Articles de revista
http://hdl.handle.net/2117/3808
2021-07-30T02:30:53Z
2021-07-30T02:30:53Z
HVAC transmission system for offshore wind power plants including mid-cable reactive power compensation: optimal design and comparison to VSC-HVDC transmission
Dakic, Jovana
Cheah Mañé, Marc
Gomis Bellmunt, Oriol
Prieto Araujo, Eduardo
http://hdl.handle.net/2117/350158
2021-07-27T11:40:57Z
2021-07-27T11:38:06Z
HVAC transmission system for offshore wind power plants including mid-cable reactive power compensation: optimal design and comparison to VSC-HVDC transmission
Dakic, Jovana; Cheah Mañé, Marc; Gomis Bellmunt, Oriol; Prieto Araujo, Eduardo
The design distance of offshore wind power plants connected through HVAC transmission systems might be extended due to the introduction of mid-cable reactors for reactive power compensation purposes and the latest developments of AC cables for higher voltages. Therefore, the applicability limits between HVAC and HVDC systems must be revised. This paper analyzes the contribution that mid-cable reactive power compensation has on increasing the distance limits of HVAC transmission systems. A methodology is developed to determine an optimal design of such transmission systems. In this methodology, cost of power losses and reactors are minimized for multiple wind speed conditions. As a result, the optimal HVAC voltage level and the optimal number of reactors and their location are determined for different OWPP rated powers and distances. Also, the final transmission system is selected between HVAC and HVDC equivalent configurations based on total costs.
2021-07-27T11:38:06Z
Dakic, Jovana
Cheah Mañé, Marc
Gomis Bellmunt, Oriol
Prieto Araujo, Eduardo
The design distance of offshore wind power plants connected through HVAC transmission systems might be extended due to the introduction of mid-cable reactors for reactive power compensation purposes and the latest developments of AC cables for higher voltages. Therefore, the applicability limits between HVAC and HVDC systems must be revised. This paper analyzes the contribution that mid-cable reactive power compensation has on increasing the distance limits of HVAC transmission systems. A methodology is developed to determine an optimal design of such transmission systems. In this methodology, cost of power losses and reactors are minimized for multiple wind speed conditions. As a result, the optimal HVAC voltage level and the optimal number of reactors and their location are determined for different OWPP rated powers and distances. Also, the final transmission system is selected between HVAC and HVDC equivalent configurations based on total costs.
A novel hybrid home energy management system considering electricity cost and greenhouse gas emissions minimization
Barja Martínez, Sara
Rücker, Fabian
Aragüés Peñalba, Mònica
Villafafila Robles, Roberto
Munné Collado, Íngrid
Lloret Gallego, Pau
http://hdl.handle.net/2117/348301
2021-07-05T13:22:41Z
2021-07-02T12:29:57Z
A novel hybrid home energy management system considering electricity cost and greenhouse gas emissions minimization
Barja Martínez, Sara; Rücker, Fabian; Aragüés Peñalba, Mònica; Villafafila Robles, Roberto; Munné Collado, Íngrid; Lloret Gallego, Pau
This paper proposes a multi-objective hybrid energy management system that minimizes both the electricity expenses and the household greenhouse gas emissions released due to consumption, considering the entire life cycle of the generation assets used to provide energy. The global warming potential indicator is used to decide if it is more sustainable to purchase electricity from the grid or use the household’s flexible generation sources like photovoltaic panels and the energy storage system. Results prove that it is possible to reduce greenhouse gas emissions without incurring expensive electricity bill costs thanks to the hybrid-based home energy management system approach. This method gives the end-users a more influential role in the climate change solution, allowing them to give more or less importance to the economic or environmental component, according to their preferences.
2021-07-02T12:29:57Z
Barja Martínez, Sara
Rücker, Fabian
Aragüés Peñalba, Mònica
Villafafila Robles, Roberto
Munné Collado, Íngrid
Lloret Gallego, Pau
This paper proposes a multi-objective hybrid energy management system that minimizes both the electricity expenses and the household greenhouse gas emissions released due to consumption, considering the entire life cycle of the generation assets used to provide energy. The global warming potential indicator is used to decide if it is more sustainable to purchase electricity from the grid or use the household’s flexible generation sources like photovoltaic panels and the energy storage system. Results prove that it is possible to reduce greenhouse gas emissions without incurring expensive electricity bill costs thanks to the hybrid-based home energy management system approach. This method gives the end-users a more influential role in the climate change solution, allowing them to give more or less importance to the economic or environmental component, according to their preferences.
