Optimal reactive power flow (ORPF) is a steady-state optimization problem used to determine reactive-power-related control settings in AC power systems while satisfying network operating constraints. In renewable-integrated transmission systems, explicitly representing the feasible reactive-power contribution of inverter-interfaced resources is essential, because wind, photovoltaic (PV), and battery energy storage system (BESS) units cannot operate as unlimited or overly flexible reactive-power sources. Their reactive capability depends on active-power output, apparent-power rating, voltage conditions, and equipment-level capability curves. This paper evaluates the impact of including these capability curves in the solution of the ORPF problem. A MATLAB-DIgSILENT PowerFactory co-simulation framework is implemented, in which MATLAB applies a hybrid particle swarm optimization-pattern search procedure and DIgSILENT PowerFactory performs repeated AC power-flow evaluations using detailed network models and predefined capability limits. The framework is tested on modified IEEE 39-bus and IEEE 118-bus systems with wind, PV, and BESS resources. The results show that neglecting capability curves can produce unrealistic reactive-power allocations for inverter-based units, whereas enforcing these limits shifts the ORPF solution toward operating points consistent with the modeled equipment capability. The study demonstrates the importance of capability-curve representation for obtaining physically meaningful steady-state ORPF results and supports clearer comparison of constrained and unconstrained dispatch cases.
In integrated wind–PV–storage renewable energy bases, the constituent stations are electrically coupled to a significant degree. At the same time, the temporal mismatch between the active-power delivery schedule issued by the dispatch center and the available wind and PV generation, compounded by the uneven voltage profile produced by collector-line impedance, readily drives the terminal voltage of end-of-feeder turbines beyond its limit. This paper proposes a coordinated active–reactive power optimization method that jointly addresses turbine terminal voltage security and network loss. The method treats battery charging and discharging, wind and PV output, and the reactive power of every source as the decision variables of a single global optimization, convexifies the problem through a second-order cone relaxation, and thereby balances the allocation of active and reactive power. A model predictive control framework then coordinates the cross-period scheduling of storage together with the reactive power of all sources. Case studies show that, compared with conventional unified power factor control, the proposed method raises the level of terminal voltage security and lowers system network loss while still satisfying the dispatch command tracking requirement.
Ye-nan Yin, Ping Zhang, G. Ying et al.· Energies· 0 citations
High photovoltaic penetration makes active distribution networks sensitive to voltage deviations, reverse power flow, and feeder operating stress. Energy storage converters can provide two complementary services: active power energy shifting and local, within-step reactive power support for voltage regulation. This paper develops a converter-aware multi-objective siting and sizing model in which installation buses, energy capacities, and PCS ratings are optimized jointly. The model explicitly represents the P-Q capability circle, voltage-droop reactive power command, reactive headroom, SOC limits, radial power flow, voltage deviation, and network loss; annualized cost and throughput-based degradation are retained as bounded planning terms rather than the sole design target. An adaptive multi-objective differential evolution (AMODE) algorithm solves the mixed discrete–continuous nonlinear problem using Latin hypercube initialization, adaptive mutation and crossover, hybrid mutation, an external archive, feasibility repair, and TOPSIS selection. IEEE33 and IEEE69 case studies are evaluated over thirty independent runs. In IEEE33, the selected plan raises the minimum voltage from 0.8866 to 0.9579 p.u. and reduces daily losses by 11.70%. The ablation study shows that removing PCS reactive support reduces the minimum voltage to 0.9190 p.u., demonstrating the technical role of converter-based Q support. The larger IEEE69 experiments further assess Pareto-front quality, feasibility, and statistical robustness. The hourly quasi-static formulation represents local converter action within each planning interval; it does not evaluate sub-second control or electromagnetic transients.
Chang Ye, Xun Xu, Liangli Xiong et al.· Energies· 0 citations
: A two-stage reactive power and voltage optimization control strategy is proposed for hybrid wind farms comprising grid-following (GFL) and grid-forming (GFM) wind turbines. The proposed method incorporates reactive power balancing to enable coordinated regulation among different devices, enhance voltage control capability under weak-grid conditions, and mitigate reactive power imbalance caused by heterogeneous control characteristics. First, a linearized optimization model is developed for the coordinated reactive power and voltage regulation of GFL and GFM wind turbines. In the day-ahead stage, equivalent short-circuit ratio (ESCR) constraints are incorporated to coordinate reactive compensation devices while ensuring operational economy, voltage security, and adequate system strength. In the intraday stage, an adaptive optimization strategy driven by wind power fluctuation levels is introduced, in which both control objectives and optimization time scales are dynamically adjusted. During periods of significant wind power fluctuations, a reactive power balancing optimization mechanism is activated to enhance coordination among wind turbines, while reactive power balancing zones are further established to determine reference reactive power values for GFL wind turbines. Finally, the effectiveness of the proposed method is validated through a case study of a hybrid wind farm consisting of 34 doubly-fed induction generators (DFIGs).
