Real‐time optimisation of short‐term frequency stability controls for a power system with renewables and multi‐infeed HVDCs

Abstract

Short-term frequency stability (STFS) is becoming a great concern for a regional receiving-end power system such as the East China Power Grid (ECPG) mainly for two reasons: (i) the increasing percentage of power injected from multi-infeed (ultra-) high-voltage DCs (HVDCs) with the skyrocketed capacities; (ii) the replacement of traditional generation by the continuously growing inertia-less renewables. However, the existing emergency control is not adaptive enough to maintain STFS under varying operation conditions. In this study, a real-time optimised control is proposed to solve the issue more efficiently. It combines emergency power boosting (EPB) of HVDC and emergency demand response (EDR) in a coordinated way. The optimal control problem is formulated based on the online-updated models that reflect the current state of the system and the dynamic responses of multiple types of generators. By converting the non-linear constraint into a linear matrix inequality, the allocation of EPB and EDR can be optimised in a real-time and coordinated way. The performance of the proposed control and its advantages over the existing one are verified by simulation studies on the model of ECPG with low, normal and high penetrations of renewables.

Review of Wide-Area Controllers for Supporting Power System Stability

“…Specifically, 16 papers address inter-area oscillations [78], [81], [115], [122], [125], [130], [151], [179], [182], [193], [199], [227], [236], [238], [241], [248] and 15 papers address rotor-angle stability [137], [139], [161], [166], [180], [204], [206], [207], [210], [213], [216], [218], [219], [231], [233]. From the remaining 34 papers, 7 address frequency stability issues [127], [146], [150], [168], [235], [237], [257] and 10 papers address voltage stability [55], [149], [152], [184], [191], [194], [201], [244], [245], [260]. The remaining papers (...…”

“…In [142], an iterative algorithm is designed considering a range of timedelays, which are included in each step of the controller as part of the design process. VOLUME 11, 2023 Some approaches based on emergency demand response (EDR)/emergency power boosting (EPB) strategies are designed with an extra power margin, in order to offset the impacts of time-delays [168], [207], [235]. In addition, several model-based strategies include both fixed or stochastic delays as part of the power system model in order to design delay-dependent WADCs through other diverse time-delay models, as in [126], [127], [128], [133], [153], [158], [163], and [172].…”

Coordinated multiple HVDC modulation emergency control for enhancing power system frequency stability

“…Therefore, DC modulation [12] is a promising way for frequency stability control, which has the advantages of fast‐acting controllability, large power modulation capacity and the outstanding reactive power, active power adjustment capability. Some researchers have been done on this topic [13–20].…”

“…Research has been done in [16] to coordinate the control of emergency generation and HVDC power for improving the long‐term frequency stability. For multi‐HVDC AC/DC hybrid system, Wang et al [17, 18] proposed a real‐time coordinated control strategy to improve the short‐term frequency dynamics stability by updating the frequency‐response model.…”

“…As the power modulation effect of different HVDC transmission line has been assessed in [19], the multi‐HVDC coordinated emergency control was firstly introduced in improving the frequency stability of the receiving‐end power system [20]. The researches have been verified that they have a good effect in limiting the post‐disturbance system steady frequency into a safe range [16–18, 20–22]. However, the frequency stability of the traditional power grid is mainly affected by the frequency tolerance of conventional generators.…”