Comparative analysis of lattice-based all-pass filter and second order generalized integrator as orthogonal system generator of a pll
Belandria, Luciano Emilio
Agudelo, Nancy Alejadra
Bergas Jané, Joan Gabriel
http://hdl.handle.net/2117/346968
2021-06-15T10:20:23Z
2021-06-09T12:29:38Z
Comparative analysis of lattice-based all-pass filter and second order generalized integrator as orthogonal system generator of a pll
Belandria, Luciano Emilio; Agudelo, Nancy Alejadra; Bergas Jané, Joan Gabriel
This paper presents a steady-state comparison of two methods that generate an orthogonal voltage system for a single-phase Phase-Locked Loop (PLL) structure: a widely accepted one based on a Second Order Generalized Integrator (SOGI) and a new one based on a All-Pass Filter (APF) with Lattice structure. Both methods are very attractive because of their simple digital implementation, low computational load and good performance under harmonically distorted grid conditions and variable frequency, so they are a good alternative to other known methods. The paper derives and analyzes the full state space models of the two methods.It is shown that these two methods are equivalent in the most common operation conditions of distributed energy resources, although the APF structure is clearly better than the SOGI one because it maintains its orthogonal generation ability for any higher notch frequencies and any lower sampling frequencies. The comparative analysis were validated by simulation with MATLAB/Simulink and experimental results using a fixed-point DSP.
2021-06-09T12:29:38Z
Belandria, Luciano Emilio
Agudelo, Nancy Alejadra
Bergas Jané, Joan Gabriel
This paper presents a steady-state comparison of two methods that generate an orthogonal voltage system for a single-phase Phase-Locked Loop (PLL) structure: a widely accepted one based on a Second Order Generalized Integrator (SOGI) and a new one based on a All-Pass Filter (APF) with Lattice structure. Both methods are very attractive because of their simple digital implementation, low computational load and good performance under harmonically distorted grid conditions and variable frequency, so they are a good alternative to other known methods. The paper derives and analyzes the full state space models of the two methods.It is shown that these two methods are equivalent in the most common operation conditions of distributed energy resources, although the APF structure is clearly better than the SOGI one because it maintains its orthogonal generation ability for any higher notch frequencies and any lower sampling frequencies. The comparative analysis were validated by simulation with MATLAB/Simulink and experimental results using a fixed-point DSP.
Over-frequency support in large-scale photovoltaic power plants using non-conventional control architectures
Madorell Batlle, Queralt
Bullich Massagué, Eduard
Cheah Mañé, Marc
Gomis Bellmunt, Oriol
http://hdl.handle.net/2117/344714
2021-05-02T18:50:11Z
2021-04-28T12:47:39Z
Over-frequency support in large-scale photovoltaic power plants using non-conventional control architectures
Madorell Batlle, Queralt; Bullich Massagué, Eduard; Cheah Mañé, Marc; Gomis Bellmunt, Oriol
Large scale photovoltaic power plants must provide a frequency regulation service, which is defined in the grid codes. This service has commonly required a response time between 15 and 30 s. But some countries are now introducing more strict regulations and requiring response times below 2 s. The typical centralized control architecture of photovoltaic power plants for frequency regulation can present undesired oscillatory responses (or even become unstable) when tuning the controller to achieve these small time response requirements. The present article proposes an alternative solution based on a hierarchical control architecture. In the proposed solution, inverter controllers apply a local frequency regulation action and the central controller corrects active power errors at the point of connection, which can be caused by power losses or lack of irradiance in some inverters. Simulation models are used to study and test the response of this new control approach. The proposed hierarchical control architecture is compared with a fully centralized and a fully decentralized archirectures. Results show that the hierarchical control architecture is not only capable to obtain a fast and accurate response, but also is robust against communication failures. The proposed hierarchical control architecture advantages could be extrapolated to other services. So, further research is proposed to confirm this hypothesis.
