This paper introduces a novel analytical approach for the identification of the admittance matrix and the generalized short-circuit ratio (gSCR) in power systems integrated with renewable energy sources. The proposed method leverages voltage and current measurements from phasor measurement units (PMUs) to construct a least squares objective function, which is then solved using matrix calculus and partial derivatives. Unlike conventional optimization algorithms, this approach provides an analytical solution that substantially reduces data requirements, enabling the efficient and accurate identification of the gSCR with smaller datasets. Additionally, its fixed computational complexity allows for real-time updates as new data are collected, ensuring continuous refinement of the system of equations and enabling rapid, precise gSCR calculations. The method also exhibits strong robustness against measurement noise, making it well-suited for practical applications in dynamic power systems. The combination of reduced data requirements, real-time adaptability, noise robustness and fixed computational load establishes this method as a highly efficient and reliable tool for real-time power system stability analysis. Case studies on an EPRI 36-bus system demonstrate the method's effectiveness, highlighting its accuracy in closely matching true gSCR values, even under diverse disturbances and noisy conditions.
{"title":"Analytical Identification Method of Generalized Short-Circuit Ratio Using Phasor Measurement Units","authors":"Zelei Han, Ping Ju, Hongyu Li, Yilu Liu","doi":"10.1049/gtd2.70026","DOIUrl":"https://doi.org/10.1049/gtd2.70026","url":null,"abstract":"<p>This paper introduces a novel analytical approach for the identification of the admittance matrix and the generalized short-circuit ratio (gSCR) in power systems integrated with renewable energy sources. The proposed method leverages voltage and current measurements from phasor measurement units (PMUs) to construct a least squares objective function, which is then solved using matrix calculus and partial derivatives. Unlike conventional optimization algorithms, this approach provides an analytical solution that substantially reduces data requirements, enabling the efficient and accurate identification of the gSCR with smaller datasets. Additionally, its fixed computational complexity allows for real-time updates as new data are collected, ensuring continuous refinement of the system of equations and enabling rapid, precise gSCR calculations. The method also exhibits strong robustness against measurement noise, making it well-suited for practical applications in dynamic power systems. The combination of reduced data requirements, real-time adaptability, noise robustness and fixed computational load establishes this method as a highly efficient and reliable tool for real-time power system stability analysis. Case studies on an EPRI 36-bus system demonstrate the method's effectiveness, highlighting its accuracy in closely matching true gSCR values, even under diverse disturbances and noisy conditions.</p>","PeriodicalId":13261,"journal":{"name":"Iet Generation Transmission & Distribution","volume":"19 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/gtd2.70026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qian Zhang, Xiaoqing Lu, Chi Zhang, Shi Su, Qingyang Xie
The interface inverter control system based on virtual synchronous generator (VSG) technology, has been widely used in new power systems due to its ability to provide system inertia. To enhance the robustness of the VSG-based inverter control system against uncertain disturbances, this paper proposes a novel sliding mode control (SMC) strategy consisting of two control layers for VSG-based inverters based on disturbance estimation. Firstly, the VSG-based outer loop control layer is established to mitigate the transient instability during pre-synchronization process, which consists of an active frequency control loop with a phase angle regulator and a reactive voltage control loop with an amplitude regulator. Secondly, an SMC-based inner loop control layer is designed to replace the traditional voltage and current dual loop control for robustness improvement, where the uncertain disturbance can be estimated and fed back to the controlled system for disturbance suppression. Moreover, both of the eigenvalue method based small signal stability and the Lyapunov functional based large signal stability are analysed for different control layers, and the comparative simulations are conducted between the proposed strategy and traditional pre-synchronization control as well as voltage current dual loop control, in scenarios of grid-connected voltage fluctuation and islanded load power variation. The dSPACE based prototype physical experiment further validates the effectiveness of the sliding mode control strategy for VSG-based inverters with disturbance estimation.
