Topology-Aware Graph Reinforcement Learning for Energy Storage Systems Optimal Dispatch in Distribution Networks
Authors: Shuyi Gao, Stavros Orfanoudakis, Shengren Hou, Peter Palensky, Pedro P. Vergara
Organizations: Department of Electrical Sustainable Energy, Delft University of Technology, Mekelweg 4, Delft, 2628 CD, The Netherlands · Beijing Energy Quant Ltd., Haidian, Beijing, 53100, China
Optimal dispatch of energy storage systems (ESSs) in distribution networks involves jointly improving operating economy and voltage security under time-varying conditions and possible topology changes. To support fast online decision making, we develop a topology-aware Reinforcement Learning architecture based on Twin Delayed Deep Deterministic Policy Gradient (TD3), which integrates graph neural networks (GNNs) as graph feature encoders for ESS dispatch. We conduct a systematic investigation of three GNN variants: graph convolutional networks (GCNs), topology adaptive graph convolutional networks (TAGConv), and graph attention networks (GATs) on the 34-bus and 69-bus systems, and evaluate robustness under multiple topology reconfiguration cases as well as cross-system transfer between networks with different system sizes. Results show that GNN-based controllers consistently reduce the number and magnitude of voltage violations, with clearer benefits on the 69-bus system and under reconfiguration; on the 69-bus system, TD3-GCN and TD3-TAGConv also achieve lower saved cost relative to the NLP benchmark than the NN baseline. We also highlight that transfer gains are case-dependent, and zero-shot transfer between fundamentally different systems results in notable performance degradation and increased voltage magnitude violations. This work is available at: https://github.com/ShuyiGao/GNNs_RL_ESSs and https://github.com/distributionnetworksTUDelft/GNNs_RL_ESSs.
Figures & tables
Figure 1: Architecture of the proposed GNN-based RL framework for distribution-network ESS optimal dispatch, consisting of the graph feature encoder, the ESS dispatch environment, the experience replay buffer, and the actor–critic networks.
Figure 2: The average reward of RL algorithms during 1000 episodes of training on (a)34 buses system, (b)69 buses system.
Figure 3: Comparison of RL algorithms on 34 buses system, (a)electricity price and ESS nodes’ active power, (b)-(f) ESS nodes’ SOC and charging/discharging strategy of NLP, TD3-NN, TD3-GCN, TD3-TAGConv, TD3-GATConv on Node 34.
Figure 4: ESS nodes’ voltage magnitude on 34 buses system, (a)without ESS control, (b)NLP, (c)TD3-NN, (d)TD3-GCN, (e)TD3-TAGConv, (f)TD3-GATConv.
Algorithms
TD3-NN
TD3-GCN
TD3-TAGConv
TD3-GATConv
NLP
Training [ h/m/s ]
2h36m6.6s
5h22m14.7s
5h58m55.8s
7h28m51.3s
-
Execution [ s ]
0.0998 (0.0990, 0.1007)
0.1968 (0.1935, 0.2001)
0.1909 (0.1898, 0.1920)
0.2274 (0.2256, 0.2291)
19.77
Saved costs [$]
197.92 (195.71, 200.13)
179.74 (175.12, 184.38)
188.04 183.53, 192.54)
195.28 (191.48, 199.07)
260.40 (252.34, 268.47)
Accuracy vs NLP [ % ]
76.31 (75.46, 77.15)
69.51 (67.72, 71.31)
72.61 (70.95, 74.26)
75.46 (74.02, 76.90)
-
Accuracy vs TD3-NN [ % ]
-
91.92 (89.87, 93.96)
96 (93.58, 98.43)
99.57 (97.68, 101.46)
-
Average Voltage Violation Counts [-]
4
5
4
5
-
Table 1: RL algorithms’ average training time [ h/m/s ], mean and 95% confidence bounds of execution time [ s ] and performances on 34 buses testsets.
Algorithms
TD3-NN
TD3-GCN
TD3-TAGConv
TD3-GATConv
NLP
Training [ h/m/s ]
2h47m42.6s
5h32m22.5s
6h11m58.2s
7h50m39.6s
-
Execution [ s ]
0.1340 (0.1327, 0.1354)
0.2351 (0.2323, 0.2378)
0.2381 (0.2347, 0.2415)
0.2878 (0.2830, 0.2927)
144.37
Saved costs [$]
458.98 (450.91, 467.06)
498.83 (489.58, 508.07)
466.44 (453.93, 478.96)
439.42 (388.57, 490.281)
868.19 (830.15, 906.25)
Accuracy vs NLP [ % ]
54.56 (53.69, 55.44)
59.30 (58.21, 60.38)
55.54 (54.25, 56.82)
52.74 (47.19, 58.29)
-
Accuracy vs TD3-NN [ % ]
-
109.87 (106.65, 113.10)
102.54 (100.86, 104.21)
97.99 (87.13, 108.86)
-
Average Voltage Violation Counts [-]
77
54
33
151
-
Table 2: RL algorithms’ average training time [ h/m/s ], mean and 95% confidence bounds of execution time [ s ] and performances on 69 buses testsets.
ID
Reconfiguration
Connections
TP1
–
Baseline topology
TP2
1 within a branch
(25,26) ⇒ (24,26)
TP3
1 within a branch
(32,33) ⇒ (31,33)
TP4
2 within a branch
(11,12) ⇒ (10,12); (29,30) ⇒ (28,30)
TP5
2 within a branch
(15,16) ⇒ (14,16); (33,34) ⇒ (32,34)
TP6
1 whole branch
(10,31) ⇒ (8,31)
Table 3: Topological Variation Scenarios or Evaluating the Generalization of GNN-based RL Algorithms on 34 Buses System.
ID
Reconfiguration
Connections
TP1
–
Baseline topology
TP2
1 within a branch
(67,68) ⇒ (13,68)
TP3
1 within a branch
(45,46) ⇒ (44,46)
TP4
2 within a branch
(35,36) ⇒ (34,36); (13,69) ⇒ (14,69)
TP5
2 within a branch
(50,51) ⇒ (49,51); (52,53) ⇒ (9,53)
TP6
1 whole branch
(12,13) ⇒ (11,13)
Table 4: Topological Variation Scenarios or Evaluating the Generalization of GNN-based RL Algorithms on 69 Buses System.
Figure 5: 34 buses system RL algorithms’ operational accuracy [ % ] on topological variations
Figure 6: 69 buses system RL algorithms’ operational accuracy [ % ] on topological variations
Figure 7: 34 buses system RL algorithms’ mean 95% confidence bounds of average voltage violation [p.u.] on topological variations.
Figure 8: 69 buses system RL algorithms’ mean 95% confidence bounds of average voltage violation [p.u.] on topological variations.
Figure 9: RL algorithms’ (a)operational accuracy [ % ] and (b) mean 95% confidence bounds of average voltage violation [p.u.] on 69 buses system with agents trained on 34 buses system
Figure 10: RL algorithms’ (a)operational accuracy [ % ] and (b) mean 95% confidence bounds of average voltage violation [p.u.] on 34 buses system with agents trained on 69 buses system