2021-04-28T12:47:39Z
Madorell Batlle, Queralt
Bullich Massagué, Eduard
Cheah Mañé, Marc
Gomis Bellmunt, Oriol
Large scale photovoltaic power plants must provide a frequency regulation service, which is defined in the grid codes. This service has commonly required a response time between 15 and 30 s. But some countries are now introducing more strict regulations and requiring response times below 2 s. The typical centralized control architecture of photovoltaic power plants for frequency regulation can present undesired oscillatory responses (or even become unstable) when tuning the controller to achieve these small time response requirements. The present article proposes an alternative solution based on a hierarchical control architecture. In the proposed solution, inverter controllers apply a local frequency regulation action and the central controller corrects active power errors at the point of connection, which can be caused by power losses or lack of irradiance in some inverters. Simulation models are used to study and test the response of this new control approach. The proposed hierarchical control architecture is compared with a fully centralized and a fully decentralized archirectures. Results show that the hierarchical control architecture is not only capable to obtain a fast and accurate response, but also is robust against communication failures. The proposed hierarchical control architecture advantages could be extrapolated to other services. So, further research is proposed to confirm this hypothesis.
Reducing cell to cell variation of lithium-ion battery packs during operation
Andreas, Ziegler
Oeser, David
Hein, Thiemo
Montesinos Miracle, Daniel
Ackva, Ansgar
http://hdl.handle.net/2117/343859
2021-04-25T18:58:59Z
2021-04-19T08:47:10Z
Reducing cell to cell variation of lithium-ion battery packs during operation
Andreas, Ziegler; Oeser, David; Hein, Thiemo; Montesinos Miracle, Daniel; Ackva, Ansgar
In this work, an experimental approach to reduce the variation from cell to cell during battery operation is evaluated to reach a better battery utilization. Numerous theoretical considerations of intelligent battery management systems without long-term experimental validation of their capabilities lead to a gap in the literature, which this work aims to address. For this purpose, the ageing behaviour of two batteries is investigated for almost 1.5 years. One battery is connected to an active balancing battery management system (BMS) and the other to a conventional passive balancing BMS. Important battery parameters, such as capacity and internal resistance, are recorded in each cycle. The battery behaviour is evaluated in detail by observing the voltage difference of the individual cells at the end of discharge and by calculating the amount of charge balanced by the BMS. Significant differences between the BMS systems used are elucidated, which illustrate the advantages of active balancing. In contrast to passive balancing, active balancing can reduce the ageing rate of the battery and achieve better utilization with a more than five times lower voltage spread at end of discharge, a up to 3.1% higher discharge capacity and a 7.7% longer service life.
2021-04-19T08:47:10Z
Andreas, Ziegler
Oeser, David
Hein, Thiemo
Montesinos Miracle, Daniel
Ackva, Ansgar
In this work, an experimental approach to reduce the variation from cell to cell during battery operation is evaluated to reach a better battery utilization. Numerous theoretical considerations of intelligent battery management systems without long-term experimental validation of their capabilities lead to a gap in the literature, which this work aims to address. For this purpose, the ageing behaviour of two batteries is investigated for almost 1.5 years. One battery is connected to an active balancing battery management system (BMS) and the other to a conventional passive balancing BMS. Important battery parameters, such as capacity and internal resistance, are recorded in each cycle. The battery behaviour is evaluated in detail by observing the voltage difference of the individual cells at the end of discharge and by calculating the amount of charge balanced by the BMS. Significant differences between the BMS systems used are elucidated, which illustrate the advantages of active balancing. In contrast to passive balancing, active balancing can reduce the ageing rate of the battery and achieve better utilization with a more than five times lower voltage spread at end of discharge, a up to 3.1% higher discharge capacity and a 7.7% longer service life.