{"title":"A Novel Sliding Mode Control Strategy for VSG-Based Inverters with Disturbance Estimation","authors":"Qian Zhang, Xiaoqing Lu, Chi Zhang, Shi Su, Qingyang Xie","doi":"10.1049/gtd2.70025","DOIUrl":"https://doi.org/10.1049/gtd2.70025","url":null,"abstract":"<p>The interface inverter control system based on virtual synchronous generator (VSG) technology, has been widely used in new power systems due to its ability to provide system inertia. To enhance the robustness of the VSG-based inverter control system against uncertain disturbances, this paper proposes a novel sliding mode control (SMC) strategy consisting of two control layers for VSG-based inverters based on disturbance estimation. Firstly, the VSG-based outer loop control layer is established to mitigate the transient instability during pre-synchronization process, which consists of an active frequency control loop with a phase angle regulator and a reactive voltage control loop with an amplitude regulator. Secondly, an SMC-based inner loop control layer is designed to replace the traditional voltage and current dual loop control for robustness improvement, where the uncertain disturbance can be estimated and fed back to the controlled system for disturbance suppression. Moreover, both of the eigenvalue method based small signal stability and the Lyapunov functional based large signal stability are analysed for different control layers, and the comparative simulations are conducted between the proposed strategy and traditional pre-synchronization control as well as voltage current dual loop control, in scenarios of grid-connected voltage fluctuation and islanded load power variation. The dSPACE based prototype physical experiment further validates the effectiveness of the sliding mode control strategy for VSG-based inverters with disturbance estimation.</p>","PeriodicalId":13261,"journal":{"name":"Iet Generation Transmission & Distribution","volume":"19 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/gtd2.70025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With replacement of synchronous generator (SG) by voltage source converter (VSC) interfaced renewables, power system dynamics is undergoing significant changes. This paper investigates the frequency dynamical behaviour of new-generation power systems composed solely of grid-following (GFL) and/or grid-forming (GFM) VSCs, without an infinitely strong bus or SG. It is found that for a system composed solely of GFL-VSC, as it lacks a frequency equilibrium point after a certain disturbance, the whole system exhibits an unusual phenomenon of frequency drifting. On the other hand, for a hybrid system composed of both GFM-VSC and GFL-VSC, as it has a frequency equilibrium point, the system can settle down to a new frequency steady-state, and the GFM-VSC and GFL-VSC show completely different behaviours in the transient process. The GFM-VSC plays a key role in the frequency dynamics, similar to the SG. Based on the inertia-centre frequency dynamics, it is observed that the GFM-VSC determines the equivalent damping of the system, and both GFM-VSC and GFL-VSC contribute to the equivalent inertia. All these findings are well supported and verified by our theoretical analysis and time-domain simulations, and they can provide physical insights in the bulk frequency dynamical behaviour of new-generation power systems dominated by converters.
{"title":"Frequency Dynamical Behaviour and Frequency Equilibrium Point of Multi-VSC Systems","authors":"Xing Yao, Ziqian Yang, Meng Zhan, Wangqianyun Tang","doi":"10.1049/gtd2.70028","DOIUrl":"https://doi.org/10.1049/gtd2.70028","url":null,"abstract":"<p>With replacement of synchronous generator (SG) by voltage source converter (VSC) interfaced renewables, power system dynamics is undergoing significant changes. This paper investigates the frequency dynamical behaviour of new-generation power systems composed solely of grid-following (GFL) and/or grid-forming (GFM) VSCs, without an infinitely strong bus or SG. It is found that for a system composed solely of GFL-VSC, as it lacks a frequency equilibrium point after a certain disturbance, the whole system exhibits an unusual phenomenon of frequency drifting. On the other hand, for a hybrid system composed of both GFM-VSC and GFL-VSC, as it has a frequency equilibrium point, the system can settle down to a new frequency steady-state, and the GFM-VSC and GFL-VSC show completely different behaviours in the transient process. The GFM-VSC plays a key role in the frequency dynamics, similar to the SG. Based on the inertia-centre frequency dynamics, it is observed that the GFM-VSC determines the equivalent damping of the system, and both GFM-VSC and GFL-VSC contribute to the equivalent inertia. All these findings are well supported and verified by our theoretical analysis and time-domain simulations, and they can provide physical insights in the bulk frequency dynamical behaviour of new-generation power systems dominated by converters.