scholarly journals Synchronous Condenser’s Loss of Excitation and Its Impact on the Performance of UHVDC

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4926
Author(s):  
Zhilin Guo ◽  
Liangliang Hao ◽  
Junyong Wu ◽  
Xingguo Wang ◽  
Hong Cao ◽  
...  
Keyword(s):  
Transient Stability ◽  
Reactive Power ◽  
Voltage Drop ◽  
Operation Mode ◽  
High Voltage Direct Current ◽  
Synchronous Condenser ◽  
Voltage Variation ◽  
Single Machine Infinite Bus ◽  
Power Response ◽  
Basic Cognition

The synchronous condenser (SC) has a broad application prospect in ultra-high-voltage direct current (UHVDC) systems. The SC’s loss of excitation (LOE) is an important grid-related fault that may cause damage to the UHVDC. However, as the premise of the scientific protection configuration, knowledge of the SC’s LOE feature and its impact on UHVDC is still missing. This article first analyzes the SC’s LOE feature, offering a basic cognition of this fault. Secondly, the LOE SC’s reactive power response to system voltage variation is studied in the single-machine infinite-bus system. This lends a foundation for transient UHVDC research. Finally, the LOE SC’s impacts on steady and transient UHVDC are evaluated, respectively, considering different AC strengths and system faults through PSCAD/EMTDC (V4.6, Manitoba HVDC Research Center, Winnipeg, MB, Canada) simulations. The results show that: (1) LOE the SC absorbs reactive power while maintaining synchronous operation, its excitation current declines monotonically; (2) the LOE SC has an insignificant effect on steady-state UHVDC; (3) the LOE SC can restrain the overvoltage and benefit the rectifier’s transient stability; and (4) to reduce the inverter’s commutation failure, keeping LOE SC is more effective than separating it beforehand, while separating the LOE SC after the system voltage drop performs best. These conclusions could provide insights for the protection’s criterion and operation mode selections.

Reactive Power Compensation Method of HVDC Commutation Failure

2014 ◽  
Vol 536-537 ◽  
pp. 1510-1513
Author(s):  
Xiao Ming Wang ◽  
Qi Zhang ◽  
Bin Qian
Keyword(s):  
Reactive Power ◽  
Voltage Drop ◽  
Critical Value ◽  
Reactive Power Compensation ◽  
Transmission System ◽  
Critical Voltage ◽  
High Voltage Direct Current ◽  
Commutation Failure ◽  
The Difference ◽  
Bus Voltage

In the high-voltage direct current transmission system, the difference value between the landing phase voltage and DC transmission system commutation failure of the critical voltage drop value, as system occurred in the critical value of commutation failure. When commutation voltage lower than the critical value would reduce arc Angle, caused by commutation failure。Therefore, by using the method of reactive power compensation to keep converter bus voltage stability, can avoid commutation failure.

scholarly journals A Quantitative Index to Evaluate the Commutation Failure Probability of LCC-HVDC with a Synchronous Condenser

2019 ◽  
Vol 9 (5) ◽  
pp. 925 ◽  
Author(s):  
Jiangbo Sha ◽  
Chunyi Guo ◽  
Atiq Rehman ◽  
Chengyong Zhao
Keyword(s):  
Failure Probability ◽  
Reactive Power ◽  
Voltage Control ◽  
Capacity Allocation ◽  
Control Device ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Synchronous Condenser ◽  
Commutation Failure ◽  
The Impact

Since thyristor cannot turn off automatically, line commutated converter based high voltage direct current (LCC-HVDC) will inevitably fail to commutate and therefore auxiliary controls or voltage control devices are needed to improve the commutation failure immunity of the LCC-HVDC system. The voltage control device, a synchronous condenser (SC), can effectively suppress the commutation failure of the LCC-HVDC system. However, there is a need for a proper evaluation index that can quantitatively assess the ability of the LCC-HVDC system to resist the occurrence of commutation failures. At present, the main quantitative evaluation indicators include the commutation failure immunity index and the commutation failure probability index. Although they can reflect the resistance of the LCC-HVDC system to commutation failures to a certain extent, they are all based on specific working conditions and cannot comprehensively evaluate the impact of SCs on suppressing the commutation failure of the LCC-HVDC system under certain fault ranges. In order to more comprehensively and quantitatively evaluate the influence of SCs on the commutation failure susceptibility of the LCC-HVDC system under certain fault ranges, this paper proposes the area ratio of commutation failure probability. The accuracy of this new index was verified through the PSCAD/EMTDC. Based on the CIGRE benchmark model, the effects of different synchronous condensers on LCC-HVDC commutation failure were analyzed. The results showed that the new index could effectively and more precisely evaluate the effect of SCs on commutation failures. Moreover, the proposed index could provide a theoretical basis for the capacity allocation of SCs in practical projects and it could also be utilized for evaluating the impact of other dynamic reactive power compensators on the commutation failure probability of the LCC-HVDC system under certain fault ranges.

scholarly journals Low Voltage Ride Through Controller for a Multi-Machine Power System Using a Unified Interphase Power Controller