Multiport interline current flow controller for meshed HVDC grids
Sau Bassols, Joan
Ferrer San José, Ricard
Prieto Araujo, Eduardo
Gomis Bellmunt, Oriol
http://hdl.handle.net/2117/341007
2021-03-07T22:47:34Z
2021-03-04T13:20:25Z
Multiport interline current flow controller for meshed HVDC grids
Sau Bassols, Joan; Ferrer San José, Ricard; Prieto Araujo, Eduardo; Gomis Bellmunt, Oriol
In meshed high voltage direct current grids, the current of each line cannot be controlled independently, since it depends on the resistances between nodes. Additional devices, such as current flow controllers (CFCs), may be needed to avoid bottlenecks or line overloads. This work presents a multiport dc-dc-based CFC topology to be connected to n lines with unidirectional current flows. The device is able to control the dc lines' currents to the desired value by inserting variable voltage sources in series. First, the modeling of the generic n-port topology is presented and then, its modulation and control strategy are described. In the first case study, the concept is validated considering a 5-port CFC by means of dynamic simulations using different control methods. Finally, in the second case study, a 3-port CFC prototype is built and tested in an experimental platform in the laboratory considering different control modes.
2021-03-04T13:20:25Z
Sau Bassols, Joan
Ferrer San José, Ricard
Prieto Araujo, Eduardo
Gomis Bellmunt, Oriol
In meshed high voltage direct current grids, the current of each line cannot be controlled independently, since it depends on the resistances between nodes. Additional devices, such as current flow controllers (CFCs), may be needed to avoid bottlenecks or line overloads. This work presents a multiport dc-dc-based CFC topology to be connected to n lines with unidirectional current flows. The device is able to control the dc lines' currents to the desired value by inserting variable voltage sources in series. First, the modeling of the generic n-port topology is presented and then, its modulation and control strategy are described. In the first case study, the concept is validated considering a 5-port CFC by means of dynamic simulations using different control methods. Finally, in the second case study, a 3-port CFC prototype is built and tested in an experimental platform in the laboratory considering different control modes.
Maximum torque per voltage flux-weakening strategy with speed limiter for PMSM drives
Miguel Espinar, Carlos
Heredero Peris, Daniel
Gross, Gabriel Igor
Llonch Masachs, Marc
Montesinos Miracle, Daniel
http://hdl.handle.net/2117/340636
2021-03-07T10:18:04Z
2021-03-01T12:26:41Z
Maximum torque per voltage flux-weakening strategy with speed limiter for PMSM drives
Miguel Espinar, Carlos; Heredero Peris, Daniel; Gross, Gabriel Igor; Llonch Masachs, Marc; Montesinos Miracle, Daniel
This paper presents an enhanced Flux Weakening (FW) control scheme for Permanent Magnet Synchronous Motors (PMSMs), focused on electric vehicle applications. The novelty of the proposed algorithm is the integration in a unified scheme of both the accelerator pedal as torque reference and the cruise speed limiter (CSL) as speed limit, without interfering between them until this limit is achieved. The dq-axis current references are calculated from the proposed algorithm by using a polar coordinate system and a per-unit system. The latter is based on the characteristic machine parameters which aim to ease and simplify the algorithm implementation. Moreover, it takes advantage of the smooth transition between the Low Back Electromotive Force (LBEF) zone and the FW zone thanks to a voltage loop which changes the current-vector angle. Another fundamental merit of the proposed scheme is its capacity to work in all the dq-plane throughout the Maximum Torque per Ampere (MTPA), Constant Torque (CT), Current and Voltage Limit (CVL), Maximum Torque per Voltage (MTPV) and Constant Speed (CS) strategies without switching the algorithm. Simulations and experimental results from a real exterior-rotor Interior Permanent Magnet Synchronous Motor (IPMSM) direct-drive emotorbike verify the effectiveness of the proposed method.
© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
2021-03-01T12:26:41Z
Miguel Espinar, Carlos
Heredero Peris, Daniel
Gross, Gabriel Igor
Llonch Masachs, Marc
Montesinos Miracle, Daniel
This paper presents an enhanced Flux Weakening (FW) control scheme for Permanent Magnet Synchronous Motors (PMSMs), focused on electric vehicle applications. The novelty of the proposed algorithm is the integration in a unified scheme of both the accelerator pedal as torque reference and the cruise speed limiter (CSL) as speed limit, without interfering between them until this limit is achieved. The dq-axis current references are calculated from the proposed algorithm by using a polar coordinate system and a per-unit system. The latter is based on the characteristic machine parameters which aim to ease and simplify the algorithm implementation. Moreover, it takes advantage of the smooth transition between the Low Back Electromotive Force (LBEF) zone and the FW zone thanks to a voltage loop which changes the current-vector angle. Another fundamental merit of the proposed scheme is its capacity to work in all the dq-plane throughout the Maximum Torque per Ampere (MTPA), Constant Torque (CT), Current and Voltage Limit (CVL), Maximum Torque per Voltage (MTPV) and Constant Speed (CS) strategies without switching the algorithm. Simulations and experimental results from a real exterior-rotor Interior Permanent Magnet Synchronous Motor (IPMSM) direct-drive emotorbike verify the effectiveness of the proposed method.