</p>","PeriodicalId":13261,"journal":{"name":"Iet Generation Transmission & Distribution","volume":"19 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/gtd2.70028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Demand-side management (DSM) tactics such as load shifting (LSP) and load curtailment (LCP) improve energy efficiency in a low-voltage microgrid (MG). LCP encourages load reduction, whereas LSP directs elastic loads to low-cost times. The MG under consideration includes price-based (PBDR) and incentive-based demand response (IBDR), as well as a hybrid DSM (HDSM) that blends LSP and IBDR. Plug-in hybrid electric vehicles (PHEVs) are also incorporated to reduce expense and pollution. LSP shifts 20% of elastic loads, while IBDR cuts 35 kW to counter PHEV demand. Optimal generator scheduling seeks to reduce costs and emissions across five load profiles, including base load. The minimum generating cost is reduced from $252 (base load) to $234, $246, and $230 for LSP, IBDR, and HDSM, respectively. Emissions remain at 2916 kg for base and LSP-based loads, while IBDR and HDSM reduce them to 2792 kg. Among all techniques, HDSM has the best trade-off, with a $237 generation cost and 3116 kg emissions.
{"title":"An innovative hybrid load shifting and curtailing technique for operating a plug-in hybrid electric vehicle integrated microgrid system in a clean and cost-effective manner","authors":"Bishwajit Dey, Soham Dutta, Santana Saikia, Ranga Seshu Kumar","doi":"10.1049/gtd2.70020","DOIUrl":"https://doi.org/10.1049/gtd2.70020","url":null,"abstract":"<p>Demand-side management (DSM) tactics such as load shifting (LSP) and load curtailment (LCP) improve energy efficiency in a low-voltage microgrid (MG). LCP encourages load reduction, whereas LSP directs elastic loads to low-cost times. The MG under consideration includes price-based (PBDR) and incentive-based demand response (IBDR), as well as a hybrid DSM (HDSM) that blends LSP and IBDR. Plug-in hybrid electric vehicles (PHEVs) are also incorporated to reduce expense and pollution. LSP shifts 20% of elastic loads, while IBDR cuts 35 kW to counter PHEV demand. Optimal generator scheduling seeks to reduce costs and emissions across five load profiles, including base load. The minimum generating cost is reduced from $252 (base load) to $234, $246, and $230 for LSP, IBDR, and HDSM, respectively. Emissions remain at 2916 kg for base and LSP-based loads, while IBDR and HDSM reduce them to 2792 kg. Among all techniques, HDSM has the best trade-off, with a $237 generation cost and 3116 kg emissions.</p>","PeriodicalId":13261,"journal":{"name":"Iet Generation Transmission & Distribution","volume":"19 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/gtd2.70020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143446718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the increasing proportion of distributed energy resources, optimisation in the active distribution network becomes highly complex and challenging. To protect user privacy and perform efficient calculations, this paper proposes an online distributed optimisation between the user and the operator. To overcome the constraint non-linearity, a new linear power flow model is adopted, which can be updated online. In addition, to solve the time-coupled conundrum of energy storage, the Lyapunov drift plus penalty method is employed to transform the long-time scale optimisation problem into an instantaneous problem. Furthermore, a novel proportional integral derivative (PID)–Lagrange algorithm is proposed to improve the efficiency, where the distributed optimisation algorithm is considered as a control process, and a PID controller is used to control it. The proposed PID–Lagrange algorithm has an explicit parameter tuning strategy and significantly improves the efficiency by 54.23% in the case study.