Chang-Jiang Wang, Bing-Qin Wang, Zhao-Wei Li· Energy Engineering· 0 citations
The large-scale integration of photovoltaic generation into distribution grids has introduced significant operational challenges, including voltage excursions, reverse power flows, and increased variability. Battery energy storage systems (BESSs) offer a versatile solution by providing coordinated active- and reactive-power support. However, their scheduling in active distribution networks is challenging because of the non-convex alternating-current (AC) power-flow equations, the nondifferentiability of battery-degradation modeling, and uncertainty in renewable generation and demand. This paper proposes a two-stage methodology for the day-ahead operation of BESSs in ADNs. In the first stage, parallel particle swarm optimization (PPSO) determines the hourly active- and reactive-power schedules of the BESS units. In the second stage, a matrix-based multi-period AC power flow based on successive approximations evaluates the schedules and verifies voltage, thermal, converter-capability, and state-of-charge (SoC) constraints. A rainflow-counting degradation model is incorporated into the objective function to account for cycling and calendar aging costs. The methodology is assessed through ablation analyses comparing active-power-only and coordinated P–Q dispatches, degradation-unaware and degradation-aware scheduling, and serial and parallel PSO implementations. It is validated on modified 33-, 69-, and 136-node systems under deterministic and uncertainty-based operating conditions, including 100 demand and PV-generation scenarios. PPSO is compared with parallel versions of the adaptive Jaya algorithm (AJAYA), genetic algorithm (GA), multi-verse optimizer (MVO), salp swarm algorithm (SSA), grey wolf optimizer (GWO), and vortex search algorithm (VSA), using operating-cost reduction, computational time, solution variability, feasibility indicators, BESS lifetime, and weekly cost analysis. Additionally, exact one-sided Wilcoxon signed-rank tests with Holm adjustment are used to assess the statistical significance of the economic differences between PPSO and the benchmark methods. Results show that PPSO provides the lowest or most competitive operating costs and the shortest computational time in the evaluated cases, while all network and storage constraints remain satisfied.
L. Grisales-Noreña, F. Machuca‐Martínez, O. D. Montoya· The Scientist· 0 citations
Strong power system infrastructure is more important than earlier due to the growing demand for electricity in the generating, transmission, and distribution sectors. Specifically, the extensive and uncontrolled usage of both linear and nonlinear loads in distribution networks creates significant power quality issues. High-voltage power systems that incorporate Static Synchronous Compensators (STATCOMs) play a crucial role in reactive power compensation, voltage management, and power quality enhancement. A unique 17-level Cascaded H-Bridge (CHB) inverter topology is proposed in this study to improve dynamic response and maintain system efficiency. A Renewable Energy Source (RES) is added to the system through a solar PV array interfaced by a Modified Luo DC-DC converter, which supports the inverter control technique and enables effective power extraction under changeable temperature and irradiance conditions. An Invasive Weed Optimization (IWO)-tuned PI controller governs the converter, dynamically adjusting the duty cycle to maintain a steady DC-link voltage for the STATCOM. With effective adjustment of the positive, negative, and harmonic components of current under dynamic grid conditions, the suggested system is put into practice using MATLAB simulation.
L. Chitra, K. Boopathy, S. Ajith et al.· International Conference on...· 0 citations
The increasing penetration of inverter-based renewable energy resources (IBRs) presents significant challenges to power system voltage stability and reactive power management due to the declining contribution of conventional synchronous generation. This study investigates the reactive power support capability of a fixed-speed pumped hydro storage (FS-PHS). A dynamic FS-PHS model was developed in MATLAB/Simulink based on a validated Sandia National Laboratories model and adapted to Aotearoa New Zealand operating conditions. The validated model was integrated into a modified IEEE 9-bus system operating at 220 kV transmission voltage. Load flow and electromagnetic transient studies showed that the FS-PHS unit provided effective voltage support and dynamic reactive power compensation under varying reactive loading conditions. The system successfully responded to changing network requirements while maintaining stable operation and acceptable bus voltage profiles. The findings demonstrate that FS-PHS can provide valuable ancillary services beyond energy storage, including voltage regulation and reactive power support. The technology represents a promising option for strengthening weak renewable-rich regions, such as Aotearoa New Zealand, where future system strength and voltage stability are expected to become increasingly important.
Balasree Muraleedharan, Daniel Burmester· Archives of Sustainable Ener...· 0 citations
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