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 585
Author(s):  
Atoosa Majlesi ◽  
Mohammad Reza Miveh ◽  
Ali Asghar Ghadimi ◽  
Akhtar Kalam
Keyword(s):  
Power System ◽  
Power Flow ◽  
Transient Stability ◽  
Reactive Power ◽  
Low Voltage ◽  
Voltage Drop ◽  
Energy Resource ◽  
Unified Power Flow Controller ◽  
Power Controller ◽  
Low Voltage Ride Through

In recent years, grid-connected photovoltaic (PV) power generations have become the most extensively used energy resource among other types of renewable energies. Increasing integration of PV sources into the power network and their dynamic performances under fault conditions is an important issue for grid code requirements. In this paper, a PV source as a unified interphase power controller (UIPC) is used to enhance the low voltage ride through (LVRT) and transient stability of a multi-machine power system. The suggested PV-based UIPC consists of two series voltage inverters and a parallel inverter. The UIPC injects the required active and reactive power to prevent voltage drop under grid fault conditions. Accordingly, a dynamic control system is designed based on proportional-integral (PI) controllers for the PV-based UIPC to operate in both normal and fault conditions. Simulations are done using Matlab/Simulink software, and the performance of the PV-based UIPC is compared with the conventional unified power flow controller (UPFC). The results of this study indicate the more favorable impact of the PV-based UIPC on the system compared to UPFC in improving LVRT capabilities and transient stability.

Improving Transient Stability in Power Systems by Using Fuzzy Logic Controlled SVC

2017 ◽  
Vol 6 (4) ◽  
pp. 227
Author(s):  
Reaza Ashrafi Habib Abadi ◽  
Amir Nekoubin
Keyword(s):  
Fuzzy Logic ◽  
Power Systems ◽  
Transient Stability ◽  
Fuzzy Logic Controller ◽  
Reactive Power ◽  
Robust Controller ◽  
Input Signals ◽  
Fixed Parameter ◽  
Terminal Voltage ◽  
Single Machine Infinite Bus

<span>This paper presents the capability of a fuzzy logic based stabilizer used for generating the supplementary control signal to voltage regulator of static VAR compensator (SVC) for improving damping oscillations in power systems. Generator speed deviation and line active power were chosen as input signals for the fuzzy logic controller (FLC). The quantity of reactive power supplied/absorbed by SVC is determined based on the two input signal and deviation of terminal voltage at each sampling time. The effectiveness and feasibility of the proposed control is demonstrated with Single Machine Infinite Bus (SMIB) system and multi machine system which show improvement over the use of a fixed parameter controller. It has been observed that a robust controller is obtained with fuzzy logic controller.</span>

Adjusting the Transient Stability of Power System Using STATCOM-SMES Combined Compensator

2012 ◽  
Vol 229-231 ◽  
pp. 1115-1119
Author(s):  
Jalil Ghahramani ◽  
Seyed Siavash Karimi Madahi
Keyword(s):  
Single Machine ◽  
Transient Stability ◽  
Reactive Power ◽  
Electrical Energy ◽  
Power Network ◽  
Facts Devices ◽  
Active And Reactive Power ◽  
Effective Operation ◽  
Single Machine Infinite Bus ◽  
Sample System

Since most of the new FACTS devices are operating in compensating active and reactive power and most of the electrical energy saving systems have an acceptable operation in compensating active and reactive power, in this paper a combined compensator of STATCOM-SMES is introduced and is exploit in order to adjust the transient stability of power network. The purpose of this paper is analyzing the more effective operation of combined compensator of STATCOM-SMES comparing with STATCOM compensator, using an appropriate strategy in adjusting the transient stability. To do this, a single machine infinite bus is assumed as sample system and using combined compensator in sample power network, appropriate results are shown for adjusting transient stability. Simulations are carried out using PSCAD/EMTDC.

scholarly journals Transient stability enhancement of statcom integration in power grid

2019 ◽  
Vol 16 (2) ◽  
pp. 553
Author(s):  
I. A Ethmane ◽  
A.K. Mahmoud ◽  
M. Maaroufi ◽  
A. Yahfdhou
Keyword(s):  
Power Quality ◽  
Power Flow ◽  
Distribution Systems ◽  
Transient Stability ◽  
Reactive Power ◽  
Voltage Drop ◽  
Flow Analysis ◽  
Drop Out ◽  
Power Flow Analysis ◽  
Facts Devices

T<span>o solve load growth of a hybrid existing electrical system, we at first build generation stations (wind, solar or thermical). And secondly in 2025 year, when the system is so meshed, some buses will be very far from production energy, the transits power will be lower than the transmission capacity, and the voltage drop out margin limit of stability. Therefore it is proposed to install Flexible AC Transmission System (FACTS) devices to enhance the transient power stability and quality in the power system. The power flow analysis of Newton Raphson method is performed on a seven (7) bus system with and without static synchronous compensator (STATCOM). The STATCOM is a shunt connected FACTS devices that are useful for reactive power compensation and mitigation of power quality problems in transmission and distribution systems. These investigations indicate the need of power flow analysis and determine best locations of STATCOM on the proposed system. The results of simulation have been programmed in MATLAB and PSS/E Simulator. In the end the expected disturbances and the power quality enhancement of the network in the horizon 2025 were attenuated by integration of STATCOM that is able to supply or absorb reactive power and to maintain the voltage at 1pu.</span>

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