Optimal current reference calculation for MMCs considering converter limitations
Westerman Spier, Daniel
Prieto-Araujo, E.
López Mestre, Joaquim
Gomis Bellmunt, Oriol
http://hdl.handle.net/2117/340632
2021-03-01T12:10:26Z
2021-03-01T12:04:11Z
Optimal current reference calculation for MMCs considering converter limitations
Westerman Spier, Daniel; Prieto-Araujo, E.; López Mestre, Joaquim; Gomis Bellmunt, Oriol
The paper addresses an optimization-based reference calculation method for Modular Multilevel Converters (MMC) operating in normal and constrained situations (when the converter needs to prioritize its quantities as it has reached voltage or current limitations, e.g. during system faults). The optimization problem prioritizes to satisfy the external AC active and reactive current set-points demanded by the grid operator through the corresponding grid code. If the operator demands are fulfilled, it uses the available MMC degrees of freedom to minimize the arm inductance losses. Otherwise, if the operator demanded AC set-points cannot be accomplished, the optimization attempts to minimize the error prioritizing between either AC active or reactive currents. The optimization problem constraints are imposed through a steady-state model considering simultaneously the external and internal AC and DC magnitudes of the converter. The steady-state model also includes the voltage variation in the equivalent arm capacitors (considering the ripple). Then, the imposed limitations are the maximum allowed grid and arm currents, the maximum allowed arm voltages and the sub-module capacitor maximum voltages. The paper presents a detailed formulation of the optimization problem and applies it to several case studies where it is shown that the presented approach can be potentially used to obtain the MMC references both in normal and fault conditions.
2021-03-01T12:04:11Z
Westerman Spier, Daniel
Prieto-Araujo, E.
López Mestre, Joaquim
Gomis Bellmunt, Oriol
The paper addresses an optimization-based reference calculation method for Modular Multilevel Converters (MMC) operating in normal and constrained situations (when the converter needs to prioritize its quantities as it has reached voltage or current limitations, e.g. during system faults). The optimization problem prioritizes to satisfy the external AC active and reactive current set-points demanded by the grid operator through the corresponding grid code. If the operator demands are fulfilled, it uses the available MMC degrees of freedom to minimize the arm inductance losses. Otherwise, if the operator demanded AC set-points cannot be accomplished, the optimization attempts to minimize the error prioritizing between either AC active or reactive currents. The optimization problem constraints are imposed through a steady-state model considering simultaneously the external and internal AC and DC magnitudes of the converter. The steady-state model also includes the voltage variation in the equivalent arm capacitors (considering the ripple). Then, the imposed limitations are the maximum allowed grid and arm currents, the maximum allowed arm voltages and the sub-module capacitor maximum voltages. The paper presents a detailed formulation of the optimization problem and applies it to several case studies where it is shown that the presented approach can be potentially used to obtain the MMC references both in normal and fault conditions.
Review of local network impedance estimation techniques
Kervyn De Meerendre, Mathieu
Prieto Araujo, Eduardo
Ahmed, Khaled H.
Gomis Bellmunt, Oriol
Xu, Lie
Egea Àlvarez, Agustí
http://hdl.handle.net/2117/340370
2021-02-28T21:32:36Z
2021-02-23T11:32:55Z
Review of local network impedance estimation techniques
Kervyn De Meerendre, Mathieu; Prieto Araujo, Eduardo; Ahmed, Khaled H.; Gomis Bellmunt, Oriol; Xu, Lie; Egea Àlvarez, Agustí
As a result of increasing variability of network impedance, interest in impedance estimation techniques is growing. This review contextualises local impedance estimation techniques by providing a historical prospective on the uses of these techniques, from the early implementations designed to monitor power quality to the latest techniques integrated into converters designed to update the controller with the most recent network information. This is followed by clear and consolidated descriptions, a complete classification and comparison tables of local estimation techniques intended to assist engineers and researchers choose an estimation technique that is suitable to their application. The discussed techniques are then ranked for a range of application priorities such as accuracy, least disruptive to the network, most suitable for wide frequency spectrum estimations and rapidity of estimation. Practical applications of impedance estimation are discussed, such as network characterisation, anti-islanding detection, filter resonance avoidance and controller tuning. To conclude the review, future trends are identified.