{"title":"An online distributed optimisation model solving the time-coupled conundrum by the Lyapunov drift plus penalty method","authors":"Molin An, Tianguang Lu, Xueshan Han, Zhaohao Ding","doi":"10.1049/gtd2.70019","DOIUrl":"https://doi.org/10.1049/gtd2.70019","url":null,"abstract":"<p>With the increasing proportion of distributed energy resources, optimisation in the active distribution network becomes highly complex and challenging. To protect user privacy and perform efficient calculations, this paper proposes an online distributed optimisation between the user and the operator. To overcome the constraint non-linearity, a new linear power flow model is adopted, which can be updated online. In addition, to solve the time-coupled conundrum of energy storage, the Lyapunov drift plus penalty method is employed to transform the long-time scale optimisation problem into an instantaneous problem. Furthermore, a novel proportional integral derivative (PID)–Lagrange algorithm is proposed to improve the efficiency, where the distributed optimisation algorithm is considered as a control process, and a PID controller is used to control it. The proposed PID–Lagrange algorithm has an explicit parameter tuning strategy and significantly improves the efficiency by 54.23% in the case study.</p>","PeriodicalId":13261,"journal":{"name":"Iet Generation Transmission & Distribution","volume":"19 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/gtd2.70019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As the number of wind turbines increase, those units like others would contribute to active power in a competitive market. Also, with development in power electronics, those units like others are able to produce reactive power and therefore can participate in reactive power market. Meanwhile, high degrees of uncertainty and prediction error are associated with this type of producing units. Due to the relationship between active and reactive power generation, this uncertainty affects both active and reactive power markets and deprives those units of the opportunity to participate in both markets. Therefore, providing an accurate model of participation in the active and reactive power market, considering the existing uncertainty and its related forecasting errors, will help those units to be able to compete with others in the active and reactive power market. In addition, the proposed model should consider the interaction between active and reactive power markets and the conditions for their simultaneous implementation. In addition, the ability of wind units to impose market power is decreased by presenting a new market power index for reactive power generation. The effectiveness of the proposed model is evaluated by implementing on 24-node IEEE RTS grid.
{"title":"Simultaneous active and reactive power market consideration of uncertainty in wind farms","authors":"Morteza Shamani, Asghar Akbari Foroud, Hamed Ahmadi","doi":"10.1049/gtd2.70017","DOIUrl":"https://doi.org/10.1049/gtd2.70017","url":null,"abstract":"<p>As the number of wind turbines increase, those units like others would contribute to active power in a competitive market. Also, with development in power electronics, those units like others are able to produce reactive power and therefore can participate in reactive power market. Meanwhile, high degrees of uncertainty and prediction error are associated with this type of producing units. Due to the relationship between active and reactive power generation, this uncertainty affects both active and reactive power markets and deprives those units of the opportunity to participate in both markets. Therefore, providing an accurate model of participation in the active and reactive power market, considering the existing uncertainty and its related forecasting errors, will help those units to be able to compete with others in the active and reactive power market. In addition, the proposed model should consider the interaction between active and reactive power markets and the conditions for their simultaneous implementation. In addition, the ability of wind units to impose market power is decreased by presenting a new market power index for reactive power generation. The effectiveness of the proposed model is evaluated by implementing on 24-node IEEE RTS grid.</p>","PeriodicalId":13261,"journal":{"name":"Iet Generation Transmission & Distribution","volume":"19 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/gtd2.70017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143424082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The increasing integration of renewable energy sources is making power systems evolve, driving the necessity to interconnect different power systems to improve the robustness and operation of grids. Here, the so-called virtual power line (VPL) control for interlinking converters (ICs) is presented, whose purpose is to couple different electric systems analogously to a classical transmission line. The VPL control employs local measurements, and it does not require any communication link to operate. Two VPL control variants are presented: the dual grid-supporting VPL control and the single grid-forming VPL (SGF-VPL) control. Both support the frequency and/or voltage of the interconnected grids, and the latter provides grid-forming capabilities for one of the interconnected systems. The performance of VPL controllers show how the frequency and voltage nadir values are improved by