Multiple Infeed Short Circuit Ratio – Aspects Related to Multiple HVDC into One AC Network (original) (raw)
Related papers
Multiple Infeed Short Circuit Ratio – Aspects Related to Multiple HVDC into One AC Network
2005 IEEE/PES Transmission & Distribution Conference & Exposition: Asia and Pacific, 2005
The paper suggests an extension of the classical definition of Short Circuit Ratio and Effective Short Circuit Ratio to multiple infeed of HVDC transmission configuration. With such new indexes, which consider the interaction between converter stations, it is possible to predict low frequency resonances, dynamic overvoltages and risk for voltage and power instability at low value of the index, similar to single infeed configuration. In this paper it is also discussed other relevant issues related to integration of multiple HVDC links when the strength of the system is relatively low compared to the amount of power delivered by the HVDC links.
On the Indexes to Qualify an HVDC Connected to Very Weak Ac Networks
2007
This paper develops a voltage stability analysis of ac/dc systems using static and modal indexes. The indexes are normalized and compared for different short circuit ratios, SCR, for several known networks at a common voltage base. Two new indexes are proposed to provide more information on reactive power requirements for voltage stability. The first index proposes critical values for several SCR´s, whereas the second allows featuring two types of systems, soft and non-soft, to qualify requirements of reactive power. The approach can assist for considering the reactive compensation or control strategies in HVDC applications.
Aspects on infeed of multiple HVDC into one ac network
2005
The paper covers the fundamental aspects of integration of multiple HVDC links feeding power into different points in the same ac network area. Considering that the number of power systems that includes this type of application of HVDC is increasing, the performance needs to be studied in detail. There are a number of technical aspects related to multiple infeed configurations with HVDC transmission links. Focus on critical network conditions where the strength of the system is relatively low as compared to the amount of power that the HVDC transmission links are feeding into the system will be given in this paper. In those cases the phenomena of concern that might occur which could result in adverse interaction among the HVDC transmission links and the receiving ac network are discussed. The following basic issues are addressed in the paper: voltage and power stability; coordination of power or voltage modulation between different HVDC links for stabilization of the ac network; nee...
Case Study of a Multi-Infeed HVDC System
There are serious concerns relating to a Multi-Infeed HVDC system when feeding a weak AC network. Typical issues concerning multi-infeed configurations are: need for coordination of the recovery control, need for different DC modulation strategies to stabilize the system, possibility of voltage instability of the area receiving large amount of power from multiple HVDC links and the risk of mutual commutation failures. In contrast, if the area receiving electrical power from multiple HVDC transmission links is relatively strong due to the presence of large amount of generation units nearby there are still some questions that need to be investigated such as the issues underlining the operation of such a multi-infeed system, the proper design of the controls of the HVDC systems and the system dynamic performance under extreme contingencies. This paper investigates into an example of such a multi-infeed HVDC system. The authors have performed small signal analysis of the system to assess instability associated with the control modes. Electromechanical and voltage stability analysis were performed for harmful contingencies. Dynamic performance analysis was also carried out to analyze the interaction amongst various HVDC inverters during disturbances.
Study of a Multi-Infeed HVDC System
2009
There are serious concerns relating to a MultiInfeed HVDC system when feeding a weak AC network. Typical issues concerning multi-infeed configurations are: need for coordination of the recovery control, need for different DC modulation strategies to stabilize the system, possibility of voltage instability of the area receiving large amount of power from multiple HVDC links and the risk of mutual commutation failures. In contrast, if the area receiving electrical power from multiple HVDC transmission links is relatively strong due to the presence of large amount of generation units nearby there are still some questions that need to be investigated such as the issues underlining the operation of such a multi-infeed system, the proper design of the controls of the HVDC systems and the system dynamic performance under extreme contingencies. This paper investigates into an example of such a multi-infeed HVDC system. The authors have performed small signal analysis of the system to assess...