2021-02-23T11:32:55Z
Kervyn De Meerendre, Mathieu
Prieto Araujo, Eduardo
Ahmed, Khaled H.
Gomis Bellmunt, Oriol
Xu, Lie
Egea Àlvarez, Agustí
As a result of increasing variability of network impedance, interest in impedance estimation techniques is growing. This review contextualises local impedance estimation techniques by providing a historical prospective on the uses of these techniques, from the early implementations designed to monitor power quality to the latest techniques integrated into converters designed to update the controller with the most recent network information. This is followed by clear and consolidated descriptions, a complete classification and comparison tables of local estimation techniques intended to assist engineers and researchers choose an estimation technique that is suitable to their application. The discussed techniques are then ranked for a range of application priorities such as accuracy, least disruptive to the network, most suitable for wide frequency spectrum estimations and rapidity of estimation. Practical applications of impedance estimation are discussed, such as network characterisation, anti-islanding detection, filter resonance avoidance and controller tuning. To conclude the review, future trends are identified.
Optimal dc voltage and current control of an lcc hvdc system to improve real-time frequency regulation in rectifier-and inverter-side grids
Kwon, Do-Hoon
Kim, Young-Jin
Gomis Bellmunt, Oriol
http://hdl.handle.net/2117/337046
2021-02-14T20:28:48Z
2021-02-08T10:02:51Z
Optimal dc voltage and current control of an lcc hvdc system to improve real-time frequency regulation in rectifier-and inverter-side grids
Kwon, Do-Hoon; Kim, Young-Jin; Gomis Bellmunt, Oriol
High-voltage direct-current (HVDC) systems for constant or intermittent power delivery have recently been developed further to support grid frequency regulation (GFR). This paper proposes a new control strategy for a line-commutated converter-based (LCC) HVDC system, wherein the dc-link voltage and current are optimally regulated to improve real-time GFR in both rectifier- and inverter-side grids. A dynamic model of an LCC HVDC system is developed using the dc voltage and current as input variables, and is integrated with feedback loops for inertia emulation and droop control. A linear quadratic Gaussian (LQG) controller is also designed for optimal secondary frequency control, while mitigating conflict between the droop controllers of HVDC converters. An eigenvalue analysis is then conducted, focusing on the effects of model parameters and controller gains on the proposed strategy. Simulation case studies are performed using the models of a real HVDC system and a CIGRE benchmark system. The case study results confirm that the proposed strategy enables the HVDC system to improve GFR, in coordination with generators in both-side grids, by exploiting the fast dynamics of HVDC converters. The proposed strategy is also effective under various conditions for the LQG parameters, inertia emulation, and droop control.
© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works
2021-02-08T10:02:51Z
Kwon, Do-Hoon
Kim, Young-Jin
Gomis Bellmunt, Oriol
High-voltage direct-current (HVDC) systems for constant or intermittent power delivery have recently been developed further to support grid frequency regulation (GFR). This paper proposes a new control strategy for a line-commutated converter-based (LCC) HVDC system, wherein the dc-link voltage and current are optimally regulated to improve real-time GFR in both rectifier- and inverter-side grids. A dynamic model of an LCC HVDC system is developed using the dc voltage and current as input variables, and is integrated with feedback loops for inertia emulation and droop control. A linear quadratic Gaussian (LQG) controller is also designed for optimal secondary frequency control, while mitigating conflict between the droop controllers of HVDC converters. An eigenvalue analysis is then conducted, focusing on the effects of model parameters and controller gains on the proposed strategy. Simulation case studies are performed using the models of a real HVDC system and a CIGRE benchmark system. The case study results confirm that the proposed strategy enables the HVDC system to improve GFR, in coordination with generators in both-side grids, by exploiting the fast dynamics of HVDC converters. The proposed strategy is also effective under various conditions for the LQG parameters, inertia emulation, and droop control.