A two-level hierarchical discrete-device control method for power networks with integrated wind farms

Abstract

Power systems depend on discrete devices, such as shunt capacitors/reactors and on-load tap changers, for their long-term reliability. In transmission systems that contain large wind farms, we must take into account the uncertainties in wind power generation when deciding when to operate these devices. In this paper, we describe a method to schedule the operation of these devices over the course of the following day. These schedules are designed to minimize wind-power generation curtailment, bus voltage violations, and dynamic reactive-power deviations, even under the worst possible conditions. Daily voltagecontrol decisions are initiated every 15 min using a dynamic optimization algorithm that predicts the state of the system over the next 4-hour period. For this, forecasts updated in real-time are employed, because they are more precise than forecasts for the day ahead. Day-ahead schedules are calculated using a two-stage robust mixedinteger optimization algorithm. The proposed control strategies were tested on a Chinese power network with wind power sources; the control performance was also validated numerically.

Autonomous-synergic Voltage Security Regions in Bulk Power Systems

“…1) Definition space: [3], [5], [7] are defined in the power injection space to determine the power outputs of each node, whereas [1], [2], [8], and the proposed methods are defined in the voltage operational state space to determine the voltage secure operational range for each bus.…”

“…B ULK power systems exhibit volt/var control deterioration, particularly in scenarios with heavy loads or high penetration level of renewable energies, resulting in largescale cascading tripping failures [1], [2]. This poses one of the major challenges of bulk power systems.…”

Fast computation of voltage/VAR feasible boundaries of wind farms: An adaptive parameter aggregation dimensionality reduction equivalence method

“…where S U W reflects the degree of voltage drop under a fault scenario, T be is the fault occurrence time, T end is the simulation end To incorporate transient constraints into the model, the perturbation method is used to transform the differential equations into algebraic Equations ( 10) and (11). Furthermore, K…”

“…Due to the limitations of the problem scale, this approach is usually only used within an individual wind farm and does not take into account the voltage security after an N−1 fault in an entire convergence area [9]. To further consider the voltage security after different N−1 fault scenarios in an entire convergence area, a hierarchical voltage control strategy was proposed to solve the problems of voltage fluctuation and cascading trip fault of wind turbines in [10,11]. In addition, to improve the computation speed to adapt to more complex and diverse scenarios, [12,13] proposed a coordinated sequential control strategy, which can determine the voltage control target in real time to guarantee voltage security.…”

Adaptive Droop Control of the VSC-MTDC Distribution Network Considering Power–Voltage Deviation

“…The continuous maturity of flexible DC equipment and control technologies in the field of electricity transmission has greatly promoted the development of DC power distribution (Li and Lao, 2017;Liao et al, 2018). Compared with the traditional AC power distribution network, the DC power distribution network has many advantages, such as lower loss, larger transmission capacity, higher power quality and power supply reliability, and easier power control, regardless of the frequency and voltage phase, more convenient for large-scale access to clean energy and lower environmental pollution (Yang et al, .2015;Jaynendra et al, 2019;Li et al, 2021a), and can effectively isolate AC side faults and disturbances in parallel with the AC system (Xu et al, 2019;Zhao et al, 2019). As an important basis of the energy internet and smart grids, a reliable, flexible, and efficient flexible DC power distribution network has gradually become an important guarantee for the safe and economic operation of the power system and power supply at a high service level (Gao et al, 2019).…”