IEEE PES Innovative Smart Grid Technologies, Europe, 2014
This paper discusses grid code compliance for pointto-point VSC-HVDC systems used for the grid connection of far and large offshore wind power plants. The study focus on the short circuit current contribution provided by VSC-HVDC system delivery. Sensitivities such as the reactive current boosting gain of the AC voltage controller, the choice of deadband and the method prioritising active versus reactive current during faulted conditions are discussed with focus on power system voltage and rotor angle stability of a multi-machine power system. The paper shows that prioritising the reactive short circuit current versus active current leads to improvement in both voltage response and transient stability of the AC power system. In addition, the removal of the dead-band while increasing the proportional gain of the AC voltage controller is proved to be beneficial for the power system stability.
Short circuit analysis of an offshore AC network having multiple grid forming VSC-HVDC links
International Journal of Electrical Power & Energy Systems
This article presents the short circuit analysis of an offshore AC network which consists of wind power plants interconnected using HVAC cables. The power generated in the offshore AC network is transmitted to several onshore grids using VSC-HVDC system. The offshore AC network is formed by the VSC-HVDC systems using frequency and voltage droop control. A coordinated control scheme is proposed for wind turbines and offshore VSCs during short circuit conditions in the offshore grid to ensure fault ride through (FRT) without compromising the system stability. The theoretical analysis used for developing this control scheme allows to calculate the system limits taking into consideration the active and reactive power capability. In order to verify the proposed control scheme, three phase symmetric faults have been applied on a wind turbine busbar, HVAC busbar, and at the AC cable that interconnects the VSC-HVDC system. Additionally, a frequency coordination control scheme without communication between wind power generation and VSC-HVDC system has been proposed. The methodology and control system have been validated by performing a nonlinear simulation.
A Multi-infeed HVDC System: Assessment of Transient Overvoltages
The paper presents an electromagnetic-transient (EMT) analysis of a multi-infeed HVDC cable system in order to assess the transient overvoltages on the cables due to different fault conditions. It is well known that the HVDC-MMC configuration needs surge arresters to reduce the transient overvoltages on the DC cable system. This work highlights how the voltage perturbations on the HVDC-LCC link due to the faults on the HVDC-MMC link are not negligible and how a reduction of transient overvoltage is necessary for both the HVDC systems. The results of this study can be useful to improve the insulation coordination of the multi-infeed HVDC system and their reliable operation.
Feasibility of HVDC for Very Weak AC Systems with SCR below 1.5
2006 12th International Power Electronics and Motion Control Conference, 2006
This paper exposes the feasibility to connect high voltage dc transmission (HVDC) systems to very weak ac networks leading to short circuit ratios (SCR) lower than 1.5. The existing literature does not provide solutions for such a low SCR systems and often the HVDC expansions cannot grow enough as expected. The studies developed are for the short-term voltage stability phenomena, where a solution using the PSCAD/EMTDC program for a very weak ac network with SCR = 1.0 is presented. The reactive power characteristics are shown since they are important to judge the behavior of solutions for ac/dc interactions.
HVDC over HVAC Transmission System- Fault Conditions Stability Study
Electric Faults can be defined as the flow of a massive current through an alternative path which leads to cause serious equipment's damage, interruption of power, personal injury or death. High Voltage Alternating Current (HVAC) is the most effective and efficient way for energy transmission in modern power systems around the world. But, it's important to use High Voltage Direct Current (HVDC) system to link between different frequency networks and at transmitting energy on very long distance. HVDC operates at one side "converter station", where, the AC is converted to DC, which is then transmitted from sending end converter station, converted back to AC at receiving end to feed the other electrical network. This paper discusses the performance of the electrical grid system at the fault occurrence in HVAC and HVDC system. Also, this paper introduces the mathematical calculation steps at different faults conditions in the transmission line. The simulation of the fault current in this paper has been performed by using MATLAB/Simulink to compare the output fault current in HVAC and HVDC system.