An Si Wang ◽  
De Zhi Chen
Keyword(s):  
Power Systems ◽  
Power System ◽  
Wind Power ◽  
Large Scale ◽  
Oscillation Mode ◽  
Equivalent Model ◽  
Synchronous Generators ◽  
Actual System ◽  
Oscillation Modes ◽  
The Impact

With the fast development of the wind power, security constraints of power systems have become the bottleneck of the acceptable capacity for wind power. The underdamping oscillation modes of the inter-area is an important aspect of the constraints. In this paper, an equivalent model of a power system with wind plants has been established, and the impact of the integration of the large-scale wind power on the inter-area oscillation modes has been studied based on the frequency-domain and time-domain simulations. The results indicate that the damping of inter-area oscillation mode can be enhanced by the replacement of synchronous generators (SGs) with the wind generators. The enhancing degree is up to the participation value of the SGs replaced. The conclusion has been verified by the actual system example of Xinjiang-Northwest grid. It can provide a reference for system programming and operation.

Power system frequency stabiliser for modern power systems

2018 ◽  
Vol 12 (9) ◽  
pp. 1961-1969 ◽  
Author(s):  
Dushyant Sharma ◽  
Sukumar Mishra
Keyword(s):  
Power Systems ◽  
Power System ◽  
System Frequency

scholarly journals A Parallel Implementation of Unscheduled Flow Control in Interconnected Power Systems

2012 ◽  
Vol 2012 ◽  
pp. 1-19
Author(s):  
G. Ozdemir Dag ◽  
Mustafa Bagriyanik
Keyword(s):  
Power Systems ◽  
Power System ◽  
Parallel Computation ◽  
High Performance ◽  
Power Flow ◽  
Parallel Implementation ◽  
Computation Time ◽  
Test System ◽  
Fuzzy Decision Making ◽  
Optimization Approach

The unscheduled power flow problem needs to be minimized or controlled as soon as possible in a deregulated power system since the transmission systems are mostly operated at their power-carrying limits or very close to it. The time spent for simulations to determine the current states of all the system and control variables of the interconnected power system is important. Taking necessary action in case of any failure of equipment or any other occurrence of an undesired situation could be critical. Using supercomputing facilities and parallel computing techniques together decreases the computation time greatly. In this study, a parallel implementation of a multiobjective optimization approach based on both genetic algorithms and fuzzy decision making to manage unscheduled flows is presented. Parallel computation techniques are applied using supercomputers (high-performance computers). The proposed method is applied to the IEEE 300 bus test system. Two different cases for some parameters of GA are considered to see the power of parallel computation technique. Then the simulation results are presented.

scholarly journals An approach for a multi-stage under-frequency based load shedding scheme for a power system network

2020 ◽  
Vol 10 (6) ◽  
pp. 6071
Author(s):  
Mkhululi Elvis Siyanda Mnguni ◽  
Yohan Darcy Mfoumboulou
Keyword(s):  
Decision Making ◽  
Power Systems ◽  
Power System ◽  
New England ◽  
Operating Conditions ◽  
Load Shedding ◽  
Power Network ◽  
Load Demand ◽  
Multi Stage ◽  
System Frequency

The integration of load shedding schemes with mainstream protection in power system networks is vital. The traditional power system network incorporates different protection schemes to protect its components. Once the power network reaches its maximum limits, and the load demand continue to increase the whole system will experience power system instability. The system frequency usually drops due to the loss of substantial generation creating imbalance. The best method to recover the system from instability is by introducing an under-frequency load shedding (UFLS) scheme in parallel with the protection schemes. This paper proposed a new UFLS scheme used in power systems and industry to maintain stability. Three case studies were implemented in this paper. Multi-stage decision-making algorithms load shedding in the environment of the DIgSILENT power factory platform is developed. The proposed algorithm speeds-up the operation of the UFLS scheme. The load shedding algorithm of the proposed scheme is implemented as a systematic process to achieve stability of the power network which is exposed to different operating conditions. The flexibility of the proposed scheme is validated with the modified IEEE 39-bus New England model. The application of the proposed novel UFLS schemes will contribute further to the development of new types of engineers.

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